forked from OSchip/llvm-project
2332 lines
89 KiB
C++
2332 lines
89 KiB
C++
//===- InlineCost.cpp - Cost analysis for inliner -------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements inline cost analysis.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/InlineCost.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SetVector.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Analysis/AssumptionCache.h"
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#include "llvm/Analysis/BlockFrequencyInfo.h"
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#include "llvm/Analysis/CFG.h"
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#include "llvm/Analysis/CodeMetrics.h"
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#include "llvm/Analysis/ConstantFolding.h"
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#include "llvm/Analysis/InstructionSimplify.h"
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#include "llvm/Analysis/LoopInfo.h"
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#include "llvm/Analysis/ProfileSummaryInfo.h"
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#include "llvm/Analysis/TargetTransformInfo.h"
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#include "llvm/Analysis/ValueTracking.h"
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#include "llvm/Config/llvm-config.h"
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#include "llvm/IR/CallingConv.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/Dominators.h"
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#include "llvm/IR/GetElementPtrTypeIterator.h"
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#include "llvm/IR/GlobalAlias.h"
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#include "llvm/IR/InstVisitor.h"
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#include "llvm/IR/IntrinsicInst.h"
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#include "llvm/IR/Operator.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DEBUG_TYPE "inline-cost"
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STATISTIC(NumCallsAnalyzed, "Number of call sites analyzed");
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static cl::opt<int> InlineThreshold(
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"inline-threshold", cl::Hidden, cl::init(225), cl::ZeroOrMore,
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cl::desc("Control the amount of inlining to perform (default = 225)"));
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static cl::opt<int> HintThreshold(
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"inlinehint-threshold", cl::Hidden, cl::init(325), cl::ZeroOrMore,
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cl::desc("Threshold for inlining functions with inline hint"));
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static cl::opt<int>
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ColdCallSiteThreshold("inline-cold-callsite-threshold", cl::Hidden,
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cl::init(45), cl::ZeroOrMore,
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cl::desc("Threshold for inlining cold callsites"));
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// We introduce this threshold to help performance of instrumentation based
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// PGO before we actually hook up inliner with analysis passes such as BPI and
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// BFI.
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static cl::opt<int> ColdThreshold(
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"inlinecold-threshold", cl::Hidden, cl::init(45), cl::ZeroOrMore,
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cl::desc("Threshold for inlining functions with cold attribute"));
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static cl::opt<int>
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HotCallSiteThreshold("hot-callsite-threshold", cl::Hidden, cl::init(3000),
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cl::ZeroOrMore,
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cl::desc("Threshold for hot callsites "));
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static cl::opt<int> LocallyHotCallSiteThreshold(
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"locally-hot-callsite-threshold", cl::Hidden, cl::init(525), cl::ZeroOrMore,
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cl::desc("Threshold for locally hot callsites "));
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static cl::opt<int> ColdCallSiteRelFreq(
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"cold-callsite-rel-freq", cl::Hidden, cl::init(2), cl::ZeroOrMore,
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cl::desc("Maximum block frequency, expressed as a percentage of caller's "
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"entry frequency, for a callsite to be cold in the absence of "
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"profile information."));
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static cl::opt<int> HotCallSiteRelFreq(
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"hot-callsite-rel-freq", cl::Hidden, cl::init(60), cl::ZeroOrMore,
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cl::desc("Minimum block frequency, expressed as a multiple of caller's "
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"entry frequency, for a callsite to be hot in the absence of "
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"profile information."));
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static cl::opt<bool> OptComputeFullInlineCost(
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"inline-cost-full", cl::Hidden, cl::init(false), cl::ZeroOrMore,
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cl::desc("Compute the full inline cost of a call site even when the cost "
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"exceeds the threshold."));
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namespace {
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class InlineCostCallAnalyzer;
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class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
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typedef InstVisitor<CallAnalyzer, bool> Base;
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friend class InstVisitor<CallAnalyzer, bool>;
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protected:
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virtual ~CallAnalyzer() {}
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/// The TargetTransformInfo available for this compilation.
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const TargetTransformInfo &TTI;
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/// Getter for the cache of @llvm.assume intrinsics.
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std::function<AssumptionCache &(Function &)> &GetAssumptionCache;
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/// Getter for BlockFrequencyInfo
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Optional<function_ref<BlockFrequencyInfo &(Function &)>> &GetBFI;
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/// Profile summary information.
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ProfileSummaryInfo *PSI;
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/// The called function.
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Function &F;
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// Cache the DataLayout since we use it a lot.
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const DataLayout &DL;
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/// The OptimizationRemarkEmitter available for this compilation.
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OptimizationRemarkEmitter *ORE;
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/// The candidate callsite being analyzed. Please do not use this to do
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/// analysis in the caller function; we want the inline cost query to be
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/// easily cacheable. Instead, use the cover function paramHasAttr.
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CallBase &CandidateCall;
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/// Extension points for handling callsite features.
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/// Called after a basic block was analyzed.
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virtual void onBlockAnalyzed(const BasicBlock *BB) {}
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/// Called at the end of the analysis of the callsite. Return the outcome of
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/// the analysis, i.e. 'InlineResult(true)' if the inlining may happen, or
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/// the reason it can't.
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virtual InlineResult finalizeAnalysis() { return InlineResult::success(); }
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/// Called when we're about to start processing a basic block, and every time
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/// we are done processing an instruction. Return true if there is no point in
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/// continuing the analysis (e.g. we've determined already the call site is
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/// too expensive to inline)
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virtual bool shouldStop() { return false; }
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/// Called before the analysis of the callee body starts (with callsite
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/// contexts propagated). It checks callsite-specific information. Return a
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/// reason analysis can't continue if that's the case, or 'true' if it may
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/// continue.
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virtual InlineResult onAnalysisStart() { return InlineResult::success(); }
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/// Called if the analysis engine decides SROA cannot be done for the given
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/// alloca.
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virtual void onDisableSROA(AllocaInst *Arg) {}
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/// Called the analysis engine determines load elimination won't happen.
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virtual void onDisableLoadElimination() {}
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/// Called to account for a call.
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virtual void onCallPenalty() {}
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/// Called to account for the expectation the inlining would result in a load
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/// elimination.
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virtual void onLoadEliminationOpportunity() {}
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/// Called to account for the cost of argument setup for the Call in the
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/// callee's body (not the callsite currently under analysis).
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virtual void onCallArgumentSetup(const CallBase &Call) {}
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/// Called to account for a load relative intrinsic.
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virtual void onLoadRelativeIntrinsic() {}
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/// Called to account for a lowered call.
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virtual void onLoweredCall(Function *F, CallBase &Call, bool IsIndirectCall) {
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}
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/// Account for a jump table of given size. Return false to stop further
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/// processing the switch instruction
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virtual bool onJumpTable(unsigned JumpTableSize) { return true; }
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/// Account for a case cluster of given size. Return false to stop further
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/// processing of the instruction.
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virtual bool onCaseCluster(unsigned NumCaseCluster) { return true; }
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/// Called at the end of processing a switch instruction, with the given
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/// number of case clusters.
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virtual void onFinalizeSwitch(unsigned JumpTableSize,
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unsigned NumCaseCluster) {}
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/// Called to account for any other instruction not specifically accounted
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/// for.
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virtual void onMissedSimplification() {}
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/// Start accounting potential benefits due to SROA for the given alloca.
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virtual void onInitializeSROAArg(AllocaInst *Arg) {}
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/// Account SROA savings for the AllocaInst value.
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virtual void onAggregateSROAUse(AllocaInst *V) {}
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bool handleSROA(Value *V, bool DoNotDisable) {
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// Check for SROA candidates in comparisons.
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if (auto *SROAArg = getSROAArgForValueOrNull(V)) {
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if (DoNotDisable) {
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onAggregateSROAUse(SROAArg);
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return true;
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}
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disableSROAForArg(SROAArg);
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}
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return false;
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}
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bool IsCallerRecursive = false;
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bool IsRecursiveCall = false;
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bool ExposesReturnsTwice = false;
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bool HasDynamicAlloca = false;
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bool ContainsNoDuplicateCall = false;
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bool HasReturn = false;
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bool HasIndirectBr = false;
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bool HasUninlineableIntrinsic = false;
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bool InitsVargArgs = false;
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/// Number of bytes allocated statically by the callee.
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uint64_t AllocatedSize = 0;
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unsigned NumInstructions = 0;
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unsigned NumVectorInstructions = 0;
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/// While we walk the potentially-inlined instructions, we build up and
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/// maintain a mapping of simplified values specific to this callsite. The
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/// idea is to propagate any special information we have about arguments to
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/// this call through the inlinable section of the function, and account for
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/// likely simplifications post-inlining. The most important aspect we track
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/// is CFG altering simplifications -- when we prove a basic block dead, that
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/// can cause dramatic shifts in the cost of inlining a function.
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DenseMap<Value *, Constant *> SimplifiedValues;
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/// Keep track of the values which map back (through function arguments) to
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/// allocas on the caller stack which could be simplified through SROA.
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DenseMap<Value *, AllocaInst *> SROAArgValues;
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/// Keep track of Allocas for which we believe we may get SROA optimization.
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DenseSet<AllocaInst *> EnabledSROAAllocas;
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/// Keep track of values which map to a pointer base and constant offset.
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DenseMap<Value *, std::pair<Value *, APInt>> ConstantOffsetPtrs;
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/// Keep track of dead blocks due to the constant arguments.
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SetVector<BasicBlock *> DeadBlocks;
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/// The mapping of the blocks to their known unique successors due to the
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/// constant arguments.
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DenseMap<BasicBlock *, BasicBlock *> KnownSuccessors;
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/// Model the elimination of repeated loads that is expected to happen
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/// whenever we simplify away the stores that would otherwise cause them to be
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/// loads.
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bool EnableLoadElimination;
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SmallPtrSet<Value *, 16> LoadAddrSet;
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AllocaInst *getSROAArgForValueOrNull(Value *V) const {
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auto It = SROAArgValues.find(V);
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if (It == SROAArgValues.end() || EnabledSROAAllocas.count(It->second) == 0)
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return nullptr;
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return It->second;
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}
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// Custom simplification helper routines.
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bool isAllocaDerivedArg(Value *V);
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void disableSROAForArg(AllocaInst *SROAArg);
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void disableSROA(Value *V);
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void findDeadBlocks(BasicBlock *CurrBB, BasicBlock *NextBB);
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void disableLoadElimination();
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bool isGEPFree(GetElementPtrInst &GEP);
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bool canFoldInboundsGEP(GetElementPtrInst &I);
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bool accumulateGEPOffset(GEPOperator &GEP, APInt &Offset);
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bool simplifyCallSite(Function *F, CallBase &Call);
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template <typename Callable>
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bool simplifyInstruction(Instruction &I, Callable Evaluate);
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ConstantInt *stripAndComputeInBoundsConstantOffsets(Value *&V);
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/// Return true if the given argument to the function being considered for
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/// inlining has the given attribute set either at the call site or the
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/// function declaration. Primarily used to inspect call site specific
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/// attributes since these can be more precise than the ones on the callee
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/// itself.
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bool paramHasAttr(Argument *A, Attribute::AttrKind Attr);
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/// Return true if the given value is known non null within the callee if
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/// inlined through this particular callsite.
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bool isKnownNonNullInCallee(Value *V);
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/// Return true if size growth is allowed when inlining the callee at \p Call.
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bool allowSizeGrowth(CallBase &Call);
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// Custom analysis routines.
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InlineResult analyzeBlock(BasicBlock *BB,
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SmallPtrSetImpl<const Value *> &EphValues);
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// Disable several entry points to the visitor so we don't accidentally use
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// them by declaring but not defining them here.
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void visit(Module *);
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void visit(Module &);
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void visit(Function *);
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void visit(Function &);
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void visit(BasicBlock *);
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void visit(BasicBlock &);
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// Provide base case for our instruction visit.
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bool visitInstruction(Instruction &I);
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// Our visit overrides.
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bool visitAlloca(AllocaInst &I);
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bool visitPHI(PHINode &I);
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bool visitGetElementPtr(GetElementPtrInst &I);
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bool visitBitCast(BitCastInst &I);
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bool visitPtrToInt(PtrToIntInst &I);
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bool visitIntToPtr(IntToPtrInst &I);
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bool visitCastInst(CastInst &I);
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bool visitUnaryInstruction(UnaryInstruction &I);
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bool visitCmpInst(CmpInst &I);
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bool visitSub(BinaryOperator &I);
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bool visitBinaryOperator(BinaryOperator &I);
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bool visitFNeg(UnaryOperator &I);
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bool visitLoad(LoadInst &I);
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bool visitStore(StoreInst &I);
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bool visitExtractValue(ExtractValueInst &I);
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bool visitInsertValue(InsertValueInst &I);
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bool visitCallBase(CallBase &Call);
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bool visitReturnInst(ReturnInst &RI);
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bool visitBranchInst(BranchInst &BI);
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bool visitSelectInst(SelectInst &SI);
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bool visitSwitchInst(SwitchInst &SI);
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bool visitIndirectBrInst(IndirectBrInst &IBI);
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bool visitResumeInst(ResumeInst &RI);
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bool visitCleanupReturnInst(CleanupReturnInst &RI);
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bool visitCatchReturnInst(CatchReturnInst &RI);
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bool visitUnreachableInst(UnreachableInst &I);
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public:
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CallAnalyzer(const TargetTransformInfo &TTI,
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std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
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Optional<function_ref<BlockFrequencyInfo &(Function &)>> &GetBFI,
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ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE,
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Function &Callee, CallBase &Call)
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: TTI(TTI), GetAssumptionCache(GetAssumptionCache), GetBFI(GetBFI),
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PSI(PSI), F(Callee), DL(F.getParent()->getDataLayout()), ORE(ORE),
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CandidateCall(Call), EnableLoadElimination(true) {}
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InlineResult analyze();
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// Keep a bunch of stats about the cost savings found so we can print them
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// out when debugging.
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unsigned NumConstantArgs = 0;
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unsigned NumConstantOffsetPtrArgs = 0;
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unsigned NumAllocaArgs = 0;
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unsigned NumConstantPtrCmps = 0;
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unsigned NumConstantPtrDiffs = 0;
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unsigned NumInstructionsSimplified = 0;
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void dump();
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};
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/// FIXME: if it is necessary to derive from InlineCostCallAnalyzer, note
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/// the FIXME in onLoweredCall, when instantiating an InlineCostCallAnalyzer
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class InlineCostCallAnalyzer final : public CallAnalyzer {
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const int CostUpperBound = INT_MAX - InlineConstants::InstrCost - 1;
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const bool ComputeFullInlineCost;
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int LoadEliminationCost = 0;
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/// Bonus to be applied when percentage of vector instructions in callee is
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/// high (see more details in updateThreshold).
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int VectorBonus = 0;
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/// Bonus to be applied when the callee has only one reachable basic block.
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int SingleBBBonus = 0;
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/// Tunable parameters that control the analysis.
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const InlineParams &Params;
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/// Upper bound for the inlining cost. Bonuses are being applied to account
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/// for speculative "expected profit" of the inlining decision.
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int Threshold = 0;
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/// Attempt to evaluate indirect calls to boost its inline cost.
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const bool BoostIndirectCalls;
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/// Inlining cost measured in abstract units, accounts for all the
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/// instructions expected to be executed for a given function invocation.
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/// Instructions that are statically proven to be dead based on call-site
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/// arguments are not counted here.
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int Cost = 0;
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bool SingleBB = true;
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unsigned SROACostSavings = 0;
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unsigned SROACostSavingsLost = 0;
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/// The mapping of caller Alloca values to their accumulated cost savings. If
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/// we have to disable SROA for one of the allocas, this tells us how much
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/// cost must be added.
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DenseMap<AllocaInst *, int> SROAArgCosts;
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/// Return true if \p Call is a cold callsite.
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bool isColdCallSite(CallBase &Call, BlockFrequencyInfo *CallerBFI);
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/// Update Threshold based on callsite properties such as callee
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/// attributes and callee hotness for PGO builds. The Callee is explicitly
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/// passed to support analyzing indirect calls whose target is inferred by
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/// analysis.
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void updateThreshold(CallBase &Call, Function &Callee);
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/// Return a higher threshold if \p Call is a hot callsite.
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Optional<int> getHotCallSiteThreshold(CallBase &Call,
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BlockFrequencyInfo *CallerBFI);
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/// Handle a capped 'int' increment for Cost.
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void addCost(int64_t Inc, int64_t UpperBound = INT_MAX) {
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assert(UpperBound > 0 && UpperBound <= INT_MAX && "invalid upper bound");
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Cost = (int)std::min(UpperBound, Cost + Inc);
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}
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void onDisableSROA(AllocaInst *Arg) override {
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auto CostIt = SROAArgCosts.find(Arg);
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if (CostIt == SROAArgCosts.end())
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return;
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addCost(CostIt->second);
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SROACostSavings -= CostIt->second;
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SROACostSavingsLost += CostIt->second;
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SROAArgCosts.erase(CostIt);
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}
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void onDisableLoadElimination() override {
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addCost(LoadEliminationCost);
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LoadEliminationCost = 0;
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}
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void onCallPenalty() override { addCost(InlineConstants::CallPenalty); }
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void onCallArgumentSetup(const CallBase &Call) override {
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// Pay the price of the argument setup. We account for the average 1
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// instruction per call argument setup here.
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addCost(Call.arg_size() * InlineConstants::InstrCost);
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}
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void onLoadRelativeIntrinsic() override {
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// This is normally lowered to 4 LLVM instructions.
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addCost(3 * InlineConstants::InstrCost);
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}
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void onLoweredCall(Function *F, CallBase &Call,
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bool IsIndirectCall) override {
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// We account for the average 1 instruction per call argument setup here.
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addCost(Call.arg_size() * InlineConstants::InstrCost);
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// If we have a constant that we are calling as a function, we can peer
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// through it and see the function target. This happens not infrequently
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// during devirtualization and so we want to give it a hefty bonus for
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// inlining, but cap that bonus in the event that inlining wouldn't pan out.
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// Pretend to inline the function, with a custom threshold.
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if (IsIndirectCall && BoostIndirectCalls) {
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auto IndirectCallParams = Params;
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IndirectCallParams.DefaultThreshold =
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InlineConstants::IndirectCallThreshold;
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/// FIXME: if InlineCostCallAnalyzer is derived from, this may need
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/// to instantiate the derived class.
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InlineCostCallAnalyzer CA(TTI, GetAssumptionCache, GetBFI, PSI, ORE, *F,
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Call, IndirectCallParams, false);
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if (CA.analyze().isSuccess()) {
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// We were able to inline the indirect call! Subtract the cost from the
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// threshold to get the bonus we want to apply, but don't go below zero.
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Cost -= std::max(0, CA.getThreshold() - CA.getCost());
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}
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} else
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// Otherwise simply add the cost for merely making the call.
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addCost(InlineConstants::CallPenalty);
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|
}
|
|
|
|
void onFinalizeSwitch(unsigned JumpTableSize,
|
|
unsigned NumCaseCluster) override {
|
|
// If suitable for a jump table, consider the cost for the table size and
|
|
// branch to destination.
|
|
// Maximum valid cost increased in this function.
|
|
if (JumpTableSize) {
|
|
int64_t JTCost = (int64_t)JumpTableSize * InlineConstants::InstrCost +
|
|
4 * InlineConstants::InstrCost;
|
|
|
|
addCost(JTCost, (int64_t)CostUpperBound);
|
|
return;
|
|
}
|
|
// Considering forming a binary search, we should find the number of nodes
|
|
// which is same as the number of comparisons when lowered. For a given
|
|
// number of clusters, n, we can define a recursive function, f(n), to find
|
|
// the number of nodes in the tree. The recursion is :
|
|
// f(n) = 1 + f(n/2) + f (n - n/2), when n > 3,
|
|
// and f(n) = n, when n <= 3.
|
|
// This will lead a binary tree where the leaf should be either f(2) or f(3)
|
|
// when n > 3. So, the number of comparisons from leaves should be n, while
|
|
// the number of non-leaf should be :
|
|
// 2^(log2(n) - 1) - 1
|
|
// = 2^log2(n) * 2^-1 - 1
|
|
// = n / 2 - 1.
|
|
// Considering comparisons from leaf and non-leaf nodes, we can estimate the
|
|
// number of comparisons in a simple closed form :
|
|
// n + n / 2 - 1 = n * 3 / 2 - 1
|
|
if (NumCaseCluster <= 3) {
|
|
// Suppose a comparison includes one compare and one conditional branch.
|
|
addCost(NumCaseCluster * 2 * InlineConstants::InstrCost);
|
|
return;
|
|
}
|
|
|
|
int64_t ExpectedNumberOfCompare = 3 * (int64_t)NumCaseCluster / 2 - 1;
|
|
int64_t SwitchCost =
|
|
ExpectedNumberOfCompare * 2 * InlineConstants::InstrCost;
|
|
|
|
addCost(SwitchCost, (int64_t)CostUpperBound);
|
|
}
|
|
void onMissedSimplification() override {
|
|
addCost(InlineConstants::InstrCost);
|
|
}
|
|
|
|
void onInitializeSROAArg(AllocaInst *Arg) override {
|
|
assert(Arg != nullptr &&
|
|
"Should not initialize SROA costs for null value.");
|
|
SROAArgCosts[Arg] = 0;
|
|
}
|
|
|
|
void onAggregateSROAUse(AllocaInst *SROAArg) override {
|
|
auto CostIt = SROAArgCosts.find(SROAArg);
|
|
assert(CostIt != SROAArgCosts.end() &&
|
|
"expected this argument to have a cost");
|
|
CostIt->second += InlineConstants::InstrCost;
|
|
SROACostSavings += InlineConstants::InstrCost;
|
|
}
|
|
|
|
void onBlockAnalyzed(const BasicBlock *BB) override {
|
|
auto *TI = BB->getTerminator();
|
|
// If we had any successors at this point, than post-inlining is likely to
|
|
// have them as well. Note that we assume any basic blocks which existed
|
|
// due to branches or switches which folded above will also fold after
|
|
// inlining.
|
|
if (SingleBB && TI->getNumSuccessors() > 1) {
|
|
// Take off the bonus we applied to the threshold.
|
|
Threshold -= SingleBBBonus;
|
|
SingleBB = false;
|
|
}
|
|
}
|
|
|
|
InlineResult finalizeAnalysis() override {
|
|
// Loops generally act a lot like calls in that they act like barriers to
|
|
// movement, require a certain amount of setup, etc. So when optimising for
|
|
// size, we penalise any call sites that perform loops. We do this after all
|
|
// other costs here, so will likely only be dealing with relatively small
|
|
// functions (and hence DT and LI will hopefully be cheap).
|
|
auto *Caller = CandidateCall.getFunction();
|
|
if (Caller->hasMinSize()) {
|
|
DominatorTree DT(F);
|
|
LoopInfo LI(DT);
|
|
int NumLoops = 0;
|
|
for (Loop *L : LI) {
|
|
// Ignore loops that will not be executed
|
|
if (DeadBlocks.count(L->getHeader()))
|
|
continue;
|
|
NumLoops++;
|
|
}
|
|
addCost(NumLoops * InlineConstants::CallPenalty);
|
|
}
|
|
|
|
// We applied the maximum possible vector bonus at the beginning. Now,
|
|
// subtract the excess bonus, if any, from the Threshold before
|
|
// comparing against Cost.
|
|
if (NumVectorInstructions <= NumInstructions / 10)
|
|
Threshold -= VectorBonus;
|
|
else if (NumVectorInstructions <= NumInstructions / 2)
|
|
Threshold -= VectorBonus / 2;
|
|
|
|
if (Cost < std::max(1, Threshold))
|
|
return InlineResult::success();
|
|
return InlineResult::failure("Cost over threshold.");
|
|
}
|
|
bool shouldStop() override {
|
|
// Bail out the moment we cross the threshold. This means we'll under-count
|
|
// the cost, but only when undercounting doesn't matter.
|
|
return Cost >= Threshold && !ComputeFullInlineCost;
|
|
}
|
|
|
|
void onLoadEliminationOpportunity() override {
|
|
LoadEliminationCost += InlineConstants::InstrCost;
|
|
}
|
|
|
|
InlineResult onAnalysisStart() override {
|
|
// Perform some tweaks to the cost and threshold based on the direct
|
|
// callsite information.
|
|
|
|
// We want to more aggressively inline vector-dense kernels, so up the
|
|
// threshold, and we'll lower it if the % of vector instructions gets too
|
|
// low. Note that these bonuses are some what arbitrary and evolved over
|
|
// time by accident as much as because they are principled bonuses.
|
|
//
|
|
// FIXME: It would be nice to remove all such bonuses. At least it would be
|
|
// nice to base the bonus values on something more scientific.
|
|
assert(NumInstructions == 0);
|
|
assert(NumVectorInstructions == 0);
|
|
|
|
// Update the threshold based on callsite properties
|
|
updateThreshold(CandidateCall, F);
|
|
|
|
// While Threshold depends on commandline options that can take negative
|
|
// values, we want to enforce the invariant that the computed threshold and
|
|
// bonuses are non-negative.
|
|
assert(Threshold >= 0);
|
|
assert(SingleBBBonus >= 0);
|
|
assert(VectorBonus >= 0);
|
|
|
|
// Speculatively apply all possible bonuses to Threshold. If cost exceeds
|
|
// this Threshold any time, and cost cannot decrease, we can stop processing
|
|
// the rest of the function body.
|
|
Threshold += (SingleBBBonus + VectorBonus);
|
|
|
|
// Give out bonuses for the callsite, as the instructions setting them up
|
|
// will be gone after inlining.
|
|
addCost(-getCallsiteCost(this->CandidateCall, DL));
|
|
|
|
// If this function uses the coldcc calling convention, prefer not to inline
|
|
// it.
|
|
if (F.getCallingConv() == CallingConv::Cold)
|
|
Cost += InlineConstants::ColdccPenalty;
|
|
|
|
// Check if we're done. This can happen due to bonuses and penalties.
|
|
if (Cost >= Threshold && !ComputeFullInlineCost)
|
|
return InlineResult::failure("high cost");
|
|
|
|
return InlineResult::success();
|
|
}
|
|
|
|
public:
|
|
InlineCostCallAnalyzer(
|
|
const TargetTransformInfo &TTI,
|
|
std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
|
|
Optional<function_ref<BlockFrequencyInfo &(Function &)>> &GetBFI,
|
|
ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE, Function &Callee,
|
|
CallBase &Call, const InlineParams &Params, bool BoostIndirect = true)
|
|
: CallAnalyzer(TTI, GetAssumptionCache, GetBFI, PSI, ORE, Callee, Call),
|
|
ComputeFullInlineCost(OptComputeFullInlineCost ||
|
|
Params.ComputeFullInlineCost || ORE),
|
|
Params(Params), Threshold(Params.DefaultThreshold),
|
|
BoostIndirectCalls(BoostIndirect) {}
|
|
void dump();
|
|
|
|
virtual ~InlineCostCallAnalyzer() {}
|
|
int getThreshold() { return Threshold; }
|
|
int getCost() { return Cost; }
|
|
};
|
|
} // namespace
|
|
|
|
/// Test whether the given value is an Alloca-derived function argument.
|
|
bool CallAnalyzer::isAllocaDerivedArg(Value *V) {
|
|
return SROAArgValues.count(V);
|
|
}
|
|
|
|
void CallAnalyzer::disableSROAForArg(AllocaInst *SROAArg) {
|
|
onDisableSROA(SROAArg);
|
|
EnabledSROAAllocas.erase(SROAArg);
|
|
disableLoadElimination();
|
|
}
|
|
/// If 'V' maps to a SROA candidate, disable SROA for it.
|
|
void CallAnalyzer::disableSROA(Value *V) {
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(V)) {
|
|
disableSROAForArg(SROAArg);
|
|
}
|
|
}
|
|
|
|
void CallAnalyzer::disableLoadElimination() {
|
|
if (EnableLoadElimination) {
|
|
onDisableLoadElimination();
|
|
EnableLoadElimination = false;
|
|
}
|
|
}
|
|
|
|
/// Accumulate a constant GEP offset into an APInt if possible.
|
|
///
|
|
/// Returns false if unable to compute the offset for any reason. Respects any
|
|
/// simplified values known during the analysis of this callsite.
|
|
bool CallAnalyzer::accumulateGEPOffset(GEPOperator &GEP, APInt &Offset) {
|
|
unsigned IntPtrWidth = DL.getIndexTypeSizeInBits(GEP.getType());
|
|
assert(IntPtrWidth == Offset.getBitWidth());
|
|
|
|
for (gep_type_iterator GTI = gep_type_begin(GEP), GTE = gep_type_end(GEP);
|
|
GTI != GTE; ++GTI) {
|
|
ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand());
|
|
if (!OpC)
|
|
if (Constant *SimpleOp = SimplifiedValues.lookup(GTI.getOperand()))
|
|
OpC = dyn_cast<ConstantInt>(SimpleOp);
|
|
if (!OpC)
|
|
return false;
|
|
if (OpC->isZero())
|
|
continue;
|
|
|
|
// Handle a struct index, which adds its field offset to the pointer.
|
|
if (StructType *STy = GTI.getStructTypeOrNull()) {
|
|
unsigned ElementIdx = OpC->getZExtValue();
|
|
const StructLayout *SL = DL.getStructLayout(STy);
|
|
Offset += APInt(IntPtrWidth, SL->getElementOffset(ElementIdx));
|
|
continue;
|
|
}
|
|
|
|
APInt TypeSize(IntPtrWidth, DL.getTypeAllocSize(GTI.getIndexedType()));
|
|
Offset += OpC->getValue().sextOrTrunc(IntPtrWidth) * TypeSize;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
/// Use TTI to check whether a GEP is free.
|
|
///
|
|
/// Respects any simplified values known during the analysis of this callsite.
|
|
bool CallAnalyzer::isGEPFree(GetElementPtrInst &GEP) {
|
|
SmallVector<Value *, 4> Operands;
|
|
Operands.push_back(GEP.getOperand(0));
|
|
for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I)
|
|
if (Constant *SimpleOp = SimplifiedValues.lookup(*I))
|
|
Operands.push_back(SimpleOp);
|
|
else
|
|
Operands.push_back(*I);
|
|
return TargetTransformInfo::TCC_Free == TTI.getUserCost(&GEP, Operands);
|
|
}
|
|
|
|
bool CallAnalyzer::visitAlloca(AllocaInst &I) {
|
|
// Check whether inlining will turn a dynamic alloca into a static
|
|
// alloca and handle that case.
|
|
if (I.isArrayAllocation()) {
|
|
Constant *Size = SimplifiedValues.lookup(I.getArraySize());
|
|
if (auto *AllocSize = dyn_cast_or_null<ConstantInt>(Size)) {
|
|
Type *Ty = I.getAllocatedType();
|
|
AllocatedSize = SaturatingMultiplyAdd(
|
|
AllocSize->getLimitedValue(), DL.getTypeAllocSize(Ty).getFixedSize(),
|
|
AllocatedSize);
|
|
return Base::visitAlloca(I);
|
|
}
|
|
}
|
|
|
|
// Accumulate the allocated size.
|
|
if (I.isStaticAlloca()) {
|
|
Type *Ty = I.getAllocatedType();
|
|
AllocatedSize =
|
|
SaturatingAdd(DL.getTypeAllocSize(Ty).getFixedSize(), AllocatedSize);
|
|
}
|
|
|
|
// We will happily inline static alloca instructions.
|
|
if (I.isStaticAlloca())
|
|
return Base::visitAlloca(I);
|
|
|
|
// FIXME: This is overly conservative. Dynamic allocas are inefficient for
|
|
// a variety of reasons, and so we would like to not inline them into
|
|
// functions which don't currently have a dynamic alloca. This simply
|
|
// disables inlining altogether in the presence of a dynamic alloca.
|
|
HasDynamicAlloca = true;
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitPHI(PHINode &I) {
|
|
// FIXME: We need to propagate SROA *disabling* through phi nodes, even
|
|
// though we don't want to propagate it's bonuses. The idea is to disable
|
|
// SROA if it *might* be used in an inappropriate manner.
|
|
|
|
// Phi nodes are always zero-cost.
|
|
// FIXME: Pointer sizes may differ between different address spaces, so do we
|
|
// need to use correct address space in the call to getPointerSizeInBits here?
|
|
// Or could we skip the getPointerSizeInBits call completely? As far as I can
|
|
// see the ZeroOffset is used as a dummy value, so we can probably use any
|
|
// bit width for the ZeroOffset?
|
|
APInt ZeroOffset = APInt::getNullValue(DL.getPointerSizeInBits(0));
|
|
bool CheckSROA = I.getType()->isPointerTy();
|
|
|
|
// Track the constant or pointer with constant offset we've seen so far.
|
|
Constant *FirstC = nullptr;
|
|
std::pair<Value *, APInt> FirstBaseAndOffset = {nullptr, ZeroOffset};
|
|
Value *FirstV = nullptr;
|
|
|
|
for (unsigned i = 0, e = I.getNumIncomingValues(); i != e; ++i) {
|
|
BasicBlock *Pred = I.getIncomingBlock(i);
|
|
// If the incoming block is dead, skip the incoming block.
|
|
if (DeadBlocks.count(Pred))
|
|
continue;
|
|
// If the parent block of phi is not the known successor of the incoming
|
|
// block, skip the incoming block.
|
|
BasicBlock *KnownSuccessor = KnownSuccessors[Pred];
|
|
if (KnownSuccessor && KnownSuccessor != I.getParent())
|
|
continue;
|
|
|
|
Value *V = I.getIncomingValue(i);
|
|
// If the incoming value is this phi itself, skip the incoming value.
|
|
if (&I == V)
|
|
continue;
|
|
|
|
Constant *C = dyn_cast<Constant>(V);
|
|
if (!C)
|
|
C = SimplifiedValues.lookup(V);
|
|
|
|
std::pair<Value *, APInt> BaseAndOffset = {nullptr, ZeroOffset};
|
|
if (!C && CheckSROA)
|
|
BaseAndOffset = ConstantOffsetPtrs.lookup(V);
|
|
|
|
if (!C && !BaseAndOffset.first)
|
|
// The incoming value is neither a constant nor a pointer with constant
|
|
// offset, exit early.
|
|
return true;
|
|
|
|
if (FirstC) {
|
|
if (FirstC == C)
|
|
// If we've seen a constant incoming value before and it is the same
|
|
// constant we see this time, continue checking the next incoming value.
|
|
continue;
|
|
// Otherwise early exit because we either see a different constant or saw
|
|
// a constant before but we have a pointer with constant offset this time.
|
|
return true;
|
|
}
|
|
|
|
if (FirstV) {
|
|
// The same logic as above, but check pointer with constant offset here.
|
|
if (FirstBaseAndOffset == BaseAndOffset)
|
|
continue;
|
|
return true;
|
|
}
|
|
|
|
if (C) {
|
|
// This is the 1st time we've seen a constant, record it.
|
|
FirstC = C;
|
|
continue;
|
|
}
|
|
|
|
// The remaining case is that this is the 1st time we've seen a pointer with
|
|
// constant offset, record it.
|
|
FirstV = V;
|
|
FirstBaseAndOffset = BaseAndOffset;
|
|
}
|
|
|
|
// Check if we can map phi to a constant.
|
|
if (FirstC) {
|
|
SimplifiedValues[&I] = FirstC;
|
|
return true;
|
|
}
|
|
|
|
// Check if we can map phi to a pointer with constant offset.
|
|
if (FirstBaseAndOffset.first) {
|
|
ConstantOffsetPtrs[&I] = FirstBaseAndOffset;
|
|
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(FirstV))
|
|
SROAArgValues[&I] = SROAArg;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
/// Check we can fold GEPs of constant-offset call site argument pointers.
|
|
/// This requires target data and inbounds GEPs.
|
|
///
|
|
/// \return true if the specified GEP can be folded.
|
|
bool CallAnalyzer::canFoldInboundsGEP(GetElementPtrInst &I) {
|
|
// Check if we have a base + offset for the pointer.
|
|
std::pair<Value *, APInt> BaseAndOffset =
|
|
ConstantOffsetPtrs.lookup(I.getPointerOperand());
|
|
if (!BaseAndOffset.first)
|
|
return false;
|
|
|
|
// Check if the offset of this GEP is constant, and if so accumulate it
|
|
// into Offset.
|
|
if (!accumulateGEPOffset(cast<GEPOperator>(I), BaseAndOffset.second))
|
|
return false;
|
|
|
|
// Add the result as a new mapping to Base + Offset.
|
|
ConstantOffsetPtrs[&I] = BaseAndOffset;
|
|
|
|
return true;
|
|
}
|
|
|
|
bool CallAnalyzer::visitGetElementPtr(GetElementPtrInst &I) {
|
|
auto *SROAArg = getSROAArgForValueOrNull(I.getPointerOperand());
|
|
|
|
// Lambda to check whether a GEP's indices are all constant.
|
|
auto IsGEPOffsetConstant = [&](GetElementPtrInst &GEP) {
|
|
for (User::op_iterator I = GEP.idx_begin(), E = GEP.idx_end(); I != E; ++I)
|
|
if (!isa<Constant>(*I) && !SimplifiedValues.lookup(*I))
|
|
return false;
|
|
return true;
|
|
};
|
|
|
|
if ((I.isInBounds() && canFoldInboundsGEP(I)) || IsGEPOffsetConstant(I)) {
|
|
if (SROAArg)
|
|
SROAArgValues[&I] = SROAArg;
|
|
|
|
// Constant GEPs are modeled as free.
|
|
return true;
|
|
}
|
|
|
|
// Variable GEPs will require math and will disable SROA.
|
|
if (SROAArg)
|
|
disableSROAForArg(SROAArg);
|
|
return isGEPFree(I);
|
|
}
|
|
|
|
/// Simplify \p I if its operands are constants and update SimplifiedValues.
|
|
/// \p Evaluate is a callable specific to instruction type that evaluates the
|
|
/// instruction when all the operands are constants.
|
|
template <typename Callable>
|
|
bool CallAnalyzer::simplifyInstruction(Instruction &I, Callable Evaluate) {
|
|
SmallVector<Constant *, 2> COps;
|
|
for (Value *Op : I.operands()) {
|
|
Constant *COp = dyn_cast<Constant>(Op);
|
|
if (!COp)
|
|
COp = SimplifiedValues.lookup(Op);
|
|
if (!COp)
|
|
return false;
|
|
COps.push_back(COp);
|
|
}
|
|
auto *C = Evaluate(COps);
|
|
if (!C)
|
|
return false;
|
|
SimplifiedValues[&I] = C;
|
|
return true;
|
|
}
|
|
|
|
bool CallAnalyzer::visitBitCast(BitCastInst &I) {
|
|
// Propagate constants through bitcasts.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getBitCast(COps[0], I.getType());
|
|
}))
|
|
return true;
|
|
|
|
// Track base/offsets through casts
|
|
std::pair<Value *, APInt> BaseAndOffset =
|
|
ConstantOffsetPtrs.lookup(I.getOperand(0));
|
|
// Casts don't change the offset, just wrap it up.
|
|
if (BaseAndOffset.first)
|
|
ConstantOffsetPtrs[&I] = BaseAndOffset;
|
|
|
|
// Also look for SROA candidates here.
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(I.getOperand(0)))
|
|
SROAArgValues[&I] = SROAArg;
|
|
|
|
// Bitcasts are always zero cost.
|
|
return true;
|
|
}
|
|
|
|
bool CallAnalyzer::visitPtrToInt(PtrToIntInst &I) {
|
|
// Propagate constants through ptrtoint.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getPtrToInt(COps[0], I.getType());
|
|
}))
|
|
return true;
|
|
|
|
// Track base/offset pairs when converted to a plain integer provided the
|
|
// integer is large enough to represent the pointer.
|
|
unsigned IntegerSize = I.getType()->getScalarSizeInBits();
|
|
unsigned AS = I.getOperand(0)->getType()->getPointerAddressSpace();
|
|
if (IntegerSize >= DL.getPointerSizeInBits(AS)) {
|
|
std::pair<Value *, APInt> BaseAndOffset =
|
|
ConstantOffsetPtrs.lookup(I.getOperand(0));
|
|
if (BaseAndOffset.first)
|
|
ConstantOffsetPtrs[&I] = BaseAndOffset;
|
|
}
|
|
|
|
// This is really weird. Technically, ptrtoint will disable SROA. However,
|
|
// unless that ptrtoint is *used* somewhere in the live basic blocks after
|
|
// inlining, it will be nuked, and SROA should proceed. All of the uses which
|
|
// would block SROA would also block SROA if applied directly to a pointer,
|
|
// and so we can just add the integer in here. The only places where SROA is
|
|
// preserved either cannot fire on an integer, or won't in-and-of themselves
|
|
// disable SROA (ext) w/o some later use that we would see and disable.
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(I.getOperand(0)))
|
|
SROAArgValues[&I] = SROAArg;
|
|
|
|
return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
|
|
}
|
|
|
|
bool CallAnalyzer::visitIntToPtr(IntToPtrInst &I) {
|
|
// Propagate constants through ptrtoint.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getIntToPtr(COps[0], I.getType());
|
|
}))
|
|
return true;
|
|
|
|
// Track base/offset pairs when round-tripped through a pointer without
|
|
// modifications provided the integer is not too large.
|
|
Value *Op = I.getOperand(0);
|
|
unsigned IntegerSize = Op->getType()->getScalarSizeInBits();
|
|
if (IntegerSize <= DL.getPointerTypeSizeInBits(I.getType())) {
|
|
std::pair<Value *, APInt> BaseAndOffset = ConstantOffsetPtrs.lookup(Op);
|
|
if (BaseAndOffset.first)
|
|
ConstantOffsetPtrs[&I] = BaseAndOffset;
|
|
}
|
|
|
|
// "Propagate" SROA here in the same manner as we do for ptrtoint above.
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(Op))
|
|
SROAArgValues[&I] = SROAArg;
|
|
|
|
return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
|
|
}
|
|
|
|
bool CallAnalyzer::visitCastInst(CastInst &I) {
|
|
// Propagate constants through casts.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getCast(I.getOpcode(), COps[0], I.getType());
|
|
}))
|
|
return true;
|
|
|
|
// Disable SROA in the face of arbitrary casts we don't whitelist elsewhere.
|
|
disableSROA(I.getOperand(0));
|
|
|
|
// If this is a floating-point cast, and the target says this operation
|
|
// is expensive, this may eventually become a library call. Treat the cost
|
|
// as such.
|
|
switch (I.getOpcode()) {
|
|
case Instruction::FPTrunc:
|
|
case Instruction::FPExt:
|
|
case Instruction::UIToFP:
|
|
case Instruction::SIToFP:
|
|
case Instruction::FPToUI:
|
|
case Instruction::FPToSI:
|
|
if (TTI.getFPOpCost(I.getType()) == TargetTransformInfo::TCC_Expensive)
|
|
onCallPenalty();
|
|
break;
|
|
default:
|
|
break;
|
|
}
|
|
|
|
return TargetTransformInfo::TCC_Free == TTI.getUserCost(&I);
|
|
}
|
|
|
|
bool CallAnalyzer::visitUnaryInstruction(UnaryInstruction &I) {
|
|
Value *Operand = I.getOperand(0);
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantFoldInstOperands(&I, COps[0], DL);
|
|
}))
|
|
return true;
|
|
|
|
// Disable any SROA on the argument to arbitrary unary instructions.
|
|
disableSROA(Operand);
|
|
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::paramHasAttr(Argument *A, Attribute::AttrKind Attr) {
|
|
return CandidateCall.paramHasAttr(A->getArgNo(), Attr);
|
|
}
|
|
|
|
bool CallAnalyzer::isKnownNonNullInCallee(Value *V) {
|
|
// Does the *call site* have the NonNull attribute set on an argument? We
|
|
// use the attribute on the call site to memoize any analysis done in the
|
|
// caller. This will also trip if the callee function has a non-null
|
|
// parameter attribute, but that's a less interesting case because hopefully
|
|
// the callee would already have been simplified based on that.
|
|
if (Argument *A = dyn_cast<Argument>(V))
|
|
if (paramHasAttr(A, Attribute::NonNull))
|
|
return true;
|
|
|
|
// Is this an alloca in the caller? This is distinct from the attribute case
|
|
// above because attributes aren't updated within the inliner itself and we
|
|
// always want to catch the alloca derived case.
|
|
if (isAllocaDerivedArg(V))
|
|
// We can actually predict the result of comparisons between an
|
|
// alloca-derived value and null. Note that this fires regardless of
|
|
// SROA firing.
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::allowSizeGrowth(CallBase &Call) {
|
|
// If the normal destination of the invoke or the parent block of the call
|
|
// site is unreachable-terminated, there is little point in inlining this
|
|
// unless there is literally zero cost.
|
|
// FIXME: Note that it is possible that an unreachable-terminated block has a
|
|
// hot entry. For example, in below scenario inlining hot_call_X() may be
|
|
// beneficial :
|
|
// main() {
|
|
// hot_call_1();
|
|
// ...
|
|
// hot_call_N()
|
|
// exit(0);
|
|
// }
|
|
// For now, we are not handling this corner case here as it is rare in real
|
|
// code. In future, we should elaborate this based on BPI and BFI in more
|
|
// general threshold adjusting heuristics in updateThreshold().
|
|
if (InvokeInst *II = dyn_cast<InvokeInst>(&Call)) {
|
|
if (isa<UnreachableInst>(II->getNormalDest()->getTerminator()))
|
|
return false;
|
|
} else if (isa<UnreachableInst>(Call.getParent()->getTerminator()))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
bool InlineCostCallAnalyzer::isColdCallSite(CallBase &Call,
|
|
BlockFrequencyInfo *CallerBFI) {
|
|
// If global profile summary is available, then callsite's coldness is
|
|
// determined based on that.
|
|
if (PSI && PSI->hasProfileSummary())
|
|
return PSI->isColdCallSite(CallSite(&Call), CallerBFI);
|
|
|
|
// Otherwise we need BFI to be available.
|
|
if (!CallerBFI)
|
|
return false;
|
|
|
|
// Determine if the callsite is cold relative to caller's entry. We could
|
|
// potentially cache the computation of scaled entry frequency, but the added
|
|
// complexity is not worth it unless this scaling shows up high in the
|
|
// profiles.
|
|
const BranchProbability ColdProb(ColdCallSiteRelFreq, 100);
|
|
auto CallSiteBB = Call.getParent();
|
|
auto CallSiteFreq = CallerBFI->getBlockFreq(CallSiteBB);
|
|
auto CallerEntryFreq =
|
|
CallerBFI->getBlockFreq(&(Call.getCaller()->getEntryBlock()));
|
|
return CallSiteFreq < CallerEntryFreq * ColdProb;
|
|
}
|
|
|
|
Optional<int>
|
|
InlineCostCallAnalyzer::getHotCallSiteThreshold(CallBase &Call,
|
|
BlockFrequencyInfo *CallerBFI) {
|
|
|
|
// If global profile summary is available, then callsite's hotness is
|
|
// determined based on that.
|
|
if (PSI && PSI->hasProfileSummary() &&
|
|
PSI->isHotCallSite(CallSite(&Call), CallerBFI))
|
|
return Params.HotCallSiteThreshold;
|
|
|
|
// Otherwise we need BFI to be available and to have a locally hot callsite
|
|
// threshold.
|
|
if (!CallerBFI || !Params.LocallyHotCallSiteThreshold)
|
|
return None;
|
|
|
|
// Determine if the callsite is hot relative to caller's entry. We could
|
|
// potentially cache the computation of scaled entry frequency, but the added
|
|
// complexity is not worth it unless this scaling shows up high in the
|
|
// profiles.
|
|
auto CallSiteBB = Call.getParent();
|
|
auto CallSiteFreq = CallerBFI->getBlockFreq(CallSiteBB).getFrequency();
|
|
auto CallerEntryFreq = CallerBFI->getEntryFreq();
|
|
if (CallSiteFreq >= CallerEntryFreq * HotCallSiteRelFreq)
|
|
return Params.LocallyHotCallSiteThreshold;
|
|
|
|
// Otherwise treat it normally.
|
|
return None;
|
|
}
|
|
|
|
void InlineCostCallAnalyzer::updateThreshold(CallBase &Call, Function &Callee) {
|
|
// If no size growth is allowed for this inlining, set Threshold to 0.
|
|
if (!allowSizeGrowth(Call)) {
|
|
Threshold = 0;
|
|
return;
|
|
}
|
|
|
|
Function *Caller = Call.getCaller();
|
|
|
|
// return min(A, B) if B is valid.
|
|
auto MinIfValid = [](int A, Optional<int> B) {
|
|
return B ? std::min(A, B.getValue()) : A;
|
|
};
|
|
|
|
// return max(A, B) if B is valid.
|
|
auto MaxIfValid = [](int A, Optional<int> B) {
|
|
return B ? std::max(A, B.getValue()) : A;
|
|
};
|
|
|
|
// Various bonus percentages. These are multiplied by Threshold to get the
|
|
// bonus values.
|
|
// SingleBBBonus: This bonus is applied if the callee has a single reachable
|
|
// basic block at the given callsite context. This is speculatively applied
|
|
// and withdrawn if more than one basic block is seen.
|
|
//
|
|
// LstCallToStaticBonus: This large bonus is applied to ensure the inlining
|
|
// of the last call to a static function as inlining such functions is
|
|
// guaranteed to reduce code size.
|
|
//
|
|
// These bonus percentages may be set to 0 based on properties of the caller
|
|
// and the callsite.
|
|
int SingleBBBonusPercent = 50;
|
|
int VectorBonusPercent = TTI.getInlinerVectorBonusPercent();
|
|
int LastCallToStaticBonus = InlineConstants::LastCallToStaticBonus;
|
|
|
|
// Lambda to set all the above bonus and bonus percentages to 0.
|
|
auto DisallowAllBonuses = [&]() {
|
|
SingleBBBonusPercent = 0;
|
|
VectorBonusPercent = 0;
|
|
LastCallToStaticBonus = 0;
|
|
};
|
|
|
|
// Use the OptMinSizeThreshold or OptSizeThreshold knob if they are available
|
|
// and reduce the threshold if the caller has the necessary attribute.
|
|
if (Caller->hasMinSize()) {
|
|
Threshold = MinIfValid(Threshold, Params.OptMinSizeThreshold);
|
|
// For minsize, we want to disable the single BB bonus and the vector
|
|
// bonuses, but not the last-call-to-static bonus. Inlining the last call to
|
|
// a static function will, at the minimum, eliminate the parameter setup and
|
|
// call/return instructions.
|
|
SingleBBBonusPercent = 0;
|
|
VectorBonusPercent = 0;
|
|
} else if (Caller->hasOptSize())
|
|
Threshold = MinIfValid(Threshold, Params.OptSizeThreshold);
|
|
|
|
// Adjust the threshold based on inlinehint attribute and profile based
|
|
// hotness information if the caller does not have MinSize attribute.
|
|
if (!Caller->hasMinSize()) {
|
|
if (Callee.hasFnAttribute(Attribute::InlineHint))
|
|
Threshold = MaxIfValid(Threshold, Params.HintThreshold);
|
|
|
|
// FIXME: After switching to the new passmanager, simplify the logic below
|
|
// by checking only the callsite hotness/coldness as we will reliably
|
|
// have local profile information.
|
|
//
|
|
// Callsite hotness and coldness can be determined if sample profile is
|
|
// used (which adds hotness metadata to calls) or if caller's
|
|
// BlockFrequencyInfo is available.
|
|
BlockFrequencyInfo *CallerBFI = GetBFI ? &((*GetBFI)(*Caller)) : nullptr;
|
|
auto HotCallSiteThreshold = getHotCallSiteThreshold(Call, CallerBFI);
|
|
if (!Caller->hasOptSize() && HotCallSiteThreshold) {
|
|
LLVM_DEBUG(dbgs() << "Hot callsite.\n");
|
|
// FIXME: This should update the threshold only if it exceeds the
|
|
// current threshold, but AutoFDO + ThinLTO currently relies on this
|
|
// behavior to prevent inlining of hot callsites during ThinLTO
|
|
// compile phase.
|
|
Threshold = HotCallSiteThreshold.getValue();
|
|
} else if (isColdCallSite(Call, CallerBFI)) {
|
|
LLVM_DEBUG(dbgs() << "Cold callsite.\n");
|
|
// Do not apply bonuses for a cold callsite including the
|
|
// LastCallToStatic bonus. While this bonus might result in code size
|
|
// reduction, it can cause the size of a non-cold caller to increase
|
|
// preventing it from being inlined.
|
|
DisallowAllBonuses();
|
|
Threshold = MinIfValid(Threshold, Params.ColdCallSiteThreshold);
|
|
} else if (PSI) {
|
|
// Use callee's global profile information only if we have no way of
|
|
// determining this via callsite information.
|
|
if (PSI->isFunctionEntryHot(&Callee)) {
|
|
LLVM_DEBUG(dbgs() << "Hot callee.\n");
|
|
// If callsite hotness can not be determined, we may still know
|
|
// that the callee is hot and treat it as a weaker hint for threshold
|
|
// increase.
|
|
Threshold = MaxIfValid(Threshold, Params.HintThreshold);
|
|
} else if (PSI->isFunctionEntryCold(&Callee)) {
|
|
LLVM_DEBUG(dbgs() << "Cold callee.\n");
|
|
// Do not apply bonuses for a cold callee including the
|
|
// LastCallToStatic bonus. While this bonus might result in code size
|
|
// reduction, it can cause the size of a non-cold caller to increase
|
|
// preventing it from being inlined.
|
|
DisallowAllBonuses();
|
|
Threshold = MinIfValid(Threshold, Params.ColdThreshold);
|
|
}
|
|
}
|
|
}
|
|
|
|
// Finally, take the target-specific inlining threshold multiplier into
|
|
// account.
|
|
Threshold *= TTI.getInliningThresholdMultiplier();
|
|
|
|
SingleBBBonus = Threshold * SingleBBBonusPercent / 100;
|
|
VectorBonus = Threshold * VectorBonusPercent / 100;
|
|
|
|
bool OnlyOneCallAndLocalLinkage =
|
|
F.hasLocalLinkage() && F.hasOneUse() && &F == Call.getCalledFunction();
|
|
// If there is only one call of the function, and it has internal linkage,
|
|
// the cost of inlining it drops dramatically. It may seem odd to update
|
|
// Cost in updateThreshold, but the bonus depends on the logic in this method.
|
|
if (OnlyOneCallAndLocalLinkage)
|
|
Cost -= LastCallToStaticBonus;
|
|
}
|
|
|
|
bool CallAnalyzer::visitCmpInst(CmpInst &I) {
|
|
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
|
|
// First try to handle simplified comparisons.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getCompare(I.getPredicate(), COps[0], COps[1]);
|
|
}))
|
|
return true;
|
|
|
|
if (I.getOpcode() == Instruction::FCmp)
|
|
return false;
|
|
|
|
// Otherwise look for a comparison between constant offset pointers with
|
|
// a common base.
|
|
Value *LHSBase, *RHSBase;
|
|
APInt LHSOffset, RHSOffset;
|
|
std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
|
|
if (LHSBase) {
|
|
std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
|
|
if (RHSBase && LHSBase == RHSBase) {
|
|
// We have common bases, fold the icmp to a constant based on the
|
|
// offsets.
|
|
Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
|
|
Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
|
|
if (Constant *C = ConstantExpr::getICmp(I.getPredicate(), CLHS, CRHS)) {
|
|
SimplifiedValues[&I] = C;
|
|
++NumConstantPtrCmps;
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// If the comparison is an equality comparison with null, we can simplify it
|
|
// if we know the value (argument) can't be null
|
|
if (I.isEquality() && isa<ConstantPointerNull>(I.getOperand(1)) &&
|
|
isKnownNonNullInCallee(I.getOperand(0))) {
|
|
bool IsNotEqual = I.getPredicate() == CmpInst::ICMP_NE;
|
|
SimplifiedValues[&I] = IsNotEqual ? ConstantInt::getTrue(I.getType())
|
|
: ConstantInt::getFalse(I.getType());
|
|
return true;
|
|
}
|
|
return handleSROA(I.getOperand(0), isa<ConstantPointerNull>(I.getOperand(1)));
|
|
}
|
|
|
|
bool CallAnalyzer::visitSub(BinaryOperator &I) {
|
|
// Try to handle a special case: we can fold computing the difference of two
|
|
// constant-related pointers.
|
|
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
|
|
Value *LHSBase, *RHSBase;
|
|
APInt LHSOffset, RHSOffset;
|
|
std::tie(LHSBase, LHSOffset) = ConstantOffsetPtrs.lookup(LHS);
|
|
if (LHSBase) {
|
|
std::tie(RHSBase, RHSOffset) = ConstantOffsetPtrs.lookup(RHS);
|
|
if (RHSBase && LHSBase == RHSBase) {
|
|
// We have common bases, fold the subtract to a constant based on the
|
|
// offsets.
|
|
Constant *CLHS = ConstantInt::get(LHS->getContext(), LHSOffset);
|
|
Constant *CRHS = ConstantInt::get(RHS->getContext(), RHSOffset);
|
|
if (Constant *C = ConstantExpr::getSub(CLHS, CRHS)) {
|
|
SimplifiedValues[&I] = C;
|
|
++NumConstantPtrDiffs;
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
|
|
// Otherwise, fall back to the generic logic for simplifying and handling
|
|
// instructions.
|
|
return Base::visitSub(I);
|
|
}
|
|
|
|
bool CallAnalyzer::visitBinaryOperator(BinaryOperator &I) {
|
|
Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
|
|
Constant *CLHS = dyn_cast<Constant>(LHS);
|
|
if (!CLHS)
|
|
CLHS = SimplifiedValues.lookup(LHS);
|
|
Constant *CRHS = dyn_cast<Constant>(RHS);
|
|
if (!CRHS)
|
|
CRHS = SimplifiedValues.lookup(RHS);
|
|
|
|
Value *SimpleV = nullptr;
|
|
if (auto FI = dyn_cast<FPMathOperator>(&I))
|
|
SimpleV = SimplifyBinOp(I.getOpcode(), CLHS ? CLHS : LHS, CRHS ? CRHS : RHS,
|
|
FI->getFastMathFlags(), DL);
|
|
else
|
|
SimpleV =
|
|
SimplifyBinOp(I.getOpcode(), CLHS ? CLHS : LHS, CRHS ? CRHS : RHS, DL);
|
|
|
|
if (Constant *C = dyn_cast_or_null<Constant>(SimpleV))
|
|
SimplifiedValues[&I] = C;
|
|
|
|
if (SimpleV)
|
|
return true;
|
|
|
|
// Disable any SROA on arguments to arbitrary, unsimplified binary operators.
|
|
disableSROA(LHS);
|
|
disableSROA(RHS);
|
|
|
|
// If the instruction is floating point, and the target says this operation
|
|
// is expensive, this may eventually become a library call. Treat the cost
|
|
// as such. Unless it's fneg which can be implemented with an xor.
|
|
using namespace llvm::PatternMatch;
|
|
if (I.getType()->isFloatingPointTy() &&
|
|
TTI.getFPOpCost(I.getType()) == TargetTransformInfo::TCC_Expensive &&
|
|
!match(&I, m_FNeg(m_Value())))
|
|
onCallPenalty();
|
|
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitFNeg(UnaryOperator &I) {
|
|
Value *Op = I.getOperand(0);
|
|
Constant *COp = dyn_cast<Constant>(Op);
|
|
if (!COp)
|
|
COp = SimplifiedValues.lookup(Op);
|
|
|
|
Value *SimpleV = SimplifyFNegInst(
|
|
COp ? COp : Op, cast<FPMathOperator>(I).getFastMathFlags(), DL);
|
|
|
|
if (Constant *C = dyn_cast_or_null<Constant>(SimpleV))
|
|
SimplifiedValues[&I] = C;
|
|
|
|
if (SimpleV)
|
|
return true;
|
|
|
|
// Disable any SROA on arguments to arbitrary, unsimplified fneg.
|
|
disableSROA(Op);
|
|
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitLoad(LoadInst &I) {
|
|
if (handleSROA(I.getPointerOperand(), I.isSimple()))
|
|
return true;
|
|
|
|
// If the data is already loaded from this address and hasn't been clobbered
|
|
// by any stores or calls, this load is likely to be redundant and can be
|
|
// eliminated.
|
|
if (EnableLoadElimination &&
|
|
!LoadAddrSet.insert(I.getPointerOperand()).second && I.isUnordered()) {
|
|
onLoadEliminationOpportunity();
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitStore(StoreInst &I) {
|
|
if (handleSROA(I.getPointerOperand(), I.isSimple()))
|
|
return true;
|
|
|
|
// The store can potentially clobber loads and prevent repeated loads from
|
|
// being eliminated.
|
|
// FIXME:
|
|
// 1. We can probably keep an initial set of eliminatable loads substracted
|
|
// from the cost even when we finally see a store. We just need to disable
|
|
// *further* accumulation of elimination savings.
|
|
// 2. We should probably at some point thread MemorySSA for the callee into
|
|
// this and then use that to actually compute *really* precise savings.
|
|
disableLoadElimination();
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitExtractValue(ExtractValueInst &I) {
|
|
// Constant folding for extract value is trivial.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getExtractValue(COps[0], I.getIndices());
|
|
}))
|
|
return true;
|
|
|
|
// SROA can look through these but give them a cost.
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitInsertValue(InsertValueInst &I) {
|
|
// Constant folding for insert value is trivial.
|
|
if (simplifyInstruction(I, [&](SmallVectorImpl<Constant *> &COps) {
|
|
return ConstantExpr::getInsertValue(/*AggregateOperand*/ COps[0],
|
|
/*InsertedValueOperand*/ COps[1],
|
|
I.getIndices());
|
|
}))
|
|
return true;
|
|
|
|
// SROA can look through these but give them a cost.
|
|
return false;
|
|
}
|
|
|
|
/// Try to simplify a call site.
|
|
///
|
|
/// Takes a concrete function and callsite and tries to actually simplify it by
|
|
/// analyzing the arguments and call itself with instsimplify. Returns true if
|
|
/// it has simplified the callsite to some other entity (a constant), making it
|
|
/// free.
|
|
bool CallAnalyzer::simplifyCallSite(Function *F, CallBase &Call) {
|
|
// FIXME: Using the instsimplify logic directly for this is inefficient
|
|
// because we have to continually rebuild the argument list even when no
|
|
// simplifications can be performed. Until that is fixed with remapping
|
|
// inside of instsimplify, directly constant fold calls here.
|
|
if (!canConstantFoldCallTo(&Call, F))
|
|
return false;
|
|
|
|
// Try to re-map the arguments to constants.
|
|
SmallVector<Constant *, 4> ConstantArgs;
|
|
ConstantArgs.reserve(Call.arg_size());
|
|
for (Value *I : Call.args()) {
|
|
Constant *C = dyn_cast<Constant>(I);
|
|
if (!C)
|
|
C = dyn_cast_or_null<Constant>(SimplifiedValues.lookup(I));
|
|
if (!C)
|
|
return false; // This argument doesn't map to a constant.
|
|
|
|
ConstantArgs.push_back(C);
|
|
}
|
|
if (Constant *C = ConstantFoldCall(&Call, F, ConstantArgs)) {
|
|
SimplifiedValues[&Call] = C;
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitCallBase(CallBase &Call) {
|
|
if (Call.hasFnAttr(Attribute::ReturnsTwice) &&
|
|
!F.hasFnAttribute(Attribute::ReturnsTwice)) {
|
|
// This aborts the entire analysis.
|
|
ExposesReturnsTwice = true;
|
|
return false;
|
|
}
|
|
if (isa<CallInst>(Call) && cast<CallInst>(Call).cannotDuplicate())
|
|
ContainsNoDuplicateCall = true;
|
|
|
|
Value *Callee = Call.getCalledOperand();
|
|
Function *F = dyn_cast_or_null<Function>(Callee);
|
|
bool IsIndirectCall = !F;
|
|
if (IsIndirectCall) {
|
|
// Check if this happens to be an indirect function call to a known function
|
|
// in this inline context. If not, we've done all we can.
|
|
F = dyn_cast_or_null<Function>(SimplifiedValues.lookup(Callee));
|
|
if (!F) {
|
|
onCallArgumentSetup(Call);
|
|
|
|
if (!Call.onlyReadsMemory())
|
|
disableLoadElimination();
|
|
return Base::visitCallBase(Call);
|
|
}
|
|
}
|
|
|
|
assert(F && "Expected a call to a known function");
|
|
|
|
// When we have a concrete function, first try to simplify it directly.
|
|
if (simplifyCallSite(F, Call))
|
|
return true;
|
|
|
|
// Next check if it is an intrinsic we know about.
|
|
// FIXME: Lift this into part of the InstVisitor.
|
|
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(&Call)) {
|
|
switch (II->getIntrinsicID()) {
|
|
default:
|
|
if (!Call.onlyReadsMemory() && !isAssumeLikeIntrinsic(II))
|
|
disableLoadElimination();
|
|
return Base::visitCallBase(Call);
|
|
|
|
case Intrinsic::load_relative:
|
|
onLoadRelativeIntrinsic();
|
|
return false;
|
|
|
|
case Intrinsic::memset:
|
|
case Intrinsic::memcpy:
|
|
case Intrinsic::memmove:
|
|
disableLoadElimination();
|
|
// SROA can usually chew through these intrinsics, but they aren't free.
|
|
return false;
|
|
case Intrinsic::icall_branch_funnel:
|
|
case Intrinsic::localescape:
|
|
HasUninlineableIntrinsic = true;
|
|
return false;
|
|
case Intrinsic::vastart:
|
|
InitsVargArgs = true;
|
|
return false;
|
|
}
|
|
}
|
|
|
|
if (F == Call.getFunction()) {
|
|
// This flag will fully abort the analysis, so don't bother with anything
|
|
// else.
|
|
IsRecursiveCall = true;
|
|
return false;
|
|
}
|
|
|
|
if (TTI.isLoweredToCall(F)) {
|
|
onLoweredCall(F, Call, IsIndirectCall);
|
|
}
|
|
|
|
if (!(Call.onlyReadsMemory() || (IsIndirectCall && F->onlyReadsMemory())))
|
|
disableLoadElimination();
|
|
return Base::visitCallBase(Call);
|
|
}
|
|
|
|
bool CallAnalyzer::visitReturnInst(ReturnInst &RI) {
|
|
// At least one return instruction will be free after inlining.
|
|
bool Free = !HasReturn;
|
|
HasReturn = true;
|
|
return Free;
|
|
}
|
|
|
|
bool CallAnalyzer::visitBranchInst(BranchInst &BI) {
|
|
// We model unconditional branches as essentially free -- they really
|
|
// shouldn't exist at all, but handling them makes the behavior of the
|
|
// inliner more regular and predictable. Interestingly, conditional branches
|
|
// which will fold away are also free.
|
|
return BI.isUnconditional() || isa<ConstantInt>(BI.getCondition()) ||
|
|
dyn_cast_or_null<ConstantInt>(
|
|
SimplifiedValues.lookup(BI.getCondition()));
|
|
}
|
|
|
|
bool CallAnalyzer::visitSelectInst(SelectInst &SI) {
|
|
bool CheckSROA = SI.getType()->isPointerTy();
|
|
Value *TrueVal = SI.getTrueValue();
|
|
Value *FalseVal = SI.getFalseValue();
|
|
|
|
Constant *TrueC = dyn_cast<Constant>(TrueVal);
|
|
if (!TrueC)
|
|
TrueC = SimplifiedValues.lookup(TrueVal);
|
|
Constant *FalseC = dyn_cast<Constant>(FalseVal);
|
|
if (!FalseC)
|
|
FalseC = SimplifiedValues.lookup(FalseVal);
|
|
Constant *CondC =
|
|
dyn_cast_or_null<Constant>(SimplifiedValues.lookup(SI.getCondition()));
|
|
|
|
if (!CondC) {
|
|
// Select C, X, X => X
|
|
if (TrueC == FalseC && TrueC) {
|
|
SimplifiedValues[&SI] = TrueC;
|
|
return true;
|
|
}
|
|
|
|
if (!CheckSROA)
|
|
return Base::visitSelectInst(SI);
|
|
|
|
std::pair<Value *, APInt> TrueBaseAndOffset =
|
|
ConstantOffsetPtrs.lookup(TrueVal);
|
|
std::pair<Value *, APInt> FalseBaseAndOffset =
|
|
ConstantOffsetPtrs.lookup(FalseVal);
|
|
if (TrueBaseAndOffset == FalseBaseAndOffset && TrueBaseAndOffset.first) {
|
|
ConstantOffsetPtrs[&SI] = TrueBaseAndOffset;
|
|
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(TrueVal))
|
|
SROAArgValues[&SI] = SROAArg;
|
|
return true;
|
|
}
|
|
|
|
return Base::visitSelectInst(SI);
|
|
}
|
|
|
|
// Select condition is a constant.
|
|
Value *SelectedV = CondC->isAllOnesValue()
|
|
? TrueVal
|
|
: (CondC->isNullValue()) ? FalseVal : nullptr;
|
|
if (!SelectedV) {
|
|
// Condition is a vector constant that is not all 1s or all 0s. If all
|
|
// operands are constants, ConstantExpr::getSelect() can handle the cases
|
|
// such as select vectors.
|
|
if (TrueC && FalseC) {
|
|
if (auto *C = ConstantExpr::getSelect(CondC, TrueC, FalseC)) {
|
|
SimplifiedValues[&SI] = C;
|
|
return true;
|
|
}
|
|
}
|
|
return Base::visitSelectInst(SI);
|
|
}
|
|
|
|
// Condition is either all 1s or all 0s. SI can be simplified.
|
|
if (Constant *SelectedC = dyn_cast<Constant>(SelectedV)) {
|
|
SimplifiedValues[&SI] = SelectedC;
|
|
return true;
|
|
}
|
|
|
|
if (!CheckSROA)
|
|
return true;
|
|
|
|
std::pair<Value *, APInt> BaseAndOffset =
|
|
ConstantOffsetPtrs.lookup(SelectedV);
|
|
if (BaseAndOffset.first) {
|
|
ConstantOffsetPtrs[&SI] = BaseAndOffset;
|
|
|
|
if (auto *SROAArg = getSROAArgForValueOrNull(SelectedV))
|
|
SROAArgValues[&SI] = SROAArg;
|
|
}
|
|
|
|
return true;
|
|
}
|
|
|
|
bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
|
|
// We model unconditional switches as free, see the comments on handling
|
|
// branches.
|
|
if (isa<ConstantInt>(SI.getCondition()))
|
|
return true;
|
|
if (Value *V = SimplifiedValues.lookup(SI.getCondition()))
|
|
if (isa<ConstantInt>(V))
|
|
return true;
|
|
|
|
// Assume the most general case where the switch is lowered into
|
|
// either a jump table, bit test, or a balanced binary tree consisting of
|
|
// case clusters without merging adjacent clusters with the same
|
|
// destination. We do not consider the switches that are lowered with a mix
|
|
// of jump table/bit test/binary search tree. The cost of the switch is
|
|
// proportional to the size of the tree or the size of jump table range.
|
|
//
|
|
// NB: We convert large switches which are just used to initialize large phi
|
|
// nodes to lookup tables instead in simplify-cfg, so this shouldn't prevent
|
|
// inlining those. It will prevent inlining in cases where the optimization
|
|
// does not (yet) fire.
|
|
|
|
unsigned JumpTableSize = 0;
|
|
BlockFrequencyInfo *BFI = GetBFI ? &((*GetBFI)(F)) : nullptr;
|
|
unsigned NumCaseCluster =
|
|
TTI.getEstimatedNumberOfCaseClusters(SI, JumpTableSize, PSI, BFI);
|
|
|
|
onFinalizeSwitch(JumpTableSize, NumCaseCluster);
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitIndirectBrInst(IndirectBrInst &IBI) {
|
|
// We never want to inline functions that contain an indirectbr. This is
|
|
// incorrect because all the blockaddress's (in static global initializers
|
|
// for example) would be referring to the original function, and this
|
|
// indirect jump would jump from the inlined copy of the function into the
|
|
// original function which is extremely undefined behavior.
|
|
// FIXME: This logic isn't really right; we can safely inline functions with
|
|
// indirectbr's as long as no other function or global references the
|
|
// blockaddress of a block within the current function.
|
|
HasIndirectBr = true;
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitResumeInst(ResumeInst &RI) {
|
|
// FIXME: It's not clear that a single instruction is an accurate model for
|
|
// the inline cost of a resume instruction.
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitCleanupReturnInst(CleanupReturnInst &CRI) {
|
|
// FIXME: It's not clear that a single instruction is an accurate model for
|
|
// the inline cost of a cleanupret instruction.
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitCatchReturnInst(CatchReturnInst &CRI) {
|
|
// FIXME: It's not clear that a single instruction is an accurate model for
|
|
// the inline cost of a catchret instruction.
|
|
return false;
|
|
}
|
|
|
|
bool CallAnalyzer::visitUnreachableInst(UnreachableInst &I) {
|
|
// FIXME: It might be reasonably to discount the cost of instructions leading
|
|
// to unreachable as they have the lowest possible impact on both runtime and
|
|
// code size.
|
|
return true; // No actual code is needed for unreachable.
|
|
}
|
|
|
|
bool CallAnalyzer::visitInstruction(Instruction &I) {
|
|
// Some instructions are free. All of the free intrinsics can also be
|
|
// handled by SROA, etc.
|
|
if (TargetTransformInfo::TCC_Free == TTI.getUserCost(&I))
|
|
return true;
|
|
|
|
// We found something we don't understand or can't handle. Mark any SROA-able
|
|
// values in the operand list as no longer viable.
|
|
for (User::op_iterator OI = I.op_begin(), OE = I.op_end(); OI != OE; ++OI)
|
|
disableSROA(*OI);
|
|
|
|
return false;
|
|
}
|
|
|
|
/// Analyze a basic block for its contribution to the inline cost.
|
|
///
|
|
/// This method walks the analyzer over every instruction in the given basic
|
|
/// block and accounts for their cost during inlining at this callsite. It
|
|
/// aborts early if the threshold has been exceeded or an impossible to inline
|
|
/// construct has been detected. It returns false if inlining is no longer
|
|
/// viable, and true if inlining remains viable.
|
|
InlineResult
|
|
CallAnalyzer::analyzeBlock(BasicBlock *BB,
|
|
SmallPtrSetImpl<const Value *> &EphValues) {
|
|
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
|
|
// FIXME: Currently, the number of instructions in a function regardless of
|
|
// our ability to simplify them during inline to constants or dead code,
|
|
// are actually used by the vector bonus heuristic. As long as that's true,
|
|
// we have to special case debug intrinsics here to prevent differences in
|
|
// inlining due to debug symbols. Eventually, the number of unsimplified
|
|
// instructions shouldn't factor into the cost computation, but until then,
|
|
// hack around it here.
|
|
if (isa<DbgInfoIntrinsic>(I))
|
|
continue;
|
|
|
|
// Skip ephemeral values.
|
|
if (EphValues.count(&*I))
|
|
continue;
|
|
|
|
++NumInstructions;
|
|
if (isa<ExtractElementInst>(I) || I->getType()->isVectorTy())
|
|
++NumVectorInstructions;
|
|
|
|
// If the instruction simplified to a constant, there is no cost to this
|
|
// instruction. Visit the instructions using our InstVisitor to account for
|
|
// all of the per-instruction logic. The visit tree returns true if we
|
|
// consumed the instruction in any way, and false if the instruction's base
|
|
// cost should count against inlining.
|
|
if (Base::visit(&*I))
|
|
++NumInstructionsSimplified;
|
|
else
|
|
onMissedSimplification();
|
|
|
|
using namespace ore;
|
|
// If the visit this instruction detected an uninlinable pattern, abort.
|
|
InlineResult IR = InlineResult::success();
|
|
if (IsRecursiveCall)
|
|
IR = InlineResult::failure("recursive");
|
|
else if (ExposesReturnsTwice)
|
|
IR = InlineResult::failure("exposes returns twice");
|
|
else if (HasDynamicAlloca)
|
|
IR = InlineResult::failure("dynamic alloca");
|
|
else if (HasIndirectBr)
|
|
IR = InlineResult::failure("indirect branch");
|
|
else if (HasUninlineableIntrinsic)
|
|
IR = InlineResult::failure("uninlinable intrinsic");
|
|
else if (InitsVargArgs)
|
|
IR = InlineResult::failure("varargs");
|
|
if (!IR.isSuccess()) {
|
|
if (ORE)
|
|
ORE->emit([&]() {
|
|
return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline",
|
|
&CandidateCall)
|
|
<< NV("Callee", &F) << " has uninlinable pattern ("
|
|
<< NV("InlineResult", IR.getFailureReason())
|
|
<< ") and cost is not fully computed";
|
|
});
|
|
return IR;
|
|
}
|
|
|
|
// If the caller is a recursive function then we don't want to inline
|
|
// functions which allocate a lot of stack space because it would increase
|
|
// the caller stack usage dramatically.
|
|
if (IsCallerRecursive &&
|
|
AllocatedSize > InlineConstants::TotalAllocaSizeRecursiveCaller) {
|
|
auto IR =
|
|
InlineResult::failure("recursive and allocates too much stack space");
|
|
if (ORE)
|
|
ORE->emit([&]() {
|
|
return OptimizationRemarkMissed(DEBUG_TYPE, "NeverInline",
|
|
&CandidateCall)
|
|
<< NV("Callee", &F) << " is "
|
|
<< NV("InlineResult", IR.getFailureReason())
|
|
<< ". Cost is not fully computed";
|
|
});
|
|
return IR;
|
|
}
|
|
|
|
if (shouldStop())
|
|
return InlineResult::failure(
|
|
"Call site analysis is not favorable to inlining.");
|
|
}
|
|
|
|
return InlineResult::success();
|
|
}
|
|
|
|
/// Compute the base pointer and cumulative constant offsets for V.
|
|
///
|
|
/// This strips all constant offsets off of V, leaving it the base pointer, and
|
|
/// accumulates the total constant offset applied in the returned constant. It
|
|
/// returns 0 if V is not a pointer, and returns the constant '0' if there are
|
|
/// no constant offsets applied.
|
|
ConstantInt *CallAnalyzer::stripAndComputeInBoundsConstantOffsets(Value *&V) {
|
|
if (!V->getType()->isPointerTy())
|
|
return nullptr;
|
|
|
|
unsigned AS = V->getType()->getPointerAddressSpace();
|
|
unsigned IntPtrWidth = DL.getIndexSizeInBits(AS);
|
|
APInt Offset = APInt::getNullValue(IntPtrWidth);
|
|
|
|
// Even though we don't look through PHI nodes, we could be called on an
|
|
// instruction in an unreachable block, which may be on a cycle.
|
|
SmallPtrSet<Value *, 4> Visited;
|
|
Visited.insert(V);
|
|
do {
|
|
if (GEPOperator *GEP = dyn_cast<GEPOperator>(V)) {
|
|
if (!GEP->isInBounds() || !accumulateGEPOffset(*GEP, Offset))
|
|
return nullptr;
|
|
V = GEP->getPointerOperand();
|
|
} else if (Operator::getOpcode(V) == Instruction::BitCast) {
|
|
V = cast<Operator>(V)->getOperand(0);
|
|
} else if (GlobalAlias *GA = dyn_cast<GlobalAlias>(V)) {
|
|
if (GA->isInterposable())
|
|
break;
|
|
V = GA->getAliasee();
|
|
} else {
|
|
break;
|
|
}
|
|
assert(V->getType()->isPointerTy() && "Unexpected operand type!");
|
|
} while (Visited.insert(V).second);
|
|
|
|
Type *IdxPtrTy = DL.getIndexType(V->getType());
|
|
return cast<ConstantInt>(ConstantInt::get(IdxPtrTy, Offset));
|
|
}
|
|
|
|
/// Find dead blocks due to deleted CFG edges during inlining.
|
|
///
|
|
/// If we know the successor of the current block, \p CurrBB, has to be \p
|
|
/// NextBB, the other successors of \p CurrBB are dead if these successors have
|
|
/// no live incoming CFG edges. If one block is found to be dead, we can
|
|
/// continue growing the dead block list by checking the successors of the dead
|
|
/// blocks to see if all their incoming edges are dead or not.
|
|
void CallAnalyzer::findDeadBlocks(BasicBlock *CurrBB, BasicBlock *NextBB) {
|
|
auto IsEdgeDead = [&](BasicBlock *Pred, BasicBlock *Succ) {
|
|
// A CFG edge is dead if the predecessor is dead or the predecessor has a
|
|
// known successor which is not the one under exam.
|
|
return (DeadBlocks.count(Pred) ||
|
|
(KnownSuccessors[Pred] && KnownSuccessors[Pred] != Succ));
|
|
};
|
|
|
|
auto IsNewlyDead = [&](BasicBlock *BB) {
|
|
// If all the edges to a block are dead, the block is also dead.
|
|
return (!DeadBlocks.count(BB) &&
|
|
llvm::all_of(predecessors(BB),
|
|
[&](BasicBlock *P) { return IsEdgeDead(P, BB); }));
|
|
};
|
|
|
|
for (BasicBlock *Succ : successors(CurrBB)) {
|
|
if (Succ == NextBB || !IsNewlyDead(Succ))
|
|
continue;
|
|
SmallVector<BasicBlock *, 4> NewDead;
|
|
NewDead.push_back(Succ);
|
|
while (!NewDead.empty()) {
|
|
BasicBlock *Dead = NewDead.pop_back_val();
|
|
if (DeadBlocks.insert(Dead))
|
|
// Continue growing the dead block lists.
|
|
for (BasicBlock *S : successors(Dead))
|
|
if (IsNewlyDead(S))
|
|
NewDead.push_back(S);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Analyze a call site for potential inlining.
|
|
///
|
|
/// Returns true if inlining this call is viable, and false if it is not
|
|
/// viable. It computes the cost and adjusts the threshold based on numerous
|
|
/// factors and heuristics. If this method returns false but the computed cost
|
|
/// is below the computed threshold, then inlining was forcibly disabled by
|
|
/// some artifact of the routine.
|
|
InlineResult CallAnalyzer::analyze() {
|
|
++NumCallsAnalyzed;
|
|
|
|
auto Result = onAnalysisStart();
|
|
if (!Result.isSuccess())
|
|
return Result;
|
|
|
|
if (F.empty())
|
|
return InlineResult::success();
|
|
|
|
Function *Caller = CandidateCall.getFunction();
|
|
// Check if the caller function is recursive itself.
|
|
for (User *U : Caller->users()) {
|
|
CallBase *Call = dyn_cast<CallBase>(U);
|
|
if (Call && Call->getFunction() == Caller) {
|
|
IsCallerRecursive = true;
|
|
break;
|
|
}
|
|
}
|
|
|
|
// Populate our simplified values by mapping from function arguments to call
|
|
// arguments with known important simplifications.
|
|
auto CAI = CandidateCall.arg_begin();
|
|
for (Function::arg_iterator FAI = F.arg_begin(), FAE = F.arg_end();
|
|
FAI != FAE; ++FAI, ++CAI) {
|
|
assert(CAI != CandidateCall.arg_end());
|
|
if (Constant *C = dyn_cast<Constant>(CAI))
|
|
SimplifiedValues[&*FAI] = C;
|
|
|
|
Value *PtrArg = *CAI;
|
|
if (ConstantInt *C = stripAndComputeInBoundsConstantOffsets(PtrArg)) {
|
|
ConstantOffsetPtrs[&*FAI] = std::make_pair(PtrArg, C->getValue());
|
|
|
|
// We can SROA any pointer arguments derived from alloca instructions.
|
|
if (auto *SROAArg = dyn_cast<AllocaInst>(PtrArg)) {
|
|
SROAArgValues[&*FAI] = SROAArg;
|
|
onInitializeSROAArg(SROAArg);
|
|
EnabledSROAAllocas.insert(SROAArg);
|
|
}
|
|
}
|
|
}
|
|
NumConstantArgs = SimplifiedValues.size();
|
|
NumConstantOffsetPtrArgs = ConstantOffsetPtrs.size();
|
|
NumAllocaArgs = SROAArgValues.size();
|
|
|
|
// FIXME: If a caller has multiple calls to a callee, we end up recomputing
|
|
// the ephemeral values multiple times (and they're completely determined by
|
|
// the callee, so this is purely duplicate work).
|
|
SmallPtrSet<const Value *, 32> EphValues;
|
|
CodeMetrics::collectEphemeralValues(&F, &GetAssumptionCache(F), EphValues);
|
|
|
|
// The worklist of live basic blocks in the callee *after* inlining. We avoid
|
|
// adding basic blocks of the callee which can be proven to be dead for this
|
|
// particular call site in order to get more accurate cost estimates. This
|
|
// requires a somewhat heavyweight iteration pattern: we need to walk the
|
|
// basic blocks in a breadth-first order as we insert live successors. To
|
|
// accomplish this, prioritizing for small iterations because we exit after
|
|
// crossing our threshold, we use a small-size optimized SetVector.
|
|
typedef SetVector<BasicBlock *, SmallVector<BasicBlock *, 16>,
|
|
SmallPtrSet<BasicBlock *, 16>>
|
|
BBSetVector;
|
|
BBSetVector BBWorklist;
|
|
BBWorklist.insert(&F.getEntryBlock());
|
|
|
|
// Note that we *must not* cache the size, this loop grows the worklist.
|
|
for (unsigned Idx = 0; Idx != BBWorklist.size(); ++Idx) {
|
|
if (shouldStop())
|
|
break;
|
|
|
|
BasicBlock *BB = BBWorklist[Idx];
|
|
if (BB->empty())
|
|
continue;
|
|
|
|
// Disallow inlining a blockaddress with uses other than strictly callbr.
|
|
// A blockaddress only has defined behavior for an indirect branch in the
|
|
// same function, and we do not currently support inlining indirect
|
|
// branches. But, the inliner may not see an indirect branch that ends up
|
|
// being dead code at a particular call site. If the blockaddress escapes
|
|
// the function, e.g., via a global variable, inlining may lead to an
|
|
// invalid cross-function reference.
|
|
// FIXME: pr/39560: continue relaxing this overt restriction.
|
|
if (BB->hasAddressTaken())
|
|
for (User *U : BlockAddress::get(&*BB)->users())
|
|
if (!isa<CallBrInst>(*U))
|
|
return InlineResult::failure("blockaddress used outside of callbr");
|
|
|
|
// Analyze the cost of this block. If we blow through the threshold, this
|
|
// returns false, and we can bail on out.
|
|
InlineResult IR = analyzeBlock(BB, EphValues);
|
|
if (!IR.isSuccess())
|
|
return IR;
|
|
|
|
Instruction *TI = BB->getTerminator();
|
|
|
|
// Add in the live successors by first checking whether we have terminator
|
|
// that may be simplified based on the values simplified by this call.
|
|
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
|
|
if (BI->isConditional()) {
|
|
Value *Cond = BI->getCondition();
|
|
if (ConstantInt *SimpleCond =
|
|
dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
|
|
BasicBlock *NextBB = BI->getSuccessor(SimpleCond->isZero() ? 1 : 0);
|
|
BBWorklist.insert(NextBB);
|
|
KnownSuccessors[BB] = NextBB;
|
|
findDeadBlocks(BB, NextBB);
|
|
continue;
|
|
}
|
|
}
|
|
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
|
|
Value *Cond = SI->getCondition();
|
|
if (ConstantInt *SimpleCond =
|
|
dyn_cast_or_null<ConstantInt>(SimplifiedValues.lookup(Cond))) {
|
|
BasicBlock *NextBB = SI->findCaseValue(SimpleCond)->getCaseSuccessor();
|
|
BBWorklist.insert(NextBB);
|
|
KnownSuccessors[BB] = NextBB;
|
|
findDeadBlocks(BB, NextBB);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// If we're unable to select a particular successor, just count all of
|
|
// them.
|
|
for (unsigned TIdx = 0, TSize = TI->getNumSuccessors(); TIdx != TSize;
|
|
++TIdx)
|
|
BBWorklist.insert(TI->getSuccessor(TIdx));
|
|
|
|
onBlockAnalyzed(BB);
|
|
}
|
|
|
|
bool OnlyOneCallAndLocalLinkage = F.hasLocalLinkage() && F.hasOneUse() &&
|
|
&F == CandidateCall.getCalledFunction();
|
|
// If this is a noduplicate call, we can still inline as long as
|
|
// inlining this would cause the removal of the caller (so the instruction
|
|
// is not actually duplicated, just moved).
|
|
if (!OnlyOneCallAndLocalLinkage && ContainsNoDuplicateCall)
|
|
return InlineResult::failure("noduplicate");
|
|
|
|
return finalizeAnalysis();
|
|
}
|
|
|
|
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
|
|
/// Dump stats about this call's analysis.
|
|
LLVM_DUMP_METHOD void InlineCostCallAnalyzer::dump() {
|
|
#define DEBUG_PRINT_STAT(x) dbgs() << " " #x ": " << x << "\n"
|
|
DEBUG_PRINT_STAT(NumConstantArgs);
|
|
DEBUG_PRINT_STAT(NumConstantOffsetPtrArgs);
|
|
DEBUG_PRINT_STAT(NumAllocaArgs);
|
|
DEBUG_PRINT_STAT(NumConstantPtrCmps);
|
|
DEBUG_PRINT_STAT(NumConstantPtrDiffs);
|
|
DEBUG_PRINT_STAT(NumInstructionsSimplified);
|
|
DEBUG_PRINT_STAT(NumInstructions);
|
|
DEBUG_PRINT_STAT(SROACostSavings);
|
|
DEBUG_PRINT_STAT(SROACostSavingsLost);
|
|
DEBUG_PRINT_STAT(LoadEliminationCost);
|
|
DEBUG_PRINT_STAT(ContainsNoDuplicateCall);
|
|
DEBUG_PRINT_STAT(Cost);
|
|
DEBUG_PRINT_STAT(Threshold);
|
|
#undef DEBUG_PRINT_STAT
|
|
}
|
|
#endif
|
|
|
|
/// Test that there are no attribute conflicts between Caller and Callee
|
|
/// that prevent inlining.
|
|
static bool functionsHaveCompatibleAttributes(Function *Caller,
|
|
Function *Callee,
|
|
TargetTransformInfo &TTI) {
|
|
return TTI.areInlineCompatible(Caller, Callee) &&
|
|
AttributeFuncs::areInlineCompatible(*Caller, *Callee);
|
|
}
|
|
|
|
int llvm::getCallsiteCost(CallBase &Call, const DataLayout &DL) {
|
|
int Cost = 0;
|
|
for (unsigned I = 0, E = Call.arg_size(); I != E; ++I) {
|
|
if (Call.isByValArgument(I)) {
|
|
// We approximate the number of loads and stores needed by dividing the
|
|
// size of the byval type by the target's pointer size.
|
|
PointerType *PTy = cast<PointerType>(Call.getArgOperand(I)->getType());
|
|
unsigned TypeSize = DL.getTypeSizeInBits(PTy->getElementType());
|
|
unsigned AS = PTy->getAddressSpace();
|
|
unsigned PointerSize = DL.getPointerSizeInBits(AS);
|
|
// Ceiling division.
|
|
unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;
|
|
|
|
// If it generates more than 8 stores it is likely to be expanded as an
|
|
// inline memcpy so we take that as an upper bound. Otherwise we assume
|
|
// one load and one store per word copied.
|
|
// FIXME: The maxStoresPerMemcpy setting from the target should be used
|
|
// here instead of a magic number of 8, but it's not available via
|
|
// DataLayout.
|
|
NumStores = std::min(NumStores, 8U);
|
|
|
|
Cost += 2 * NumStores * InlineConstants::InstrCost;
|
|
} else {
|
|
// For non-byval arguments subtract off one instruction per call
|
|
// argument.
|
|
Cost += InlineConstants::InstrCost;
|
|
}
|
|
}
|
|
// The call instruction also disappears after inlining.
|
|
Cost += InlineConstants::InstrCost + InlineConstants::CallPenalty;
|
|
return Cost;
|
|
}
|
|
|
|
InlineCost llvm::getInlineCost(
|
|
CallBase &Call, const InlineParams &Params, TargetTransformInfo &CalleeTTI,
|
|
std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
|
|
Optional<function_ref<BlockFrequencyInfo &(Function &)>> GetBFI,
|
|
ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
|
|
return getInlineCost(Call, Call.getCalledFunction(), Params, CalleeTTI,
|
|
GetAssumptionCache, GetBFI, PSI, ORE);
|
|
}
|
|
|
|
InlineCost llvm::getInlineCost(
|
|
CallBase &Call, Function *Callee, const InlineParams &Params,
|
|
TargetTransformInfo &CalleeTTI,
|
|
std::function<AssumptionCache &(Function &)> &GetAssumptionCache,
|
|
Optional<function_ref<BlockFrequencyInfo &(Function &)>> GetBFI,
|
|
ProfileSummaryInfo *PSI, OptimizationRemarkEmitter *ORE) {
|
|
|
|
// Cannot inline indirect calls.
|
|
if (!Callee)
|
|
return llvm::InlineCost::getNever("indirect call");
|
|
|
|
// Never inline calls with byval arguments that does not have the alloca
|
|
// address space. Since byval arguments can be replaced with a copy to an
|
|
// alloca, the inlined code would need to be adjusted to handle that the
|
|
// argument is in the alloca address space (so it is a little bit complicated
|
|
// to solve).
|
|
unsigned AllocaAS = Callee->getParent()->getDataLayout().getAllocaAddrSpace();
|
|
for (unsigned I = 0, E = Call.arg_size(); I != E; ++I)
|
|
if (Call.isByValArgument(I)) {
|
|
PointerType *PTy = cast<PointerType>(Call.getArgOperand(I)->getType());
|
|
if (PTy->getAddressSpace() != AllocaAS)
|
|
return llvm::InlineCost::getNever("byval arguments without alloca"
|
|
" address space");
|
|
}
|
|
|
|
// Calls to functions with always-inline attributes should be inlined
|
|
// whenever possible.
|
|
if (Call.hasFnAttr(Attribute::AlwaysInline)) {
|
|
auto IsViable = isInlineViable(*Callee);
|
|
if (IsViable.isSuccess())
|
|
return llvm::InlineCost::getAlways("always inline attribute");
|
|
return llvm::InlineCost::getNever(IsViable.getFailureReason());
|
|
}
|
|
|
|
// Never inline functions with conflicting attributes (unless callee has
|
|
// always-inline attribute).
|
|
Function *Caller = Call.getCaller();
|
|
if (!functionsHaveCompatibleAttributes(Caller, Callee, CalleeTTI))
|
|
return llvm::InlineCost::getNever("conflicting attributes");
|
|
|
|
// Don't inline this call if the caller has the optnone attribute.
|
|
if (Caller->hasOptNone())
|
|
return llvm::InlineCost::getNever("optnone attribute");
|
|
|
|
// Don't inline a function that treats null pointer as valid into a caller
|
|
// that does not have this attribute.
|
|
if (!Caller->nullPointerIsDefined() && Callee->nullPointerIsDefined())
|
|
return llvm::InlineCost::getNever("nullptr definitions incompatible");
|
|
|
|
// Don't inline functions which can be interposed at link-time.
|
|
if (Callee->isInterposable())
|
|
return llvm::InlineCost::getNever("interposable");
|
|
|
|
// Don't inline functions marked noinline.
|
|
if (Callee->hasFnAttribute(Attribute::NoInline))
|
|
return llvm::InlineCost::getNever("noinline function attribute");
|
|
|
|
// Don't inline call sites marked noinline.
|
|
if (Call.isNoInline())
|
|
return llvm::InlineCost::getNever("noinline call site attribute");
|
|
|
|
LLVM_DEBUG(llvm::dbgs() << " Analyzing call of " << Callee->getName()
|
|
<< "... (caller:" << Caller->getName() << ")\n");
|
|
|
|
InlineCostCallAnalyzer CA(CalleeTTI, GetAssumptionCache, GetBFI, PSI, ORE,
|
|
*Callee, Call, Params);
|
|
InlineResult ShouldInline = CA.analyze();
|
|
|
|
LLVM_DEBUG(CA.dump());
|
|
|
|
// Check if there was a reason to force inlining or no inlining.
|
|
if (!ShouldInline.isSuccess() && CA.getCost() < CA.getThreshold())
|
|
return InlineCost::getNever(ShouldInline.getFailureReason());
|
|
if (ShouldInline.isSuccess() && CA.getCost() >= CA.getThreshold())
|
|
return InlineCost::getAlways("empty function");
|
|
|
|
return llvm::InlineCost::get(CA.getCost(), CA.getThreshold());
|
|
}
|
|
|
|
InlineResult llvm::isInlineViable(Function &F) {
|
|
bool ReturnsTwice = F.hasFnAttribute(Attribute::ReturnsTwice);
|
|
for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE; ++BI) {
|
|
// Disallow inlining of functions which contain indirect branches.
|
|
if (isa<IndirectBrInst>(BI->getTerminator()))
|
|
return InlineResult::failure("contains indirect branches");
|
|
|
|
// Disallow inlining of blockaddresses which are used by non-callbr
|
|
// instructions.
|
|
if (BI->hasAddressTaken())
|
|
for (User *U : BlockAddress::get(&*BI)->users())
|
|
if (!isa<CallBrInst>(*U))
|
|
return InlineResult::failure("blockaddress used outside of callbr");
|
|
|
|
for (auto &II : *BI) {
|
|
CallBase *Call = dyn_cast<CallBase>(&II);
|
|
if (!Call)
|
|
continue;
|
|
|
|
// Disallow recursive calls.
|
|
if (&F == Call->getCalledFunction())
|
|
return InlineResult::failure("recursive call");
|
|
|
|
// Disallow calls which expose returns-twice to a function not previously
|
|
// attributed as such.
|
|
if (!ReturnsTwice && isa<CallInst>(Call) &&
|
|
cast<CallInst>(Call)->canReturnTwice())
|
|
return InlineResult::failure("exposes returns-twice attribute");
|
|
|
|
if (Call->getCalledFunction())
|
|
switch (Call->getCalledFunction()->getIntrinsicID()) {
|
|
default:
|
|
break;
|
|
case llvm::Intrinsic::icall_branch_funnel:
|
|
// Disallow inlining of @llvm.icall.branch.funnel because current
|
|
// backend can't separate call targets from call arguments.
|
|
return InlineResult::failure(
|
|
"disallowed inlining of @llvm.icall.branch.funnel");
|
|
case llvm::Intrinsic::localescape:
|
|
// Disallow inlining functions that call @llvm.localescape. Doing this
|
|
// correctly would require major changes to the inliner.
|
|
return InlineResult::failure(
|
|
"disallowed inlining of @llvm.localescape");
|
|
case llvm::Intrinsic::vastart:
|
|
// Disallow inlining of functions that initialize VarArgs with
|
|
// va_start.
|
|
return InlineResult::failure(
|
|
"contains VarArgs initialized with va_start");
|
|
}
|
|
}
|
|
}
|
|
|
|
return InlineResult::success();
|
|
}
|
|
|
|
// APIs to create InlineParams based on command line flags and/or other
|
|
// parameters.
|
|
|
|
InlineParams llvm::getInlineParams(int Threshold) {
|
|
InlineParams Params;
|
|
|
|
// This field is the threshold to use for a callee by default. This is
|
|
// derived from one or more of:
|
|
// * optimization or size-optimization levels,
|
|
// * a value passed to createFunctionInliningPass function, or
|
|
// * the -inline-threshold flag.
|
|
// If the -inline-threshold flag is explicitly specified, that is used
|
|
// irrespective of anything else.
|
|
if (InlineThreshold.getNumOccurrences() > 0)
|
|
Params.DefaultThreshold = InlineThreshold;
|
|
else
|
|
Params.DefaultThreshold = Threshold;
|
|
|
|
// Set the HintThreshold knob from the -inlinehint-threshold.
|
|
Params.HintThreshold = HintThreshold;
|
|
|
|
// Set the HotCallSiteThreshold knob from the -hot-callsite-threshold.
|
|
Params.HotCallSiteThreshold = HotCallSiteThreshold;
|
|
|
|
// If the -locally-hot-callsite-threshold is explicitly specified, use it to
|
|
// populate LocallyHotCallSiteThreshold. Later, we populate
|
|
// Params.LocallyHotCallSiteThreshold from -locally-hot-callsite-threshold if
|
|
// we know that optimization level is O3 (in the getInlineParams variant that
|
|
// takes the opt and size levels).
|
|
// FIXME: Remove this check (and make the assignment unconditional) after
|
|
// addressing size regression issues at O2.
|
|
if (LocallyHotCallSiteThreshold.getNumOccurrences() > 0)
|
|
Params.LocallyHotCallSiteThreshold = LocallyHotCallSiteThreshold;
|
|
|
|
// Set the ColdCallSiteThreshold knob from the
|
|
// -inline-cold-callsite-threshold.
|
|
Params.ColdCallSiteThreshold = ColdCallSiteThreshold;
|
|
|
|
// Set the OptMinSizeThreshold and OptSizeThreshold params only if the
|
|
// -inlinehint-threshold commandline option is not explicitly given. If that
|
|
// option is present, then its value applies even for callees with size and
|
|
// minsize attributes.
|
|
// If the -inline-threshold is not specified, set the ColdThreshold from the
|
|
// -inlinecold-threshold even if it is not explicitly passed. If
|
|
// -inline-threshold is specified, then -inlinecold-threshold needs to be
|
|
// explicitly specified to set the ColdThreshold knob
|
|
if (InlineThreshold.getNumOccurrences() == 0) {
|
|
Params.OptMinSizeThreshold = InlineConstants::OptMinSizeThreshold;
|
|
Params.OptSizeThreshold = InlineConstants::OptSizeThreshold;
|
|
Params.ColdThreshold = ColdThreshold;
|
|
} else if (ColdThreshold.getNumOccurrences() > 0) {
|
|
Params.ColdThreshold = ColdThreshold;
|
|
}
|
|
return Params;
|
|
}
|
|
|
|
InlineParams llvm::getInlineParams() {
|
|
return getInlineParams(InlineThreshold);
|
|
}
|
|
|
|
// Compute the default threshold for inlining based on the opt level and the
|
|
// size opt level.
|
|
static int computeThresholdFromOptLevels(unsigned OptLevel,
|
|
unsigned SizeOptLevel) {
|
|
if (OptLevel > 2)
|
|
return InlineConstants::OptAggressiveThreshold;
|
|
if (SizeOptLevel == 1) // -Os
|
|
return InlineConstants::OptSizeThreshold;
|
|
if (SizeOptLevel == 2) // -Oz
|
|
return InlineConstants::OptMinSizeThreshold;
|
|
return InlineThreshold;
|
|
}
|
|
|
|
InlineParams llvm::getInlineParams(unsigned OptLevel, unsigned SizeOptLevel) {
|
|
auto Params =
|
|
getInlineParams(computeThresholdFromOptLevels(OptLevel, SizeOptLevel));
|
|
// At O3, use the value of -locally-hot-callsite-threshold option to populate
|
|
// Params.LocallyHotCallSiteThreshold. Below O3, this flag has effect only
|
|
// when it is specified explicitly.
|
|
if (OptLevel > 2)
|
|
Params.LocallyHotCallSiteThreshold = LocallyHotCallSiteThreshold;
|
|
return Params;
|
|
}
|