73 lines
2.3 KiB
C++
73 lines
2.3 KiB
C++
//==-- OverflowInstAnalysis.cpp - Utils to fold overflow insts ----*- C++ -*-=//
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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 holds routines to help analyse overflow instructions
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// and fold them into constants or other overflow instructions
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/OverflowInstAnalysis.h"
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#include "llvm/IR/Constants.h"
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#include "llvm/IR/Instructions.h"
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#include "llvm/IR/PatternMatch.h"
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using namespace llvm;
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using namespace llvm::PatternMatch;
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bool llvm::isCheckForZeroAndMulWithOverflow(Value *Op0, Value *Op1, bool IsAnd,
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Use *&Y) {
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ICmpInst::Predicate Pred;
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Value *X, *NotOp1;
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int XIdx;
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IntrinsicInst *II;
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if (!match(Op0, m_ICmp(Pred, m_Value(X), m_Zero())))
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return false;
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/// %Agg = call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %???)
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/// %V = extractvalue { i4, i1 } %Agg, 1
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auto matchMulOverflowCheck = [X, &II, &XIdx](Value *V) {
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auto *Extract = dyn_cast<ExtractValueInst>(V);
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// We should only be extracting the overflow bit.
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if (!Extract || !Extract->getIndices().equals(1))
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return false;
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II = dyn_cast<IntrinsicInst>(Extract->getAggregateOperand());
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if (!II ||
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!match(II, m_CombineOr(m_Intrinsic<Intrinsic::umul_with_overflow>(),
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m_Intrinsic<Intrinsic::smul_with_overflow>())))
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return false;
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if (II->getArgOperand(0) == X)
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XIdx = 0;
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else if (II->getArgOperand(1) == X)
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XIdx = 1;
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else
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return false;
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return true;
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};
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bool Matched =
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(IsAnd && Pred == ICmpInst::Predicate::ICMP_NE &&
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matchMulOverflowCheck(Op1)) ||
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(!IsAnd && Pred == ICmpInst::Predicate::ICMP_EQ &&
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match(Op1, m_Not(m_Value(NotOp1))) && matchMulOverflowCheck(NotOp1));
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if (!Matched)
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return false;
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Y = &II->getArgOperandUse(!XIdx);
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return true;
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}
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bool llvm::isCheckForZeroAndMulWithOverflow(Value *Op0, Value *Op1,
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bool IsAnd) {
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Use *Y;
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return isCheckForZeroAndMulWithOverflow(Op0, Op1, IsAnd, Y);
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}
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