forked from OSchip/llvm-project
134 lines
4.7 KiB
C++
134 lines
4.7 KiB
C++
//===-- WebAssemblyCallIndirectFixup.cpp - Fix call_indirects -------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// \brief This file converts pseudo call_indirect instructions into real
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/// call_indirects.
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///
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/// The order of arguments for a call_indirect is the arguments to the function
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/// call, followed by the function pointer. There's no natural way to express
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/// a machineinstr with varargs followed by one more arg, so we express it as
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/// the function pointer followed by varargs, then rewrite it here.
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///
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/// We need to rewrite the order of the arguments on the machineinstrs
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/// themselves so that register stackification knows the order they'll be
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/// executed in.
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///
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//===----------------------------------------------------------------------===//
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#include "WebAssembly.h"
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#include "MCTargetDesc/WebAssemblyMCTargetDesc.h" // for WebAssembly::ARGUMENT_*
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#include "WebAssemblyMachineFunctionInfo.h"
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#include "WebAssemblySubtarget.h"
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#include "llvm/Analysis/AliasAnalysis.h"
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#include "llvm/CodeGen/LiveIntervalAnalysis.h"
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#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
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#include "llvm/CodeGen/MachineDominators.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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#include "llvm/CodeGen/Passes.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 "wasm-call-indirect-fixup"
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namespace {
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class WebAssemblyCallIndirectFixup final : public MachineFunctionPass {
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StringRef getPassName() const override {
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return "WebAssembly CallIndirect Fixup";
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}
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bool runOnMachineFunction(MachineFunction &MF) override;
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public:
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static char ID; // Pass identification, replacement for typeid
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WebAssemblyCallIndirectFixup() : MachineFunctionPass(ID) {}
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};
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} // end anonymous namespace
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char WebAssemblyCallIndirectFixup::ID = 0;
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FunctionPass *llvm::createWebAssemblyCallIndirectFixup() {
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return new WebAssemblyCallIndirectFixup();
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}
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static unsigned GetNonPseudoCallIndirectOpcode(const MachineInstr &MI) {
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switch (MI.getOpcode()) {
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using namespace WebAssembly;
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case PCALL_INDIRECT_VOID: return CALL_INDIRECT_VOID;
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case PCALL_INDIRECT_I32: return CALL_INDIRECT_I32;
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case PCALL_INDIRECT_I64: return CALL_INDIRECT_I64;
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case PCALL_INDIRECT_F32: return CALL_INDIRECT_F32;
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case PCALL_INDIRECT_F64: return CALL_INDIRECT_F64;
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case PCALL_INDIRECT_v16i8: return CALL_INDIRECT_v16i8;
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case PCALL_INDIRECT_v8i16: return CALL_INDIRECT_v8i16;
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case PCALL_INDIRECT_v4i32: return CALL_INDIRECT_v4i32;
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case PCALL_INDIRECT_v4f32: return CALL_INDIRECT_v4f32;
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default: return INSTRUCTION_LIST_END;
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}
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}
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static bool IsPseudoCallIndirect(const MachineInstr &MI) {
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return GetNonPseudoCallIndirectOpcode(MI) !=
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WebAssembly::INSTRUCTION_LIST_END;
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}
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bool WebAssemblyCallIndirectFixup::runOnMachineFunction(MachineFunction &MF) {
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DEBUG(dbgs() << "********** Fixing up CALL_INDIRECTs **********\n"
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<< MF.getName() << '\n');
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bool Changed = false;
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const WebAssemblyInstrInfo *TII =
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MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
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for (MachineBasicBlock &MBB : MF) {
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for (MachineInstr &MI : MBB) {
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if (IsPseudoCallIndirect(MI)) {
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DEBUG(dbgs() << "Found call_indirect: " << MI << '\n');
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// Rewrite pseudo to non-pseudo
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const MCInstrDesc &Desc = TII->get(GetNonPseudoCallIndirectOpcode(MI));
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MI.setDesc(Desc);
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// Rewrite argument order
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SmallVector<MachineOperand, 8> Ops;
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// Set up a placeholder for the type signature immediate.
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Ops.push_back(MachineOperand::CreateImm(0));
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// Set up the flags immediate, which currently has no defined flags
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// so it's always zero.
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Ops.push_back(MachineOperand::CreateImm(0));
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for (const MachineOperand &MO :
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make_range(MI.operands_begin() +
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MI.getDesc().getNumDefs() + 1,
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MI.operands_begin() +
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MI.getNumExplicitOperands()))
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Ops.push_back(MO);
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Ops.push_back(MI.getOperand(MI.getDesc().getNumDefs()));
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// Replace the instructions operands.
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while (MI.getNumOperands() > MI.getDesc().getNumDefs())
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MI.RemoveOperand(MI.getNumOperands() - 1);
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for (const MachineOperand &MO : Ops)
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MI.addOperand(MO);
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DEBUG(dbgs() << " After transform: " << MI);
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Changed = true;
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}
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}
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}
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DEBUG(dbgs() << "\nDone fixing up CALL_INDIRECTs\n\n");
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return Changed;
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}
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