234 lines
8.3 KiB
C++
234 lines
8.3 KiB
C++
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//===-- WebAssemblyInstrInfo.cpp - WebAssembly Instruction Information ----===//
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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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/// \file
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/// This file contains the WebAssembly implementation of the
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/// TargetInstrInfo class.
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///
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//===----------------------------------------------------------------------===//
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#include "WebAssemblyInstrInfo.h"
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#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
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#include "WebAssembly.h"
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#include "WebAssemblyMachineFunctionInfo.h"
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#include "WebAssemblySubtarget.h"
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#include "WebAssemblyUtilities.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineMemOperand.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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using namespace llvm;
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#define DEBUG_TYPE "wasm-instr-info"
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#define GET_INSTRINFO_CTOR_DTOR
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#include "WebAssemblyGenInstrInfo.inc"
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// defines WebAssembly::getNamedOperandIdx
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#define GET_INSTRINFO_NAMED_OPS
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#include "WebAssemblyGenInstrInfo.inc"
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WebAssemblyInstrInfo::WebAssemblyInstrInfo(const WebAssemblySubtarget &STI)
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: WebAssemblyGenInstrInfo(WebAssembly::ADJCALLSTACKDOWN,
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WebAssembly::ADJCALLSTACKUP,
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WebAssembly::CATCHRET),
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RI(STI.getTargetTriple()) {}
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bool WebAssemblyInstrInfo::isReallyTriviallyReMaterializable(
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const MachineInstr &MI) const {
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switch (MI.getOpcode()) {
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case WebAssembly::CONST_I32:
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case WebAssembly::CONST_I64:
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case WebAssembly::CONST_F32:
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case WebAssembly::CONST_F64:
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// TargetInstrInfo::isReallyTriviallyReMaterializable misses these
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// because of the ARGUMENTS implicit def, so we manualy override it here.
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return true;
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default:
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return TargetInstrInfo::isReallyTriviallyReMaterializable(MI);
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}
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}
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void WebAssemblyInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I,
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const DebugLoc &DL, MCRegister DestReg,
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MCRegister SrcReg, bool KillSrc) const {
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// This method is called by post-RA expansion, which expects only pregs to
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// exist. However we need to handle both here.
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auto &MRI = MBB.getParent()->getRegInfo();
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const TargetRegisterClass *RC =
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Register::isVirtualRegister(DestReg)
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? MRI.getRegClass(DestReg)
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: MRI.getTargetRegisterInfo()->getMinimalPhysRegClass(DestReg);
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unsigned CopyOpcode = WebAssembly::getCopyOpcodeForRegClass(RC);
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BuildMI(MBB, I, DL, get(CopyOpcode), DestReg)
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.addReg(SrcReg, KillSrc ? RegState::Kill : 0);
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}
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MachineInstr *WebAssemblyInstrInfo::commuteInstructionImpl(
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MachineInstr &MI, bool NewMI, unsigned OpIdx1, unsigned OpIdx2) const {
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// If the operands are stackified, we can't reorder them.
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WebAssemblyFunctionInfo &MFI =
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*MI.getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
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if (MFI.isVRegStackified(MI.getOperand(OpIdx1).getReg()) ||
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MFI.isVRegStackified(MI.getOperand(OpIdx2).getReg()))
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return nullptr;
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// Otherwise use the default implementation.
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return TargetInstrInfo::commuteInstructionImpl(MI, NewMI, OpIdx1, OpIdx2);
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}
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// Branch analysis.
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bool WebAssemblyInstrInfo::analyzeBranch(MachineBasicBlock &MBB,
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MachineBasicBlock *&TBB,
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MachineBasicBlock *&FBB,
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SmallVectorImpl<MachineOperand> &Cond,
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bool /*AllowModify*/) const {
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const auto &MFI = *MBB.getParent()->getInfo<WebAssemblyFunctionInfo>();
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// WebAssembly has control flow that doesn't have explicit branches or direct
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// fallthrough (e.g. try/catch), which can't be modeled by analyzeBranch. It
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// is created after CFGStackify.
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if (MFI.isCFGStackified())
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return true;
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bool HaveCond = false;
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for (MachineInstr &MI : MBB.terminators()) {
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switch (MI.getOpcode()) {
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default:
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// Unhandled instruction; bail out.
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return true;
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case WebAssembly::BR_IF:
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if (HaveCond)
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return true;
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Cond.push_back(MachineOperand::CreateImm(true));
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Cond.push_back(MI.getOperand(1));
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TBB = MI.getOperand(0).getMBB();
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HaveCond = true;
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break;
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case WebAssembly::BR_UNLESS:
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if (HaveCond)
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return true;
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Cond.push_back(MachineOperand::CreateImm(false));
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Cond.push_back(MI.getOperand(1));
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TBB = MI.getOperand(0).getMBB();
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HaveCond = true;
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break;
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case WebAssembly::BR:
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if (!HaveCond)
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TBB = MI.getOperand(0).getMBB();
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else
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FBB = MI.getOperand(0).getMBB();
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break;
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}
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if (MI.isBarrier())
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break;
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}
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return false;
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}
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unsigned WebAssemblyInstrInfo::removeBranch(MachineBasicBlock &MBB,
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int *BytesRemoved) const {
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assert(!BytesRemoved && "code size not handled");
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MachineBasicBlock::instr_iterator I = MBB.instr_end();
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unsigned Count = 0;
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while (I != MBB.instr_begin()) {
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--I;
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if (I->isDebugInstr())
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continue;
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if (!I->isTerminator())
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break;
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// Remove the branch.
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I->eraseFromParent();
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I = MBB.instr_end();
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++Count;
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}
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return Count;
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}
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unsigned WebAssemblyInstrInfo::insertBranch(
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MachineBasicBlock &MBB, MachineBasicBlock *TBB, MachineBasicBlock *FBB,
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ArrayRef<MachineOperand> Cond, const DebugLoc &DL, int *BytesAdded) const {
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assert(!BytesAdded && "code size not handled");
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if (Cond.empty()) {
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if (!TBB)
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return 0;
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BuildMI(&MBB, DL, get(WebAssembly::BR)).addMBB(TBB);
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return 1;
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}
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assert(Cond.size() == 2 && "Expected a flag and a successor block");
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if (Cond[0].getImm())
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BuildMI(&MBB, DL, get(WebAssembly::BR_IF)).addMBB(TBB).add(Cond[1]);
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else
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BuildMI(&MBB, DL, get(WebAssembly::BR_UNLESS)).addMBB(TBB).add(Cond[1]);
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if (!FBB)
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return 1;
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BuildMI(&MBB, DL, get(WebAssembly::BR)).addMBB(FBB);
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return 2;
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}
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bool WebAssemblyInstrInfo::reverseBranchCondition(
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SmallVectorImpl<MachineOperand> &Cond) const {
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assert(Cond.size() == 2 && "Expected a flag and a condition expression");
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Cond.front() = MachineOperand::CreateImm(!Cond.front().getImm());
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return false;
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}
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ArrayRef<std::pair<int, const char *>>
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WebAssemblyInstrInfo::getSerializableTargetIndices() const {
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static const std::pair<int, const char *> TargetIndices[] = {
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{WebAssembly::TI_LOCAL, "wasm-local"},
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{WebAssembly::TI_GLOBAL_FIXED, "wasm-global-fixed"},
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{WebAssembly::TI_OPERAND_STACK, "wasm-operand-stack"},
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{WebAssembly::TI_GLOBAL_RELOC, "wasm-global-reloc"},
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{WebAssembly::TI_LOCAL_INDIRECT, "wasm-local-indirect"}};
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return ArrayRef(TargetIndices);
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}
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const MachineOperand &
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WebAssemblyInstrInfo::getCalleeOperand(const MachineInstr &MI) const {
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return WebAssembly::getCalleeOp(MI);
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}
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// This returns true when the instruction defines a value of a TargetIndex
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// operand that can be tracked by offsets. For Wasm, this returns true for only
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// local.set/local.tees. This is currently used by LiveDebugValues analysis.
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//
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// These are not included:
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// - In theory we need to add global.set here too, but we don't have global
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// indices at this point because they are relocatable and we address them by
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// names until linking, so we don't have 'offsets' (which are used to store
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// local/global indices) to deal with in LiveDebugValues. And we don't
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// associate debug info in values in globals anyway.
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// - All other value-producing instructions, i.e. instructions with defs, can
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// define values in the Wasm stack, which is represented by TI_OPERAND_STACK
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// TargetIndex. But they don't have offset info within the instruction itself,
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// and debug info analysis for them is handled separately in
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// WebAssemblyDebugFixup pass, so we don't worry about them here.
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bool WebAssemblyInstrInfo::isExplicitTargetIndexDef(const MachineInstr &MI,
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int &Index,
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int64_t &Offset) const {
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unsigned Opc = MI.getOpcode();
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if (WebAssembly::isLocalSet(Opc) || WebAssembly::isLocalTee(Opc)) {
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Index = WebAssembly::TI_LOCAL;
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Offset = MI.explicit_uses().begin()->getImm();
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return true;
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}
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return false;
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}
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