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//=- WebAssemblySetP2AlignOperands.cpp - Set alignments on loads and stores -=//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file
/// This file sets the p2align operands on load and store instructions.
///
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "WebAssembly.h"
#include "WebAssemblyInstrInfo.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
#include "llvm/CodeGen/MachineMemOperand.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "wasm-set-p2align-operands"
namespace {
class WebAssemblySetP2AlignOperands final : public MachineFunctionPass {
public:
static char ID; // Pass identification, replacement for typeid
WebAssemblySetP2AlignOperands() : MachineFunctionPass(ID) {}
StringRef getPassName() const override {
return "WebAssembly Set p2align Operands";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addPreserved<MachineBlockFrequencyInfo>();
AU.addPreservedID(MachineDominatorsID);
MachineFunctionPass::getAnalysisUsage(AU);
}
bool runOnMachineFunction(MachineFunction &MF) override;
};
} // end anonymous namespace
char WebAssemblySetP2AlignOperands::ID = 0;
INITIALIZE_PASS(WebAssemblySetP2AlignOperands, DEBUG_TYPE,
"Set the p2align operands for WebAssembly loads and stores",
false, false)
FunctionPass *llvm::createWebAssemblySetP2AlignOperands() {
return new WebAssemblySetP2AlignOperands();
}
static void rewriteP2Align(MachineInstr &MI, unsigned OperandNo) {
assert(MI.getOperand(OperandNo).getImm() == 0 &&
"ISel should set p2align operands to 0");
assert(MI.hasOneMemOperand() &&
"Load and store instructions have exactly one mem operand");
assert((*MI.memoperands_begin())->getSize() ==
(UINT64_C(1) << WebAssembly::GetDefaultP2Align(MI.getOpcode())) &&
"Default p2align value should be natural");
assert(MI.getDesc().operands()[OperandNo].OperandType ==
WebAssembly::OPERAND_P2ALIGN &&
"Load and store instructions should have a p2align operand");
uint64_t P2Align = Log2((*MI.memoperands_begin())->getAlign());
// WebAssembly does not currently support supernatural alignment.
P2Align = std::min(P2Align,
uint64_t(WebAssembly::GetDefaultP2Align(MI.getOpcode())));
MI.getOperand(OperandNo).setImm(P2Align);
}
bool WebAssemblySetP2AlignOperands::runOnMachineFunction(MachineFunction &MF) {
LLVM_DEBUG({
dbgs() << "********** Set p2align Operands **********\n"
<< "********** Function: " << MF.getName() << '\n';
});
bool Changed = false;
for (auto &MBB : MF) {
for (auto &MI : MBB) {
int16_t P2AlignOpNum = WebAssembly::getNamedOperandIdx(
MI.getOpcode(), WebAssembly::OpName::p2align);
if (P2AlignOpNum != -1) {
rewriteP2Align(MI, P2AlignOpNum);
Changed = true;
}
}
}
return Changed;
}
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