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llvm-mirror/lib/Target/WebAssembly/WebAssemblySetP2AlignOperands.cpp
Thomas Lively f98161801a [WebAssembly] Use named operands to identify loads and stores
Summary:
Uses the named operands tablegen feature to look up the indices of
offset, address, and p2align operands for all load and store
instructions. This replaces brittle, incorrect logic for identifying
loads and store when eliminating frame indices, which previously
crashed on bulk-memory ops. It also cleans up the SetP2Alignment pass.

Reviewers: aheejin, dschuff

Subscribers: sbc100, jgravelle-google, hiraditya, sunfish, jfb, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D59007

llvm-svn: 355770
2019-03-09 04:31:37 +00:00

98 lines
3.3 KiB
C++

//=- 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().OpInfo[OperandNo].OperandType ==
WebAssembly::OPERAND_P2ALIGN &&
"Load and store instructions should have a p2align operand");
uint64_t P2Align = Log2_64((*MI.memoperands_begin())->getAlignment());
// 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;
}