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llvm-mirror/lib/Target/WebAssembly/WebAssemblyRegNumbering.cpp
Heejin Ahn 37702c2638 [WebAssembly] Put utility functions in Utils directory (NFC)
This CL
1. Creates Utils/ directory under lib/Target/WebAssembly
2. Moves existing WebAssemblyUtilities.cpp|h into the Utils/ directory
3. Creates Utils/WebAssemblyTypeUtilities.cpp|h and put type
   declarataions and type conversion functions scattered in various
   places into this single place.

It has been suggested several times that it is not easy to share utility
functions between subdirectories (AsmParser, DIsassembler, MCTargetDesc,
...). Sometimes we ended up [[ https://reviews.llvm.org/D92840#2478863 | duplicating ]] the same function because of
this.

There are already other targets doing this: AArch64, AMDGPU, and ARM
have Utils/ subdirectory under their target directory.

This extracts the utility functions into a single directory Utils/ and
make them sharable among all passes in WebAssembly/ and its
subdirectories. Also I believe gathering all type-related conversion
functionalities into a single place makes it more usable. (Actually I
was working on another CL that uses various type conversion functions
scattered in multiple places, which became the motivation for this CL.)

Reviewed By: dschuff, aardappel

Differential Revision: https://reviews.llvm.org/D100995
2021-04-22 15:29:43 -07:00

111 lines
3.9 KiB
C++

//===-- WebAssemblyRegNumbering.cpp - Register Numbering ------------------===//
//
// 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 implements a pass which assigns WebAssembly register
/// numbers for CodeGen virtual registers.
///
//===----------------------------------------------------------------------===//
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "Utils/WebAssemblyUtilities.h"
#include "WebAssembly.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySubtarget.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
#define DEBUG_TYPE "wasm-reg-numbering"
namespace {
class WebAssemblyRegNumbering final : public MachineFunctionPass {
StringRef getPassName() const override {
return "WebAssembly Register Numbering";
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
MachineFunctionPass::getAnalysisUsage(AU);
}
bool runOnMachineFunction(MachineFunction &MF) override;
public:
static char ID; // Pass identification, replacement for typeid
WebAssemblyRegNumbering() : MachineFunctionPass(ID) {}
};
} // end anonymous namespace
char WebAssemblyRegNumbering::ID = 0;
INITIALIZE_PASS(WebAssemblyRegNumbering, DEBUG_TYPE,
"Assigns WebAssembly register numbers for virtual registers",
false, false)
FunctionPass *llvm::createWebAssemblyRegNumbering() {
return new WebAssemblyRegNumbering();
}
bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) {
LLVM_DEBUG(dbgs() << "********** Register Numbering **********\n"
"********** Function: "
<< MF.getName() << '\n');
WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
MachineRegisterInfo &MRI = MF.getRegInfo();
MFI.initWARegs(MRI);
// WebAssembly argument registers are in the same index space as local
// variables. Assign the numbers for them first.
MachineBasicBlock &EntryMBB = MF.front();
for (MachineInstr &MI : EntryMBB) {
if (!WebAssembly::isArgument(MI.getOpcode()))
break;
int64_t Imm = MI.getOperand(1).getImm();
LLVM_DEBUG(dbgs() << "Arg VReg " << MI.getOperand(0).getReg()
<< " -> WAReg " << Imm << "\n");
MFI.setWAReg(MI.getOperand(0).getReg(), Imm);
}
// Then assign regular WebAssembly registers for all remaining used
// virtual registers. TODO: Consider sorting the registers by frequency of
// use, to maximize usage of small immediate fields.
unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs();
unsigned NumStackRegs = 0;
// Start the numbering for locals after the arg regs
unsigned CurReg = MFI.getParams().size();
for (unsigned VRegIdx = 0; VRegIdx < NumVRegs; ++VRegIdx) {
unsigned VReg = Register::index2VirtReg(VRegIdx);
// Skip unused registers.
if (MRI.use_empty(VReg))
continue;
// Handle stackified registers.
if (MFI.isVRegStackified(VReg)) {
LLVM_DEBUG(dbgs() << "VReg " << VReg << " -> WAReg "
<< (INT32_MIN | NumStackRegs) << "\n");
MFI.setWAReg(VReg, INT32_MIN | NumStackRegs++);
continue;
}
if (MFI.getWAReg(VReg) == WebAssemblyFunctionInfo::UnusedReg) {
LLVM_DEBUG(dbgs() << "VReg " << VReg << " -> WAReg " << CurReg << "\n");
MFI.setWAReg(VReg, CurReg++);
}
}
return true;
}