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//===-- WebAssemblyRegNumbering.cpp - Register Numbering ------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
///
/// \file
/// \brief This file implements a pass which assigns WebAssembly register
/// numbers for CodeGen virtual registers.
///
//===----------------------------------------------------------------------===//
#include "WebAssembly.h"
#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
#include "WebAssemblyMachineFunctionInfo.h"
#include "WebAssemblySubtarget.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.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 {
const char *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;
FunctionPass *llvm::createWebAssemblyRegNumbering() {
return new WebAssemblyRegNumbering();
}
bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) {
DEBUG(dbgs() << "********** Register Numbering **********\n"
"********** Function: "
<< MF.getName() << '\n');
WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
MachineRegisterInfo &MRI = MF.getRegInfo();
const MachineFrameInfo &FrameInfo = *MF.getFrameInfo();
MFI.initWARegs();
// 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) {
switch (MI.getOpcode()) {
case WebAssembly::ARGUMENT_I32:
case WebAssembly::ARGUMENT_I64:
case WebAssembly::ARGUMENT_F32:
case WebAssembly::ARGUMENT_F64:
MFI.setWAReg(MI.getOperand(0).getReg(), MI.getOperand(1).getImm());
break;
default:
break;
}
}
// 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 NumArgRegs = MFI.getParams().size();
unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs();
unsigned NumStackRegs = 0;
unsigned CurReg = 0;
for (unsigned VRegIdx = 0; VRegIdx < NumVRegs; ++VRegIdx) {
unsigned VReg = TargetRegisterInfo::index2VirtReg(VRegIdx);
// Handle stackified registers.
if (MFI.isVRegStackified(VReg)) {
MFI.setWAReg(VReg, INT32_MIN | NumStackRegs++);
continue;
}
// Skip unused registers.
if (MRI.use_empty(VReg))
continue;
if (MFI.getWAReg(VReg) == WebAssemblyFunctionInfo::UnusedReg)
MFI.setWAReg(VReg, NumArgRegs + CurReg++);
}
// Allocate locals for used physical registers
if (FrameInfo.getStackSize() > 0)
MFI.addPReg(WebAssembly::SP32, CurReg++);
return true;
}
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