1 //===-- WebAssemblyRegNumbering.cpp - Register Numbering ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// \brief This file implements a pass which assigns WebAssembly register
12 /// numbers for CodeGen virtual registers.
14 //===----------------------------------------------------------------------===//
16 #include "WebAssembly.h"
17 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
18 #include "WebAssemblyMachineFunctionInfo.h"
19 #include "WebAssemblySubtarget.h"
20 #include "llvm/ADT/SCCIterator.h"
21 #include "llvm/CodeGen/MachineFrameInfo.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/CodeGen/MachineInstrBuilder.h"
24 #include "llvm/CodeGen/MachineLoopInfo.h"
25 #include "llvm/CodeGen/MachineRegisterInfo.h"
26 #include "llvm/CodeGen/Passes.h"
27 #include "llvm/Support/Debug.h"
28 #include "llvm/Support/raw_ostream.h"
31 #define DEBUG_TYPE "wasm-reg-numbering"
34 class WebAssemblyRegNumbering final : public MachineFunctionPass {
35 const char *getPassName() const override {
36 return "WebAssembly Register Numbering";
39 void getAnalysisUsage(AnalysisUsage &AU) const override {
41 MachineFunctionPass::getAnalysisUsage(AU);
44 bool runOnMachineFunction(MachineFunction &MF) override;
47 static char ID; // Pass identification, replacement for typeid
48 WebAssemblyRegNumbering() : MachineFunctionPass(ID) {}
50 } // end anonymous namespace
52 char WebAssemblyRegNumbering::ID = 0;
53 FunctionPass *llvm::createWebAssemblyRegNumbering() {
54 return new WebAssemblyRegNumbering();
57 bool WebAssemblyRegNumbering::runOnMachineFunction(MachineFunction &MF) {
58 DEBUG(dbgs() << "********** Register Numbering **********\n"
59 "********** Function: "
60 << MF.getName() << '\n');
62 WebAssemblyFunctionInfo &MFI = *MF.getInfo<WebAssemblyFunctionInfo>();
63 MachineRegisterInfo &MRI = MF.getRegInfo();
67 // WebAssembly argument registers are in the same index space as local
68 // variables. Assign the numbers for them first.
69 MachineBasicBlock &EntryMBB = MF.front();
70 for (MachineInstr &MI : EntryMBB) {
71 switch (MI.getOpcode()) {
72 case WebAssembly::ARGUMENT_I32:
73 case WebAssembly::ARGUMENT_I64:
74 case WebAssembly::ARGUMENT_F32:
75 case WebAssembly::ARGUMENT_F64: {
76 int64_t Imm = MI.getOperand(1).getImm();
77 DEBUG(dbgs() << "Arg VReg " << MI.getOperand(0).getReg() << " -> WAReg "
79 MFI.setWAReg(MI.getOperand(0).getReg(), Imm);
87 // Then assign regular WebAssembly registers for all remaining used
88 // virtual registers. TODO: Consider sorting the registers by frequency of
89 // use, to maximize usage of small immediate fields.
90 unsigned NumVRegs = MF.getRegInfo().getNumVirtRegs();
91 unsigned NumStackRegs = 0;
92 // Start the numbering for locals after the arg regs
93 unsigned CurReg = MFI.getParams().size();
94 for (unsigned VRegIdx = 0; VRegIdx < NumVRegs; ++VRegIdx) {
95 unsigned VReg = TargetRegisterInfo::index2VirtReg(VRegIdx);
96 // Skip unused registers.
97 if (MRI.use_empty(VReg))
99 // Handle stackified registers.
100 if (MFI.isVRegStackified(VReg)) {
101 DEBUG(dbgs() << "VReg " << VReg << " -> WAReg "
102 << (INT32_MIN | NumStackRegs) << "\n");
103 MFI.setWAReg(VReg, INT32_MIN | NumStackRegs++);
106 if (MFI.getWAReg(VReg) == WebAssemblyFunctionInfo::UnusedReg) {
107 DEBUG(dbgs() << "VReg " << VReg << " -> WAReg " << CurReg << "\n");
108 MFI.setWAReg(VReg, CurReg++);