1 //=--- RegUsageInfoPropagate.cpp - Register Usage Informartion Propagation --=//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 /// This pass is required to take advantage of the interprocedural register
10 /// allocation infrastructure.
12 /// This pass iterates through MachineInstrs in a given MachineFunction and at
13 /// each callsite queries RegisterUsageInfo for RegMask (calculated based on
14 /// actual register allocation) of the callee function, if the RegMask detail
15 /// is available then this pass will update the RegMask of the call instruction.
16 /// This updated RegMask will be used by the register allocator while allocating
17 /// the current MachineFunction.
19 //===----------------------------------------------------------------------===//
21 #include "llvm/CodeGen/MachineBasicBlock.h"
22 #include "llvm/CodeGen/MachineFunctionPass.h"
23 #include "llvm/CodeGen/MachineFrameInfo.h"
24 #include "llvm/CodeGen/MachineInstr.h"
25 #include "llvm/CodeGen/MachineRegisterInfo.h"
26 #include "llvm/CodeGen/Passes.h"
27 #include "llvm/CodeGen/RegisterUsageInfo.h"
28 #include "llvm/IR/Module.h"
29 #include "llvm/PassAnalysisSupport.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/raw_ostream.h"
32 #include "llvm/Target/TargetMachine.h"
38 #define DEBUG_TYPE "ip-regalloc"
40 #define RUIP_NAME "Register Usage Information Propagation"
44 class RegUsageInfoPropagation : public MachineFunctionPass {
46 RegUsageInfoPropagation() : MachineFunctionPass(ID) {
47 PassRegistry &Registry = *PassRegistry::getPassRegistry();
48 initializeRegUsageInfoPropagationPass(Registry);
51 StringRef getPassName() const override { return RUIP_NAME; }
53 bool runOnMachineFunction(MachineFunction &MF) override;
55 void getAnalysisUsage(AnalysisUsage &AU) const override {
56 AU.addRequired<PhysicalRegisterUsageInfo>();
58 MachineFunctionPass::getAnalysisUsage(AU);
64 static void setRegMask(MachineInstr &MI, ArrayRef<uint32_t> RegMask) {
65 assert(RegMask.size() ==
66 MachineOperand::getRegMaskSize(MI.getParent()->getParent()
67 ->getRegInfo().getTargetRegisterInfo()
69 && "expected register mask size");
70 for (MachineOperand &MO : MI.operands()) {
72 MO.setRegMask(RegMask.data());
77 } // end of anonymous namespace
79 INITIALIZE_PASS_BEGIN(RegUsageInfoPropagation, "reg-usage-propagation",
80 RUIP_NAME, false, false)
81 INITIALIZE_PASS_DEPENDENCY(PhysicalRegisterUsageInfo)
82 INITIALIZE_PASS_END(RegUsageInfoPropagation, "reg-usage-propagation",
83 RUIP_NAME, false, false)
85 char RegUsageInfoPropagation::ID = 0;
87 // Assumes call instructions have a single reference to a function.
88 static const Function *findCalledFunction(const Module &M,
89 const MachineInstr &MI) {
90 for (const MachineOperand &MO : MI.operands()) {
92 return dyn_cast<const Function>(MO.getGlobal());
95 return M.getFunction(MO.getSymbolName());
101 bool RegUsageInfoPropagation::runOnMachineFunction(MachineFunction &MF) {
102 const Module &M = *MF.getFunction().getParent();
103 PhysicalRegisterUsageInfo *PRUI = &getAnalysis<PhysicalRegisterUsageInfo>();
105 LLVM_DEBUG(dbgs() << " ++++++++++++++++++++ " << getPassName()
106 << " ++++++++++++++++++++ \n");
107 LLVM_DEBUG(dbgs() << "MachineFunction : " << MF.getName() << "\n");
109 const MachineFrameInfo &MFI = MF.getFrameInfo();
110 if (!MFI.hasCalls() && !MFI.hasTailCall())
113 bool Changed = false;
115 for (MachineBasicBlock &MBB : MF) {
116 for (MachineInstr &MI : MBB) {
121 << "Call Instruction Before Register Usage Info Propagation : \n");
122 LLVM_DEBUG(dbgs() << MI << "\n");
124 auto UpdateRegMask = [&](const Function &F) {
125 const ArrayRef<uint32_t> RegMask = PRUI->getRegUsageInfo(F);
128 setRegMask(MI, RegMask);
132 if (const Function *F = findCalledFunction(M, MI)) {
135 LLVM_DEBUG(dbgs() << "Failed to find call target function\n");
139 dbgs() << "Call Instruction After Register Usage Info Propagation : "
145 dbgs() << " +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"
150 FunctionPass *llvm::createRegUsageInfoPropPass() {
151 return new RegUsageInfoPropagation();