1//===-- llvm/CodeGen/FinalizeISel.cpp ---------------------------*- C++ -*-===//
2//
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
6//
7//===----------------------------------------------------------------------===//
8//
9/// This pass expands Pseudo-instructions produced by ISel, fixes register
10/// reservations and may do machine frame information adjustments.
11/// The pseudo instructions are used to allow the expansion to contain control
12/// flow, such as a conditional move implemented with a conditional branch and a
13/// phi, or an atomic operation implemented with a loop.
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/CodeGen/MachineFrameInfo.h"
18#include "llvm/CodeGen/MachineFunction.h"
19#include "llvm/CodeGen/MachineFunctionPass.h"
20#include "llvm/CodeGen/TargetInstrInfo.h"
21#include "llvm/CodeGen/TargetLowering.h"
22#include "llvm/CodeGen/TargetSubtargetInfo.h"
23#include "llvm/InitializePasses.h"
24using namespace llvm;
25
26#define DEBUG_TYPE "finalize-isel"
27
28namespace {
29 class FinalizeISel : public MachineFunctionPass {
30 public:
31 static char ID; // Pass identification, replacement for typeid
32 FinalizeISel() : MachineFunctionPass(ID) {}
33
34 private:
35 bool runOnMachineFunction(MachineFunction &MF) override;
36
37 void getAnalysisUsage(AnalysisUsage &AU) const override {
38 MachineFunctionPass::getAnalysisUsage(AU);
39 }
40 };
41} // end anonymous namespace
42
43char FinalizeISel::ID = 0;
44char &llvm::FinalizeISelID = FinalizeISel::ID;
45INITIALIZE_PASS(FinalizeISel, DEBUG_TYPE,
46 "Finalize ISel and expand pseudo-instructions", false, false)
47
48bool FinalizeISel::runOnMachineFunction(MachineFunction &MF) {
49 bool Changed = false;
50 const TargetInstrInfo *TII = MF.getSubtarget().getInstrInfo();
51 const TargetLowering *TLI = MF.getSubtarget().getTargetLowering();
52
53 // Iterate through each instruction in the function, looking for pseudos.
54 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
55 MachineBasicBlock *MBB = &*I;
56 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
57 MBBI != MBBE; ) {
58 MachineInstr &MI = *MBBI++;
59
60 // Set AdjustsStack to true if the instruction selector emits a stack
61 // frame setup instruction or a stack aligning inlineasm.
62 if (TII->isFrameInstr(I: MI) || MI.isStackAligningInlineAsm())
63 MF.getFrameInfo().setAdjustsStack(true);
64
65 // If MI is a pseudo, expand it.
66 if (MI.usesCustomInsertionHook()) {
67 Changed = true;
68 MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
69 // The expansion may involve new basic blocks.
70 if (NewMBB != MBB) {
71 MBB = NewMBB;
72 I = NewMBB->getIterator();
73 MBBI = NewMBB->begin();
74 MBBE = NewMBB->end();
75 }
76 }
77 }
78 }
79
80 TLI->finalizeLowering(MF);
81
82 return Changed;
83}
84

source code of llvm/lib/CodeGen/FinalizeISel.cpp