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/MachineFunction.h"
18#include "llvm/CodeGen/MachineFunctionPass.h"
19#include "llvm/CodeGen/TargetLowering.h"
20#include "llvm/CodeGen/TargetSubtargetInfo.h"
21#include "llvm/InitializePasses.h"
22using namespace llvm;
23
24#define DEBUG_TYPE "finalize-isel"
25
26namespace {
27 class FinalizeISel : public MachineFunctionPass {
28 public:
29 static char ID; // Pass identification, replacement for typeid
30 FinalizeISel() : MachineFunctionPass(ID) {}
31
32 private:
33 bool runOnMachineFunction(MachineFunction &MF) override;
34
35 void getAnalysisUsage(AnalysisUsage &AU) const override {
36 MachineFunctionPass::getAnalysisUsage(AU);
37 }
38 };
39} // end anonymous namespace
40
41char FinalizeISel::ID = 0;
42char &llvm::FinalizeISelID = FinalizeISel::ID;
43INITIALIZE_PASS(FinalizeISel, DEBUG_TYPE,
44 "Finalize ISel and expand pseudo-instructions", false, false)
45
46bool FinalizeISel::runOnMachineFunction(MachineFunction &MF) {
47 bool Changed = false;
48 const TargetLowering *TLI = MF.getSubtarget().getTargetLowering();
49
50 // Iterate through each instruction in the function, looking for pseudos.
51 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
52 MachineBasicBlock *MBB = &*I;
53 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
54 MBBI != MBBE; ) {
55 MachineInstr &MI = *MBBI++;
56
57 // If MI is a pseudo, expand it.
58 if (MI.usesCustomInsertionHook()) {
59 Changed = true;
60 MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
61 // The expansion may involve new basic blocks.
62 if (NewMBB != MBB) {
63 MBB = NewMBB;
64 I = NewMBB->getIterator();
65 MBBI = NewMBB->begin();
66 MBBE = NewMBB->end();
67 }
68 }
69 }
70 }
71
72 TLI->finalizeLowering(MF);
73
74 return Changed;
75}
76

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