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/Passes.h"
20 #include "llvm/CodeGen/TargetLowering.h"
21 #include "llvm/CodeGen/TargetSubtargetInfo.h"
22 #include "llvm/InitializePasses.h"
23 #include "llvm/Support/Debug.h"
24 using namespace llvm;
25
26 #define DEBUG_TYPE "finalize-isel"
27
28 namespace {
29 class FinalizeISel : public MachineFunctionPass {
30 public:
31 static char ID; // Pass identification, replacement for typeid
FinalizeISel()32 FinalizeISel() : MachineFunctionPass(ID) {}
33
34 private:
35 bool runOnMachineFunction(MachineFunction &MF) override;
36
getAnalysisUsage(AnalysisUsage & AU) const37 void getAnalysisUsage(AnalysisUsage &AU) const override {
38 MachineFunctionPass::getAnalysisUsage(AU);
39 }
40 };
41 } // end anonymous namespace
42
43 char FinalizeISel::ID = 0;
44 char &llvm::FinalizeISelID = FinalizeISel::ID;
45 INITIALIZE_PASS(FinalizeISel, DEBUG_TYPE,
46 "Finalize ISel and expand pseudo-instructions", false, false)
47
runOnMachineFunction(MachineFunction & MF)48 bool FinalizeISel::runOnMachineFunction(MachineFunction &MF) {
49 bool Changed = false;
50 const TargetLowering *TLI = MF.getSubtarget().getTargetLowering();
51
52 // Iterate through each instruction in the function, looking for pseudos.
53 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
54 MachineBasicBlock *MBB = &*I;
55 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
56 MBBI != MBBE; ) {
57 MachineInstr &MI = *MBBI++;
58
59 // If MI is a pseudo, expand it.
60 if (MI.usesCustomInsertionHook()) {
61 Changed = true;
62 MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
63 // The expansion may involve new basic blocks.
64 if (NewMBB != MBB) {
65 MBB = NewMBB;
66 I = NewMBB->getIterator();
67 MBBI = NewMBB->begin();
68 MBBE = NewMBB->end();
69 }
70 }
71 }
72 }
73
74 TLI->finalizeLowering(MF);
75
76 return Changed;
77 }
78