1 //===-- llvm/CodeGen/ExpandISelPseudos.cpp ----------------------*- C++ -*-===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // Expand Pseudo-instructions produced by ISel. These are usually to allow
11 // the expansion to contain control flow, such as a conditional move
12 // implemented with a conditional branch and a phi, or an atomic operation
13 // implemented with a loop.
14 //
15 //===----------------------------------------------------------------------===//
16
17 #include "llvm/CodeGen/Passes.h"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineFunctionPass.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Target/TargetLowering.h"
22 #include "llvm/Target/TargetSubtargetInfo.h"
23 using namespace llvm;
24
25 #define DEBUG_TYPE "expand-isel-pseudos"
26
27 namespace {
28 class ExpandISelPseudos : public MachineFunctionPass {
29 public:
30 static char ID; // Pass identification, replacement for typeid
ExpandISelPseudos()31 ExpandISelPseudos() : MachineFunctionPass(ID) {}
32
33 private:
34 bool runOnMachineFunction(MachineFunction &MF) override;
35
getAnalysisUsage(AnalysisUsage & AU) const36 void getAnalysisUsage(AnalysisUsage &AU) const override {
37 MachineFunctionPass::getAnalysisUsage(AU);
38 }
39 };
40 } // end anonymous namespace
41
42 char ExpandISelPseudos::ID = 0;
43 char &llvm::ExpandISelPseudosID = ExpandISelPseudos::ID;
44 INITIALIZE_PASS(ExpandISelPseudos, "expand-isel-pseudos",
45 "Expand ISel Pseudo-instructions", false, false)
46
runOnMachineFunction(MachineFunction & MF)47 bool ExpandISelPseudos::runOnMachineFunction(MachineFunction &MF) {
48 bool Changed = false;
49 const TargetLowering *TLI = MF.getSubtarget().getTargetLowering();
50
51 // Iterate through each instruction in the function, looking for pseudos.
52 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
53 MachineBasicBlock *MBB = &*I;
54 for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
55 MBBI != MBBE; ) {
56 MachineInstr &MI = *MBBI++;
57
58 // If MI is a pseudo, expand it.
59 if (MI.usesCustomInsertionHook()) {
60 Changed = true;
61 MachineBasicBlock *NewMBB = TLI->EmitInstrWithCustomInserter(MI, MBB);
62 // The expansion may involve new basic blocks.
63 if (NewMBB != MBB) {
64 MBB = NewMBB;
65 I = NewMBB->getIterator();
66 MBBI = NewMBB->begin();
67 MBBE = NewMBB->end();
68 }
69 }
70 }
71 }
72
73 return Changed;
74 }
75