• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
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 #define DEBUG_TYPE "expand-isel-pseudos"
18 #include "llvm/CodeGen/MachineFunction.h"
19 #include "llvm/CodeGen/MachineFunctionPass.h"
20 #include "llvm/CodeGen/Passes.h"
21 #include "llvm/Target/TargetLowering.h"
22 #include "llvm/Target/TargetMachine.h"
23 #include "llvm/Support/Debug.h"
24 using namespace llvm;
25 
26 namespace {
27   class ExpandISelPseudos : public MachineFunctionPass {
28   public:
29     static char ID; // Pass identification, replacement for typeid
ExpandISelPseudos()30     ExpandISelPseudos() : MachineFunctionPass(ID) {}
31 
32   private:
33     virtual bool runOnMachineFunction(MachineFunction &MF);
34 
getPassName() const35     const char *getPassName() const {
36       return "Expand ISel Pseudo-instructions";
37     }
38 
getAnalysisUsage(AnalysisUsage & AU) const39     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
40       MachineFunctionPass::getAnalysisUsage(AU);
41     }
42   };
43 } // end anonymous namespace
44 
45 char ExpandISelPseudos::ID = 0;
46 INITIALIZE_PASS(ExpandISelPseudos, "expand-isel-pseudos",
47                 "Expand CodeGen Pseudo-instructions", false, false)
48 
createExpandISelPseudosPass()49 FunctionPass *llvm::createExpandISelPseudosPass() {
50   return new ExpandISelPseudos();
51 }
52 
runOnMachineFunction(MachineFunction & MF)53 bool ExpandISelPseudos::runOnMachineFunction(MachineFunction &MF) {
54   bool Changed = false;
55   const TargetLowering *TLI = MF.getTarget().getTargetLowering();
56 
57   // Iterate through each instruction in the function, looking for pseudos.
58   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
59     MachineBasicBlock *MBB = I;
60     for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
61          MBBI != MBBE; ) {
62       MachineInstr *MI = MBBI++;
63 
64       // If MI is a pseudo, expand it.
65       const MCInstrDesc &MCID = MI->getDesc();
66       if (MCID.usesCustomInsertionHook()) {
67         Changed = true;
68         MachineBasicBlock *NewMBB =
69           TLI->EmitInstrWithCustomInserter(MI, MBB);
70         // The expansion may involve new basic blocks.
71         if (NewMBB != MBB) {
72           MBB = NewMBB;
73           I = NewMBB;
74           MBBI = NewMBB->begin();
75           MBBE = NewMBB->end();
76         }
77       }
78     }
79   }
80 
81   return Changed;
82 }
83