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/TargetMachine.h"
23using namespace llvm;
24
25#define DEBUG_TYPE "expand-isel-pseudos"
26
27namespace {
28  class ExpandISelPseudos : public MachineFunctionPass {
29  public:
30    static char ID; // Pass identification, replacement for typeid
31    ExpandISelPseudos() : MachineFunctionPass(ID) {}
32
33  private:
34    bool runOnMachineFunction(MachineFunction &MF) override;
35
36    void getAnalysisUsage(AnalysisUsage &AU) const override {
37      MachineFunctionPass::getAnalysisUsage(AU);
38    }
39  };
40} // end anonymous namespace
41
42char ExpandISelPseudos::ID = 0;
43char &llvm::ExpandISelPseudosID = ExpandISelPseudos::ID;
44INITIALIZE_PASS(ExpandISelPseudos, "expand-isel-pseudos",
45                "Expand ISel Pseudo-instructions", false, false)
46
47bool ExpandISelPseudos::runOnMachineFunction(MachineFunction &MF) {
48  bool Changed = false;
49  const TargetLowering *TLI = MF.getTarget().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 =
62          TLI->EmitInstrWithCustomInserter(MI, MBB);
63        // The expansion may involve new basic blocks.
64        if (NewMBB != MBB) {
65          MBB = NewMBB;
66          I = NewMBB;
67          MBBI = NewMBB->begin();
68          MBBE = NewMBB->end();
69        }
70      }
71    }
72  }
73
74  return Changed;
75}
76