llvm-6502/lib/CodeGen/ExpandISelPseudos.cpp

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//===-- llvm/CodeGen/ExpandISelPseudos.cpp ----------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Expand Psuedo-instructions produced by ISel. These are usually to allow
// the expansion to contain control flow, such as a conditional move
// implemented with a conditional branch and a phi, or an atomic operation
// implemented with a loop.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "expand-isel-pseudos"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
namespace {
class ExpandISelPseudos : public MachineFunctionPass {
public:
static char ID; // Pass identification, replacement for typeid
ExpandISelPseudos() : MachineFunctionPass(ID) {}
private:
virtual bool runOnMachineFunction(MachineFunction &MF);
const char *getPassName() const {
return "Expand ISel Pseudo-instructions";
}
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
MachineFunctionPass::getAnalysisUsage(AU);
}
};
} // end anonymous namespace
char ExpandISelPseudos::ID = 0;
INITIALIZE_PASS(ExpandISelPseudos, "expand-isel-pseudos",
"Expand CodeGen Pseudo-instructions", false, false)
FunctionPass *llvm::createExpandISelPseudosPass() {
return new ExpandISelPseudos();
}
bool ExpandISelPseudos::runOnMachineFunction(MachineFunction &MF) {
bool Changed = false;
const TargetLowering *TLI = MF.getTarget().getTargetLowering();
// Iterate through each instruction in the function, looking for pseudos.
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
MachineBasicBlock *MBB = I;
for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
MBBI != MBBE; ) {
MachineInstr *MI = MBBI++;
// If MI is a pseudo, expand it.
const TargetInstrDesc &TID = MI->getDesc();
if (TID.usesCustomInsertionHook()) {
Changed = true;
MachineBasicBlock *NewMBB =
TLI->EmitInstrWithCustomInserter(MI, MBB);
// The expansion may involve new basic blocks.
if (NewMBB != MBB) {
MBB = NewMBB;
I = NewMBB;
MBBI = NewMBB->begin();
MBBE = NewMBB->end();
}
}
}
}
return Changed;
}