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Add debugging info. Use the newly created "hasUnmodelledSideEffects" method.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45178 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bill Wendling 2007-12-18 21:38:04 +00:00
parent 7a0678cae6
commit 280f4565eb
1 changed files with 38 additions and 21 deletions
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59
lib/CodeGen/MachineLICM.cpp
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@ -103,25 +103,6 @@ namespace {
return LI->getLoopFor(BB) != CurLoop;
}
/// CanHoistInst - Checks that this instructions is one that can be hoisted
/// out of the loop. I.e., it has no side effects, isn't a control flow
/// instr, etc.
///
bool CanHoistInst(MachineInstr &I) const {
#ifndef NDEBUG
DEBUG({
DOUT << "--- Checking if we can hoist " << I << "\n";
if (I.getInstrDescriptor()->ImplicitUses)
DOUT << " * Instruction has implicit uses.\n";
else if (!TII->isTriviallyReMaterializable(&I))
DOUT << " * Instruction has side effects.\n";
});
#endif
// Don't hoist if this instruction implicitly reads physical registers.
if (I.getInstrDescriptor()->ImplicitUses) return false;
return TII->isTriviallyReMaterializable(&I);
}
/// IsLoopInvariantInst - Returns true if the instruction is loop
/// invariant. I.e., all virtual register operands are defined outside of
/// the loop, physical registers aren't accessed (explicitly or implicitly),
@ -272,13 +253,46 @@ void MachineLICM::HoistRegion(MachineDomTreeNode *N) {
/// instruction is hoistable.
///
bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) {
if (!CanHoistInst(I)) return false;
DEBUG({
DOUT << "--- Checking if we can hoist " << I;
if (I.getInstrDescriptor()->ImplicitUses) {
DOUT << " * Instruction has implicit uses:\n";
const TargetMachine &TM = CurMF->getTarget();
const MRegisterInfo *MRI = TM.getRegisterInfo();
const unsigned *ImpUses = I.getInstrDescriptor()->ImplicitUses;
for (; *ImpUses; ++ImpUses)
DOUT << " -> " << MRI->getName(*ImpUses) << "\n";
}
if (I.getInstrDescriptor()->ImplicitDefs) {
DOUT << " * Instruction has implicit defines:\n";
const TargetMachine &TM = CurMF->getTarget();
const MRegisterInfo *MRI = TM.getRegisterInfo();
const unsigned *ImpDefs = I.getInstrDescriptor()->ImplicitDefs;
for (; *ImpDefs; ++ImpDefs)
DOUT << " -> " << MRI->getName(*ImpDefs) << "\n";
}
if (TII->hasUnmodelledSideEffects(&I))
DOUT << " * Instruction has side effects.\n";
});
#if 0
// FIXME: Don't hoist if this instruction implicitly reads physical registers.
if (I.getInstrDescriptor()->ImplicitUses ||
I.getInstrDescriptor()->ImplicitDefs)
return false;
#endif
// The instruction is loop invariant if all of its operands are loop-invariant
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
const MachineOperand &MO = I.getOperand(i);
if (!MO.isRegister() || !MO.isUse())
if (!(MO.isRegister() && MO.getReg() && MO.isUse()))
continue;
unsigned Reg = MO.getReg();
@ -295,6 +309,9 @@ bool MachineLICM::IsLoopInvariantInst(MachineInstr &I) {
return false;
}
// Don't hoist something that has side effects.
if (TII->hasUnmodelledSideEffects(&I)) return false;
// If we got this far, the instruction is loop invariant!
return true;
}