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Transpose the calculation of spill weights such that we are calculating one

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register at a time. This turns out to be slightly faster than iterating over
instructions, but more importantly, it allows us to compute spill weights for
new registers created after the spill weight pass has run.

Also compute the allocation hint at the same time as the spill weight. This
allows us to use the spill weight as a cost metric for copies, and choose the
most profitable hint if there is more than one possibility.

The new hints provide a very small (< 0.1%) but universal code size improvement.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110631 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2010-08-10 00:02:26 +00:00
parent 533a7df02d
commit df30cf9e61
7 changed files with 169 additions and 116 deletions
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5
lib/CodeGen/SimpleRegisterCoalescing.cpp
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@ -1044,7 +1044,7 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
if (CP.isPhys()) {
DEBUG(dbgs() <<" with physreg %" << tri_->getName(CP.getDstReg()) << "\n");
// Only coalesce to allocatable physreg.
if (!allocatableRegs_[CP.getDstReg()]) {
if (!li_->isAllocatable(CP.getDstReg())) {
DEBUG(dbgs() << "\tRegister is an unallocatable physreg.\n");
return false; // Not coalescable.
}
@ -1093,7 +1093,6 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
// happens.
if (li_->hasInterval(CP.getDstReg()) &&
li_->getInterval(CP.getDstReg()).ranges.size() > 1000) {
mri_->setRegAllocationHint(CP.getSrcReg(), 0, CP.getDstReg());
++numAborts;
DEBUG(dbgs()
<< "\tPhysical register live interval too complicated, abort!\n");
@ -1112,7 +1111,6 @@ bool SimpleRegisterCoalescing::JoinCopy(CopyRec &TheCopy, bool &Again) {
ReMaterializeTrivialDef(JoinVInt, CP.getDstReg(), 0, CopyMI))
return true;
mri_->setRegAllocationHint(CP.getSrcReg(), 0, CP.getDstReg());
++numAborts;
DEBUG(dbgs() << "\tMay tie down a physical register, abort!\n");
Again = true; // May be possible to coalesce later.
@ -1693,7 +1691,6 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
<< "********** Function: "
<< ((Value*)mf_->getFunction())->getName() << '\n');
allocatableRegs_ = tri_->getAllocatableSet(fn);
for (TargetRegisterInfo::regclass_iterator I = tri_->regclass_begin(),
E = tri_->regclass_end(); I != E; ++I)
allocatableRCRegs_.insert(std::make_pair(*I,