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[RA CopyHints] Fix compile-time regression
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Authored by jonpa on Oct 3 2018, 3:01 AM.

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Summary

This patch makes sure that a register is only hinted once to RA. In extreme cases the same register can otherwise be hinted numerous times and cause a compile time slowdown.

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jonpa created this revision.Oct 3 2018, 3:01 AM

Herald added a subscriber: qcolombet. · View Herald TranscriptOct 3 2018, 3:01 AM

jonpa added a subscriber: llvm-commits.Oct 3 2018, 3:04 AM

LGTM

This revision is now accepted and ready to land.Oct 3 2018, 5:18 AM

r343686

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lib/

CodeGen/

CalcSpillWeights.cpp

6 lines

Diff 168089

lib/CodeGen/CalcSpillWeights.cpp

Show First 20 Lines • Show All 281 Lines • ▼ Show 20 Lines	#endif
Hint.clear();		Hint.clear();

// Pass all the sorted copy hints to mri.		// Pass all the sorted copy hints to mri.
if (updateLI && CopyHints.size()) {		if (updateLI && CopyHints.size()) {
// Remove a generic hint if previously added by target.		// Remove a generic hint if previously added by target.
if (TargetHint.first == 0 && TargetHint.second)		if (TargetHint.first == 0 && TargetHint.second)
mri.clearSimpleHint(li.reg);		mri.clearSimpleHint(li.reg);

		std::set<unsigned> HintedRegs;
for (auto &Hint : CopyHints) {		for (auto &Hint : CopyHints) {
if (TargetHint.first != 0 && Hint.Reg == TargetHint.second)		if (!HintedRegs.insert(Hint.Reg).second \|\|
// Don't add again the target-type hint.		(TargetHint.first != 0 && Hint.Reg == TargetHint.second))
		// Don't add the same reg twice or the target-type hint again.
continue;		continue;
mri.addRegAllocationHint(li.reg, Hint.Reg);		mri.addRegAllocationHint(li.reg, Hint.Reg);
if (!tri.enableMultipleCopyHints())		if (!tri.enableMultipleCopyHints())
break;		break;
}		}

// Weakly boost the spill weight of hinted registers.		// Weakly boost the spill weight of hinted registers.
totalWeight *= 1.01F;		totalWeight *= 1.01F;
Show All 26 Lines