This is an archive of the discontinued LLVM Phabricator instance.

[GlobalMerge] Stable sort GlobalSets to fix non-deterministic sort order
ClosedPublic

Authored by mgrang on Nov 4 2017, 8:33 PM.

Download Raw Diff

Details

Reviewers

ab
asl

Commits

rG8c60365d74ac: [GlobalMerge] Stable sort GlobalSets to fix non-deterministic sort order
rL317817: [GlobalMerge] Stable sort GlobalSets to fix non-deterministic sort order

Summary

This fixes failure in CodeGen/AArch64/global-merge-group-by-use.ll uncovered by D39245.

Diff Detail

Repository: rL LLVM

Event Timeline

mgrang created this revision.Nov 4 2017, 8:33 PM

Herald added subscribers: kristof.beyls, aemerson. · View Herald TranscriptNov 4 2017, 8:33 PM

Ping for reviews please.

LGTM, thanks!

This revision is now accepted and ready to land.Nov 9 2017, 9:26 AM

Closed by commit rL317817: [GlobalMerge] Stable sort GlobalSets to fix non-deterministic sort order (authored by mgrang). · Explain WhyNov 9 2017, 10:05 AM

This revision was automatically updated to reflect the committed changes.

Revision Contents

Path

Size

lib/

CodeGen/

GlobalMerge.cpp

2 lines

Diff 121613

lib/CodeGen/GlobalMerge.cpp

Show First 20 Lines • Show All 380 Lines • ▼ Show 20 Lines	bool GlobalMerge::doMerge(SmallVectorImpl<GlobalVariable*> &Globals,
}		}

// Now we found a bunch of sets of globals used together. We accumulated		// Now we found a bunch of sets of globals used together. We accumulated
// the number of times we encountered the sets (i.e., the number of blocks		// the number of times we encountered the sets (i.e., the number of blocks
// that use that exact set of globals).		// that use that exact set of globals).
//		//
// Multiply that by the size of the set to give us a crude profitability		// Multiply that by the size of the set to give us a crude profitability
// metric.		// metric.
std::sort(UsedGlobalSets.begin(), UsedGlobalSets.end(),		std::stable_sort(UsedGlobalSets.begin(), UsedGlobalSets.end(),
[](const UsedGlobalSet &UGS1, const UsedGlobalSet &UGS2) {		[](const UsedGlobalSet &UGS1, const UsedGlobalSet &UGS2) {
return UGS1.Globals.count() * UGS1.UsageCount <		return UGS1.Globals.count() * UGS1.UsageCount <
UGS2.Globals.count() * UGS2.UsageCount;		UGS2.Globals.count() * UGS2.UsageCount;
});		});

// We can choose to merge all globals together, but ignore globals never used		// We can choose to merge all globals together, but ignore globals never used
// with another global. This catches the obviously non-profitable cases of		// with another global. This catches the obviously non-profitable cases of
// having a single global, but is aggressive enough for any other case.		// having a single global, but is aggressive enough for any other case.
▲ Show 20 Lines • Show All 256 Lines • Show Last 20 Lines