[StandardInstrumentations] Verify function doesn't change if analyses are preserved

[aeubanks]

Summary

Reuse StructuralHash and allow it to be used in non-expensive checks builds.

Move PreservedAnalysisChecker further down StandardInstrumentations so other Instrumentations (e.g. printing) have a chance to run before PreservedAnalysisChecker crashes.

[yrouban]

Looks good in general, but it would be better to have this patch split into several smaller patches: renaming NFC, InstructionCounter intro, one for each particular pass fix.

llvm/lib/Passes/StandardInstrumentations.cpp

1076

may be rename to Value?

2201

I think the time profiling pass has to be the last one.

[nikic]

Please split out the fixes to individual passes.

llvm/lib/Passes/StandardInstrumentations.cpp

46–47

Better move the default behind EXPENSIVE_CHECKS.

1072

Instead of instruction count, it would be better to use StructuralHash. It exists for exactly this purpose.

llvm/lib/Transforms/Coroutines/CoroCleanup.cpp

133 ↗

(On Diff #504895)

Can preserve CFG here.

llvm/lib/Transforms/Utils/AssumeBundleBuilder.cpp

568 ↗

(On Diff #504895)

Can preserve CFG here.

616 ↗

(On Diff #504895)

Should return from salvageKnowledge whether something was salvaged...

[aeubanks]

split out other changes, use StructuralHash instead

[nikic]

nontrivial-unswitch-markloopasdeleted.ll failure looks legit.

llvm/lib/Passes/StandardInstrumentations.cpp

1121–1131

Hm, aren't we going to skip the CFG check below if only CFGAnalyses are preserved (but not AllAnalyses)?

[aeubanks]

rebase after cleanups
fix tests

[aeubanks]

llvm/lib/Passes/StandardInstrumentations.cpp

1121–1131

no longer a worry after D146096

[nikic]

LG