Backport D74999: [WebAssembly] Fix a non-determinism problem in FixIrreducibleControlFlow #68
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Summary: We already sorted the blocks when fixing up a set of mutual loop entries, however, there can be multiple sets of such mutual loop entries, and the order we encounter them should not be random, so sort them too. Fixes https://bugs.llvm.org/show_bug.cgi?id=44982 Patch by Alon Zakai (kripken) Reviewers: aheejin, sbc100, dschuff Subscribers: mgrang, sunfish, hiraditya, jgravelle-google, llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D74999
vext01
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68: Fix multiple locations in stackmaps r=ltratt a=ptersilie Co-authored-by: Lukas Diekmann <lukas.diekmann@gmail.com>
nikic
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llvm#67069) We noticed some performance issue while in lldb-vscode for grabing the name of the SBValue. Profiling shows SBValue::GetName() can cause synthetic children provider of shared/unique_ptr to deference underlying object and complete it type. This patch lazily moves the dereference from synthetic child provider's Update() method to GetChildAtIndex() so that SBValue::GetName() won't trigger the slow code path. Here is the culprit slow code path: ``` ... frame rust-lang#59: 0x00007ff4102e0660 liblldb.so.15`SymbolFileDWARF::CompleteType(this=<unavailable>, compiler_type=0x00007ffdd9829450) at SymbolFileDWARF.cpp:1567:25 [opt] ... frame rust-lang#67: 0x00007ff40fdf9bd4 liblldb.so.15`lldb_private::ValueObject::Dereference(this=0x0000022bb5dfe980, error=0x00007ffdd9829970) at ValueObject.cpp:2672:41 [opt] frame rust-lang#68: 0x00007ff41011bb0a liblldb.so.15`(anonymous namespace)::LibStdcppSharedPtrSyntheticFrontEnd::Update(this=0x000002298fb94380) at LibStdcpp.cpp:403:40 [opt] frame rust-lang#69: 0x00007ff41011af9a liblldb.so.15`lldb_private::formatters::LibStdcppSharedPtrSyntheticFrontEndCreator(lldb_private::CXXSyntheticChildren*, std::shared_ptr<lldb_private::ValueObject>) [inlined] (anonymous namespace)::LibStdcppSharedPtrSyntheticFrontEnd::LibStdcppSharedPtrSyntheticFrontEnd(this=0x000002298fb94380, valobj_sp=<unavailable>) at LibStdcpp.cpp:371:5 [opt] ... frame rust-lang#78: 0x00007ff40fdf6e42 liblldb.so.15`lldb_private::ValueObject::CalculateSyntheticValue(this=0x000002296c66a500) at ValueObject.cpp:1836:27 [opt] frame rust-lang#79: 0x00007ff40fdf1939 liblldb.so.15`lldb_private::ValueObject::GetSyntheticValue(this=<unavailable>) at ValueObject.cpp:1867:3 [opt] frame rust-lang#80: 0x00007ff40fc89008 liblldb.so.15`ValueImpl::GetSP(this=0x0000022c71b90de0, stop_locker=0x00007ffdd9829d00, lock=0x00007ffdd9829d08, error=0x00007ffdd9829d18) at SBValue.cpp:141:46 [opt] frame rust-lang#81: 0x00007ff40fc7d82a liblldb.so.15`lldb::SBValue::GetSP(ValueLocker&) const [inlined] ValueLocker::GetLockedSP(this=0x00007ffdd9829d00, in_value=<unavailable>) at SBValue.cpp:208:21 [opt] frame rust-lang#82: 0x00007ff40fc7d817 liblldb.so.15`lldb::SBValue::GetSP(this=0x00007ffdd9829d90, locker=0x00007ffdd9829d00) const at SBValue.cpp:1047:17 [opt] frame rust-lang#83: 0x00007ff40fc7da6f liblldb.so.15`lldb::SBValue::GetName(this=0x00007ffdd9829d90) at SBValue.cpp:294:32 [opt] ... ``` Differential Revision: https://reviews.llvm.org/D159542
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See https://reviews.llvm.org/D74999. Stumbled upon the nondeterministic behavior in the wild (a large wasm codebase), tracked it down to the wasm-specific
FixIrreducibleControlFlowpass, and found this fix.I've confirmed that cherry-picking this commit fixes the nondeterminism I was observing with both
llcandrustc.