[libc++abi] Apply simplify scan_eh_tab to SjLj #68
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Previous "simplify scan_eh_tab" patch, https://reviews.llvm.org/D93190, saves landingpad if and only if the target is not using SjLj exceptions. However, the landingpad is used by SjLj exception handler also. This patch changes to set landingpad for both exception handlers.
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Pass regression tests. @simoll -san, please review this one too. |
kaz7
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Sep 25, 2023
…… (#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 #59: 0x00007ff4102e0660 liblldb.so.15`SymbolFileDWARF::CompleteType(this=<unavailable>, compiler_type=0x00007ffdd9829450) at SymbolFileDWARF.cpp:1567:25 [opt] ... frame #67: 0x00007ff40fdf9bd4 liblldb.so.15`lldb_private::ValueObject::Dereference(this=0x0000022bb5dfe980, error=0x00007ffdd9829970) at ValueObject.cpp:2672:41 [opt] frame #68: 0x00007ff41011bb0a liblldb.so.15`(anonymous namespace)::LibStdcppSharedPtrSyntheticFrontEnd::Update(this=0x000002298fb94380) at LibStdcpp.cpp:403:40 [opt] frame #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 #78: 0x00007ff40fdf6e42 liblldb.so.15`lldb_private::ValueObject::CalculateSyntheticValue(this=0x000002296c66a500) at ValueObject.cpp:1836:27 [opt] frame #79: 0x00007ff40fdf1939 liblldb.so.15`lldb_private::ValueObject::GetSyntheticValue(this=<unavailable>) at ValueObject.cpp:1867:3 [opt] frame #80: 0x00007ff40fc89008 liblldb.so.15`ValueImpl::GetSP(this=0x0000022c71b90de0, stop_locker=0x00007ffdd9829d00, lock=0x00007ffdd9829d08, error=0x00007ffdd9829d18) at SBValue.cpp:141:46 [opt] frame #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 #82: 0x00007ff40fc7d817 liblldb.so.15`lldb::SBValue::GetSP(this=0x00007ffdd9829d90, locker=0x00007ffdd9829d00) const at SBValue.cpp:1047:17 [opt] frame #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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Previous "simplify scan_eh_tab" patch, https://reviews.llvm.org/D93190,
saves landingpad if and only if the target is not using SjLj exceptions.
However, the landingpad is used by SjLj exception handler also. This
patch changes to set landingpad for both exception handlers.