Make x86 __ehhandler comdat if parent function is
Summary:
This change comes from using lld for i686-windows-msvc. Before this change, lld
emits an error of:
error: relocation against symbol in discarded section: .xdata
It's possible that this could be addressed in lld, but I think this change is
reasonable on its own.
At a high level, this is being generated:
A (.text comdat) -> B (.text) -> C (.xdata comdat)
Where A is a C++ inline function, which references B, an exception handler
thunk, which references C, the exception handling info.
With this structure, lld will error when applying relocations to B if the C it
references has been discarded (some other C has been selected).
This change checks if A is comdat, and if so places the exception registration
thunk (B) in the comdata group of A (and B).
It appears that MSVC makes the __ehhandler function comdat.
Is it possible that duplicate thunks are being emitted into the final binary
with other linkers, or are they stripping the unused thunks?
Reviewers: rnk, majnemer, compnerd, smeenai
Reviewed By: rnk, compnerd
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38940
llvm-svn: 316219
2017-10-21 01:04:43 +08:00
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; RUN: opt -mtriple=i686-unknown-windows-msvc -S -x86-winehstate < %s | FileCheck %s
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$f = comdat any
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define void @f() comdat personality i32 (...)* @__CxxFrameHandler3 {
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invoke void @g() to label %return unwind label %unwind
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return:
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ret void
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unwind:
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%pad = cleanuppad within none []
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cleanupret from %pad unwind to caller
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}
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declare void @g()
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declare i32 @__CxxFrameHandler3(...)
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2019-08-03 22:28:34 +08:00
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; CHECK: define internal i32 @"__ehhandler$f"(i8* %0, i8* %1, i8* %2, i8* %3){{ .+}} comdat($f) {
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