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Darwin -fsanitize=cfi -flto=thin causes raw bitcode to be emitted, instead of Mach-O-wrapped bitcode #32088

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ahmedbougacha opened this issue Apr 22, 2017 · 2 comments
Open

Darwin -fsanitize=cfi -flto=thin causes raw bitcode to be emitted, instead of Mach-O-wrapped bitcode #32088

ahmedbougacha opened this issue Apr 22, 2017 · 2 comments
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@ahmedbougacha
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Bugzilla Link 32741
Version unspecified
OS All
CC @pcc

Extended Description

r301016 enabled CFI tests using ThinLTO on Darwin, but those are failing:

ld: warning: ignoring file /var/folders/09/r4vw4v8n5kb67jl66zvlbljw0000gn/T/lit_tmp_j2NEGY/nvcall-1477f4.o, file was built for unsupported file format ( 0x42 0x43 0xC0 0xDE 0x35 0x14 0x00 0x00 0x05 0x00 0x00 0x00 0x62 0x0C 0x30 0x24 ) which is not the architecture being linked (x86_64): /var/folders/09/r4vw4v8n5kb67jl66zvlbljw0000gn/T/lit_tmp_j2NEGY/nvcall-1477f4.o
Undefined symbols for architecture x86_64:
"_main", referenced from:
implicit entry/start for main executable
ld: symbol(s) not found for architecture x86_64

http://green.lab.llvm.org/green/job/clang-stage1-configure-RA_check/30480/consoleFull#-121919748349ba4694-19c4-4d7e-bec5-911270d8a58c

It seems that -fsanitize=cfi somehow causes -flto=thin to emit bitcode instead of mach-o:

$ ./bin/clang -flto=thin -fvisibility=hidden -fsanitize=cfi /tmp/t.cpp -c && file t.o
t.o: LLVM IR bitcode
$ ./bin/clang -flto=thin -fvisibility=hidden /tmp/t.cpp -c && file t.o
t.o: LLVM bitcode, wrapper x86_64

And it seems that ld64 doesn't accept raw bitcode.
@pcc
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pcc commented Apr 22, 2017

This has no hope of working until ld64 is changed to use the resolution-based LTO API. Until then, we will need to change the clang driver to prevent the use of -flto=thin with -fsanitize=cfi (and -fwhole-program-vtables).

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pcc commented Apr 22, 2017

...on Darwin.

@llvmbot llvmbot transferred this issue from llvm/llvm-bugzilla-archive Dec 10, 2021
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