shylie/llvm-project
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[libunwind][cmake] Compile _Unwind* routines with -fexceptions (#121819)

Browse Source 
When building libunwind with LTO, we found that routines, like
_Unwind_RaiseException were marked `nounwind`. This causes problems when
libunwind is then used with exception throwing code, since many of the
routines are marked `nounwind` and the compiler infers that something
like a try/catch block cannot throw resulting in a miscompile
(see #120657). Similarly, in #56825, it was pointed out that marking
_Unwind_Resume as `nounwind` causes bad exception table generation.

This patch adds the `-fexceptions` flag to the build of the C files that
define these routines, as proposed in #56825.

Fixes #56825 #120657

---------

Co-authored-by: Petr Hosek <phosek@google.com>
This commit is contained in:
Paul Kirth 2025-01-16 13:44:55 -08:00 committed by GitHub
parent 7ea5f19503
commit 92f1f99d2e
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
1 changed files with 6 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
libunwind/src/CMakeLists.txt
View File

@ -20,7 +20,12 @@ set(LIBUNWIND_C_SOURCES
)
set_source_files_properties(${LIBUNWIND_C_SOURCES}
PROPERTIES
COMPILE_FLAGS "-std=c99")
# We need to set `-fexceptions` here so that key
# unwinding functions, like
# _UNWIND_RaiseException, are not marked as
# `nounwind`, which breaks LTO builds of
# libunwind. See #56825 and #120657 for context.
COMPILE_FLAGS "-std=c99 -fexceptions")
set(LIBUNWIND_ASM_SOURCES
UnwindRegistersRestore.S