corysanin/tubestation
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Bug 1945507 - improve asm memory barrier in AnnotateMozCrashReason r=gsvelto

Browse Source 
Adding explicit reference to gMozCrashReason as an input memory operand
with r/w effect seems to prevent extra optimisation. The original
snippet is inspired from google benchmark implementation of
`DoNotOptimize`.

Differential Revision: https://phabricator.services.mozilla.com/D236553
This commit is contained in:
serge-sans-paille
2025-02-20 05:08:22 +00:00
parent feb5e07602
commit 187ba0c3f7
1 changed files with 7 additions and 3 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
mfbt/Assertions.h
View File

@@ -53,9 +53,13 @@ MOZ_END_EXTERN_C
#if defined(MOZ_HAS_MOZGLUE) || defined(MOZILLA_INTERNAL_API) #if defined(MOZ_HAS_MOZGLUE) || defined(MOZILLA_INTERNAL_API)
static inline void AnnotateMozCrashReason(const char* reason) { static inline void AnnotateMozCrashReason(const char* reason) {
gMozCrashReason = reason; gMozCrashReason = reason;
// See bug 1681846, on 32-bit Android ARM the compiler removes the store to // The following assembly fakes a memory read/write to the compiler, which
// gMozCrashReason if this barrier is not present. // prevents the removal of gMozCrashReason store. See bug 1681846 and 1945507.
asm volatile("" ::: "memory"); # if defined(__clang__)
asm volatile("" : "+r,m"(gMozCrashReason) : : "memory");
# else
asm volatile("" : "+m,r"(gMozCrashReason) : : "memory");
# endif
} }
# define MOZ_CRASH_ANNOTATE(...) AnnotateMozCrashReason(__VA_ARGS__) # define MOZ_CRASH_ANNOTATE(...) AnnotateMozCrashReason(__VA_ARGS__)
#else #else