https://gcc.gnu.org/bugzilla/show_bug.cgi?id=42497
Peter Cordes <peter at cordes dot ca> changed:
What |Removed |Added
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CC| |peter at cordes dot ca
--- Comment #3 from Peter Cordes <peter at cordes dot ca> ---
This bug is still present with gcc 5.2 -O3 (which does include
-foptimize-sibling-calls).
void fire_special_event(void);
void conditional_call(int cond) { if(cond) fire_special_event(); }
The above code compiles to (x86-64 gcc 5.2 -O3)
testl %edi, %edi
jne .L4
rep ret
.L4:
jmp fire_special_event
This sequence would be better:
testl %edi, %edi
jne fire_special_event
ret
godbolt link: https://goo.gl/0K6EZx
Later functions in that listing are related to
http://stackoverflow.com/questions/97987/advantage-of-switch-over-if-else-statement
Is there a linker limitation on relocations for conditional-branch targets
that aren't part of the current compilation unit? neither clang 3.7 nor icc 13
do any better than gcc. It seems to work for me when modifying the asm by hand
to jnz _Z18fire_special_eventv, and linking to a
separately-compiled definition.
