https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63533
Andrew Pinski <pinskia at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution|--- |FIXED
Target Milestone|--- |10.0
--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> The attached reprocase contains an innocent function which can not ever
> benefit from inlining.
That is not true any more.
In GCC 10+, we get:
g:
testl %edi, %edi
jne .L8
subq $1016, %rsp
xorl %eax, %eax
movq %rsp, %rdi
call f
addq $1016, %rsp
ret
.p2align 4,,10
.p2align 3
.L8:
jmp g.part.0
g.part.0:
subq $8, %rsp
xorl %eax, %eax
call f
xorl %eax, %eax
call f
xorl %eax, %eax
call f
xorl %eax, %eax
call f
xorl %eax, %eax
addq $8, %rsp
jmp f
So we conserve stack space now due to two things, conditional shrink wrapping
and being able to tail callto g.part.0. The performance miss is just one
unconditional jump (there is another bug handling conditional tail calls
already).
So all fixed in GCC 10+.
