https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95778
Bug ID: 95778
Summary: target_clones indirection eliminates requires noinline
Product: gcc
Version: 10.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: other
Assignee: unassigned at gcc dot gnu.org
Reporter: yyc1992 at gmail dot com
Target Milestone: ---
Compiling
```
static __attribute__((noinline,target_clones("default,avx2"))) int f2(int *p)
{
asm volatile ("" :: "r"(p) : "memory");
return *p;
}
__attribute__((target_clones("default,avx2"))) int g2(int *p)
{
return f2(p);
}
```
with `-fPIC -O3` generates
```
g2.avx2.0:
jmp f2.avx2.0
```
However, if any of the two `noinline` is removed, the generated code becomes,
```
g2.avx2.0:
jmp f2@PLT
```
which cannot get eliminated later
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95776
I think this should be possible to do and should be possible without LTO (hence
a slightly different bug than
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95776 even though if that one is
fixed turning on LTO can particially fix this).
Also, in this case, the `f2` should be inlinable to `g2`. However, no
combination of `inline`, `always_inline`, `flatten` I've tested can do that,
even though when both functions are marked with `noinline` gcc clearly knows
which function is calling what so it should have no problem inlining.
