Hi Michael,
on 2022/2/9 上午11:27, Michael Meissner via Gcc-patches wrote:
> Reset -mpower8-fusion for power9 inlining power8 functions, PR 102059.
>
> This patch is an attempt to make a much simpler patch to fix PR target/102059
> than the previous patch.
>
> It just fixes the issue that if a function is specifically declared as a
> power8
> function, you can't inline in functions that are specified with power9 or
> power10 options.
>
> The issue is -mpower8-fusion is cleared when you use -mcpu=power9 or
> -mcpu=power10. When I wrote the code for controlling which function can
> inline
> other functions, -mpower8-fusion was set for -mcpu=power9 (-mcpu=power10 was
> not an option at that time). This patch fixes this particular problem.
>
> Perhaps -mpower8-fusion should go away in the GCC 13 time frame. This patch
> just goes in and resets the fusion bit for testing inlines.
>
> I have built a bootstrapped little endian compiler on power9 and the tests had
> no regressions.
>
> I have built a bootstrapped big endian compiler on power8 and I tested both
> 32-bit and 64-bit builds, and there were no regressions.
>
> Can I install this into the trunk and back port it into GCC 11 after a burn-in
> period?
>
Thanks for the patch! I guess we also need this for GCC 10 as:
$cat htm.c
__attribute__((always_inline)) int foo(int *b) {
*b += 10;
return *b;
}
#pragma GCC target "cpu=power10,htm"
int bar(int* a){
*a = foo(a);
return 0;
}
/opt/at14.0/bin/gcc -flto -S htm.c -mcpu=power8
htm.c:1:36: warning: ‘always_inline’ function might not be inlinable
[-Wattributes]
1 | __attribute__((always_inline)) int foo(int *b) {
| ^~~
htm.c: In function ‘bar’:
htm.c:1:36: error: inlining failed in call to ‘always_inline’ ‘foo’: target
specific option mismatch
htm.c:8:8: note: called from here
8 | *a = foo(a);
| ^~~~~~
Besides, as I noted in the PR, with this fix we can safely remove the option
"-mno-power8-fusion" in gcc/testsuite/gcc.dg/lto/pr102059-1_0.c, which has
the coverage for lto (though I didn't test ;-)).
BR,
Kewen
> 2022-02-08 Michael Meissner <meiss...@linux.ibm.com>
>
> gcc/
>
> PR target/102059
> * config/rs6000/rs6000.cc (rs6000_can_inline_p): Don't test for
> power8-fusion if the caller was power9 or power10.
>
> gcc/testsuite/
> PR target/102059
> * gcc.target/powerpc/pr102059-4.c: New test.
> ---
> gcc/config/rs6000/rs6000.cc | 8 ++++++++
> gcc/testsuite/gcc.target/powerpc/pr102059-4.c | 20 +++++++++++++++++++
> 2 files changed, 28 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/powerpc/pr102059-4.c
>
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index eaba9a2d698..e2d94421ae9 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -25278,6 +25278,14 @@ rs6000_can_inline_p (tree caller, tree callee)
> callee_isa &= ~OPTION_MASK_HTM;
> explicit_isa &= ~OPTION_MASK_HTM;
> }
> +
> + /* Power9 and power10 do not set power8-fusion. If the callee was
> + explicitly compiled for power8, and the caller was power9 or
> + power10, ignore the power8-fusion bits if it was set by
> + default. */
> + if ((caller_isa & OPTION_MASK_P8_FUSION) == 0
> + && (explicit_isa & OPTION_MASK_P8_FUSION) == 0)
> + callee_isa &= ~OPTION_MASK_P8_FUSION;
> }
>
> /* The callee's options must be a subset of the caller's options, i.e.
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr102059-4.c
> b/gcc/testsuite/gcc.target/powerpc/pr102059-4.c
> new file mode 100644
> index 00000000000..627c6f820c7
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr102059-4.c
> @@ -0,0 +1,20 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mdejagnu-cpu=power10 -Wno-attributes" } */
> +
> +/* Verify that power10 can explicity include functions compiled for power8.
> + The issue is -mcpu=power8 enables -mpower8-fusion, but -mcpu=power9 or
> + -mcpu=power10 do not set power8-fusion by default. */
> +
> +static inline int __attribute__ ((always_inline,target("cpu=power8")))
> +foo (int *b)
> +{
> + *b += 10;
> + return *b;
> +}
> +
> +int
> +bar (int *a)
> +{
> + *a = foo (a);
> + return 0;
> +}
>
