Re: [PATCH][PR target/81535] Fix tests on Power

[Segher Boessenkool <segher at kernel dot crashing dot org>]

Hi Yuri,

Sorry I missed this.  Please cc: me to prevent that from happening.

On Fri, Jul 28, 2017 at 05:42:00AM +0100, Yury Gribov wrote:
> This patch fixes issues reported in 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81535
> 
> I removed call to g in pr79439.c because gcc was duplicating the basic 
> block with call depending on compiler flags (so scan-assembler-times 
> pattern wasn't reliable anymore).  I also added alias to prevent 
> inlining introduced by recent PR56727 patch.
> 
> I added Power-specific pattern in pr56727-2.c testcase and disabled 
> testing on Power in pr56727-1.c.
> 
> Tested on powerpc64-unknown-linux-gnu.  Ok for trunk?

Did you also test this with -m32?  And on powerpc64le-linux, the target
the bug is reported against?  The three ABIs are different.

> 	PR target/81535
> 	* gcc.dg/pr56727-1.c: Do not check output on Power.
> 	* gcc.dg/pr56727-2.c: Fix pattern for Power.

Please name the actual target triple here, i.e. powerpc*-*-* .

> 	* gcc.target/powerpc/pr79439.c: Prevent inlining.

> diff -rupN gcc/gcc/testsuite/gcc.dg/pr56727-1.c gcc-81535/gcc/testsuite/gcc.dg/pr56727-1.c
> --- gcc/gcc/testsuite/gcc.dg/pr56727-1.c	2017-07-28 02:39:54.770046466 +0000
> +++ gcc-81535/gcc/testsuite/gcc.dg/pr56727-1.c	2017-07-28 04:25:04.805648587 +0000
> @@ -1,6 +1,6 @@
>  /* { dg-do compile { target fpic } } */
>  /* { dg-options "-O2 -fPIC" } */
> -/* { dg-final { scan-assembler-not "@(PLT|plt)" { target i?86-*-* x86_64-*-* powerpc*-*-* } } } */
> +/* { dg-final { scan-assembler-not "@(PLT|plt)" { target i?86-*-* x86_64-*-* } } } */
>  
>  #define define_func(type) \
>    void f_ ## type (type b) { f_ ## type (0); } \

Is it correct that current GCC does not do the call via the PLT?

> diff -rupN gcc/gcc/testsuite/gcc.dg/pr56727-2.c gcc-81535/gcc/testsuite/gcc.dg/pr56727-2.c
> --- gcc/gcc/testsuite/gcc.dg/pr56727-2.c	2017-07-28 02:39:54.770046466 +0000
> +++ gcc-81535/gcc/testsuite/gcc.dg/pr56727-2.c	2017-07-28 04:21:19.195215187 +0000
> @@ -1,10 +1,10 @@
>  /* { dg-do compile { target fpic } } */
>  /* { dg-options "-O2 -fPIC" } */
> -/* { dg-final { scan-assembler "@(PLT|plt)" { target i?86-*-* x86_64-*-* powerpc*-*-linux* } } } */
>  
>  __attribute__((noinline, noclone))
>  void f (short b)
>  {
> +  __builtin_setjmp (0);  /* Prevent tailcall */
>    f (0);
>  }
>  

This change is not mentioned in the changelog.

> @@ -14,3 +14,5 @@ void h ()
>  {
>    g (0);
>  }
> +/* { dg-final { scan-assembler "@(PLT|plt)" { target i?86-*-* x86_64-*-* } } } */
> +/* { dg-final { scan-assembler "bl f\n\[ \t\]*nop" { target powerpc*-*-linux* } } } */

Is there a real reason there cannot be a tailcall here?  You can write
this as  { scan-assembler {\mbl f\s+nop\M} }  btw.

> diff -rupN gcc/gcc/testsuite/gcc.target/powerpc/pr79439.c gcc-81535/gcc/testsuite/gcc.target/powerpc/pr79439.c
> --- gcc/gcc/testsuite/gcc.target/powerpc/pr79439.c	2017-07-28 02:39:55.750048426 +0000
> +++ gcc-81535/gcc/testsuite/gcc.target/powerpc/pr79439.c	2017-07-28 04:13:47.834177237 +0000
> @@ -8,22 +8,17 @@
>  
>  int f (void);
>  
> -void
> -g (void)
> -{
> -}
> -
>  int
>  rec (int a)
>  {
>    int ret = 0;
>    if (a > 10 && f ())
>      ret += rec (a - 1);
> -  g ();
>    return a + ret;
>  }
>  
> +void rec_alias (short) __attribute__ ((alias ("rec")));
> +
>  /* { dg-final { scan-assembler-times {\mbl f\M}   1 } } */
> -/* { dg-final { scan-assembler-times {\mbl g\M}   1 } } */
>  /* { dg-final { scan-assembler-times {\mbl rec\M} 1 } } */
> -/* { dg-final { scan-assembler-times {\mnop\M}    3 } } */
> +/* { dg-final { scan-assembler-times {\mnop\M}    2 } } */

The changelog says "prevent inlining", but you actually delete the code.
Is that okay, wasn't the testcase actually testing for something here?


Segher