Re: [PATCH] rs6000: Fix ICE expanding lxvp and stxvp gimple built-ins [PR101849]

[Bill Schmidt <wschmidt@linux.ibm.com>]

Hi Peter,

On 8/13/21 12:01 PM, Peter Bergner wrote:
> On 8/12/21 1:20 PM, David Edelsohn wrote:
>> On Tue, Aug 10, 2021 at 7:37 PM Peter Bergner <bergner@linux.ibm.com> wrote:
>>> gcc/
>>>          PR target/101849
>>>          * config/rs6000/rs6000-call.c (rs6000_gimple_fold_mma_builtin): Cast
>>>          pointer to __vector_pair *.
>>>
>>> gcc/testsuite/
>>>          PR target/101849
>>>          * gcc.target/powerpc/pr101849.c: New test.
>> Okay.
>>
>> Thanks, David
> V2:
>    The previous patch was "ok'd" by David, but in the bugzilla, richi made
> a suggestion that using build2, the ptr's type is ignored and we could just
> pass in the pointer type we want, which is a little simpler, so that is
> what I have done with this version, which I think is better than the
> previous one.  I have also expanded the test case a little to test both
> constant and non-constant offsets.
>
> This version passed bootstrap and regression testing on powerpc64le-linux
> with no regressions.  Ok for mainline?  This also affects GCC 11 and 10,
> so ok there too after it has baked on trunk for a few days?
>
> ...or do we want to stick with the previous patch?
>
> Peter

Honestly, I don't see how it matters.  So far as I can tell, all you've 
done here is hand-inlined what build_simple_mem_ref would do.  So I 
guess I have a slight preference for your original patch (but with the 
new test case, of course).  Up to you guys.

Thanks,
Bill

>
>
>
> rs6000: Fix ICE expanding lxvp and stxvp gimple built-ins [PR101849]
>
> PR101849 shows we ICE on a test case when we pass a non __vector_pair *
> pointer to the __builtin_vsx_lxvp and __builtin_vsx_stxvp built-ins
> that is cast to __vector_pair *.  The problem is that when we expand
> the built-in, the cast has already been removed from gimple and we are
> only given the base pointer.  The solution used here (which fixes the ICE)
> is to always use a __vector_pair * pointer when expanding the built-in.
>
> gcc/
> 	PR target/101849
> 	* config/rs6000/rs6000-call.c (rs6000_gimple_fold_mma_builtin): Force
> 	pointer to __vector_pair *.
>
> gcc/testsuite/
> 	PR target/101849
> 	* gcc.target/powerpc/pr101849.c: New test.
>
>
> diff --git a/gcc/config/rs6000/rs6000-call.c b/gcc/config/rs6000/rs6000-call.c
> index 904e104c058..90d7171fa46 100644
> --- a/gcc/config/rs6000/rs6000-call.c
> +++ b/gcc/config/rs6000/rs6000-call.c
> @@ -11919,8 +11919,10 @@ rs6000_gimple_fold_mma_builtin (gimple_stmt_iterator *gsi)
>         tree offset = gimple_call_arg (stmt, 0);
>         tree ptr = gimple_call_arg (stmt, 1);
>         tree lhs = gimple_call_lhs (stmt);
> -      tree mem = build_simple_mem_ref (build2 (POINTER_PLUS_EXPR,
> -					       TREE_TYPE (ptr), ptr, offset));
> +      tree ptr_t = build_pointer_type (vector_pair_type_node);
> +      tree mem = build2 (MEM_REF, vector_pair_type_node,
> +			 build2 (POINTER_PLUS_EXPR, ptr_t, ptr, offset),
> +			 build_int_cst (ptr_t, 0));
>         gimplify_assign (lhs, mem, &new_seq);
>         pop_gimplify_context (NULL);
>         gsi_replace_with_seq (gsi, new_seq, true);
> @@ -11932,8 +11934,10 @@ rs6000_gimple_fold_mma_builtin (gimple_stmt_iterator *gsi)
>         tree src = gimple_call_arg (stmt, 0);
>         tree offset = gimple_call_arg (stmt, 1);
>         tree ptr = gimple_call_arg (stmt, 2);
> -      tree mem = build_simple_mem_ref (build2 (POINTER_PLUS_EXPR,
> -					       TREE_TYPE (ptr), ptr, offset));
> +      tree ptr_t = build_pointer_type (vector_pair_type_node);
> +      tree mem = build2 (MEM_REF, vector_pair_type_node,
> +			 build2 (POINTER_PLUS_EXPR, ptr_t, ptr, offset),
> +			 build_int_cst (ptr_t, 0));
>         gimplify_assign (mem, src, &new_seq);
>         pop_gimplify_context (NULL);
>         gsi_replace_with_seq (gsi, new_seq, true);
> diff --git a/gcc/testsuite/gcc.target/powerpc/pr101849.c b/gcc/testsuite/gcc.target/powerpc/pr101849.c
> new file mode 100644
> index 00000000000..823fbfe9647
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/pr101849.c
> @@ -0,0 +1,22 @@
> +/* PR target/101849 */
> +/* { dg-do compile } */
> +/* { dg-require-effective-target power10_ok } */
> +/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
> +
> +/* Verify we do not ICE on the tests below.  */
> +
> +void
> +foo (__vector_pair *dst, double *x, long offset)
> +{
> +  dst[0] = __builtin_vsx_lxvp (0, (__vector_pair *)(void *)x);
> +  dst[1] = __builtin_vsx_lxvp (32, (__vector_pair *)(void *)x);
> +  dst[2] = __builtin_vsx_lxvp (offset, (__vector_pair *)(void *)x);
> +}
> +
> +void
> +bar (__vector_pair *src, double *x, long offset)
> +{
> +  __builtin_vsx_stxvp (src[0], 0, (__vector_pair *)(void *)x);
> +  __builtin_vsx_stxvp (src[1], 32, (__vector_pair *)(void *)x);
> +  __builtin_vsx_stxvp (src[2], offset, (__vector_pair *)(void *)x);
> +}
>
>