Re: [PATCH] rs6000: Don't ICE when we disassemble an MMA variable [PR101322]

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Peter,

Thanks for the patch!  Some comments are inline as below.

on 2022/8/27 11:50, Peter Bergner via Gcc-patches wrote:
> When we expand an MMA disassemble built-in with C++ using a pointer that
> is casted to a valid MMA type, the type isn't passed down to the expand
> machinery and we end up using the base type of the pointer which leads to
> an ICE.  This patch enforces we always use the correct MMA type regardless
> of the pointer type being used.
> 
> This passed bootstrap and regtesting on powerpc64le-linux with no regressions.
> Ok for trunk and backports after some burn-in time?
> 
> Peter
> 
> gcc/
> 	PR target/101322
> 	* config/rs6000/rs6000-builtin.cc (rs6000_gimple_fold_mma_builtin):
> 	Enforce the use of a valid MMA pointer type.
> 
> gcc/testsuite/
> 	PR target/101322
> 	* g++.target/powerpc/pr101322.C: New test.
> 
> diff --git a/gcc/config/rs6000/rs6000-builtin.cc b/gcc/config/rs6000/rs6000-builtin.cc
> index 12afa86854c..e796e74f072 100644
> --- a/gcc/config/rs6000/rs6000-builtin.cc
> +++ b/gcc/config/rs6000/rs6000-builtin.cc
> @@ -1085,7 +1085,12 @@ rs6000_gimple_fold_mma_builtin (gimple_stmt_iterator *gsi,
>        unsigned nvec = (fncode == RS6000_BIF_DISASSEMBLE_ACC) ? 4 : 2;
>        tree dst_ptr = gimple_call_arg (stmt, 0);
>        tree src_ptr = gimple_call_arg (stmt, 1);
> -      tree src_type = TREE_TYPE (src_ptr);
> +      tree src_type = (fncode == RS6000_BIF_DISASSEMBLE_ACC)
> +		      ? build_pointer_type (vector_quad_type_node)
> +		      : build_pointer_type (vector_pair_type_node);

Nit: it seems we can use existing ptr_vector_quad_type_node and ptr_vector_pair_type_node?
I assume the const qualifier is fine since it's for disassembling.

> +      if (TREE_TYPE (TREE_TYPE (src_ptr)) != src_type)

This line looks unexpected, the former is type char while the latter is type __vector_pair *.

I guess you meant to compare the type of pointer type like: 
   
   TREE_TYPE (TREE_TYPE (src_ptr)) != TREE_TYPE (src_type)

or even with mode like:

   TYPE_MODE (TREE_TYPE (TREE_TYPE (src_ptr))) != TYPE_MODE (TREE_TYPE (src_type))

> +	src_ptr = build1 (VIEW_CONVERT_EXPR, src_type, src_ptr);

Nit: NOP_EXPR seems to be better suited here for pointer conversion.

BR,
Kewen

> +
>        tree src = create_tmp_reg_or_ssa_name (TREE_TYPE (src_type));
>        gimplify_assign (src, build_simple_mem_ref (src_ptr), &new_seq);
>  
> diff --git a/gcc/testsuite/g++.target/powerpc/pr101322.C b/gcc/testsuite/g++.target/powerpc/pr101322.C
> new file mode 100644
> index 00000000000..59e71e8eb89
> --- /dev/null
> +++ b/gcc/testsuite/g++.target/powerpc/pr101322.C
> @@ -0,0 +1,17 @@
> +/* PR target/101322 */
> +/* { dg-options "-O2 -mdejagnu-cpu=power10" } */
> +/* { dg-require-effective-target power10_ok } */
> +
> +/* Verify we don't ICE on the following test cases.  */
> +
> +void
> +foo (char *resp, char *vpp)
> +{
> +  __builtin_vsx_disassemble_pair (resp, (__vector_pair *) vpp);
> +}
> +
> +void
> +bar (char *resp, char *vpp)
> +{
> +  __builtin_mma_disassemble_acc (resp, (__vector_quad *)vpp);
> +}