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

[Peter Bergner via Gcc-patches]

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);
+      if (TREE_TYPE (TREE_TYPE (src_ptr)) != src_type)
+       src_ptr = build1 (VIEW_CONVERT_EXPR, src_type, src_ptr);
+
       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);
+}