[Bug target/81317] builtin_vec_ld fails for powerpc with altivec

["segher at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81317

--- Comment #11 from Segher Boessenkool <segher at gcc dot gnu.org> ---
The original testcase still ICEs ("smaller reproducer" I never got to fail).

(trunk, no options whatsoever):

81317-1.c: In function 'jsimd_ycc_rgb_convert_altivec':
81317-1.c:184:6: internal compiler error: Segmentation fault
 void jsimd_ycc_rgb_convert_altivec (JDIMENSION out_width, JSAMPIMAGE
input_buf,
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
0x108f8edb crash_signal
        /home/segher/src/gcc/gcc/toplev.c:338
0x1093ed98 contains_struct_check(tree_node*, tree_node_structure_enum, char
const*, int, char const*)
        /home/segher/src/gcc/gcc/tree.h:3196
0x1093ed98 verify_gimple_assign_binary
        /home/segher/src/gcc/gcc/tree-cfg.c:3828
0x10946927 verify_gimple_in_seq_2
        /home/segher/src/gcc/gcc/tree-cfg.c:4936
0x1094c0ef verify_gimple_in_seq(gimple*)
        /home/segher/src/gcc/gcc/tree-cfg.c:4975
0x105af4a7 gimplify_body(tree_node*, bool)
        /home/segher/src/gcc/gcc/gimplify.c:12589
0x105af91f gimplify_function_tree(tree_node*)
        /home/segher/src/gcc/gcc/gimplify.c:12679
0x1039d487 cgraph_node::analyze()
        /home/segher/src/gcc/gcc/cgraphunit.c:668
0x103a11d7 analyze_functions
        /home/segher/src/gcc/gcc/cgraphunit.c:1129
0x103a298f symbol_table::finalize_compilation_unit()
        /home/segher/src/gcc/gcc/cgraphunit.c:2607


  __builtin_altivec_vsubuhm (cbh, pw_cj);


is transformed to


 = cbh - pw_cj;


and that blows up.