[Bug testsuite/63175] [4.9/5 regression] FAIL: gcc.dg/vect/costmodel/ppc/costmodel-bb-slp-9a.c scan-tree-dump-times slp2" basic block vectorized using SLP" 1

["rguenther at suse dot de" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63175

--- Comment #21 from rguenther at suse dot de <rguenther at suse dot de> ---
On March 2, 2015 5:58:28 PM CET, "msebor at gcc dot gnu.org"
<gcc-bugzilla@gcc.gnu.org> wrote:
>https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63175
>
>--- Comment #20 from Martin Sebor <msebor at gcc dot gnu.org> ---
>(In reply to rguenther@suse.de from comment #19)
>
>Please remove the extern from the first test and try again (it's a
>vestige of
>the second test).  Here's the assembly emitted by 4.8.3 for the first
>test
>(without the extern):
>
>$ cat u.c && gcc -DT="int" -O2 -ftree-vectorize -maltivec -S u.c && cat
>u.s
>const T a [] = { 1, 2, 3, 4, 5 };
>T b[sizeof a / sizeof *a];
>
>void g (void)
>{
>    const T *p = a;
>    T *q = b + 1;
>
>    *q++ = *p++;
>    *q++ = *p++;
>    *q++ = *p++;
>    *q++ = *p++;
>}
>    .file    "u.c"
>    .section    ".toc","aw"
>    .section    ".text"
>    .section    ".toc","aw"
>.LC0:
>    .quad    b
>    .section    ".text"
>    .align 2
>    .p2align 4,,15
>    .globl g
>    .section    ".opd","aw"
>    .align 3
>g:
>    .quad    .L.g,.TOC.@tocbase
>    .previous
>    .type    g, @function
>.L.g:
>    addis 9,2,.LC1@toc@ha
>    addis 10,2,.LC0@toc@ha
>    addi 9,9,.LC1@toc@l
>    lxvw4x 32,0,9
>    ld 9,.LC0@toc@l(10)
>    li 10,4
>    stxvw4x 32,9,10

But isn't this simply wrong-code?!

>    blr
>    .long 0
>    .byte 0,0,0,0,0,0,0,0
>    .size    g,.-.L.g
>    .comm    b,20,4
>    .globl a
>    .section    .rodata
>    .align 4
>    .type    a, @object
>    .size    a, 20
>a:
>    .long    1
>    .long    2
>    .long    3
>    .long    4
>    .long    5
>    .section    .rodata.cst16,"aM",@progbits,16
>    .align 4
>.LC1:
>    .4byte    1
>    .4byte    2
>    .4byte    3
>    .4byte    4
>    .ident    "GCC: (GNU) 4.8.3 20140911 (Red Hat 4.8.3-9)"
>    .section    .note.GNU-stack,"",@progbits