[Bug target/65010] ppc backend generates unnecessary signed extension

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65010

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |msebor at gcc dot gnu.org

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
Also seen on ppc64.  For the somewhat simpler test case (below) recent trunk
emits the following (on both ppc64 and ppc64le):

foobar:
    .quad    .L.foobar,.TOC.@tocbase,0
    .previous
    .type    foobar, @function
.L.foobar:
    addi 3,3,1
    extsw 3,3
    blr
    .long 0
    .byte 0,0,0,0,0,0,0,0
    .size    foobar,.-.L.foobar
    .ident    "GCC: (GNU) 5.0.0 20150221 (experimental)"

int foobar (signed char c) { return c + 1; }