[Bug target/64507] SH inlined builtin strncmp doesn't return 0 for 0 length

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

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64507

--- Comment #4 from chrbr at gcc dot gnu.org ---
Actually, the code could be slightly better by factorizing the return sequences

        ;; check length
        mov    #0,r0
        ;; goto .l2
        ;; else init r1,r0
        ;; goto .l1
.l2:
        rtx
    nop
.l1:
    rts    
    sub    r1,r0

into
       ;; check length
       mov r1,r0
       ;; goto l1
       ;; else init r1,r0
.l1:        
       rts
       sub   r1,r0

however this creates an unitilized mov (which we don´t care) but the backend
keeps forcing an useless mov #0,r1
>From gcc-bugs-return-472368-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Wed Jan 07 09:37:41 2015
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From: "maurits.de.jong at ericsson dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/64509] _Generic throws error in unselected generic association
Date: Wed, 07 Jan 2015 09:37:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd509

--- Comment #4 from Martien de Jong <maurits.de.jong at ericsson dot com> ---
I understand. What a shallow and ugly feature it is then. I think it can only
usefully be employed using a preprocessor macro, yet it is part of the
expression syntax. It is meant to resolve type issues, yet all variants
should be type-sane. You can indeed implement something like tgmath.h with it,
but only if the types can be implictly converted.

BTW, I notice that

./gcc/ginclude/tgmath.h

uses

__builtin_classify_type
__builtin_types_compatible_p
__builtin_choose_expr

Will it move to using _Generic() ?