[Bug rtl-optimization/44249] [4.6/4.7 Regression] IRA generates extra register move

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44249

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.6/4.7/4.8 Regression]    |[4.6/4.7 Regression] IRA
                   |IRA generates extra         |generates extra register
                   |register move               |move

--- Comment #5 from Steven Bosscher <steven at gcc dot gnu.org> 2012-10-09 21:01:08 UTC ---
No extra move with trunk today:

$ cat t.c
extern unsigned long table[];

unsigned long foo(unsigned char *p) {
    unsigned long tag = *p;
    return table[tag >> 4] + table[tag & 0xf];
}

$ cat t.s
        .file   "t.c"
        .text
        .p2align 4,,15
        .globl  foo
        .type   foo, @function
foo:
.LFB0:
        .cfi_startproc
        movzbl  (%rdi), %edx
        movq    %rdx, %rax
        shrq    $4, %rdx
        andl    $15, %eax
        movq    table(,%rax,8), %rax
        addq    table(,%rdx,8), %rax
        ret
        .cfi_endproc
.LFE0:
        .size   foo, .-foo
        .ident  "GCC: (GNU) 4.8.0 20121008 (experimental) \
[trunk revision 192219]"
        .section        .note.GNU-stack,"",@progbits