[Bug rtl-optimization/5739] "const" and "pure" function attributes pessimize code due to poor RA

[pinskia at gcc dot gnu dot org]

------- Comment #10 from pinskia at gcc dot gnu dot org  2008-09-14 04:18 
-------
Hmm, IRA for x87 produces worse code for even the non pure/const case.
before:
L2:
        fstl    (%eax)
        leal    -24(%ebp), %ecx
        flds    (%edx)
        fstpl   8(%eax)
        addl    $16, %eax
        cmpl    %ecx, %eax
        jne     L2

After:
        jmp     L2
L11:
        fxch    %st(1)
L2:
        fstl    (%eax)
        fxch    %st(1)
        leal    -24(%ebp), %edx
        fstl    8(%eax)
        addl    $16, %eax
        cmpl    %edx, %eax
        jne     L11


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=5739