[Bug c++/35585] Miscompiled inline assembly

[nicos at maunakeatech dot com]

------- Comment #4 from nicos at maunakeatech dot com  2008-03-15 01:07 -------
I think I need some help here, I looked to bug 323 and I can't see how it is
related to this issue.
The assertion at the end of the test case compares integers, and the iFloor
function is only applied to 0 in the test. My problem is that the result in
sp.bbox[0] seems total garbage.
I looked at the assembly code generated by gcc (-S flag), the portion
corresponding to:

sp.bbox[0] = std::min(sp.bbox[0], iFloor(txcum) );

is:

.L201:
        fld     %st(1)
        fadd    %st(2), %st
        fsubs   .LC4
#APP
        fistpl -44(%ebp)
#NO_APP
        movl    -44(%ebp), %edi
        movl    -88(%ebp), %eax
        sarl    %edi
        cmpl    16(%ebx), %edi
        jge     .L204
        leal    -28(%ebp), %eax
.L204:
        fld     %st(0)
        movl    (%eax), %eax
        fadd    %st(1), %st
        fsubs   .LC4
        movl    %eax, 16(%ebx)

The result of iFloor is stored in %edi but whatever the result of cmpl, the
value in %edi isn't used (instead the value at -28(%ebp), which appears to be
uninitialized, is stored into sp.bbox[0]).


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35585