https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67814
Bug ID: 67814
Summary: pentium4 cmp instruction register allocation error
(tree-pre?)
Product: gcc
Version: 5.2.0
Status: UNCONFIRMED
Severity: major
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: vtjnash at gmail dot com
Target Milestone: ---
Created attachment 36437
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=36437&action=edit
alloc.c compile unit containing jl_compute_field_offsets
when building code with
`gcc -m32 -march=pentium4 -fPIC -O1 -ftree-pre`, I observed the following
register allocation (?) error when the compiler was creating what should have
been a `cmp %eax,%edx` instruction (dropping any one of those flags seems to be
sufficient to avoid the error):
size_t alsz = LLT_ALIGN(sz, al);
cc8: 8b 55 e4 mov -0x1c(%ebp),%edx
ccb: 89 d0 mov %edx,%eax
ccd: 83 e8 01 sub $0x1,%eax
cd0: 01 d8 add %ebx,%eax
cd2: 21 c8 and %ecx,%eax
cd4: 89 45 e4 mov %eax,-0x1c(%ebp)
if (alsz > sz)
** cd7: 39 d2 cmp %edx,%edx **
cd9: 76 04 jbe cdf
<jl_compute_field_offsets+0x108>
st->haspadding = 1;
cdb: 80 4f 27 20 orb $0x20,0x27(%edi)
The original source code can be found at
https://github.com/JuliaLang/julia/blob/26b58c6138b3e8e704ba35762e79b982b4e69b33/src/alloc.c#L583-L585,
the .i file is attached.
