https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112672
Bug ID: 112672
Summary: [14 Regression] wrong code with __builtin_parityl() at
-O and above on x86_64
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Keywords: wrong-code
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: zsojka at seznam dot cz
Target Milestone: ---
Host: x86_64-pc-linux-gnu
Target: x86_64-pc-linux-gnu
Created attachment 56666
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56666&action=edit
reduced testcase
Output:
$ x86_64-pc-linux-gnu-gcc -O testcase.c
$ ./a.out
Aborted
$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=/repo/gcc-trunk/binary-latest-amd64/bin/x86_64-pc-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/repo/gcc-trunk/binary-trunk-r14-5761-20231122145100-ge9b39df9333-checking-yes-rtl-df-extra-nobootstrap-amd64/bin/../libexec/gcc/x86_64-pc-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-trunk//configure --enable-languages=c,c++
--enable-valgrind-annotations --disable-nls --enable-checking=yes,rtl,df,extra
--disable-bootstrap --with-cloog --with-ppl --with-isl
--build=x86_64-pc-linux-gnu --host=x86_64-pc-linux-gnu
--target=x86_64-pc-linux-gnu --with-ld=/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=/usr/bin/x86_64-pc-linux-gnu-as --disable-libstdcxx-pch
--prefix=/repo/gcc-trunk//binary-trunk-r14-5761-20231122145100-ge9b39df9333-checking-yes-rtl-df-extra-nobootstrap-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 14.0.0 20231122 (experimental) (GCC)
At the asm output, the problem is obvious:
main:
# testcase.c:8: u *= g;
movzx eax, WORD PTR g[rip] # tmp110, g
sal eax, 2 # u,
# testcase.c:9: return u + __builtin_parityl (u);
xor al, ah # u <== THIS OVERWRITES "u" in eax
setnp dl #, tmp105
movzx edx, dl # tmp105, tmp105
# testcase.c:9: return u + __builtin_parityl (u);
add eax, edx # tmp107, tmp105 <== THIS READ "u", but it has
been lost
# testcase.c:16: if (x != 4 * 254 + 1)
cmp ax, 1017 # tmp107,
jne .L6 #,
# testcase.c:19: }
mov eax, 0 #,
ret
