[Bug middle-end/124583] wrong code at -O2 when compiling with PGO on x86_64-pc-linux-gnu

[xintong.zhou1 at uwaterloo dot ca]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124583

--- Comment #2 from Xintong Zhou <xintong.zhou1 at uwaterloo dot ca> ---
(In reply to Richard Biener from comment #1)
> Hmm, can't reproduce.

Hi, it still reproduces on the latest version on my end.

$ gcc-trunk -v                                                                  
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/data/x27zhou/compiler-nightly/install/gcc/libexec/gcc/x86_64-pc-linux-gnu/16.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /data/x27zhou/compiler-nightly/src/gcc/configure
--enable-checking=yes --disable-bootstrap --disable-multilib
--enable-languages=c,c++ --prefix=/data/x27zhou/compiler-nightly/install/gcc
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 16.0.1 20260322 (experimental) (GCC)
$
$ gcc-trunk -O2 -fprofile-use -Wno-coverage-mismatch small.c && ./a.out
0
$ gcc-trunk -O2 small.c && ./a.out                                     
2

Btw, gcov-dump shows the profile as:

$ gcov-dump -l -p a-small.gcda                                         
a-small.gcda:data:magic `gcda':version `B60 '
a-small.gcda:stamp 73902325
a-small.gcda:checksum 2429308459
a-small.gcda:   16:  a1000000:   8:OBJECT_SUMMARY runs=1, sum_max=1024
a-small.gcda:   32:  01000000:  12:FUNCTION ident=721827547,
lineno_checksum=0x8c624c09, cfg_checksum=0x73ff2042
a-small.gcda:   52:    01a10000:  24:COUNTERS arcs 3 counts
a-small.gcda:   84:                   0: 3579999111 0 0

What's the output on your end?