riscv64/gcc15/HwyDemoteTestGroup/HwyDemoteTest.TestAllReorderDemote2To/EMU128

[malaterre]

Hi folks,

Before I dive into the actual issue could someone confirm what I see for riscv64+gcc15:

https://buildd.debian.org/status/fetch.php?pkg=highway&arch=riscv64&ver=1.2.0-4&stamp=1762482541&raw=0

[...]
141/365 Test #141: HwyDemoteTestGroup/HwyDemoteTest.TestAllReorderDemote2To/EMU128 # GetParam() = 2305843009213693952 ...................................................***Failed 0.07 sec
Running main() from ./googletest/src/gtest_main.cc
Note: Google Test filter = HwyDemoteTestGroup/HwyDemoteTest.TestAllReorderDemote2To/EMU128
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from HwyDemoteTestGroup/HwyDemoteTest
[ RUN ] HwyDemoteTestGroup/HwyDemoteTest.TestAllReorderDemote2To/EMU128

u8x16 expect [0+ ->]:
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
u8x16 actual [0+ ->]:
0x49,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
Abort at demote_test.cc:587: EMU128, u8x16 lane 0 mismatch: expected '0xFF', got '0x49'.

    Start 142: HwyDemoteTestGroup/HwyDemoteTest.TestAllOrderedDemote2To/EMU128  # GetParam() = 2305843009213693952

142/365 Test #142: HwyDemoteTestGroup/HwyDemoteTest.TestAllOrderedDemote2To/EMU128 # GetParam() = 2305843009213693952 ...................................................***Failed 0.07 sec
Running main() from ./googletest/src/gtest_main.cc
Note: Google Test filter = HwyDemoteTestGroup/HwyDemoteTest.TestAllOrderedDemote2To/EMU128
[==========] Running 1 test from 1 test suite.
[----------] Global test environment set-up.
[----------] 1 test from HwyDemoteTestGroup/HwyDemoteTest
[ RUN ] HwyDemoteTestGroup/HwyDemoteTest.TestAllOrderedDemote2To/EMU128

u8x16 expect [9+ ->]:
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
u8x16 actual [9+ ->]:
0xFF,0xFF,0x49,0xFF,0xFF,0xFF,0xFF,
Abort at demote_test.cc:730: EMU128, u8x16 lane 11 mismatch: expected '0xFF', got '0x49'.
[...]

gcc-14 seems fine back then:

• https://buildd.debian.org/status/fetch.php?pkg=highway&arch=riscv64&ver=1.2.0-2%2Bb2&stamp=1736210367&raw=0

[johnplatts]

I reported this GCC 15 compiler bug at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122692 with a reduced test case.

[johnplatts]

@malaterre - There is now a fix for this GCC 15 bug on RISC-V in commit gcc-mirror/gcc@8615c85 of the GCC trunk, and there are plans to backport this bug fix to GCC 15.3.