Fix GH-14551: PGO build fails with xxhash #18814
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Turns out that the instrumentation added for gcov can change inlining decisions of the compiler, which results in a mismatch between the profile data CFG and the actual generated CFG between compiles. There are two functions that suffer from this issue: 1. _PHP_XXH3_Init: Removing the inline hint fixes this one. In fact, always inlining this makes no sense as there's no real opportunity for specialising. It just bloats the binary and increases I$ pressure. So besides fixing this issue it's beneficial on its own to drop the attribute. 2. PHP_XXH3_128_Final: Sometimes XXH128_canonicalFromHash gets inlined and sometimes not. Make sure it gets always inlined.
Girgias
approved these changes
Jun 12, 2025
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So we don't forget: #18842 |
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Turns out that the instrumentation added for gcov can change inlining decisions of the compiler, which results in a mismatch between the profile data CFG and the actual generated CFG between compiles.
There are two functions that suffer from this issue:
As a side note, since we already have some custom patches to
xxhash.h, it would be beneficial to: