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Fix GH-14551: PGO build fails with xxhash #18814

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Fix GH-14551: PGO build fails with xxhash #18814

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c53c078
Fix GH-14551: PGO build fails with xxhash
nielsdos Jun 9, 2025
28c5864
fix warn
nielsdos Jun 9, 2025
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Fix GH-14551: PGO build fails with xxhash 
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.
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@nielsdos
nielsdos committed Jun 9, 2025
commit c53c078f16e33d4b2e39e39afe8320f45a20b38a
2 changes: 1 addition & 1 deletion ext/hash/hash_xxhash.c
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Expand Up @@ -154,7 +154,7 @@ const php_hash_ops php_hash_xxh3_64_ops = {
typedef XXH_errorcode (*xxh3_reset_with_secret_func_t)(XXH3_state_t*, const void*, size_t);
typedef XXH_errorcode (*xxh3_reset_with_seed_func_t)(XXH3_state_t*, XXH64_hash_t);

zend_always_inline static void _PHP_XXH3_Init(PHP_XXH3_64_CTX *ctx, HashTable *args,
static void _PHP_XXH3_Init(PHP_XXH3_64_CTX *ctx, HashTable *args,
xxh3_reset_with_seed_func_t func_init_seed, xxh3_reset_with_secret_func_t func_init_secret, const char* algo_name)
{
memset(&ctx->s, 0, sizeof ctx->s);
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4 changes: 2 additions & 2 deletions ext/hash/xxhash/xxhash.h
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Expand Up @@ -931,7 +931,7 @@ XXH_PUBLIC_API int XXH128_cmp(const void* h128_1, const void* h128_2);

/******* Canonical representation *******/
typedef struct { unsigned char digest[sizeof(XXH128_hash_t)]; } XXH128_canonical_t;
XXH_PUBLIC_API void XXH128_canonicalFromHash(XXH128_canonical_t* dst, XXH128_hash_t hash);
XXH_PUBLIC_API zend_always_inline void XXH128_canonicalFromHash(XXH128_canonical_t* dst, XXH128_hash_t hash);
XXH_PUBLIC_API XXH128_hash_t XXH128_hashFromCanonical(const XXH128_canonical_t* src);


Expand Down Expand Up @@ -5503,7 +5503,7 @@ XXH_PUBLIC_API int XXH128_cmp(const void* h128_1, const void* h128_2)

/*====== Canonical representation ======*/
/*! @ingroup xxh3_family */
XXH_PUBLIC_API void
XXH_PUBLIC_API zend_always_inline void
XXH128_canonicalFromHash(XXH128_canonical_t* dst, XXH128_hash_t hash)
{
XXH_STATIC_ASSERT(sizeof(XXH128_canonical_t) == sizeof(XXH128_hash_t));
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