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| author | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2021-02-16 17:02:44 +0000 |
|---|---|---|
| committer | Szabolcs Nagy <szabolcs.nagy@arm.com> | 2021-03-26 11:03:06 +0000 |
| commit | 9d61722b599a02a6d3caed1d75417a7f5e661693 (patch) | |
| tree | 565e05bea7b1b44d556a197525d9ac5a3e43dc63 | |
| parent | c076a0bc698c537f72c33bad2925f4e3da59d23c (diff) | |
| download | glibc-9d61722b599a02a6d3caed1d75417a7f5e661693.tar.gz glibc-9d61722b599a02a6d3caed1d75417a7f5e661693.tar.xz glibc-9d61722b599a02a6d3caed1d75417a7f5e661693.zip | |
malloc: Change calloc when tagging is disabled
When glibc is built with memory tagging support (USE_MTAG) but it is not enabled at runtime (mtag_enabled) then unconditional memset was used even though that can be often avoided. This is for performance when tagging is supported but not enabled. The extra check should have no overhead: tag_new_zero_region already had a runtime check which the compiler can now optimize away. Reviewed-by: DJ Delorie <dj@redhat.com>
| -rw-r--r-- | malloc/malloc.c | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/malloc/malloc.c b/malloc/malloc.c index 9cfea1f878..69ea04f4a7 100644 --- a/malloc/malloc.c +++ b/malloc/malloc.c @@ -3591,11 +3591,9 @@ __libc_calloc (size_t n, size_t elem_size) mchunkptr oldtop; INTERNAL_SIZE_T sz, oldtopsize; void *mem; -#ifndef USE_MTAG unsigned long clearsize; unsigned long nclears; INTERNAL_SIZE_T *d; -#endif ptrdiff_t bytes; if (__glibc_unlikely (__builtin_mul_overflow (n, elem_size, &bytes))) @@ -3674,12 +3672,13 @@ __libc_calloc (size_t n, size_t elem_size) return 0; mchunkptr p = mem2chunk (mem); + /* If we are using memory tagging, then we need to set the tags regardless of MORECORE_CLEARS, so we zero the whole block while doing so. */ -#ifdef USE_MTAG - return tag_new_zero_region (mem, CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ); -#else + if (__glibc_unlikely (mtag_enabled)) + return tag_new_zero_region (mem, CHUNK_AVAILABLE_SIZE (p) - CHUNK_HDR_SZ); + INTERNAL_SIZE_T csz = chunksize (p); /* Two optional cases in which clearing not necessary */ @@ -3733,7 +3732,6 @@ __libc_calloc (size_t n, size_t elem_size) } return mem; -#endif } /* |