From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1944) id A93E53893C23; Thu, 11 Mar 2021 17:39:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org A93E53893C23 Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Szabolcs Nagy To: glibc-cvs@sourceware.org Subject: [glibc/nsz/mtag] malloc: Change calloc when tagging is disabled X-Act-Checkin: glibc X-Git-Author: Szabolcs Nagy X-Git-Refname: refs/heads/nsz/mtag X-Git-Oldrev: 8ec6e98d17b23ddc04a3b3beba159835c17cf526 X-Git-Newrev: f33e5f9a8301e7905985301b479fc4bc29d0063d Message-Id: <20210311173915.A93E53893C23@sourceware.org> Date: Thu, 11 Mar 2021 17:39:15 +0000 (GMT) X-BeenThere: glibc-cvs@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Glibc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 11 Mar 2021 17:39:15 -0000 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=f33e5f9a8301e7905985301b479fc4bc29d0063d commit f33e5f9a8301e7905985301b479fc4bc29d0063d Author: Szabolcs Nagy Date: Tue Feb 16 17:02:44 2021 +0000 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 Diff: --- malloc/malloc.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) diff --git a/malloc/malloc.c b/malloc/malloc.c index 01cf6e9325..0b2aff3768 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 } /*