From 83231d0ab5ed60015797c3d1ad9056295ac3b2bb Mon Sep 17 00:00:00 2001 From: Hans Boehm Date: Thu, 15 Mar 2012 21:09:05 +0400 Subject: [PATCH] Speedup calloc size overflow check by preventing division if small values * malloc.c (GC_SQRT_SIZE_MAX): New macro. * malloc.c (calloc): Add fast initial size overflow check to avoid integer division for reasonably small values passed. --- malloc.c | 5 ++++- 1 files changed, 4 insertions(+), 1 deletions(-) diff --git a/malloc.c b/malloc.c index cb49a5c..c9b9eb6 100644 --- a/malloc.c +++ b/malloc.c @@ -381,9 +381,12 @@ void * malloc(size_t lb) # define GC_SIZE_MAX (~(size_t)0) #endif +#define GC_SQRT_SIZE_MAX ((1U << (WORDSZ / 2)) - 1) + void * calloc(size_t n, size_t lb) { - if (lb && n > GC_SIZE_MAX / lb) + if ((lb | n) > GC_SQRT_SIZE_MAX /* fast initial test */ + && lb && n > GC_SIZE_MAX / lb) return NULL; # if defined(GC_LINUX_THREADS) /* && !defined(USE_PROC_FOR_LIBRARIES) */ /* libpthread allocated some memory that is only pointed to by */ -- 1.7.7