Commit 2d4950c8 authored by Nick Mathewson's avatar Nick Mathewson
Browse files

Malloc and friends are critical-path: Thus, add an it-wont-happen branch...

Malloc and friends are critical-path: Thus, add an it-wont-happen branch prediction for NULL returns, and skip the malloc(0) check on platforms where malloc(0) returns a pointer.

svn:r8431
parent 7b0ec744
......@@ -3,6 +3,8 @@ Changes in version 0.1.2.2-alpha - 2006-??-??
o Minor Bugfixes
- Small performance improvements on parsing and inserting
descriptors.
- Make the common memory allocation path faster on machines where
malloc(0) returns a pointer.
Changes in version 0.1.2.1-alpha - 2006-08-27
o Major features:
......
......@@ -558,6 +558,33 @@ if test $tor_cv_null_is_zero = yes; then
[Define to 1 iff memset(0) sets pointers to NULL])
fi
# And what happens when we malloc zero?
if test -z "$CROSS_COMPILE"; then
AC_CACHE_CHECK([whether we can malloc(0) safely.], tor_cv_malloc_zero_works,
[AC_RUN_IFELSE([AC_LANG_SOURCE(
[[#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#ifdef HAVE_STDDEF_H
#include <stddef.h>
#endif
int main () { return malloc(0)?0:1; }]])],
[tor_cv_malloc_zero_works=yes],
[tor_cv_malloc_zero_works=no],
[tor_cv_malloc_zero_works=cross])])
else
# Cross-compiling; let's hope that the target isn't raving mad.
AC_MSG_NOTICE([Cross-compiling: we'll assume that we need to check malloc() arguments for 0.])
tor_cv_malloc_zero_works=no
fi
if test $tor_cv_malloc_zero_works = yes; then
AC_DEFINE([MALLOC_ZERO_WORKS], 1,
[Define to 1 iff malloc(0) returns a pointer])
fi
# Whether we should use the dmalloc memory allocation debugging library.
AC_MSG_CHECKING(whether to use dmalloc (debug memory allocation library))
AC_ARG_WITH(dmalloc,
......
......@@ -106,13 +106,15 @@ _tor_malloc(size_t size DMALLOC_PARAMS)
{
void *result;
#ifndef MALLOC_ZERO_WORKS
/* Some libcs don't do the right thing on size==0. Override them. */
if (size==0) {
size=1;
}
#endif
result = dmalloc_malloc(file, line, size, DMALLOC_FUNC_MALLOC, 0, 0);
if (!result) {
if (PREDICT(result == NULL, 0)) {
log_err(LD_MM,"Out of memory. Dying.");
/* If these functions die within a worker process, they won't call
* spawn_exit, but that's ok, since the parent will run out of memory soon
......@@ -144,7 +146,7 @@ _tor_realloc(void *ptr, size_t size DMALLOC_PARAMS)
void *result;
result = dmalloc_realloc(file, line, ptr, size, DMALLOC_FUNC_REALLOC, 0);
if (!result) {
if (PREDICT(result == NULL, 0)) {
log_err(LD_MM,"Out of memory. Dying.");
exit(1);
}
......@@ -162,7 +164,7 @@ _tor_strdup(const char *s DMALLOC_PARAMS)
tor_assert(s);
dup = dmalloc_strdup(file, line, s, 0);
if (!dup) {
if (PREDICT(dup == NULL, 0)) {
log_err(LD_MM,"Out of memory. Dying.");
exit(1);
}
......
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