Revision: 1246
http://www.exim.org/viewvc/pcre2?view=rev&revision=1246
Author: ph10
Date: 2020-04-23 17:50:45 +0100 (Thu, 23 Apr 2020)
Log Message:
-----------
Added tests for __attribute__((uninitialized)) to both the configure and
CMake build files. Used to disable initialization of the match stack frames
vector (clang has an automatic initialization feature).
Modified Paths:
--------------
code/trunk/CMakeLists.txt
code/trunk/ChangeLog
code/trunk/config-cmake.h.in
code/trunk/configure.ac
code/trunk/src/config.h.in
code/trunk/src/pcre2_internal.h
code/trunk/src/pcre2_match.c
Modified: code/trunk/CMakeLists.txt
===================================================================
--- code/trunk/CMakeLists.txt 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/CMakeLists.txt 2020-04-23 16:50:45 UTC (rev 1246)
@@ -87,6 +87,7 @@
# 2020-03-16 PH renamed dftables as pcre2_dftables (as elsewhere)
# 2020-03-24 PH changed CMAKE_MODULE_PATH definition to add, not replace
# 2020-04-08 Carlo added function check for secure_getenv, fixed strerror
+# 2020-04-16 enh added check for __attribute__((uninitialized))
PROJECT(PCRE2 C)
@@ -113,8 +114,9 @@
# Configuration checks
+INCLUDE(CheckCSourceCompiles)
+INCLUDE(CheckFunctionExists)
INCLUDE(CheckIncludeFile)
-INCLUDE(CheckFunctionExists)
INCLUDE(CheckTypeSize)
CHECK_INCLUDE_FILE(dirent.h HAVE_DIRENT_H)
@@ -130,6 +132,14 @@
CHECK_FUNCTION_EXISTS(strerror HAVE_STRERROR)
CHECK_FUNCTION_EXISTS(secure_getenv HAVE_SECURE_GETENV)
+set(ORIG_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -Werror")
+CHECK_C_SOURCE_COMPILES(
+ "int main() { char buf[128] __attribute__((uninitialized)); (void)buf; return 0; }"
+ HAVE_ATTRIBUTE_UNINITIALIZED
+)
+set(CMAKE_REQUIRED_FLAGS ${ORIG_CMAKE_REQUIRED_FLAGS})
+
# User-configurable options
#
# Note: CMakeSetup displays these in alphabetical order, regardless of
Modified: code/trunk/ChangeLog
===================================================================
--- code/trunk/ChangeLog 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/ChangeLog 2020-04-23 16:50:45 UTC (rev 1246)
@@ -104,7 +104,13 @@
25. Avoid using [-1] as a suffix in pcre2test because it can provoke a compiler
warning.
+26. Added tests for __attribute__((uninitialized)) to both the configure and
+CMake build files, and then applied this attribute to the variable called
+stack_frames_vector[] in pcre2_match(). When implemented, this disables
+automatic initialization (a facility in clang), which can take time on big
+variables.
+
Version 10.34 21-November-2019
------------------------------
Modified: code/trunk/config-cmake.h.in
===================================================================
--- code/trunk/config-cmake.h.in 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/config-cmake.h.in 2020-04-23 16:50:45 UTC (rev 1246)
@@ -1,5 +1,6 @@
/* config.h for CMake builds */
+#cmakedefine HAVE_ATTRIBUTE_UNINITIALIZED 1
#cmakedefine HAVE_DIRENT_H 1
#cmakedefine HAVE_INTTYPES_H 1
#cmakedefine HAVE_STDINT_H 1
Modified: code/trunk/configure.ac
===================================================================
--- code/trunk/configure.ac 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/configure.ac 2020-04-23 16:50:45 UTC (rev 1246)
@@ -10,7 +10,7 @@
m4_define(pcre2_major, [10])
m4_define(pcre2_minor, [35])
-m4_define(pcre2_prerelease, [-RC1])
+m4_define(pcre2_prerelease, [-RC2])
m4_define(pcre2_date, [2020-04-15])
# NOTE: The CMakeLists.txt file searches for the above variables in the first
@@ -72,6 +72,24 @@
PCRE2_VISIBILITY
+# Check for Clang __attribute__((uninitialized)) feature
+
+AC_MSG_CHECKING([for __attribute__((uninitialized))])
+AC_LANG_PUSH([C])
+tmp_CFLAGS=$CFLAGS
+CFLAGS="$CFLAGS -Werror"
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,
+ [[char buf[128] __attribute__((uninitialized));(void)buf]])],
+ [pcre2_cc_cv_attribute_uninitialized=yes],
+ [pcre2_cc_cv_attribute_uninitialized=no])
+AC_MSG_RESULT([$pcre2_cc_cv_attribute_uninitialized])
+if test "$pcre2_cc_cv_attribute_uninitialized" = yes; then
+ AC_DEFINE([HAVE_ATTRIBUTE_UNINITIALIZED], 1, [Define this if your compiler
+ supports __attribute__((uninitialized))])
+fi
+CFLAGS=$tmp_CFLAGS
+AC_LANG_POP([C])
+
# Versioning
PCRE2_MAJOR="pcre2_major"
Modified: code/trunk/src/config.h.in
===================================================================
--- code/trunk/src/config.h.in 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/src/config.h.in 2020-04-23 16:50:45 UTC (rev 1246)
@@ -52,6 +52,9 @@
LF does in an ASCII/Unicode environment. */
#undef EBCDIC_NL25
+/* Define this if your compiler supports __attribute__((uninitialized)) */
+#undef HAVE_ATTRIBUTE_UNINITIALIZED
+
/* Define to 1 if you have the `bcopy' function. */
#undef HAVE_BCOPY
Modified: code/trunk/src/pcre2_internal.h
===================================================================
--- code/trunk/src/pcre2_internal.h 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/src/pcre2_internal.h 2020-04-23 16:50:45 UTC (rev 1246)
@@ -76,6 +76,17 @@
#include <valgrind/memcheck.h>
#endif
+/* -ftrivial-auto-var-init support supports initializing all local variables
+to avoid some classes of bug, but this can cause an unacceptable slowdown
+for large on-stack arrays in hot functions. This macro lets us annotate
+such arrays. */
+
+#ifdef HAVE_ATTRIBUTE_UNINITIALIZED
+#define PCRE2_KEEP_UNINITIALIZED __attribute__((uninitialized))
+#else
+#define PCRE2_KEEP_UNINITIALIZED
+#endif
+
/* Older versions of MSVC lack snprintf(). This define allows for
warning/error-free compilation and testing with MSVC compilers back to at least
MSVC 10/2010. Except for VC6 (which is missing some fundamentals and fails). */
Modified: code/trunk/src/pcre2_match.c
===================================================================
--- code/trunk/src/pcre2_match.c 2020-04-23 15:41:23 UTC (rev 1245)
+++ code/trunk/src/pcre2_match.c 2020-04-23 16:50:45 UTC (rev 1246)
@@ -6164,7 +6164,8 @@
vector of the size required that is aligned for pointers, allocate it as a
vector of pointers. */
-PCRE2_SPTR stack_frames_vector[START_FRAMES_SIZE/sizeof(PCRE2_SPTR)];
+PCRE2_SPTR stack_frames_vector[START_FRAMES_SIZE/sizeof(PCRE2_SPTR)]
+ PCRE2_KEEP_UNINITIALIZED;
mb->stack_frames = (heapframe *)stack_frames_vector;
/* A length equal to PCRE2_ZERO_TERMINATED implies a zero-terminated
