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).
This commit is contained in:
Philip.Hazel 2020-04-23 16:50:45 +00:00
parent ca55d0be6b
commit 5ec5c45423
7 changed files with 53 additions and 3 deletions

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@ -87,6 +87,7 @@
# 2020-03-16 PH renamed dftables as pcre2_dftables (as elsewhere) # 2020-03-16 PH renamed dftables as pcre2_dftables (as elsewhere)
# 2020-03-24 PH changed CMAKE_MODULE_PATH definition to add, not replace # 2020-03-24 PH changed CMAKE_MODULE_PATH definition to add, not replace
# 2020-04-08 Carlo added function check for secure_getenv, fixed strerror # 2020-04-08 Carlo added function check for secure_getenv, fixed strerror
# 2020-04-16 enh added check for __attribute__((uninitialized))
PROJECT(PCRE2 C) PROJECT(PCRE2 C)
@ -113,8 +114,9 @@ FIND_PACKAGE( Editline )
# Configuration checks # Configuration checks
INCLUDE(CheckIncludeFile) INCLUDE(CheckCSourceCompiles)
INCLUDE(CheckFunctionExists) INCLUDE(CheckFunctionExists)
INCLUDE(CheckIncludeFile)
INCLUDE(CheckTypeSize) INCLUDE(CheckTypeSize)
CHECK_INCLUDE_FILE(dirent.h HAVE_DIRENT_H) CHECK_INCLUDE_FILE(dirent.h HAVE_DIRENT_H)
@ -130,6 +132,14 @@ CHECK_FUNCTION_EXISTS(memmove HAVE_MEMMOVE)
CHECK_FUNCTION_EXISTS(strerror HAVE_STRERROR) CHECK_FUNCTION_EXISTS(strerror HAVE_STRERROR)
CHECK_FUNCTION_EXISTS(secure_getenv HAVE_SECURE_GETENV) 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 # User-configurable options
# #
# Note: CMakeSetup displays these in alphabetical order, regardless of # Note: CMakeSetup displays these in alphabetical order, regardless of

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@ -104,6 +104,12 @@ LIST(APPEND...) to allow a setting from the command line to be included.
25. Avoid using [-1] as a suffix in pcre2test because it can provoke a compiler 25. Avoid using [-1] as a suffix in pcre2test because it can provoke a compiler
warning. 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 Version 10.34 21-November-2019
------------------------------ ------------------------------

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@ -1,5 +1,6 @@
/* config.h for CMake builds */ /* config.h for CMake builds */
#cmakedefine HAVE_ATTRIBUTE_UNINITIALIZED 1
#cmakedefine HAVE_DIRENT_H 1 #cmakedefine HAVE_DIRENT_H 1
#cmakedefine HAVE_INTTYPES_H 1 #cmakedefine HAVE_INTTYPES_H 1
#cmakedefine HAVE_STDINT_H 1 #cmakedefine HAVE_STDINT_H 1

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@ -10,7 +10,7 @@ dnl be defined as -RC2, for example. For real releases, it should be empty.
m4_define(pcre2_major, [10]) m4_define(pcre2_major, [10])
m4_define(pcre2_minor, [35]) m4_define(pcre2_minor, [35])
m4_define(pcre2_prerelease, [-RC1]) m4_define(pcre2_prerelease, [-RC2])
m4_define(pcre2_date, [2020-04-15]) m4_define(pcre2_date, [2020-04-15])
# NOTE: The CMakeLists.txt file searches for the above variables in the first # NOTE: The CMakeLists.txt file searches for the above variables in the first
@ -72,6 +72,24 @@ AC_PROG_LN_S
PCRE2_VISIBILITY 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 # Versioning
PCRE2_MAJOR="pcre2_major" PCRE2_MAJOR="pcre2_major"

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@ -52,6 +52,9 @@ sure both macros are undefined; an emulation function will then be used. */
LF does in an ASCII/Unicode environment. */ LF does in an ASCII/Unicode environment. */
#undef EBCDIC_NL25 #undef EBCDIC_NL25
/* Define this if your compiler supports __attribute__((uninitialized)) */
#undef HAVE_ATTRIBUTE_UNINITIALIZED
/* Define to 1 if you have the `bcopy' function. */ /* Define to 1 if you have the `bcopy' function. */
#undef HAVE_BCOPY #undef HAVE_BCOPY

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@ -76,6 +76,17 @@ typedef int BOOL;
#include <valgrind/memcheck.h> #include <valgrind/memcheck.h>
#endif #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 /* Older versions of MSVC lack snprintf(). This define allows for
warning/error-free compilation and testing with MSVC compilers back to at least 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). */ MSVC 10/2010. Except for VC6 (which is missing some fundamentals and fails). */

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@ -6164,7 +6164,8 @@ proves to be too small, it is replaced by a larger one on the heap. To get a
vector of the size required that is aligned for pointers, allocate it as a vector of the size required that is aligned for pointers, allocate it as a
vector of pointers. */ 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; mb->stack_frames = (heapframe *)stack_frames_vector;
/* A length equal to PCRE2_ZERO_TERMINATED implies a zero-terminated /* A length equal to PCRE2_ZERO_TERMINATED implies a zero-terminated