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Reapply "Remove configure checks for supported instruction sets"

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I reverted this previously for 7.4 because of bug #78769. Relanding
it now for master, because I still believe that this change is
right, and if it causes complications, those indicate a bug elsewhere.

---

These were checking whether the instruction set is supported by
the host CPU, however they were only used to condition on whether
this instruction set is targeted at all. It would still use dynamic
dispatch (e.g. based on ifunc resolvers) to select the actual
implementation. Whether the target is guaranteed to support the
instruction set without dispatch is determined based on pre-defined
macros like __SSE2__.

This removes the configure-time builtin cpu checks to remove
confusion. Additionally this allows targeting an architecture that
is newer than the host architecture.
This commit is contained in:
Nikita Popov 2019-10-31 11:27:53 +01:00
parent a0abc26ef7
commit 5dc9418a97
3 changed files with 6 additions and 36 deletions
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12
Zend/zend_portability.h
View file

@ -494,21 +494,21 @@ extern "C++" {
#endif
#if (defined(__i386__) || defined(__x86_64__))
# if PHP_HAVE_SSSE3_INSTRUCTIONS && defined(HAVE_TMMINTRIN_H)
# define PHP_HAVE_SSSE3
# if defined(HAVE_TMMINTRIN_H)
# define PHP_HAVE_SSSE3
# endif
# if PHP_HAVE_SSE4_2_INSTRUCTIONS && defined(HAVE_NMMINTRIN_H)
# define PHP_HAVE_SSE4_2
# if defined(HAVE_NMMINTRIN_H)
# define PHP_HAVE_SSE4_2
# endif
/*
* AVX2 support was added in gcc 4.7, but AVX2 intrinsics don't work in
* __attribute__((target("avx2"))) functions until gcc 4.9.
*/
# if PHP_HAVE_AVX2_INSTRUCTIONS && defined(HAVE_IMMINTRIN_H) && \
# if defined(HAVE_IMMINTRIN_H) && \
(defined(__llvm__) || defined(__clang__) || (defined(__GNUC__) && ZEND_GCC_VERSION >= 4009))
# define PHP_HAVE_AVX2
# define PHP_HAVE_AVX2
# endif
#endif

24
build/php.m4
View file

@ -2669,30 +2669,6 @@ AC_DEFUN([PHP_CHECK_BUILTIN_CPU_SUPPORTS], [
[$have_builtin_cpu_supports], [Whether the compiler supports __builtin_cpu_supports])
])
dnl
dnl PHP_CHECK_CPU_SUPPORTS
dnl
AC_DEFUN([PHP_CHECK_CPU_SUPPORTS], [
AC_REQUIRE([PHP_CHECK_BUILTIN_CPU_INIT])
AC_REQUIRE([PHP_CHECK_BUILTIN_CPU_SUPPORTS])
have_ext_instructions=0
if test $have_builtin_cpu_supports = 1; then
AC_MSG_CHECKING([for $1 instructions supports])
AC_RUN_IFELSE([AC_LANG_SOURCE([[
int main() {
return __builtin_cpu_supports("$1")? 0 : 1;
}
]])], [
have_ext_instructions=1
AC_MSG_RESULT([yes])
], [
AC_MSG_RESULT([no])
], [AC_MSG_RESULT([no])])
fi
AC_DEFINE_UNQUOTED(AS_TR_CPP([PHP_HAVE_$1_INSTRUCTIONS]),
[$have_ext_instructions], [Whether the compiler supports $1 instructions])
])
dnl
dnl PHP_PATCH_CONFIG_HEADERS([FILE])
dnl

6
configure.ac
View file

@ -499,12 +499,6 @@ PHP_CHECK_BUILTIN_CPU_INIT
dnl Check __builtin_cpu_supports
PHP_CHECK_BUILTIN_CPU_SUPPORTS
dnl Check instructions.
PHP_CHECK_CPU_SUPPORTS([ssse3])
PHP_CHECK_CPU_SUPPORTS([sse4.2])
PHP_CHECK_CPU_SUPPORTS([avx])
PHP_CHECK_CPU_SUPPORTS([avx2])
dnl Check for structure members.
AC_CHECK_MEMBERS([struct tm.tm_gmtoff],,,[#include <time.h>])
AC_CHECK_MEMBERS([struct stat.st_blksize, struct stat.st_rdev])