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aarch64: use -mtls-size=12 for faster tls reads #22284

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aarch64: use -mtls-size=12 for faster tls reads #22284

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16 changes: 16 additions & 0 deletions Zend/Zend.m4
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Original file line number Diff line number Diff line change
Expand Up @@ -178,6 +178,22 @@ AC_MSG_RESULT([$ZEND_ZTS])
AS_VAR_IF([ZEND_ZTS], [yes], [
AC_DEFINE([ZTS], [1], [Define to 1 if thread safety (ZTS) is enabled.])
AS_VAR_APPEND([CFLAGS], [" -DZTS"])

dnl -mtls-size=12 drops the dead high-bits offset add from TLS access,
dnl valid while the thread-local block stays under 4 KiB.
AC_CACHE_CHECK([whether -mtls-size=12 compiles and links],
[php_cv_flag_mtls_size_12],
[save_CFLAGS=$CFLAGS
AS_VAR_IF([GCC], [yes], [php_tls_size_werror=-Werror], [php_tls_size_werror=])
CFLAGS="$CFLAGS -mtls-size=12 $php_tls_size_werror"
AC_LINK_IFELSE([AC_LANG_PROGRAM(
[[static __thread void *tls_probe __attribute__((tls_model("local-exec")));]],
[[tls_probe = &tls_probe; return !!tls_probe;]])],
[php_cv_flag_mtls_size_12=yes],
[php_cv_flag_mtls_size_12=no])
CFLAGS=$save_CFLAGS])
AS_VAR_IF([php_cv_flag_mtls_size_12], [yes],
[AS_VAR_APPEND([CFLAGS], [" -mtls-size=12"])])
])

AC_MSG_CHECKING([whether to enable Zend debugging])
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