From c86b726c048eddc1be320c0bf64a897658bee13d Mon Sep 17 00:00:00 2001 From: Uros Bizjak <ubizjak@gmail.com> Date: Wed, 18 May 2022 20:03:26 +0200 Subject: [PATCH] x86: Fix -fsplit-stack feature detection via TARGET_CAN_SPLIT_STACK MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Since commit c163647ffbc9a20c8feb6e079dbecccfe016c82e -fsplit-stack is only supported on glibc targets. However, this original commit required some fixups. As part of the fixup, the changes to the gnu-user-common.h and gnu.h were partially reverted in commit 60953a23d57b13a672f751bec0c6eefc059eb1ab thus causing TARGET_CAN_SPLIT_STACK to be defined for non-glibc targets even though -fsplit-stack is actually not supported and attempting to use it causes a runtime error. This causes gcc internal code, such as ./gcc/go/gospec.c to not correctly detect that -fsplit-stack is not supported and thus causes gccgo to fail compilation on non-glibc targets. This commit ensures that TARGET_CAN_SPLIT_STACK is only set if the default libc is glibc. It is presently unclear to me if there is a better way to detect glibc at pre-processor time. The proposed changes have been tested on x86 and x86_64 Alpine Linux (which uses musl libc) and fix compilation of gccgo for this target. Signed-off-by: Sören Tempel <soeren@soeren-tempel.net> gcc/ChangeLog: * config/i386/gnu-user-common.h (defined): Only define TARGET_CAN_SPLIT_STACK for glibc targets. * config/i386/gnu.h (defined): Ditto. --- gcc/config/i386/gnu-user-common.h | 5 +++-- gcc/config/i386/gnu.h | 5 +++-- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/gcc/config/i386/gnu-user-common.h b/gcc/config/i386/gnu-user-common.h index 23b54c5be52..cab9be2bfb7 100644 --- a/gcc/config/i386/gnu-user-common.h +++ b/gcc/config/i386/gnu-user-common.h @@ -66,7 +66,8 @@ along with GCC; see the file COPYING3. If not see #define STACK_CHECK_STATIC_BUILTIN 1 /* We only build the -fsplit-stack support in libgcc if the - assembler has full support for the CFI directives. */ -#if HAVE_GAS_CFI_PERSONALITY_DIRECTIVE + assembler has full support for the CFI directives. Also + we only support -fsplit-stack on glibc targets. */ +#if (DEFAULT_LIBC == LIBC_GLIBC) && HAVE_GAS_CFI_PERSONALITY_DIRECTIVE #define TARGET_CAN_SPLIT_STACK #endif diff --git a/gcc/config/i386/gnu.h b/gcc/config/i386/gnu.h index 401e60c9a02..fb8d69a97d8 100644 --- a/gcc/config/i386/gnu.h +++ b/gcc/config/i386/gnu.h @@ -41,8 +41,9 @@ along with GCC. If not, see <http://www.gnu.org/licenses/>. #define TARGET_THREAD_SSP_OFFSET 0x14 /* We only build the -fsplit-stack support in libgcc if the - assembler has full support for the CFI directives. */ -#if HAVE_GAS_CFI_PERSONALITY_DIRECTIVE + assembler has full support for the CFI directives. Also + we only support -fsplit-stack on glibc targets. */ +#if (DEFAULT_LIBC == LIBC_GLIBC) && HAVE_GAS_CFI_PERSONALITY_DIRECTIVE #define TARGET_CAN_SPLIT_STACK #endif /* We steal the last transactional memory word. */