Successfully identified regression in *gcc* in CI configuration tcwg_gnu_cross_build/master-arm. So far, this commit has regressed CI configurations: - tcwg_gnu_cross_build/master-arm

Culprit: <cut> commit caf81d3b57501b1f58dcd9b1ef9d7b4bc76f4ab1 Author: Sebastian Huber sebastian.huber@embedded-brains.de Date: Tue Aug 17 09:53:43 2021 +0200

Use __builtin_trap() for abort() if inhibit_libc

abort() is used in gcc_assert() and gcc_unreachable() which is used by target libraries such as libgcov.a. This patch changes the abort() definition under certain conditions. If inhibit_libc is defined and abort is not already defined, then abort() is defined to __builtin_trap().

The inhibit_libc define is usually defined if GCC is built for targets running in embedded systems which may optionally use a C standard library. If inhibit_libc is defined, then there may be still a full featured abort() available. abort() is a heavy weight function which depends on signals and file streams. For statically linked applications, this means that a dependency on gcc_assert() pulls in the support for signals and file streams. This could prevent using gcov to test low end targets for example. Using __builtin_trap() avoids these dependencies if the target implements a "trap" instruction. The application or operating system could use a trap handler to react to failed GCC runtime checks which caused a trap.

gcc/

* tsystem.h (abort): Define abort() if inhibit_libc is defined and it is not already defined. </cut>

Results regressed to (for first_bad == caf81d3b57501b1f58dcd9b1ef9d7b4bc76f4ab1) # reset_artifacts: -10 # true: 0 # build_abe binutils: 1 # First few build errors in logs: # 00:01:44 cc1: error: no include path in which to search for stdc-predef.h # 00:02:05 /home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/snapshots/gcc.git~master/libgcc/unwind-arm-common.inc:55:24: error: macro passed 1 arguments, but takes just 0 # 00:02:05 make[2]: *** [/home/tcwg-buildslave/workspace/tcwg_gnu_1/abe/snapshots/gcc.git~master/libgcc/static-object.mk:17: unwind-arm.o] Error 1 # 00:02:06 make[1]: *** [Makefile:12484: all-target-libgcc] Error 2 # 00:02:06 make: *** [Makefile:953: all] Error 2

from (for last_good == d7e56b084d0b230ae5ee280f569d679fa0f09f4d) # reset_artifacts: -10 # true: 0 # build_abe binutils: 1 # build_abe stage1: 2 # build_abe linux: 3 # build_abe glibc: 4 # build_abe stage2: 5 # build_abe gdb: 6 # build_abe qemu: 7

Artifacts of last_good build: https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/artifact/... Artifacts of first_bad build: https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/artifact/... Build top page/logs: https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/

Configuration details:

Reproduce builds: <cut> mkdir investigate-gcc-caf81d3b57501b1f58dcd9b1ef9d7b4bc76f4ab1 cd investigate-gcc-caf81d3b57501b1f58dcd9b1ef9d7b4bc76f4ab1

git clone https://git.linaro.org/toolchain/jenkins-scripts

mkdir -p artifacts/manifests curl -o artifacts/manifests/build-baseline.sh https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/artifact/... --fail curl -o artifacts/manifests/build-parameters.sh https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/artifact/... --fail curl -o artifacts/test.sh https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/artifact/... --fail chmod +x artifacts/test.sh

# Reproduce the baseline build (build all pre-requisites) ./jenkins-scripts/tcwg_gnu-build.sh @@ artifacts/manifests/build-baseline.sh

# Save baseline build state (which is then restored in artifacts/test.sh) mkdir -p ./bisect rsync -a --del --delete-excluded --exclude /bisect/ --exclude /artifacts/ --exclude /gcc/ ./ ./bisect/baseline/

cd gcc

# Reproduce first_bad build git checkout --detach caf81d3b57501b1f58dcd9b1ef9d7b4bc76f4ab1 ../artifacts/test.sh

# Reproduce last_good build git checkout --detach d7e56b084d0b230ae5ee280f569d679fa0f09f4d ../artifacts/test.sh

cd .. </cut>

History of pending regressions and results: https://git.linaro.org/toolchain/ci/base-artifacts.git/log/?h=linaro-local/c...

Artifacts: https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/artifact/... Build log: https://ci.linaro.org/job/tcwg_gnu_cross_build-bisect-master-arm/1/consoleTe...

Full commit (up to 1000 lines): <cut> commit caf81d3b57501b1f58dcd9b1ef9d7b4bc76f4ab1 Author: Sebastian Huber sebastian.huber@embedded-brains.de Date: Tue Aug 17 09:53:43 2021 +0200

Use __builtin_trap() for abort() if inhibit_libc

abort() is used in gcc_assert() and gcc_unreachable() which is used by target libraries such as libgcov.a. This patch changes the abort() definition under certain conditions. If inhibit_libc is defined and abort is not already defined, then abort() is defined to __builtin_trap().

The inhibit_libc define is usually defined if GCC is built for targets running in embedded systems which may optionally use a C standard library. If inhibit_libc is defined, then there may be still a full featured abort() available. abort() is a heavy weight function which depends on signals and file streams. For statically linked applications, this means that a dependency on gcc_assert() pulls in the support for signals and file streams. This could prevent using gcov to test low end targets for example. Using __builtin_trap() avoids these dependencies if the target implements a "trap" instruction. The application or operating system could use a trap handler to react to failed GCC runtime checks which caused a trap.

gcc/

* tsystem.h (abort): Define abort() if inhibit_libc is defined and it is not already defined. --- gcc/tsystem.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/tsystem.h b/gcc/tsystem.h index e1e6a96a4f4..5c72c69ff3e 100644 --- a/gcc/tsystem.h +++ b/gcc/tsystem.h @@ -59,7 +59,7 @@ extern int atexit (void (*)(void)); #endif

#ifndef abort -extern void abort (void) __attribute__ ((__noreturn__)); +#define abort() __builtin_trap () #endif

#ifndef strlen </cut>