On 08/10/12 08:29, Terry Guo wrote:
Hi,When running libstdc++ regression test on Cortex-M0, the case 49445.cc fails with error message: /tmp/ccMqZdgc.o: In function `std::atomic<float>::load(std::memory_order) const':^M /home/build/work/GCC-4-7-build/build-native/gcc-final/arm-none-eabi/armv6-m/ libstdc++-v3/include/atomic:202: undefined reference to `__sync_synchronize'^M /home/build/work/GCC-4-7-build/build-native/gcc-final/arm-none-eabi/armv6-m/ libstdc++-v3/include/atomic:202: undefined reference to `__sync_synchronize'^M /tmp/ccMqZdgc.o: In function `std::atomic<tacos>::load(std::memory_order) const':^M /home/build/work/GCC-4-7-build/build-native/gcc-final/arm-none-eabi/armv6-m/ libstdc++-v3/include/atomic:202: undefined reference to `__sync_synchronize'^M /home/build/work/GCC-4-7-build/build-native/gcc-final/arm-none-eabi/armv6-m/ libstdc++-v3/include/atomic:202: undefined reference to `__sync_synchronize'^M collect2: error: ld returned 1 exit status^M compiler exited with status 1 After investigation, the reason is current gcc doesn't think armv6-m has DMB instruction. While according to ARM manuals, it has. With this wrong assumption, the expand_mem_thread_fence will generate a call to library function __sync_synchronize rather than DMB instruction. While no code to implement this library function, so the error generates. The attached patch intends to fix this issue by letting gcc also think armv6-m has DMB instruction. Is it OK to trunk? BR, Terry 2012-10-08 Terry Guo <terry....@arm.com> * config/arm/arm.c (arm_arch6m): New variable to denote armv6-m architecture. * config/arm/arm.h (TARGET_HAVE_DMB): The armv6-m also has DMB instruction.
Ok. R.
