> -----Original Message----- > From: Richard Earnshaw > Sent: Tuesday, October 09, 2012 10:01 PM > To: Terry Guo > Cc: gcc-patches@gcc.gnu.org > Subject: Re: [Patch ARM] Fix that miss DMB instruction for ARMv6-M > > 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.
Thanks Richard. Is it OK to 4.7? BR, Terry
