Yvan, LDAR is intended for an atomic load acquire. See
http://gcc.gnu.org/ml/gcc-patches/2012-11/msg01397.html for compiler support upstream. regards, Ramana > -----Original Message----- > From: linaro-toolchain-boun...@lists.linaro.org [mailto:linaro- > toolchain-boun...@lists.linaro.org] On Behalf Of Yvan Roux > Sent: 29 November 2012 09:19 > To: linaro-toolchain@lists.linaro.org; Linaro Private ARMv8 > Subject: ARMv8 load acquire / store release question > > Hi, > > I'm working on the libatomic-ops (part of the Boehm gc) AArch64 > support, > I mainly use GCC's __atomic builtins to do this, but in our 4.7 version > they don't use the load acquire / store release instructions now > available > in the ARMv8 ISA. These instructions are used in the mainline GCC > (in atomic.md) but not in their exclusive form, I understand that it > should > be due to the performance penalty, but I want your feeling on that > point > as I don't find the ARMv8 ISA really clear. > > If we want to implement an atomic load acquire, is > > LDAR x1, [x0] > > sufficient, or do we have to write it like that : > > L: LDAXR x0, [x3] > STEX x1, x0, [x3] > CBZ x0, L1 > > Thanks > Yvan > > _______________________________________________ > linaro-toolchain mailing list > linaro-toolchain@lists.linaro.org > http://lists.linaro.org/mailman/listinfo/linaro-toolchain _______________________________________________ linaro-toolchain mailing list linaro-toolchain@lists.linaro.org http://lists.linaro.org/mailman/listinfo/linaro-toolchain
