On 01/07/2018 03:58 PM, H.J. Lu wrote: > This set of patches for GCC 8 mitigates variant #2 of the speculative > execution > vulnerabilities on x86 processors identified by CVE-2017-5715, aka Spectre. > They > convert indirect branches to call and return thunks to avoid speculative > execution > via indirect call and jmp. > > > H.J. Lu (5): > x86: Add -mindirect-branch= > x86: Add -mindirect-branch-loop= > x86: Add -mfunction-return= > x86: Add -mindirect-branch-register > x86: Add 'V' register operand modifier > > gcc/config/i386/constraints.md | 12 +- > gcc/config/i386/i386-opts.h | 14 + > gcc/config/i386/i386-protos.h | 2 + > gcc/config/i386/i386.c | 655 > ++++++++++++++++++++- > gcc/config/i386/i386.h | 10 + > gcc/config/i386/i386.md | 51 +- > gcc/config/i386/i386.opt | 45 ++ > gcc/config/i386/predicates.md | 21 +- > gcc/doc/extend.texi | 22 + > gcc/doc/invoke.texi | 37 +- My fundamental problem with this patchkit is that it is 100% x86/x86_64 specific.
ISTM we want a target independent mechanism (ie, new standard patterns, options, etc) then an x86/x86_64 implementation using that target independent framework (ie, the actual implementation of those new standard patterns). jeff
