On 01/07/2018 03:59 PM, H.J. Lu wrote: > Add -mindirect-branch-loop= option to control loop filler in call and > return thunks generated by -mindirect-branch=. 'lfence' uses "lfence" > as loop filler. 'pause' uses "pause" as loop filler. 'nop' uses "nop" > as loop filler. The default is 'lfence'. > > gcc/ > > * config/i386/i386-opts.h (indirect_branch_loop): New. > * config/i386/i386.c (output_indirect_thunk): Support > -mindirect-branch-loop=. > * config/i386/i386.opt (mindirect-branch-loop=): New option. > (indirect_branch_loop): New. > (lfence): Likewise. > (pause): Likewise. > (nop): Likewise. > * doc/invoke.texi: Document -mindirect-branch-loop= option. > > gcc/testsuite/ > > * gcc.target/i386/indirect-thunk-loop-1.c: New test. > * gcc.target/i386/indirect-thunk-loop-2.c: Likewise. > * gcc.target/i386/indirect-thunk-loop-3.c: Likewise. > * gcc.target/i386/indirect-thunk-loop-4.c: Likewise. > * gcc.target/i386/indirect-thunk-loop-5.c: Likewise. I think we should drop the ability to change the filler until such time as we really need it. Just pick one and go with it. I think David suggested that they wanted "pause". I'm obviously fine with that.
jeff
