[llvm-dev] [X86] MoveImm flag for instructions

Craig Topper via llvm-dev llvm-dev at lists.llvm.org
Fri Feb 9 12:17:28 PST 2018

That flag is specifically used by the foldImmediate optimization in the
Peephole pass. We don't implement the TLI foldImmediate hook the peephole
pass uses on x86 so we have no reason to set the flag on any instructions

What are you trying to do?


On Fri, Feb 9, 2018 at 11:45 AM, S. Bharadwaj Yadavalli via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

> Hi,
> I had (naively?) expected that the instruction to move immediate to
> register or memory (such as MOV32mi, MOV32ri, MOV64mi32, MOV64ri,
> MOV64ri32) would be marked with the flag MCID::MovImm via the
> X86InstrInfo.td (and hence in the generated X86GenInstrInfo.inc).
> I do not see that to be the case.
> Can someone please tell me if my expectation is flawed? Is there a
> better/different way to determine to test for move immediate to
> register/memory instruction on X86 other that the existing interface
> MCID::isMoveImmediate()?
> Thanks,
> Bharadwaj
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