[LLVMdev] [PATCH] Apply Thumb2 ROR optimization only when Thumb2 is supported

[Jim Grosbach]

Hi Matt,

You're absolutely right, that pattern should definitely have an "only-in-Thumb2" predicate attached.

Do you have commit access? Also, if you have a reduced test case, that would be awesome, but the patch is correct as-is even if not.

-Jim

On Jul 2, 2012, at 8:05 AM, Matt Fischer <mattfischer84 at gmail.com> wrote:

> I've been playing around with using LLVM on one of our projects, which
> runs on an arm1176jzf-s processor.  When compiling for Thumb, a couple
> of the generated assembly files end up with a 'ror.w' instruction,
> which is a Thumb2 instruction.  Since arm1176jzf-s doesn't support
> Thumb2, the assembler then turns around and barfs on it.
> 
> I don't have any experience with this codebase, but after looking
> around for a while, I think I found the culprit--there was a change
> back in #130502 which added a peephole optimization to generate that
> instruction, but the pattern was not made conditional on being in
> Thumb2 mode.  If that's correct, then I believe the attached patch
> will fix it (at the very least, it made my specific error go away).
> Is this the right fix?
> 
> Thanks,
> Matt
> <0001-Apply-Thumb2-ROR-optimization-only-when-Thumb2-is-su.patch>_______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev