[LLVMdev] [PATCH] Apply Thumb2 ROR optimization only when Thumb2 is supported (original) (raw)

Matt Fischer mattfischer84 at gmail.com
Mon Jul 2 12:47:41 PDT 2012

Well, I hadn't even built LLVM for the first time until last week, so I definitely don't have commit access. :)

Thanks for pushing the fix. Moreover, thanks for still supporting those of us who are stuck using silly old ARM11 processors!

On Mon, Jul 2, 2012 at 12:23 PM, Bob Wilson <bob.wilson at apple.com> wrote:

I went ahead and committed it, along with a basic test case, in svn r159538.

On Jul 2, 2012, at 9:34 AM, Jim Grosbach <grosbach at apple.com> wrote:

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

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