[PATCH] D84550: [AArch64][GlobalISe] Fold G_AND and G_LSHR into ubfm

Mon Jul 27 23:35:59 PDT 2020

aemerson added inline comments.

================
Comment at: llvm/lib/Target/AArch64/GISel/AArch64InstructionSelector.cpp:1681
+  //
+  // %dst = UBFM %something, immr, imms
+  //
----------------
arsenm wrote:
> aemerson wrote:
> > arsenm wrote:
> > > I think we should introduce a generic code for these and combine to it. Currently at least 4 backends are reproducing all of the patterns to match it
> > A generic opcode for UBFM? Seems a bit specific to me.
> It's not very specific, the only target specific detail here is that the fields need to be immediates. BFE and BFM are available on multiple targets, and every target with these shouldn't have to reproduce the same matching logic
Fair enough. A G_BITFIELD_EXTRACT operation could be useful enough to justify inclusion then.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D84550/new/

https://reviews.llvm.org/D84550