[PATCH] D58475: [X86] Improve detection of unneeded shift amount masking to also handle the case that the LHS has known zeroes in it

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: llvm/trunk/lib/Target/X86/X86InstrCompiler.td:1803
   // (shift x (and y, 63)) ==> (shift x, y)
-  def : Pat<(frag GR64:$src1, GR64:$src2, (and CL, immShift64)),
+  def : Pat<(frag GR64:$src1, GR64:$src2, (shiftMask32 CL)),
             (!cast<Instruction>(name # "64rrCL") GR64:$src1, GR64:$src2)>;
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craig.topper wrote:
> RKSimon wrote:
> > @craig.topper This looks like a typo - shouldn't it be ShiftMask64 for the GR64 case?
> Yeah that does look like a typo. Must have copy/pasted too much.
Cheers, D75748 replaces all this code but I just wanted to make sure I hadn't made a dumb assumption about SHLD/SHRD.


Repository:
  rL LLVM

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D58475/new/

https://reviews.llvm.org/D58475