[PATCH] D123577: [MIPS][SelectionDAG] Enable TargetLowering::hasBitTest for masks that fit in ANDI.

[LiqinWeng via Phabricator via llvm-commits]

Miss_Grape added inline comments.


================
Comment at: llvm/lib/Target/Mips/MipsISelLowering.cpp:1179
+  // We can use ANDI+SLTIU as a bit test. Y contains the bit position.
+  auto *C = dyn_cast<ConstantSDNode>(Y);
+  return C && C->getAPIntValue().ule(14);
----------------
Miss_Grape wrote:
> sdardis wrote:
> > I believe this code would be clearer if it was the likes of:
> > 
> > 
> > ```
> >   if (auto *C = dyn_Cast<ConstantSDNode>(Y))
> >     return C->getAPIntValue().ule(14);
> > 
> >   return false; 
> > ```
> > 
> > Also, the `14` should be `15` here. `andi` takes a 16-bit immediate.
> > 
> > 
> This number represents the shift， As shown below
> {F22821521}
> 
Sorry, the immediate range of the and instruction of Mips is uimm6 instead of sim16. I have fixed and corrected the test case


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  https://reviews.llvm.org/D123577/new/

https://reviews.llvm.org/D123577