[PATCH] D155328: [RISCV] Add a DAG combine for (czero_eq X, (xor Y, 1)) -> (czero_ne X, Y) if Y is 0 or 1.

[Mikhail Gudim via Phabricator via llvm-commits]

mgudim added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:12728
+    return SDValue();
+
   case RISCVISD::SELECT_CC: {
----------------
craig.topper wrote:
> craig.topper wrote:
> > mgudim wrote:
> > > Why not express this using pattern?
> > I'm not sure what you mean.
> Do you mean an isel pattern in tablegen? I'd need a PatFrag or ComplexPattern to call MaskValueIsZero. So there doesn't seem to be any advantage.
def : Pat<(XLenVT (riscv_czero_eqz GPR:$rs1, (xor GPR:$rc, 1))),
          (CZERO_NEZ GPR:$rs1, GPR:$rc)>;



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  https://reviews.llvm.org/D155328/new/

https://reviews.llvm.org/D155328