[PATCH] D152128: [RISCV] Fold special case (xor (setcc constant, y, setlt), 1) -> (setcc y, constant + 1, setlt)

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.
Herald added a subscriber: wangpc.


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Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:10484
+      SDLoc DL(N0);
+      int64_t Imm = ConstN00->getSExtValue();
+      if (isInt<12>(Imm + 1))
----------------
Use APInt methods here. I don't think we're protected against types being larger than i64 here. So getSExtValue() might assert.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:10485
+      int64_t Imm = ConstN00->getSExtValue();
+      if (isInt<12>(Imm + 1))
+        return DAG.getSetCC(DL, VT, N0.getOperand(1),
----------------
`Imm+1` is undefined behavior if Imm happens to be INT64_MAX. Another reason to use APInt.


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  https://reviews.llvm.org/D152128/new/

https://reviews.llvm.org/D152128