[PATCH] D152147: [RISCV] Fold binary op into select if profitable.

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


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Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:5784
+  unsigned OtherSelOpNo = 2;
+  SDValue ConstSelOp = Sel->getOperand(1);
+  ConstantSDNode *ConstSelOpNode = dyn_cast<ConstantSDNode>(ConstSelOp);
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Can `ConstSelOp` and `ConstSelOpNode` be moved below the if by using `ConstSelOpNo`?


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Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:5846
 
+  if (Op.hasOneUse() && isBinOp(Op->use_begin()->getOpcode())) {
+    SDNode *BinOp = *Op->use_begin();
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Is this safe for division/remainder? The select could be sanitizing inputs. RISC-V doesn't have traps for div/rem, but IR/SelectionDAG semantics consider division by 0 to be immediate UB. Same with (sdiv -1, INT_MIN)


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D152147/new/

https://reviews.llvm.org/D152147