[PATCH] D131471: [RISCV] Fold (sub constant, (setcc x, y, eq/neq)) -> (add constant - 1, (setcc x, y, neq/eq))

[Craig Topper via Phabricator via llvm-commits]

craig.topper added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:8275
+  // (add constant - 1, (setcc x, y, neq/eq))
+  if (isa<ConstantSDNode>(N0) && N1.getOpcode() == ISD::SETCC) {
+    auto *Nnz0 = cast<ConstantSDNode>(N0);
----------------
Do we need to check that this is the only user of the setcc?


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:8279
+    ISD::CondCode CCVal = CC->get();
+    if (!Nnz0->isZero() && (CCVal == ISD::SETEQ || CCVal == ISD::SETNE)) {
+      EVT VT = N->getValueType(0);
----------------
Use `ISD::isIntEqualitySetCC(CCVal)`


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:8287
+                                  N1->getOperand(1), CCInverse);
+      return DAG.getNode(ISD::ADD, SDLoc(N), VT, NewN0, NewN1);
+    }
----------------
Put these in canonical order with constant on the RHS.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D131471/new/

https://reviews.llvm.org/D131471