[PATCH] D113937: [RISCV] Override TargetLowering::hasAndNot for Zbb.

[Jessica Clarke via Phabricator via llvm-commits]

jrtc27 added inline comments.


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:1115-1118
+  if (!Subtarget.hasStdExtZbb())
+    return false;
+
+  return !isa<ConstantSDNode>(Y);
----------------
Might possibly make more sense to write as:
```
if (Subtarget.hasStdExtZbb() && isa<ConstantSDNode>(Y))
  return true;

return false;
```
depending on how this will be extended in future (e.g. with vector support?)


================
Comment at: llvm/lib/Target/RISCV/RISCVISelLowering.cpp:1118
+
+  return !isa<ConstantSDNode>(Y);
+}
----------------
I think your code size regressions come from this not using Y.getNode()? SDValue is never a ConstantSDNode, so for Zbb this always returns true.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D113937/new/

https://reviews.llvm.org/D113937