[llvm] [DAGCombiner][RISCV] Add target hook to decide hoisting LogicOp with extension (PR #136677)

[Luke Lau via llvm-commits]

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@@ -4462,6 +4462,16 @@ class TargetLowering : public TargetLoweringBase {
     return false;
   }
 
+  /// Return true if it is profitable to hoist a LogicOp where both operands
+  /// have the same extension op. This transformation may not be desirable if
+  /// it disrupts a particularly auspicious target-specific tree (e.g.
+  /// (or disjoint (zext A), (zext B)) -> vwaddu.vv on RISC-V). By default it
+  /// returns true.
+  virtual bool isDesirableToHoistLogicOpWithExt(const SDNode *LogicOp,
+                                                unsigned ExtOp) const {
+    return true;
+  }
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lukel97 wrote:

See #136716 

https://github.com/llvm/llvm-project/pull/136677