[llvm] [VPlan] Support masked VPInsts, use for predication (NFC) (PR #142285)

[Luke Lau via llvm-commits]

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@@ -1282,6 +1282,48 @@ class LLVM_ABI_FOR_TEST VPInstruction : public VPRecipeWithIRFlags,
     }
   }
 
+  /// Returns true if the VPInstruction has a mask operand.
+  bool isMasked() const {
+    return getNumOperandsForOpcode() + 1 == getNumOperands();
+  }
+
+  /// Returns true if the opcode needs and supports masking.
+  bool needsMask() const {
+    // Don't use masks to synthetic VPInstructions for now, i.e. ones that do
+    // not have underlying values.
+    if (!getUnderlyingValue())
+      return false;
+
+    return Opcode != Instruction::ExtractValue && Opcode != Instruction::PHI &&
+           Opcode != Instruction::ICmp && Opcode != Instruction::FCmp &&
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lukel97 wrote:

How come we don't predicate ICmp/FCmp/GetElementPtr? Can they not end up using the mask in handleReplication?

https://github.com/llvm/llvm-project/pull/142285