[VPlan] Add VPlan::getTrue/getFalse convenience helpers (NFC).

Makes it slightly more convenient to create true/false constants.

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -4132,6 +4132,18 @@ class VPlan {
     return It->second;
   }
 
+  /// Return a VPValue wrapping i1 true.
+  VPValue *getTrue() {
+    LLVMContext &Ctx = getContext();
+    return getOrAddLiveIn(ConstantInt::getTrue(Ctx));
+  }
+
+  /// Return a VPValue wrapping i1 false.
+  VPValue *getFalse() {
+    LLVMContext &Ctx = getContext();
+    return getOrAddLiveIn(ConstantInt::getFalse(Ctx));
+  }
+
   /// Return the live-in VPValue for \p V, if there is one or nullptr otherwise.
   VPValue *getLiveIn(Value *V) const { return Value2VPValue.lookup(V); }
 

llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp

@@ -570,8 +570,7 @@ void VPlanTransforms::prepareForVectorization(
   VPBuilder Builder(MiddleVPBB);
   VPValue *Cmp;
   if (!RequiresScalarEpilogueCheck)
-    Cmp = Plan.getOrAddLiveIn(
-        ConstantInt::getFalse(IntegerType::getInt1Ty(Plan.getContext())));
+    Cmp = Plan.getFalse();
   else if (TailFolded)
     Cmp = Plan.getOrAddLiveIn(
         ConstantInt::getTrue(IntegerType::getInt1Ty(Plan.getContext())));

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -1502,10 +1502,8 @@ static bool simplifyBranchConditionForVFAndUF(VPlan &Plan, ElementCount BestVF,
   } else {
     // The vector region contains header phis for which we cannot remove the
     // loop region yet.
-    LLVMContext &Ctx = SE.getContext();
-    auto *BOC = new VPInstruction(
-        VPInstruction::BranchOnCond,
-        {Plan.getOrAddLiveIn(ConstantInt::getTrue(Ctx))}, Term->getDebugLoc());
+    auto *BOC = new VPInstruction(VPInstruction::BranchOnCond, {Plan.getTrue()},
+                                  Term->getDebugLoc());
     ExitingVPBB->appendRecipe(BOC);
   }
 
@@ -2171,7 +2169,7 @@ static void transformRecipestoEVLRecipes(VPlan &Plan, VPValue &EVL) {
   Type *CanonicalIVType = Plan.getCanonicalIV()->getScalarType();
   VPTypeAnalysis TypeInfo(CanonicalIVType);
   LLVMContext &Ctx = CanonicalIVType->getContext();
-  VPValue *AllOneMask = Plan.getOrAddLiveIn(ConstantInt::getTrue(Ctx));
+  VPValue *AllOneMask = Plan.getTrue();
   VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
   VPBasicBlock *Header = LoopRegion->getEntryBasicBlock();