[llvm] [LV] Introduce and use VPBuilder::createScalarZExtOrTrunc [nfc] (PR #144946)

[Philip Reames via llvm-commits]

https://github.com/preames created https://github.com/llvm/llvm-project/pull/144946

Reduce redundant code, make the flow slightly easier to read.

>From 514a53d27a593d00ea22b091d77116495d513866 Mon Sep 17 00:00:00 2001
From: Philip Reames <preames at rivosinc.com>
Date: Thu, 19 Jun 2025 11:50:51 -0700
Subject: [PATCH] [LV] Introduce and use VPBuilder::createScalarZExtOrTrunc
 [nfc]

Reduce redundant code, make the flow slightly easier to read.
---
 .../Vectorize/LoopVectorizationPlanner.h      | 11 +++++
 .../Transforms/Vectorize/VPlanTransforms.cpp  | 40 +++++++------------
 2 files changed, 26 insertions(+), 25 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h b/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
index 70f541d64b305..d17c64a778e86 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h
@@ -278,6 +278,17 @@ class VPBuilder {
         new VPInstructionWithType(Opcode, Op, ResultTy, {}, DL));
   }
 
+  VPValue *createScalarZExtOrTrunc(VPValue *Op, Type *ResultTy, Type *SrcTy,
+                                   DebugLoc DL) {
+    if (ResultTy == SrcTy)
+      return Op;
+    Instruction::CastOps CastOp =
+        ResultTy->getScalarSizeInBits() < SrcTy->getScalarSizeInBits()
+            ? Instruction::Trunc
+            : Instruction::ZExt;
+    return createScalarCast(CastOp, Op, ResultTy, DL);
+  }
+
   VPWidenCastRecipe *createWidenCast(Instruction::CastOps Opcode, VPValue *Op,
                                      Type *ResultTy) {
     return tryInsertInstruction(new VPWidenCastRecipe(Opcode, Op, ResultTy));
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 11f0f2a930329..351f6ccebaeeb 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -797,15 +797,8 @@ static VPValue *optimizeEarlyExitInductionUser(VPlan &Plan,
   VPValue *FirstActiveLane =
       B.createNaryOp(VPInstruction::FirstActiveLane, Mask, DL);
   Type *FirstActiveLaneType = TypeInfo.inferScalarType(FirstActiveLane);
-  if (CanonicalIVType != FirstActiveLaneType) {
-    Instruction::CastOps CastOp =
-        CanonicalIVType->getScalarSizeInBits() <
-                FirstActiveLaneType->getScalarSizeInBits()
-            ? Instruction::Trunc
-            : Instruction::ZExt;
-    FirstActiveLane =
-        B.createScalarCast(CastOp, FirstActiveLane, CanonicalIVType, DL);
-  }
+  FirstActiveLane = B.createScalarZExtOrTrunc(FirstActiveLane, CanonicalIVType,
+                                              FirstActiveLaneType, DL);
   EndValue = B.createNaryOp(Instruction::Add, {EndValue, FirstActiveLane}, DL);
 
   // `getOptimizableIVOf()` always returns the pre-incremented IV, so if it
@@ -2182,13 +2175,10 @@ static void transformRecipestoEVLRecipes(VPlan &Plan, VPValue &EVL) {
     VPValue *MaxEVL = &Plan.getVF();
     // Emit VPScalarCastRecipe in preheader if VF is not a 32 bits integer.
     VPBuilder Builder(LoopRegion->getPreheaderVPBB());
-    if (unsigned VFSize =
-            TypeInfo.inferScalarType(MaxEVL)->getScalarSizeInBits();
-        VFSize != 32) {
-      MaxEVL = Builder.createScalarCast(
-          VFSize > 32 ? Instruction::Trunc : Instruction::ZExt, MaxEVL,
-          Type::getInt32Ty(Ctx), DebugLoc());
-    }
+    MaxEVL = Builder.createScalarZExtOrTrunc(MaxEVL, Type::getInt32Ty(Ctx),
+                                             TypeInfo.inferScalarType(MaxEVL),
+                                             DebugLoc());
+
     Builder.setInsertPoint(Header, Header->getFirstNonPhi());
     PrevEVL = Builder.createScalarPhi({MaxEVL, &EVL}, DebugLoc(), "prev.evl");
   }
@@ -2286,6 +2276,7 @@ bool VPlanTransforms::tryAddExplicitVectorLength(
     return false;
 
   auto *CanonicalIVPHI = Plan.getCanonicalIV();
+  auto *CanIVTy = CanonicalIVPHI->getScalarType();
   VPValue *StartV = CanonicalIVPHI->getStartValue();
 
   // Create the ExplicitVectorLengthPhi recipe in the main loop.
@@ -2297,8 +2288,8 @@ bool VPlanTransforms::tryAddExplicitVectorLength(
       Instruction::Sub, {Plan.getTripCount(), EVLPhi}, DebugLoc(), "avl");
   if (MaxSafeElements) {
     // Support for MaxSafeDist for correct loop emission.
-    VPValue *AVLSafe = Plan.getOrAddLiveIn(
-        ConstantInt::get(CanonicalIVPHI->getScalarType(), *MaxSafeElements));
+    VPValue *AVLSafe =
+        Plan.getOrAddLiveIn(ConstantInt::get(CanIVTy, *MaxSafeElements));
     VPValue *Cmp = Builder.createICmp(ICmpInst::ICMP_ULT, AVL, AVLSafe);
     AVL = Builder.createSelect(Cmp, AVL, AVLSafe, DebugLoc(), "safe_avl");
   }
@@ -2308,13 +2299,12 @@ bool VPlanTransforms::tryAddExplicitVectorLength(
   auto *CanonicalIVIncrement =
       cast<VPInstruction>(CanonicalIVPHI->getBackedgeValue());
   Builder.setInsertPoint(CanonicalIVIncrement);
-  VPSingleDefRecipe *OpVPEVL = VPEVL;
-  if (unsigned IVSize = CanonicalIVPHI->getScalarType()->getScalarSizeInBits();
-      IVSize != 32) {
-    OpVPEVL = Builder.createScalarCast(
-        IVSize < 32 ? Instruction::Trunc : Instruction::ZExt, OpVPEVL,
-        CanonicalIVPHI->getScalarType(), CanonicalIVIncrement->getDebugLoc());
-  }
+  VPValue *OpVPEVL = VPEVL;
+
+  auto *I32Ty = Type::getInt32Ty(CanIVTy->getContext());
+  OpVPEVL = Builder.createScalarZExtOrTrunc(
+      OpVPEVL, CanIVTy, I32Ty, CanonicalIVIncrement->getDebugLoc());
+
   auto *NextEVLIV = Builder.createOverflowingOp(
       Instruction::Add, {OpVPEVL, EVLPhi},
       {CanonicalIVIncrement->hasNoUnsignedWrap(),