[llvm] [LV] Check if the VF is scalar by VFRange instead of VPlan in `handleUncountableEarlyExit` NFC. (PR #135294)

[Elvis Wang via llvm-commits]

https://github.com/ElvisWang123 created https://github.com/llvm/llvm-project/pull/135294

This patch check if the plan contains scalar VF by VFRange instead of Plan. Then we can further clamp the range after this transformation.

Split from #113903.

>From 1b83ae508b9c9e73a0ff98b04be4af699217bac3 Mon Sep 17 00:00:00 2001
From: Elvis Wang <elvis.wang at sifive.com>
Date: Thu, 10 Apr 2025 17:32:46 -0700
Subject: [PATCH] [LV] Check if the VF is scalar by VFRange instead of VPlan in
 `handleUncountableEarlyExit` NFC.

This patch check if the plan contains scalar VF by VFRange instead of
Plan. Then we can furthur clamp the range after this transformation.

Split by #113903.
---
 llvm/lib/Transforms/Vectorize/LoopVectorize.cpp   | 2 +-
 llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp | 5 +++--
 llvm/lib/Transforms/Vectorize/VPlanTransforms.h   | 4 +++-
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index a4d546f698d5f..0cec4c5c87f67 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -9744,7 +9744,7 @@ LoopVectorizationPlanner::tryToBuildVPlanWithVPRecipes(VFRange &Range) {
           Legal->getUncountableEarlyExitingBlock()) {
     VPlanTransforms::runPass(VPlanTransforms::handleUncountableEarlyExit, *Plan,
                              *PSE.getSE(), OrigLoop, UncountableExitingBlock,
-                             RecipeBuilder);
+                             RecipeBuilder, Range);
   }
   DenseMap<VPValue *, VPValue *> IVEndValues;
   addScalarResumePhis(RecipeBuilder, *Plan, IVEndValues);
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
index 67a55aa67c978..b49a0c452fa1e 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp
@@ -17,6 +17,7 @@
 #include "VPlanAnalysis.h"
 #include "VPlanCFG.h"
 #include "VPlanDominatorTree.h"
+#include "VPlanHelpers.h"
 #include "VPlanPatternMatch.h"
 #include "VPlanUtils.h"
 #include "VPlanVerifier.h"
@@ -2380,7 +2381,7 @@ void VPlanTransforms::convertToConcreteRecipes(VPlan &Plan) {
 
 void VPlanTransforms::handleUncountableEarlyExit(
     VPlan &Plan, ScalarEvolution &SE, Loop *OrigLoop,
-    BasicBlock *UncountableExitingBlock, VPRecipeBuilder &RecipeBuilder) {
+    BasicBlock *UncountableExitingBlock, VPRecipeBuilder &RecipeBuilder, VFRange &Range) {
   VPRegionBlock *LoopRegion = Plan.getVectorLoopRegion();
   auto *LatchVPBB = cast<VPBasicBlock>(LoopRegion->getExiting());
   VPBuilder Builder(LatchVPBB->getTerminator());
@@ -2436,7 +2437,7 @@ void VPlanTransforms::handleUncountableEarlyExit(
       ExitIRI->extractLastLaneOfOperand(MiddleBuilder);
     }
     // Add the incoming value from the early exit.
-    if (!IncomingFromEarlyExit->isLiveIn() && !Plan.hasScalarVFOnly()) {
+    if (!IncomingFromEarlyExit->isLiveIn() && !Range.Start.isScalar()) {
       VPValue *FirstActiveLane = EarlyExitB.createNaryOp(
           VPInstruction::FirstActiveLane, {EarlyExitTakenCond}, nullptr,
           "first.active.lane");
diff --git a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
index c23ff38265670..85649367c3478 100644
--- a/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
+++ b/llvm/lib/Transforms/Vectorize/VPlanTransforms.h
@@ -28,6 +28,7 @@ class PredicatedScalarEvolution;
 class TargetLibraryInfo;
 class VPBuilder;
 class VPRecipeBuilder;
+class VFRange;
 
 extern cl::opt<bool> VerifyEachVPlan;
 
@@ -174,7 +175,8 @@ struct VPlanTransforms {
   static void handleUncountableEarlyExit(VPlan &Plan, ScalarEvolution &SE,
                                          Loop *OrigLoop,
                                          BasicBlock *UncountableExitingBlock,
-                                         VPRecipeBuilder &RecipeBuilder);
+                                         VPRecipeBuilder &RecipeBuilder,
+                                         VFRange &Range);
 
   /// Lower abstract recipes to concrete ones, that can be codegen'd.
   static void convertToConcreteRecipes(VPlan &Plan);