[llvm] a485e0e - [VPlan] Retrieve vector TC for epilogue from resume phi (NFC).

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2025-08-07T07:52:35+01:00
New Revision: a485e0eae01beaf68a94d1f050838866e849bd48

URL: https://github.com/llvm/llvm-project/commit/a485e0eae01beaf68a94d1f050838866e849bd48
DIFF: https://github.com/llvm/llvm-project/commit/a485e0eae01beaf68a94d1f050838866e849bd48.diff

LOG: [VPlan] Retrieve vector TC for epilogue from resume phi (NFC).

Instead of relying on getOrCreateVectorTripCount to initialize
EPI.VectorTripCount, delay initialization after we retrieved the resume
phi and get the trip count from there. This makes the code independent
of legacy vector trip count creation.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 323e4226fe70c..be00fd6a416e5 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7530,9 +7530,6 @@ BasicBlock *EpilogueVectorizerMainLoop::createEpilogueVectorizedLoopSkeleton() {
   EPI.MainLoopIterationCountCheck =
       emitIterationCountCheck(LoopScalarPreHeader, false);
 
-  // Generate the induction variable.
-  EPI.VectorTripCount = getOrCreateVectorTripCount(LoopVectorPreHeader);
-
   replaceVPBBWithIRVPBB(Plan.getScalarPreheader(), LoopScalarPreHeader);
   return LoopVectorPreHeader;
 }
@@ -9808,7 +9805,7 @@ static void preparePlanForMainVectorLoop(VPlan &MainPlan, VPlan &EpiPlan) {
 static void
 preparePlanForEpilogueVectorLoop(VPlan &Plan, Loop *L,
                                  const SCEV2ValueTy &ExpandedSCEVs,
-                                 const EpilogueLoopVectorizationInfo &EPI) {
+                                 EpilogueLoopVectorizationInfo &EPI) {
   VPRegionBlock *VectorLoop = Plan.getVectorLoopRegion();
   VPBasicBlock *Header = VectorLoop->getEntryBasicBlock();
   Header->setName("vec.epilog.vector.body");
@@ -9826,30 +9823,13 @@ preparePlanForEpilogueVectorLoop(VPlan &Plan, Loop *L,
       // loop.
       using namespace llvm::PatternMatch;
       PHINode *EPResumeVal = &*L->getLoopPreheader()->phis().begin();
-      assert(EPResumeVal->getType() == IV->getScalarType() &&
-             match(EPResumeVal->getIncomingValueForBlock(
-                       EPI.MainLoopIterationCountCheck),
-                   m_SpecificInt(0)) &&
-             EPResumeVal ==
-                 find_singleton<PHINode>(
-                     L->getLoopPreheader()->phis(),
-                     [&EPI, IV](PHINode &P, bool) -> PHINode * {
-                       if (P.getType() == IV->getScalarType() &&
-                           match(P.getIncomingValueForBlock(
-                                     EPI.MainLoopIterationCountCheck),
-                                 m_SpecificInt(0)) &&
-                           any_of(P.incoming_values(),
-                                  [&EPI](Value *Inc) {
-                                    return Inc == EPI.VectorTripCount;
-                                  }) &&
-                           all_of(P.incoming_values(), [&EPI](Value *Inc) {
-                             return Inc == EPI.VectorTripCount ||
-                                    match(Inc, m_SpecificInt(0));
-                           }))
-                         return &P;
-                       return nullptr;
-                     }) &&
-             "Epilogue resume phis do not match!");
+      for (Value *Inc : EPResumeVal->incoming_values()) {
+        if (match(Inc, m_SpecificInt(0)))
+          continue;
+        assert(!EPI.VectorTripCount &&
+               "Must only have a single non-zero incoming value");
+        EPI.VectorTripCount = Inc;
+      }
       VPValue *VPV = Plan.getOrAddLiveIn(EPResumeVal);
       assert(all_of(IV->users(),
                     [](const VPUser *U) {