[llvm] 9de31c4 - [VPlan] Create zero resume value for CanIV directly (NFC).

[Florian Hahn via llvm-commits]

Author: Florian Hahn
Date: 2026-03-14T21:13:20Z
New Revision: 9de31c4a3e77ceb1e736d4df3ae9e3f5a1dc8748

URL: https://github.com/llvm/llvm-project/commit/9de31c4a3e77ceb1e736d4df3ae9e3f5a1dc8748
DIFF: https://github.com/llvm/llvm-project/commit/9de31c4a3e77ceb1e736d4df3ae9e3f5a1dc8748.diff

LOG: [VPlan] Create zero resume value for CanIV directly (NFC).

The start value of the canonical IV is always 0. Assert and generate
zero VPValue manually in preparation for
https://github.com/llvm/llvm-project/pull/156262. Split off as
suggested.

Added: 
    

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

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 177aa0830064e..ec7d6b3472745 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -9069,11 +9069,15 @@ static void preparePlanForMainVectorLoop(VPlan &MainPlan, VPlan &EpiPlan) {
       });
   VPPhi *ResumePhi = nullptr;
   if (ResumePhiIter == MainScalarPH->phis().end()) {
+    using namespace llvm::VPlanPatternMatch;
+    assert(
+        match(MainPlan.getVectorLoopRegion()->getCanonicalIV()->getStartValue(),
+              m_ZeroInt()) &&
+        "canonical IV must start at 0");
+    Type *Ty = VPTypeAnalysis(MainPlan).inferScalarType(VectorTC);
     VPBuilder ScalarPHBuilder(MainScalarPH, MainScalarPH->begin());
     ResumePhi = ScalarPHBuilder.createScalarPhi(
-        {VectorTC,
-         MainPlan.getVectorLoopRegion()->getCanonicalIV()->getStartValue()},
-        {}, "vec.epilog.resume.val");
+        {VectorTC, MainPlan.getZero(Ty)}, {}, "vec.epilog.resume.val");
   } else {
     ResumePhi = cast<VPPhi>(&*ResumePhiIter);
     if (MainScalarPH->begin() == MainScalarPH->end())