[llvm] [VPlan] Delay adding canonical IV increment and exit branches. (PR #82270)

[Florian Hahn via llvm-commits]

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@@ -1426,22 +1388,18 @@ bool VPlanTransforms::tryAddExplicitVectorLength(VPlan &Plan) {
                                   {EVLPhi, Plan.getTripCount()});
   VPEVL->insertBefore(*Header, Header->getFirstNonPhi());
 
-  auto *CanonicalIVIncrement =
-      cast<VPInstruction>(CanonicalIVPHI->getBackedgeValue());
   VPSingleDefRecipe *OpVPEVL = VPEVL;
   if (unsigned IVSize = CanonicalIVPHI->getScalarType()->getScalarSizeInBits();
       IVSize != 32) {
     OpVPEVL = new VPScalarCastRecipe(IVSize < 32 ? Instruction::Trunc
                                                  : Instruction::ZExt,
                                      OpVPEVL, CanonicalIVPHI->getScalarType());
-    OpVPEVL->insertBefore(CanonicalIVIncrement);
+    Latch->appendRecipe(OpVPEVL);
   }
   auto *NextEVLIV =
-      new VPInstruction(Instruction::Add, {OpVPEVL, EVLPhi},
-                        {CanonicalIVIncrement->hasNoUnsignedWrap(),
-                         CanonicalIVIncrement->hasNoSignedWrap()},
-                        CanonicalIVIncrement->getDebugLoc(), "index.evl.next");
-  NextEVLIV->insertBefore(CanonicalIVIncrement);
+      new VPInstruction(Instruction::Add, {OpVPEVL, EVLPhi}, {false, false},
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fhahn wrote:

Yes at this point we don't know if it wraps or not. Without https://github.com/llvm/llvm-project/pull/111758, the flags for EVL increment would always be false I think, as it always folds the tail.

With it, we could update it when introducing the increment (currently not done)

https://github.com/llvm/llvm-project/pull/82270