[VPlan] Manage VPWidenPointerInduction debug location via recipe.

Update VPWidenPointerInduction to manage its debug location via recipe.
This makes sure we emit a proper debug location for
VPWidenPointerInductionRecipes.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -8466,7 +8466,8 @@ VPHeaderPHIRecipe *VPRecipeBuilder::tryToOptimizeInductionPHI(
             [&](ElementCount VF) {
               return CM.isScalarAfterVectorization(Phi, VF);
             },
-            Range));
+            Range),
+        Phi->getDebugLoc());
   }
   return nullptr;
 }

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -2211,8 +2211,8 @@ class VPWidenPointerInductionRecipe : public VPHeaderPHIRecipe,
   /// Start.
   VPWidenPointerInductionRecipe(PHINode *Phi, VPValue *Start, VPValue *Step,
                                 const InductionDescriptor &IndDesc,
-                                bool IsScalarAfterVectorization)
-      : VPHeaderPHIRecipe(VPDef::VPWidenPointerInductionSC, Phi),
+                                bool IsScalarAfterVectorization, DebugLoc DL)
+      : VPHeaderPHIRecipe(VPDef::VPWidenPointerInductionSC, Phi, nullptr, DL),
         IndDesc(IndDesc),
         IsScalarAfterVectorization(IsScalarAfterVectorization) {
     addOperand(Start);
@@ -2224,7 +2224,7 @@ class VPWidenPointerInductionRecipe : public VPHeaderPHIRecipe,
   VPWidenPointerInductionRecipe *clone() override {
     return new VPWidenPointerInductionRecipe(
         cast<PHINode>(getUnderlyingInstr()), getOperand(0), getOperand(1),
-        IndDesc, IsScalarAfterVectorization);
+        IndDesc, IsScalarAfterVectorization, getDebugLoc());
   }
 
   VP_CLASSOF_IMPL(VPDef::VPWidenPointerInductionSC)

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -3182,6 +3182,7 @@ void VPWidenPointerInductionRecipe::execute(VPTransformState &State) {
     NewPointerPhi = PHINode::Create(ScStValueType, 2, "pointer.phi",
                                     CanonicalIV->getIterator());
     NewPointerPhi->addIncoming(ScalarStartValue, VectorPH);
+    NewPointerPhi->setDebugLoc(getDebugLoc());
   } else {
     // The recipe has been unrolled. In that case, fetch the single pointer phi
     // shared among all unrolled parts of the recipe.

llvm/test/Transforms/LoopVectorize/preserve-dbg-loc-and-loop-metadata.ll

@@ -31,13 +31,15 @@ for.end:                                          ; preds = %for.body
   ret void
 }
 
-; FIXME: Missing debug location for pointer induction in vector loop
 define void @widen_ptr_induction_dbg(ptr %start, ptr %end) {
 ; DEBUGLOC-LABEL: define void @widen_ptr_induction_dbg(
 ; DEBUGLOC: vector.body:
-; DEBUGLOC-NOT: = phi ptr {{.+}}, !dbg
+; DEBUGLOC-NEXT: = phi ptr {{.+}}, !dbg ![[PTRIVLOC:[0-9]+]]
 ; DEBUGLOC: = phi i64
 ;
+; DEBUGLOC: loop:
+; DEBUGLOC-NEXT: = phi ptr {{.+}}, !dbg ![[PTRIVLOC]]
+;
 entry:
   br label %loop
 
@@ -59,3 +61,4 @@ exit:
 ; CHECK: !{!"llvm.loop.isvectorized", i32 1}
 
 ; DEBUGLOC: ![[RESUMELOC]] = !DILocation(line: 2
+; DEBUGLOC: ![[PTRIVLOC]] = !DILocation(line: 12