[SLP] Rework `findBuildAggregate()` from ercursive form to iterative, NFC.

Reviewers: mkuper

Subscribers: llvm-commits, mzolotukhin

Differential Revision: https://reviews.llvm.org/D30103

llvm-svn: 295641

1 files changed, 12 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 33b4f986015..5c95f88a3f9 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -4614,16 +4614,19 @@ static bool findBuildVector(InsertElementInst *FirstInsertElem,
 static bool findBuildAggregate(InsertValueInst *IV,
                                SmallVectorImpl<Value *> &BuildVector,
                                SmallVectorImpl<Value *> &BuildVectorOpds) {
-  if (!IV->hasOneUse())
-    return false;
-  Value *V = IV->getAggregateOperand();
-  if (!isa<UndefValue>(V)) {
-    InsertValueInst *I = dyn_cast<InsertValueInst>(V);
-    if (!I || !findBuildAggregate(I, BuildVector, BuildVectorOpds))
+  Value *V = IV;
+  do {
+    BuildVector.push_back(IV);
+    BuildVectorOpds.push_back(IV->getInsertedValueOperand());
+    V = IV->getAggregateOperand();
+    if (isa<UndefValue>(V))
+      break;
+    IV = dyn_cast<InsertValueInst>(V);
+    if (!IV || !IV->hasOneUse())
       return false;
-  }
-  BuildVector.push_back(IV);
-  BuildVectorOpds.push_back(IV->getInsertedValueOperand());
+  } while (true);
+  std::reverse(BuildVector.begin(), BuildVector.end());
+  std::reverse(BuildVectorOpds.begin(), BuildVectorOpds.end());
   return true;
 }