[llvm] 3129bdc - [DAG] visitINSERT_VECTOR_ELT - move mergeInsertEltWithShuffle / combineInsertEltToShuffle folds after canonicalization

[Simon Pilgrim via llvm-commits]

Author: Simon Pilgrim
Date: 2023-01-20T14:57:33Z
New Revision: 3129bdce8dddefbf03ab3ef52170132eb4bcf929

URL: https://github.com/llvm/llvm-project/commit/3129bdce8dddefbf03ab3ef52170132eb4bcf929
DIFF: https://github.com/llvm/llvm-project/commit/3129bdce8dddefbf03ab3ef52170132eb4bcf929.diff

LOG: [DAG] visitINSERT_VECTOR_ELT - move mergeInsertEltWithShuffle / combineInsertEltToShuffle folds after canonicalization

Noticed while triaging D127115 regressions - there's no need to attempt these costly folds until after the easy canonicalization cases have been addressed

Added: 
    

Modified: 
    llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

Removed: 
    


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diff  --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 4e3afebe268f..3b8a136f0d55 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -20149,12 +20149,6 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
   // We must know which element is being inserted for folds below here.
   unsigned Elt = IndexC->getZExtValue();
 
-  if (SDValue Shuf = mergeInsertEltWithShuffle(N, Elt))
-    return Shuf;
-
-  if (SDValue Shuf = combineInsertEltToShuffle(N, Elt))
-    return Shuf;
-
   // Handle <1 x ???> vector insertion special cases.
   if (NumElts == 1) {
     // insert_vector_elt(x, extract_vector_elt(y, 0), 0) -> y
@@ -20184,6 +20178,12 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
     }
   }
 
+  if (SDValue Shuf = mergeInsertEltWithShuffle(N, Elt))
+    return Shuf;
+
+  if (SDValue Shuf = combineInsertEltToShuffle(N, Elt))
+    return Shuf;
+
   // Attempt to convert an insert_vector_elt chain into a legal build_vector.
   if (!LegalOperations || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)) {
     // vXi1 vector - we don't need to recurse.