[llvm] 734b016 - Revert "[SLP] Improve gather tree nodes matching when users are PHIs. (#69392)"

[Douglas Yung via llvm-commits]

Author: Douglas Yung
Date: 2023-10-20T10:59:07-07:00
New Revision: 734b016b66c7bc1ef93b294c9bf7bbbd2c02a044

URL: https://github.com/llvm/llvm-project/commit/734b016b66c7bc1ef93b294c9bf7bbbd2c02a044
DIFF: https://github.com/llvm/llvm-project/commit/734b016b66c7bc1ef93b294c9bf7bbbd2c02a044.diff

LOG: Revert "[SLP] Improve gather tree nodes matching when users are PHIs. (#69392)"

This reverts commit c80b50349648dcf7fcbf4ae69c62b3d34bee0c70.

This change causes a fatal error in the backend and is filed as issue #69670.

Added: 
    

Modified: 
    llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
    llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
index 1142d2112803106..f694ab88ccab8ea 100644
--- a/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
+++ b/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp
@@ -9043,7 +9043,6 @@ BoUpSLP::isGatherShuffledEntry(const TreeEntry *TE, ArrayRef<Value *> VL,
   // blocks.
   if (auto *PHI = dyn_cast<PHINode>(TEUseEI.UserTE->getMainOp())) {
     TEInsertBlock = PHI->getIncomingBlock(TEUseEI.EdgeIdx);
-    TEInsertPt = TEInsertBlock->getTerminator();
   } else {
     TEInsertBlock = TEInsertPt->getParent();
   }
@@ -9107,10 +9106,9 @@ BoUpSLP::isGatherShuffledEntry(const TreeEntry *TE, ArrayRef<Value *> VL,
       const Instruction *InsertPt =
           UserPHI ? UserPHI->getIncomingBlock(UseEI.EdgeIdx)->getTerminator()
                   : &getLastInstructionInBundle(UseEI.UserTE);
-      if (TEInsertPt == InsertPt) {
-        // If 2 gathers are operands of the same entry (regardless of wether
-        // user is PHI or else), compare operands indices, use the earlier one
-        // as the base.
+      if (!UserPHI && TEInsertPt == InsertPt) {
+        // If 2 gathers are operands of the same non-PHI entry,
+        // compare operands indices, use the earlier one as the base.
         if (TEUseEI.UserTE == UseEI.UserTE && TEUseEI.EdgeIdx < UseEI.EdgeIdx)
           continue;
         // If the user instruction is used for some reason in 
diff erent

diff  --git a/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll b/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
index e5d7ad138b4def2..28e0b06f6967368 100644
--- a/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
+++ b/llvm/test/Transforms/SLPVectorizer/X86/matching-gather-nodes-phi-users.ll
@@ -8,7 +8,7 @@
 ; YAML: Function:        test
 ; YAML: Args:
 ; YAML:   - String:          'Stores SLP vectorized with cost '
-; YAML:   - Cost:            '-6'
+; YAML:   - Cost:            '-3'
 ; YAML:   - String:          ' and with tree size '
 ; YAML:   - TreeSize:        '14'
 ; YAML: ...