[PATCH] D103419: [VectorCombine] Fix alignment in single element store

[Qiu Chaofan via Phabricator via llvm-commits]

qiucf updated this revision to Diff 351074.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D103419/new/

https://reviews.llvm.org/D103419

Files:
  llvm/lib/Transforms/Vectorize/VectorCombine.cpp
  llvm/test/Transforms/VectorCombine/load-insert-store.ll


Index: llvm/test/Transforms/VectorCombine/load-insert-store.ll
===================================================================
--- llvm/test/Transforms/VectorCombine/load-insert-store.ll
+++ llvm/test/Transforms/VectorCombine/load-insert-store.ll
@@ -20,7 +20,7 @@
 ; CHECK-LABEL: @insert_store_i16_align1(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds <8 x i16>, <8 x i16>* [[Q:%.*]], i32 0, i32 3
-; CHECK-NEXT:    store i16 [[S:%.*]], i16* [[TMP0]], align 1
+; CHECK-NEXT:    store i16 [[S:%.*]], i16* [[TMP0]], align 2
 ; CHECK-NEXT:    ret void
 ;
 entry:
@@ -125,6 +125,7 @@
   ret void
 }
 
+; To verify align here is narrowed to scalar store size
 define void @insert_store_nonconst_large_alignment(<4 x i32>* %q, i32 zeroext %s, i32 %idx) {
 ; CHECK-LABEL: @insert_store_nonconst_large_alignment(
 ; CHECK-NEXT:  entry:
@@ -148,7 +149,7 @@
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[IDX:%.*]], 2
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds <8 x i64>, <8 x i64>* [[Q:%.*]], i32 0, i32 [[IDX]]
-; CHECK-NEXT:    store i64 [[S:%.*]], i64* [[TMP1]], align 4
+; CHECK-NEXT:    store i64 [[S:%.*]], i64* [[TMP1]], align 8
 ; CHECK-NEXT:    ret void
 ;
   %cmp = icmp ult i32 %idx, 2
@@ -180,7 +181,7 @@
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp ult i32 [[IDX:%.*]], 2
 ; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    [[TMP1:%.*]] = getelementptr inbounds <8 x i64>, <8 x i64>* [[Q:%.*]], i32 0, i32 [[IDX]]
-; CHECK-NEXT:    store i64 [[S:%.*]], i64* [[TMP1]], align 2
+; CHECK-NEXT:    store i64 [[S:%.*]], i64* [[TMP1]], align 4
 ; CHECK-NEXT:    ret void
 ;
   %cmp = icmp ult i32 %idx, 2
Index: llvm/lib/Transforms/Vectorize/VectorCombine.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/VectorCombine.cpp
+++ llvm/lib/Transforms/Vectorize/VectorCombine.cpp
@@ -831,8 +831,15 @@
     Builder.Insert(GEP);
     StoreInst *NSI = Builder.CreateStore(NewElement, GEP);
     NSI->copyMetadata(*SI);
-    if (SI->getAlign() < NSI->getAlign())
-      NSI->setAlignment(SI->getAlign());
+    Align NewAlignment = std::max(SI->getAlign(), Load->getAlign());
+    if (auto *C = dyn_cast<ConstantInt>(Idx))
+      NewAlignment = commonAlignment(
+          NewAlignment,
+          C->getZExtValue() * DL.getTypeStoreSize(NewElement->getType()));
+    else
+      NewAlignment = commonAlignment(
+          NewAlignment, DL.getTypeStoreSize(NewElement->getType()));
+    NSI->setAlignment(NewAlignment);
     replaceValue(I, *NSI);
     // Need erasing the store manually.
     I.eraseFromParent();


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