[PATCH] D98114: [Loads] Forward constant vector store to load of first element

[Nikita Popov via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGb552e16b0b04: [Loads] Forward constant vector store to load of first element (authored by nikic).

Changed prior to commit:
  https://reviews.llvm.org/D98114?vs=328763&id=335075#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D98114/new/

https://reviews.llvm.org/D98114

Files:
  llvm/lib/Analysis/Loads.cpp
  llvm/test/Transforms/InstCombine/load-store-forward.ll


Index: llvm/test/Transforms/InstCombine/load-store-forward.ll
===================================================================
--- llvm/test/Transforms/InstCombine/load-store-forward.ll
+++ llvm/test/Transforms/InstCombine/load-store-forward.ll
@@ -22,8 +22,7 @@
 ; CHECK-LABEL: @vec_store_load_first(
 ; CHECK-NEXT:    [[P2:%.*]] = bitcast i32* [[P:%.*]] to <2 x i32>*
 ; CHECK-NEXT:    store <2 x i32> <i32 1, i32 2>, <2 x i32>* [[P2]], align 8
-; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[P]], align 4
-; CHECK-NEXT:    ret i32 [[LOAD]]
+; CHECK-NEXT:    ret i32 1
 ;
   %p2 = bitcast i32* %p to <2 x i32>*
   store <2 x i32> <i32 1, i32 2>, <2 x i32>* %p2
@@ -31,6 +30,19 @@
   ret i32 %load
 }
 
+define i32 @vec_store_load_first_constexpr(i32* %p) {
+; CHECK-LABEL: @vec_store_load_first_constexpr(
+; CHECK-NEXT:    [[P2:%.*]] = bitcast i32* [[P:%.*]] to <2 x i32>*
+; CHECK-NEXT:    store <2 x i32> bitcast (i64 ptrtoint (i32 (i32*)* @vec_store_load_first to i64) to <2 x i32>), <2 x i32>* [[P2]], align 8
+; CHECK-NEXT:    [[LOAD:%.*]] = load i32, i32* [[P]], align 4
+; CHECK-NEXT:    ret i32 [[LOAD]]
+;
+  %p2 = bitcast i32* %p to <2 x i32>*
+  store <2 x i32> bitcast (i64 ptrtoint (i32 (i32*)* @vec_store_load_first to i64) to <2 x i32>), <2 x i32>* %p2, align 8
+  %load = load i32, i32* %p, align 4
+  ret i32 %load
+}
+
 define i32 @vec_store_load_second(i32* %p) {
 ; CHECK-LABEL: @vec_store_load_second(
 ; CHECK-NEXT:    [[P2:%.*]] = bitcast i32* [[P:%.*]] to <2 x i32>*
Index: llvm/lib/Analysis/Loads.cpp
===================================================================
--- llvm/lib/Analysis/Loads.cpp
+++ llvm/lib/Analysis/Loads.cpp
@@ -495,12 +495,15 @@
     if (!AreEquivalentAddressValues(StorePtr, Ptr))
       return nullptr;
 
+    if (IsLoadCSE)
+      *IsLoadCSE = false;
+
     Value *Val = SI->getValueOperand();
-    if (CastInst::isBitOrNoopPointerCastable(Val->getType(), AccessTy, DL)) {
-      if (IsLoadCSE)
-        *IsLoadCSE = false;
+    if (CastInst::isBitOrNoopPointerCastable(Val->getType(), AccessTy, DL))
       return Val;
-    }
+
+    if (auto *C = dyn_cast<Constant>(Val))
+      return ConstantFoldLoadThroughBitcast(C, AccessTy, DL);
   }
 
   return nullptr;


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