Enhance LICM to promote alias sets whose pointers themselves are stored,

which doesn't affect the memory address being promoted.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122172 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 34 insertions, 1 deletions

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 46fffccb3a..6d5b24a01b 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -691,7 +691,10 @@ void LICM::PromoteAliasSet(AliasSet &AS) {
       if (isa<LoadInst>(Use))
         assert(!cast<LoadInst>(Use)->isVolatile() && "AST broken");
       else if (isa<StoreInst>(Use)) {
-        if (Use->getOperand(0) == ASIV) return;
+        // Stores *of* the pointer are not interesting, only stores *to* the
+        // pointer.
+        if (Use->getOperand(1) != ASIV)
+          continue;
         assert(!cast<StoreInst>(Use)->isVolatile() && "AST broken");
       } else
         return; // Not a load or store.
diff --git a/test/Transforms/LICM/scalar_promote.ll b/test/Transforms/LICM/scalar_promote.ll
index 67ad5bc0f4..d8acdc1a3a 100644
--- a/test/Transforms/LICM/scalar_promote.ll
+++ b/test/Transforms/LICM/scalar_promote.ll
@@ -118,3 +118,33 @@ exit:
   ret void
 }
 
+define void @test5(i32 %i, i32** noalias %P2) {
+Entry:
+	br label %Loop
+; CHECK: @test5
+; CHECK: Entry:
+; CHECK-NEXT:   load i32* @X
+; CHECK-NEXT:   br label %Loop
+
+
+Loop:		; preds = %Loop, %0
+	%j = phi i32 [ 0, %Entry ], [ %Next, %Loop ]		; <i32> [#uses=1]
+	%x = load i32* @X		; <i32> [#uses=1]
+	%x2 = add i32 %x, 1		; <i32> [#uses=1]
+	store i32 %x2, i32* @X
+        
+        volatile store i32* @X, i32** %P2
+        
+	%Next = add i32 %j, 1		; <i32> [#uses=2]
+	%cond = icmp eq i32 %Next, 0		; <i1> [#uses=1]
+	br i1 %cond, label %Out, label %Loop
+
+Out:	
+	ret void
+; CHECK: Out:
+; CHECK-NEXT:   store i32 %x2, i32* @X
+; CHECK-NEXT:   ret void
+
+}
+
+