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

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 46fffccb3ac044b05cacd12312dfc0bbfad46684..6d5b24a01b2647ff794ca8b87cf67c880c9af049 100644 (file)
--- 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 67ad5bc0f4dcb9aa55b7bc8261c25df49f43bc2a..d8acdc1a3ad7594c84b73308a2581765aacf33ef 100644 (file)
--- 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
+
+}
+
+