1 files changed, 34 insertions, 0 deletions
diff --git a/llvm/test/Transforms/InstCombine/prefetch-load.ll b/llvm/test/Transforms/InstCombine/prefetch-load.ll
new file mode 100644
index 00000000000..f98b7ae00bf
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/prefetch-load.ll
@@ -0,0 +1,34 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+%struct.C = type { %struct.C*, i32 }
+
+; Check that we instcombine the load across the prefetch.
+
+; CHECK-LABEL: define signext i32 @foo
+define signext i32 @foo(%struct.C* %c) local_unnamed_addr #0 {
+; CHECK: store i32 %dec, i32* %length_
+; CHECK-NOT: load
+; CHECK: llvm.prefetch
+; CHECK-NEXT: ret
+entry:
+  %next_ = getelementptr inbounds %struct.C, %struct.C* %c, i32 0, i32 0
+  %0 = load %struct.C*, %struct.C** %next_, align 8
+  %next_1 = getelementptr inbounds %struct.C, %struct.C* %0, i32 0, i32 0
+  %1 = load %struct.C*, %struct.C** %next_1, align 8
+  store %struct.C* %1, %struct.C** %next_, align 8
+  %length_ = getelementptr inbounds %struct.C, %struct.C* %c, i32 0, i32 1
+  %2 = load i32, i32* %length_, align 8
+  %dec = add nsw i32 %2, -1
+  store i32 %dec, i32* %length_, align 8
+  %3 = bitcast %struct.C* %1 to i8*
+  call void @llvm.prefetch(i8* %3, i32 0, i32 0, i32 1)
+  %4 = load i32, i32* %length_, align 8
+  ret i32 %4
+}
+
+; Function Attrs: inaccessiblemem_or_argmemonly nounwind
+declare void @llvm.prefetch(i8* nocapture readonly, i32, i32, i32) 
+
+attributes #0 = { noinline nounwind }
+; We've explicitly removed the function attrs from llvm.prefetch so we get the defaults.
+; attributes #1 = { inaccessiblemem_or_argmemonly nounwind }