Imported Upstream version 6.0.0.172

Former-commit-id: f3cc9b82f3e5bd8f0fd3ebc098f789556b44e9cd

external/llvm/test/Transforms/InstCombine/2004-02-23-ShiftShiftOverflow.ll

@@ -0,0 +1,15 @@
+; RUN: opt < %s -instcombine -S | not grep 34
+
+define i32 @test(i32 %X) {
+        ; Do not fold into shr X, 34, as this uses undefined behavior!
+        %Y = ashr i32 %X, 17            ; <i32> [#uses=1]
+        %Z = ashr i32 %Y, 17            ; <i32> [#uses=1]
+        ret i32 %Z
+}
+
+define i32 @test2(i32 %X) {
+        ; Do not fold into shl X, 34, as this uses undefined behavior!
+        %Y = shl i32 %X, 17             ; <i32> [#uses=1]
+        %Z = shl i32 %Y, 17             ; <i32> [#uses=1]
+        ret i32 %Z
+}