1 files changed, 80 insertions, 0 deletions
diff --git a/llvm/test/Transforms/GlobalOpt/global-demotion.ll b/llvm/test/Transforms/GlobalOpt/global-demotion.ll
new file mode 100644
index 00000000000..7965cb89620
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/global-demotion.ll
@@ -0,0 +1,80 @@
+; RUN: opt -globalopt -S < %s | FileCheck %s
+
+@G1 = internal global i32 5
+@G2 = internal global i32 5
+@G3 = internal global i32 5
+@G4 = internal global i32 5
+@G5 = internal global i32 5
+
+; CHECK-LABEL: @test1
+define internal i32 @test1() norecurse {
+; CHECK-NOT: @G1
+  store i32 4, i32* @G1
+  %a = load i32, i32* @G1
+; CHECK: ret
+  ret i32 %a
+}
+
+; The load comes before the store which makes @G2 live before the call.
+; CHECK-LABEL: @test2
+define internal i32 @test2() norecurse {
+; CHECK-NOT: %G2
+  %a = load i32, i32* @G2
+  store i32 4, i32* @G2
+; CHECK: ret
+  ret i32 %a
+}
+
+; This global is indexed by a GEP - this makes it partial alias and we bail out.
+; FIXME: We don't actually have to bail out in this case.
+
+; CHECK-LABEL: @test3
+define internal i32 @test3() norecurse {
+; CHECK-NOT: %G3
+  %x = getelementptr i32,i32* @G3, i32 0
+  %a = load i32, i32* %x
+  store i32 4, i32* @G3
+; CHECK: ret
+  ret i32 %a
+}
+
+; The global is casted away to a larger type then loaded. The store only partially
+; covers the load, so we must not demote.
+
+; CHECK-LABEL: @test4
+define internal i32 @test4() norecurse {
+; CHECK-NOT: %G4
+  store i32 4, i32* @G4
+  %x = bitcast i32* @G4 to i64*
+  %a = load i64, i64* %x
+  %b = trunc i64 %a to i32
+; CHECK: ret
+  ret i32 %b
+}
+
+; The global is casted away to a smaller type then loaded. This one is fine.
+
+; CHECK-LABEL: @test5
+define internal i32 @test5() norecurse {
+; CHECK-NOT: @G5
+  store i32 4, i32* @G5
+  %x = bitcast i32* @G5 to i16*
+  %a = load i16, i16* %x
+  %b = zext i16 %a to i32
+; CHECK: ret
+  ret i32 %b
+}
+
+define i32 @main() norecurse {
+  %a = call i32 @test1()
+  %b = call i32 @test2()
+  %c = call i32 @test3()
+  %d = call i32 @test4()
+  %e = call i32 @test5()
+
+  %x = or i32 %a, %b
+  %y = or i32 %x, %c
+  %z = or i32 %y, %d
+  %w = or i32 %z, %e
+  ret i32 %w
+}