1 files changed, 120 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/X86/loop-rotate.ll b/llvm/test/CodeGen/X86/loop-rotate.ll
new file mode 100644
index 00000000000..3f0a390e7c1
--- /dev/null
+++ b/llvm/test/CodeGen/X86/loop-rotate.ll
@@ -0,0 +1,120 @@
+; RUN: llc -mtriple=i686-linux < %s | FileCheck %s
+
+; Don't rotate the loop if the number of fall through to exit is not larger
+; than the number of fall through to header.
+define void @no_rotate() {
+; CHECK-LABEL: no_rotate
+; CHECK: %entry
+; CHECK: %header
+; CHECK: %middle
+; CHECK: %latch1
+; CHECK: %latch2
+; CHECK: %end
+entry:
+  br label %header
+
+header:
+  %val1 = call i1 @foo()
+  br i1 %val1, label %middle, label %end
+
+middle:
+  %val2 = call i1 @foo()
+  br i1 %val2, label %latch1, label %end
+
+latch1:
+  %val3 = call i1 @foo()
+  br i1 %val3, label %latch2, label %header
+
+latch2:
+  %val4 = call i1 @foo()
+  br label %header
+
+end:
+  ret void
+}
+
+define void @do_rotate() {
+; CHECK-LABEL: do_rotate
+; CHECK: %entry
+; CHECK: %then
+; CHECK: %else
+; CHECK: %latch1
+; CHECK: %latch2
+; CHECK: %header
+; CHECK: %end
+entry:
+  %val0 = call i1 @foo()
+  br i1 %val0, label %then, label %else
+
+then:
+  call void @a()
+  br label %header
+
+else:
+  call void @b()
+  br label %header
+
+header:
+  %val1 = call i1 @foo()
+  br i1 %val1, label %latch1, label %end
+
+latch1:
+  %val3 = call i1 @foo()
+  br i1 %val3, label %latch2, label %header
+
+latch2:
+  %val4 = call i1 @foo()
+  br label %header
+
+end:
+  ret void
+}
+
+; The loop structure is same as in @no_rotate, but the loop header's predecessor
+; doesn't fall through to it, so it should be rotated to get exit fall through.
+define void @do_rotate2() {
+; CHECK-LABEL: do_rotate2
+; CHECK: %entry
+; CHECK: %then
+; CHECK: %middle
+; CHECK: %latch1
+; CHECK: %latch2
+; CHECK: %header
+; CHECK: %exit
+entry:
+  %val0 = call i1 @foo()
+  br i1 %val0, label %then, label %header, !prof !1
+
+then:
+  call void @a()
+  br label %end
+
+header:
+  %val1 = call i1 @foo()
+  br i1 %val1, label %middle, label %exit
+
+middle:
+  %val2 = call i1 @foo()
+  br i1 %val2, label %latch1, label %exit
+
+latch1:
+  %val3 = call i1 @foo()
+  br i1 %val3, label %latch2, label %header
+
+latch2:
+  %val4 = call i1 @foo()
+  br label %header
+
+exit:
+  call void @b()
+  br label %end
+
+end:
+  ret void
+}
+
+declare i1 @foo()
+declare void @a()
+declare void @b()
+
+!1 = !{!"branch_weights", i32 10, i32 1}