1 files changed, 144 insertions, 0 deletions
diff --git a/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll b/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
new file mode 100644
index 00000000000..3b14aed6eb0
--- /dev/null
+++ b/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
@@ -0,0 +1,144 @@
+; RUN: opt -codegenprepare  < %s  -mtriple=aarch64-none-linux-gnu -S  | FileCheck %s
+
+target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-gnu"
+
+; Expect to skip merging two empty blocks (sw.bb and sw.bb2) into sw.epilog
+; as both of them are unlikely executed.
+define i32 @f_switch(i32 %c)  {
+; CHECK-LABEL: @f_switch
+; CHECK-LABEL: entry:
+; CHECK: i32 10, label %sw.bb
+; CHECK: i32 20, label %sw.bb2
+entry:
+  switch i32 %c, label %sw.default [
+    i32 10, label %sw.bb
+    i32 20, label %sw.bb2
+    i32 30, label %sw.bb3
+    i32 40, label %sw.bb4
+  ], !prof !0
+
+sw.bb:                                            ; preds = %entry
+  br label %sw.epilog
+
+sw.bb2:                                           ; preds = %entry
+  br label %sw.epilog
+
+sw.bb3:                                           ; preds = %entry
+  call void bitcast (void (...)* @callcase3 to void ()*)()
+  br label %sw.epilog
+
+sw.bb4:                                           ; preds = %entry
+  call void bitcast (void (...)* @callcase4 to void ()*)()
+  br label %sw.epilog
+
+sw.default:                                       ; preds = %entry
+  call void bitcast (void (...)* @calldefault to void ()*)()
+  br label %sw.epilog
+
+; CHECK-LABEL: sw.epilog:
+; CHECK: %fp.0 = phi void (...)* [ @FD, %sw.default ], [ @F4, %sw.bb4 ], [ @F3, %sw.bb3 ], [ @F2, %sw.bb2 ], [ @F1, %sw.bb ]
+sw.epilog:                                        ; preds = %sw.default, %sw.bb3, %sw.bb2, %sw.bb
+  %fp.0 = phi void (...)* [ @FD, %sw.default ], [ @F4, %sw.bb4 ], [ @F3, %sw.bb3 ], [ @F2, %sw.bb2 ], [ @F1, %sw.bb ]
+  %callee.knr.cast = bitcast void (...)* %fp.0 to void ()*
+  call void %callee.knr.cast()
+  ret i32 0
+}
+
+; Expect not to merge sw.bb2 because of the conflict in the incoming value from
+; sw.bb which is already merged.
+define i32 @f_switch2(i32 %c)  {
+; CHECK-LABEL: @f_switch2
+; CHECK-LABEL: entry:
+; CHECK: i32 10, label %sw.epilog
+; CHECK: i32 20, label %sw.bb2
+entry:
+  switch i32 %c, label %sw.default [
+    i32 10, label %sw.bb
+    i32 20, label %sw.bb2
+    i32 30, label %sw.bb3
+    i32 40, label %sw.bb4
+  ], !prof !1
+
+sw.bb:                                            ; preds = %entry
+  br label %sw.epilog
+
+sw.bb2:                                           ; preds = %entry
+  br label %sw.epilog
+
+sw.bb3:                                           ; preds = %entry
+  call void bitcast (void (...)* @callcase3 to void ()*)()
+  br label %sw.epilog
+
+sw.bb4:                                           ; preds = %entry
+  call void bitcast (void (...)* @callcase4 to void ()*)()
+  br label %sw.epilog
+
+sw.default:                                       ; preds = %entry
+  call void bitcast (void (...)* @calldefault to void ()*)()
+  br label %sw.epilog
+
+; CHECK-LABEL: sw.epilog:
+; CHECK: %fp.0 = phi void (...)* [ @FD, %sw.default ], [ @F4, %sw.bb4 ], [ @F3, %sw.bb3 ], [ @F2, %sw.bb2 ], [ @F1, %entry ]
+sw.epilog:                                        ; preds = %sw.default, %sw.bb3, %sw.bb2, %sw.bb
+  %fp.0 = phi void (...)* [ @FD, %sw.default ], [ @F4, %sw.bb4 ], [ @F3, %sw.bb3 ], [ @F2, %sw.bb2 ], [ @F1, %sw.bb ]
+  %callee.knr.cast = bitcast void (...)* %fp.0 to void ()*
+  call void %callee.knr.cast()
+  ret i32 0
+}
+
+; Multiple empty blocks should be considered together if all incoming values
+; from them are same.  We expect to merge both empty blocks (sw.bb and sw.bb2)
+; because the sum of frequencies are higer than the threshold.
+define i32 @f_switch3(i32 %c)  {
+; CHECK-LABEL: @f_switch3
+; CHECK-LABEL: entry:
+; CHECK: i32 10, label %sw.epilog
+; CHECK: i32 20, label %sw.epilog
+entry:
+  switch i32 %c, label %sw.default [
+    i32 10, label %sw.bb
+    i32 20, label %sw.bb2
+    i32 30, label %sw.bb3
+    i32 40, label %sw.bb4
+  ], !prof !2
+
+sw.bb:                                            ; preds = %entry
+  br label %sw.epilog
+
+sw.bb2:                                           ; preds = %entry
+  br label %sw.epilog
+
+sw.bb3:                                           ; preds = %entry
+  call void bitcast (void (...)* @callcase3 to void ()*)()
+  br label %sw.epilog
+
+sw.bb4:                                           ; preds = %entry
+  call void bitcast (void (...)* @callcase4 to void ()*)()
+  br label %sw.epilog
+
+sw.default:                                       ; preds = %entry
+  call void bitcast (void (...)* @calldefault to void ()*)()
+  br label %sw.epilog
+
+; CHECK-LABEL: sw.epilog:
+; CHECK: %fp.0 = phi void (...)* [ @FD, %sw.default ], [ @F4, %sw.bb4 ], [ @F3, %sw.bb3 ], [ @F1, %entry ], [ @F1, %entry ]
+sw.epilog:                                        ; preds = %sw.default, %sw.bb3, %sw.bb2, %sw.bb
+  %fp.0 = phi void (...)* [ @FD, %sw.default ], [ @F4, %sw.bb4 ], [ @F3, %sw.bb3 ], [ @F1, %sw.bb2 ], [ @F1, %sw.bb ]
+  %callee.knr.cast = bitcast void (...)* %fp.0 to void ()*
+  call void %callee.knr.cast()
+  ret i32 0
+}
+
+declare void @F1(...) local_unnamed_addr
+declare void @F2(...) local_unnamed_addr
+declare void @F3(...) local_unnamed_addr
+declare void @F4(...) local_unnamed_addr
+declare void @FD(...) local_unnamed_addr
+declare void @callcase3(...) local_unnamed_addr
+declare void @callcase4(...) local_unnamed_addr
+declare void @calldefault(...) local_unnamed_addr
+
+!0 = !{!"branch_weights", i32 5, i32 1, i32 1,i32 5, i32 5}
+!1 = !{!"branch_weights", i32 1 , i32 5, i32 1,i32 1, i32 1}
+!2 = !{!"branch_weights", i32 1 , i32 4, i32 1,i32 1, i32 1}