Revert "[CGP] Merge empty case blocks if no extra moves are added."

This reverts commit r316711. The domtree isn't getting updated correctly.

llvm-svn: 316721
diff --git a/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll b/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
index b062e5f..194c86b 100644
--- a/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
+++ b/llvm/test/Transforms/CodeGenPrepare/skip-merging-case-block.ll
@@ -143,107 +143,11 @@
 !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}
 
-; while.cond does not dominate return, expect to skip merging empty block
-; return.loopexit into return.
-@b = external global i32, align 4
-@a = external global i32*, align 8
-
-define void @f_switch4(i32 %i) local_unnamed_addr personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
-; CHECK-LABEL: @f_switch4
-entry:
-  %0 = load i32, i32* @b, align 4
-  %cond = icmp eq i32 %0, 6
-  br i1 %cond, label %return, label %if.end
-
-if.end:                                           ; preds = %entry
-  %add = add i32 %i, 2
-  %1 = load i32*, i32** @a, align 8
-  %magicptr = ptrtoint i32* %1 to i32
-  br label %while.cond
-
-; CHECK-LABEL: while.cond:
-; CHECK: i32 0, label %return.loopexit
-; CHECK: i32 47, label %return.loopexit
-while.cond:                                       ; preds = %while.cond.backedge, %if.end
-  switch i32 %magicptr, label %while.cond.if.end10_crit_edge [
-    i32 0, label %return.loopexit
-    i32 47, label %return.loopexit
-  ]
-
-while.cond.if.end10_crit_edge:                    ; preds = %while.cond
-  br label %while.cond.backedge
-
-while.cond.backedge:                              ; preds = %while.cond.if.end10_crit_edge, %if.then9
-  br label %while.cond
-
-return.loopexit:                                  ; preds = %while.cond
-  br label %return
-
-; CHECK_LABEL: return:
-; CHECK: %{{.*}} = phi i32 [ 0, %entry ], [ %add, %return.loopexit ]
-return:                                           ; preds = %return.loopexit, %entry
-  %retval.4 = phi i32 [ 0, %entry ], [ %add, %return.loopexit ]
-  ret void
-}
-declare i32 @__gxx_personality_v0(...)
-
-; Expect to merge empty block while.cond2.loopexit into while.cond2
-define i32 @f_switch5(i32 %i) local_unnamed_addr {
-; CHECK-LABEL: @f_switch5
-entry:
-  %0 = load i32, i32* @b, align 4
-  %cond = icmp eq i32 %0, 6
-  br i1 %cond, label %while.cond.preheader, label %sw.epilog
-
-while.cond.preheader:                             ; preds = %entry
-  %1 = load i32*, i32** @a, align 8
-  %magicptr = ptrtoint i32* %1 to i64
-  %arrayidx = getelementptr inbounds i32, i32* %1, i64 1
-  br label %while.cond
-
-; CHECK-LABEL: while.cond:
-; CHECK: i64 32, label %while.cond2
-; CHECK: i64 0, label %while.cond2
-while.cond:                                       ; preds = %land.rhs, %while.cond.preheader
-  switch i64 %magicptr, label %land.rhs [
-    i64 32, label %while.cond2.loopexit
-    i64 0, label %while.cond2.loopexit
-  ]
-
-land.rhs:                                         ; preds = %while.cond
-  %2 = load i32, i32* %arrayidx, align 4
-  %tobool1 = icmp eq i32 %2, 0
-  br i1 %tobool1, label %while.cond2thread-pre-split.loopexit, label %while.cond
-
-while.cond2thread-pre-split.loopexit:             ; preds = %land.rhs
-  br label %while.cond2thread-pre-split
-
-while.cond2thread-pre-split:                      ; preds = %while.body4, %while.cond2thread-pre-split.loopexit
-  %.pr = phi i32* [ %.pr.pre, %while.body4 ], [ %1, %while.cond2thread-pre-split.loopexit ]
-  br label %while.cond2
-
-while.cond2.loopexit:                             ; preds = %while.cond, %while.cond
-  br label %while.cond2
-
-; CHECK-LABEL: while.cond2:
-; CHECK: %{{.*}} = phi i32* [ %.pr.pre, %while.body4 ], [ %1, %land.rhs ], [ %1, %while.cond ], [ %1, %while.cond ]
-while.cond2:                                      ; preds = %while.cond2.loopexit, %while.cond2thread-pre-split
-  %3 = phi i32* [ %.pr, %while.cond2thread-pre-split ], [ %1, %while.cond2.loopexit ]
-  %tobool3 = icmp eq i32* %3, null
-  br i1 %tobool3, label %sw.epilog, label %while.body4
-
-while.body4:                                      ; preds = %while.cond2
-  tail call void bitcast (void (...)* @fn2 to void ()*)()
-  %.pr.pre = load i32*, i32** @a, align 8
-  br label %while.cond2thread-pre-split
-
-sw.epilog:                                        ; preds = %while.cond2, %entry
-  ret i32 undef
-}
-
 
 ; This test that BFI/BPI is created without any assertion in isMergingEmptyBlockProfitable()
 ; in the case where empty blocks are removed before creating BFI/BPI.
+@b = common global i32 0, align 4
+@a = common global i32* null, align 8
 define i32 @should_not_assert(i32 %i) local_unnamed_addr {
 entry:
   %0 = load i32, i32* @b, align 4