Update dom tree. Fix PR 2372.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@51887 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopUnswitch.cpp b/lib/Transforms/Scalar/LoopUnswitch.cpp
index 767ea1d..e0fb4c6 100644
--- a/lib/Transforms/Scalar/LoopUnswitch.cpp
+++ b/lib/Transforms/Scalar/LoopUnswitch.cpp
@@ -569,7 +569,6 @@
 
   // Insert the new branch.
   BranchInst::Create(TrueDest, FalseDest, BranchVal, InsertPt);
-
 }
 
 
@@ -607,6 +606,10 @@
   // insert the new conditional branch.
   EmitPreheaderBranchOnCondition(Cond, Val, NewExit, NewPH, 
                                  OrigPH->getTerminator());
+  if (DT) {
+    DT->changeImmediateDominator(NewExit, OrigPH);
+    DT->changeImmediateDominator(NewPH, OrigPH);
+  }
   LPM->deleteSimpleAnalysisValue(OrigPH->getTerminator(), L);
   OrigPH->getTerminator()->eraseFromParent();
 
diff --git a/test/Transforms/LoopUnswitch/2008-06-02-DomInfo.ll b/test/Transforms/LoopUnswitch/2008-06-02-DomInfo.ll
new file mode 100644
index 0000000..dcf41c3
--- /dev/null
+++ b/test/Transforms/LoopUnswitch/2008-06-02-DomInfo.ll
@@ -0,0 +1,26 @@
+; RUN: llvm-as < %s | opt -loop-unswitch -instcombine -gvn -disable-output
+; PR2372
+target triple = "i386-pc-linux-gnu"
+
+define i32 @func_3(i16 signext  %p_5, i16 signext  %p_6) nounwind  {
+entry:
+	%tmp3 = icmp eq i16 %p_5, 0		; <i1> [#uses=1]
+	%tmp1314 = sext i16 %p_6 to i32		; <i32> [#uses=1]
+	%tmp28 = icmp ugt i32 %tmp1314, 3		; <i1> [#uses=1]
+	%bothcond = or i1 %tmp28, false		; <i1> [#uses=1]
+	br label %bb
+bb:		; preds = %bb54, %entry
+	br i1 %tmp3, label %bb54, label %bb5
+bb5:		; preds = %bb
+	br i1 %bothcond, label %bb54, label %bb31
+bb31:		; preds = %bb5
+	br label %bb54
+bb54:		; preds = %bb31, %bb5, %bb
+	br i1 false, label %bb64, label %bb
+bb64:		; preds = %bb54
+	%tmp6566 = sext i16 %p_6 to i32		; <i32> [#uses=1]
+	%tmp68 = tail call i32 (...)* @func_18( i32 1, i32 %tmp6566, i32 1 ) nounwind 		; <i32> [#uses=0]
+	ret i32 undef
+}
+
+declare i32 @func_18(...)