[DDG] Data Dependence Graph - Topological Sort

Summary:
In this patch the DDG DAG is sorted topologically to put the
nodes in the graph in the order that would satisfy all
dependencies. This helps transformations that would like to
generate code based on the DDG. Since the DDG is a DAG a
reverse-post-order traversal would give us the topological
ordering. This patch also sorts the basic blocks passed to
the builder based on program order to ensure that the
dependencies are computed in the correct direction.

Authored By: bmahjour

Reviewer: Meinersbur, fhahn, myhsu, xtian, dmgreen, kbarton, jdoerfert

Reviewed By: Meinersbur

Subscribers: ychen, arphaman, simoll, a.elovikov, mgorny, hiraditya, jfb, wuzish, llvm-commits, jsji, Whitney, etiotto, ppc-slack

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70609

4 files changed, 356 insertions, 349 deletions

diff --git a/llvm/test/Analysis/DDG/basic-a.ll b/llvm/test/Analysis/DDG/basic-a.ll
index 920e71f6717..a52e8c258f5 100644
--- a/llvm/test/Analysis/DDG/basic-a.ll
+++ b/llvm/test/Analysis/DDG/basic-a.ll
@@ -1,7 +1,44 @@
 ; RUN: opt < %s -disable-output "-passes=print<ddg>" 2>&1 | FileCheck %s
 
 ; CHECK-LABEL: 'DDG' for loop 'test1.for.body':
-; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
+
+; CHECK: Node Address:[[PI:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT: --- start of nodes in pi-block ---
+; CHECK-NEXT: Node Address:[[N10:0x[0-9a-f]*]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %inc = add i64 %i.02, 1
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N11:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N11]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test1.for.body ], [ 0, %test1.for.body.preheader ]
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N10]]
+; CHECK-NEXT: --- end of nodes in pi-block ---
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N1:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N7]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %exitcond = icmp ne i64 %inc, %n
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N8]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    br i1 %exitcond, label %test1.for.body, label %for.end.loopexit
+; CHECK-NEXT: Edges:none!
+
+; CHECK: Node Address:[[N6]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %arrayidx1 = getelementptr inbounds float, float* %a, i64 %i.02
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N5:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N1]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
 ; CHECK-NEXT: Edges:
@@ -23,12 +60,6 @@
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %add = fadd float %0, %conv
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N5:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N6:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx1 = getelementptr inbounds float, float* %a, i64 %i.02
-; CHECK-NEXT: Edges:
 ; CHECK-NEXT:  [def-use] to [[N5]]
 
 ; CHECK: Node Address:[[N5]]:single-instruction
@@ -36,36 +67,6 @@
 ; CHECK-NEXT:    store float %add, float* %arrayidx1, align 4
 ; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N7:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %exitcond = icmp ne i64 %inc, %n
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N8]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %exitcond, label %test1.for.body, label %for.end.loopexit
-; CHECK-NEXT: Edges:none!
-
-; CHECK: Node Address:[[N9:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT: --- start of nodes in pi-block ---
-; CHECK-NEXT: Node Address:[[N10:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc = add i64 %i.02, 1
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N11:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N11]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test1.for.body ], [ 0, %test1.for.body.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N10]]
-; CHECK-NEXT: --- end of nodes in pi-block ---
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N1]]
-; CHECK-NEXT:  [def-use] to [[N6]]
-; CHECK-NEXT:  [def-use] to [[N7]]
-
 
 ;; No memory dependencies.
 ;; void test1(unsigned long n, float * restrict a, float * restrict b) {
@@ -96,78 +97,80 @@ for.end:                                          ; preds = %test1.for.body, %en
 
 
 ; CHECK-LABEL: 'DDG' for loop 'test2.for.body':
-; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N2]]:single-instruction
+; CHECK: Node Address:[[PI:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT: --- start of nodes in pi-block ---
+; CHECK: Node Address:[[N11:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %0 = load float, float* %arrayidx, align 4
+; CHECK-NEXT:    %inc = add i64 %i.02, 1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N12:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N4:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N12]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx1 = getelementptr inbounds float, float* %a, i64 %i.02
+; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test2.for.body ], [ 0, %test2.for.body.preheader ]
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N5:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N11]]
+; CHECK-NEXT: --- end of nodes in pi-block ---
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N1:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N5]]:single-instruction
+; CHECK: Node Address:[[N8]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %1 = load float, float* %arrayidx1, align 4
+; CHECK-NEXT:    %exitcond = icmp ne i64 %inc, %n
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N3]]
-; CHECK-NEXT:  [memory] to [[N6:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N3]]:single-instruction
+; CHECK: Node Address:[[N9]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %add = fadd float %0, %1
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N6]]
+; CHECK-NEXT:    br i1 %exitcond, label %test2.for.body, label %for.end.loopexit
+; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N7:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N7]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %arrayidx2 = getelementptr inbounds float, float* %a, i64 %i.02
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N6]]
+; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N6]]:single-instruction
+; CHECK: Node Address:[[N4]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    store float %add, float* %arrayidx2, align 4
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %arrayidx1 = getelementptr inbounds float, float* %a, i64 %i.02
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N5:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N8:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N5]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %exitcond = icmp ne i64 %inc, %n
+; CHECK-NEXT:    %1 = load float, float* %arrayidx1, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
+; CHECK-NEXT:  [memory] to [[N6]]
 
-; CHECK: Node Address:[[N9]]:single-instruction
+; CHECK: Node Address:[[N1]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %exitcond, label %test2.for.body, label %for.end.loopexit
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N10:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT: --- start of nodes in pi-block ---
-; CHECK: Node Address:[[N11:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N2]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc = add i64 %i.02, 1
+; CHECK-NEXT:    %0 = load float, float* %arrayidx, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N12:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N3]]
 
-; CHECK: Node Address:[[N12]]:single-instruction
+; CHECK: Node Address:[[N3]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test2.for.body ], [ 0, %test2.for.body.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N11]]
-; CHECK-NEXT: --- end of nodes in pi-block ---
+; CHECK-NEXT:    %add = fadd float %0, %1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N1]]
-; CHECK-NEXT:  [def-use] to [[N4]]
-; CHECK-NEXT:  [def-use] to [[N7]]
-; CHECK-NEXT:  [def-use] to [[N8]]
+; CHECK-NEXT:  [def-use] to [[N6]]
+
+; CHECK: Node Address:[[N6]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    store float %add, float* %arrayidx2, align 4
+; CHECK-NEXT: Edges:none!
+
 
 
 ;; Loop-independent memory dependencies.
diff --git a/llvm/test/Analysis/DDG/basic-b.ll b/llvm/test/Analysis/DDG/basic-b.ll
index f83f7fe92f3..757c706193a 100644
--- a/llvm/test/Analysis/DDG/basic-b.ll
+++ b/llvm/test/Analysis/DDG/basic-b.ll
@@ -1,19 +1,45 @@
 ; RUN: opt < %s -disable-output "-passes=print<ddg>" 2>&1 | FileCheck %s
 
 ; CHECK-LABEL: 'DDG' for loop 'test1.for.body':
-; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
+
+; CHECK: Node Address:[[N9:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT:--- start of nodes in pi-block ---
+; CHECK: Node Address:[[N13:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
+; CHECK-NEXT:    %inc = add i64 %i.02, 1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N14:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N2]]:single-instruction
+; CHECK: Node Address:[[N14]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %0 = load float, float* %arrayidx, align 4
+; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test1.for.body ], [ 1, %test1.for.body.preheader ]
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N13]]
+; CHECK-NEXT:--- end of nodes in pi-block ---
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N1:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N7]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %cmp = icmp ult i64 %inc, %sub
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N8]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    br i1 %cmp, label %test1.for.body, label %for.end.loopexit
+; CHECK-NEXT: Edges:none!
+
+; CHECK: Node Address:[[N6]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %arrayidx3 = getelementptr inbounds float, float* %a, i64 %i.02
 ; CHECK-NEXT: Edges:
 ; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N4:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N4]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %sub1 = add i64 %i.02, -1
 ; CHECK-NEXT: Edges:
@@ -25,22 +51,17 @@
 ; CHECK-NEXT: Edges:
 ; CHECK-NEXT:  [def-use] to [[N3]]
 
-; CHECK: Node Address:[[N6:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N1]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx3 = getelementptr inbounds float, float* %a, i64 %i.02
+; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N3]]
+; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N7:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N2]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %cmp = icmp ult i64 %inc, %sub
+; CHECK-NEXT:    %0 = load float, float* %arrayidx, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N8]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %cmp, label %test1.for.body, label %for.end.loopexit
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:  [def-use] to [[N3]]
 
 ; CHECK: Node Address:[[N3]]:pi-block
 ; CHECK-NEXT: --- start of nodes in pi-block ---
@@ -64,25 +85,6 @@
 ; CHECK-NEXT:--- end of nodes in pi-block ---
 ; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N9:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT:--- start of nodes in pi-block ---
-; CHECK: Node Address:[[N13:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc = add i64 %i.02, 1
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N14:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N14]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test1.for.body ], [ 1, %test1.for.body.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N13]]
-; CHECK-NEXT:--- end of nodes in pi-block ---
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N1]]
-; CHECK-NEXT:  [def-use] to [[N4]]
-; CHECK-NEXT:  [def-use] to [[N6]]
-; CHECK-NEXT:  [def-use] to [[N7]]
 
 
 ;; Loop-carried dependence requiring edge-reversal to expose a cycle
@@ -117,19 +119,45 @@ for.end:                                          ; preds = %test1.for.body, %en
 }
 
 ; CHECK-LABEL: 'DDG' for loop 'test2.for.body':
-; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
+
+; CHECK: Node Address:[[N11:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT:--- start of nodes in pi-block ---
+; CHECK: Node Address:[[N12:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
+; CHECK-NEXT:    %inc = add i64 %i.02, 1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N13:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N2]]:single-instruction
+; CHECK: Node Address:[[N13]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %0 = load float, float* %arrayidx, align 4
+; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test2.for.body ], [ 1, %test2.for.body.preheader ]
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N12]]
+; CHECK-NEXT:--- end of nodes in pi-block ---
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N1:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N9]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %cmp = icmp ult i64 %inc, %sub
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N10:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N10]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    br i1 %cmp, label %test2.for.body, label %for.end.loopexit
+; CHECK-NEXT: Edges:none!
+
+; CHECK: Node Address:[[N8]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %arrayidx3 = getelementptr inbounds float, float* %a, i64 %i.02
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N4:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N4]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %add1 = add i64 %i.02, 1
 ; CHECK-NEXT: Edges:
@@ -145,57 +173,33 @@ for.end:                                          ; preds = %test1.for.body, %en
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %1 = load float, float* %arrayidx2, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N3]]
-; CHECK-NEXT:  [memory] to [[N7:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
+; CHECK-NEXT:  [memory] to [[N7]]
 
-; CHECK: Node Address:[[N3]]:single-instruction
+; CHECK: Node Address:[[N1]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %add = fadd float %0, %1
+; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %i.02
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N7]]
+; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N8:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N2]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx3 = getelementptr inbounds float, float* %a, i64 %i.02
+; CHECK-NEXT:    %0 = load float, float* %arrayidx, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N7]]
+; CHECK-NEXT:  [def-use] to [[N3]]
 
-; CHECK: Node Address:[[N7]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    store float %add, float* %arrayidx3, align 4
-; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N9:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N3]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %cmp = icmp ult i64 %inc, %sub
+; CHECK-NEXT:    %add = fadd float %0, %1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N10:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N7]]
 
-; CHECK: Node Address:[[N10]]:single-instruction
+; CHECK: Node Address:[[N7]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %cmp, label %test2.for.body, label %for.end.loopexit
+; CHECK-NEXT:    store float %add, float* %arrayidx3, align 4
 ; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N11:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT:--- start of nodes in pi-block ---
-; CHECK: Node Address:[[N12:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc = add i64 %i.02, 1
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N13:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N13]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %i.02 = phi i64 [ %inc, %test2.for.body ], [ 1, %test2.for.body.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N12]]
-; CHECK-NEXT:--- end of nodes in pi-block ---
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N1]]
-; CHECK-NEXT:  [def-use] to [[N4]]
-; CHECK-NEXT:  [def-use] to [[N8]]
-; CHECK-NEXT:  [def-use] to [[N9]]
-
 
 ;; Forward loop-carried dependence *not* causing a cycle.
 ;; void test2(unsigned long n, float * restrict a, float * restrict b) {
diff --git a/llvm/test/Analysis/DDG/basic-loopnest.ll b/llvm/test/Analysis/DDG/basic-loopnest.ll
index aded488ef23..41c2cbbdc7a 100644
--- a/llvm/test/Analysis/DDG/basic-loopnest.ll
+++ b/llvm/test/Analysis/DDG/basic-loopnest.ll
@@ -2,73 +2,65 @@
 
 
 ; CHECK-LABEL: 'DDG' for loop 'test1.for.cond1.preheader':
-; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %sub = add i64 %n, -1
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
-; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N3]]:single-instruction
+; CHECK: Node Address:[[N28:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT:--- start of nodes in pi-block ---
+; CHECK: Node Address:[[N29:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %cmp21 = icmp ult i64 1, %sub
+; CHECK-NEXT:    %inc = add i64 %j.02, 1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N4]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %cmp21, label %for.body4.preheader, label %for.inc12
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:  [def-use] to [[N30:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N5:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N30]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %0 = mul nsw i64 %i.04, %n
+; CHECK-NEXT:    %j.02 = phi i64 [ %inc, %for.body4 ], [ 1, %for.body4.preheader ]
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N6]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %0
+; CHECK-NEXT:  [def-use] to [[N29]]
+; CHECK-NEXT:--- end of nodes in pi-block ---
 ; CHECK-NEXT: Edges:
 ; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N13:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N16:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N7]]:single-instruction
+; CHECK: Node Address:[[N13]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx5 = getelementptr inbounds float, float* %arrayidx, i64 %j.02
+; CHECK-NEXT:    %sub7 = add i64 %j.02, -1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N12:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N8]]:single-instruction
+; CHECK: Node Address:[[N25:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT:--- start of nodes in pi-block ---
+; CHECK: Node Address:[[N26:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %1 = load float, float* %arrayidx5, align 4
+; CHECK-NEXT:    %inc13 = add i64 %i.04, 1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N27:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N10:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N27]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %2 = mul nsw i64 %i.04, %n
+; CHECK-NEXT:    %i.04 = phi i64 [ %inc13, %for.inc12 ], [ 0, %test1.for.cond1.preheader.preheader ]
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N11:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N11]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx6 = getelementptr inbounds float, float* %a, i64 %2
+; CHECK-NEXT:  [def-use] to [[N26]]
+; CHECK-NEXT:--- end of nodes in pi-block ---
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N12:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N5:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N10:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N14:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N18:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N13:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N18]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %sub7 = add i64 %j.02, -1
+; CHECK-NEXT:    %exitcond = icmp ne i64 %inc13, %n
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N12]]
+; CHECK-NEXT:  [def-use] to [[N19:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N12]]:single-instruction
+; CHECK: Node Address:[[N19]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx8 = getelementptr inbounds float, float* %arrayidx6, i64 %sub7
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N9]]
+; CHECK-NEXT:    br i1 %exitcond, label %test1.for.cond1.preheader, label %for.end14.loopexit
+; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N14:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N14]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %4 = mul nsw i64 %i.04, %n
 ; CHECK-NEXT: Edges:
@@ -78,45 +70,55 @@
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %arrayidx10 = getelementptr inbounds float, float* %a, i64 %4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N16:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N16]]
 
 ; CHECK: Node Address:[[N16]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %arrayidx11 = getelementptr inbounds float, float* %arrayidx10, i64 %j.02
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N9]]
+; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N2]]:single-instruction
+; CHECK: Node Address:[[N10]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %cmp2 = icmp ult i64 %inc, %sub
+; CHECK-NEXT:    %2 = mul nsw i64 %i.04, %n
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N17:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N11:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N17]]:single-instruction
+; CHECK: Node Address:[[N11]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %cmp2, label %for.body4, label %for.inc12.loopexit
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %arrayidx6 = getelementptr inbounds float, float* %a, i64 %2
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N12]]
 
-; CHECK: Node Address:[[N18:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N12]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %exitcond = icmp ne i64 %inc13, %n
+; CHECK-NEXT:    %arrayidx8 = getelementptr inbounds float, float* %arrayidx6, i64 %sub7
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N19:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N9]]
 
-; CHECK: Node Address:[[N19]]:single-instruction
+; CHECK: Node Address:[[N5]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %exitcond, label %test1.for.cond1.preheader, label %for.end14.loopexit
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %0 = mul nsw i64 %i.04, %n
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N20:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N6]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br label %for.body4
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %0
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N7]]
 
-; CHECK: Node Address:[[N21:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N7]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br label %for.inc12
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %arrayidx5 = getelementptr inbounds float, float* %arrayidx, i64 %j.02
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N8]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %1 = load float, float* %arrayidx5, align 4
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N9]]
 
 ; CHECK: Node Address:[[N9]]:pi-block
 ; CHECK-NEXT:--- start of nodes in pi-block ---
@@ -140,46 +142,44 @@
 ; CHECK-NEXT:--- end of nodes in pi-block ---
 ; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N25:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT:--- start of nodes in pi-block ---
-; CHECK: Node Address:[[N26:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N21:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc13 = add i64 %i.04, 1
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N27:0x[0-9a-f]*]]
+; CHECK-NEXT:    br label %for.inc12
+; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N27]]:single-instruction
+; CHECK: Node Address:[[N20:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %i.04 = phi i64 [ %inc13, %for.inc12 ], [ 0, %test1.for.cond1.preheader.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N26]]
-; CHECK-NEXT:--- end of nodes in pi-block ---
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N5]]
-; CHECK-NEXT:  [def-use] to [[N10]]
-; CHECK-NEXT:  [def-use] to [[N14]]
-; CHECK-NEXT:  [def-use] to [[N18]]
+; CHECK-NEXT:    br label %for.body4
+; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N28:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT:--- start of nodes in pi-block ---
-; CHECK: Node Address:[[N29:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc = add i64 %j.02, 1
+; CHECK-NEXT:    %sub = add i64 %n, -1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N30:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N2]]
+; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N30]]:single-instruction
+; CHECK: Node Address:[[N3]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %j.02 = phi i64 [ %inc, %for.body4 ], [ 1, %for.body4.preheader ]
+; CHECK-NEXT:    %cmp21 = icmp ult i64 1, %sub
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N29]]
-; CHECK-NEXT:--- end of nodes in pi-block ---
+; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N4]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    br i1 %cmp21, label %for.body4.preheader, label %for.inc12
+; CHECK-NEXT: Edges:none!
+
+; CHECK: Node Address:[[N2]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %cmp2 = icmp ult i64 %inc, %sub
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N7]]
-; CHECK-NEXT:  [def-use] to [[N13]]
-; CHECK-NEXT:  [def-use] to [[N16]]
-; CHECK-NEXT:  [def-use] to [[N2]]
+; CHECK-NEXT:  [def-use] to [[N17:0x[0-9a-f]*]]
 
+; CHECK: Node Address:[[N17]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    br i1 %cmp2, label %for.body4, label %for.inc12.loopexit
+; CHECK-NEXT: Edges:none!
 
 
 ;; This test has a cycle.
@@ -232,49 +232,83 @@ for.end14:                                        ; preds = %for.inc12, %entry
 
 
 ; CHECK-LABEL: 'DDG' for loop 'test2.for.cond1.preheader':
-; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
+
+; CHECK: Node Address:[[PI1:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT:--- start of nodes in pi-block ---
+; CHECK: Node Address:[[N28:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %sub = add i64 %n, -1
+; CHECK-NEXT:    %inc = add i64 %j.02, 1
 ; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N29:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N29]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %j.02 = phi i64 [ %inc, %for.body4 ], [ 1, %for.body4.preheader ]
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N28]]
+; CHECK-NEXT:--- end of nodes in pi-block ---
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N13:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N18:0x[0-9a-f]*]]
 ; CHECK-NEXT:  [def-use] to [[N2:0x[0-9a-f]*]]
-; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N3]]:single-instruction
+; CHECK: Node Address:[[N13]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %cmp21 = icmp ult i64 1, %sub
+; CHECK-NEXT:    %add7 = add i64 %j.02, 1
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N12:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N4]]:single-instruction
+; CHECK: Node Address:[[N24:0x[0-9a-f]*]]:pi-block
+; CHECK-NEXT:--- start of nodes in pi-block ---
+; CHECK: Node Address:[[N25:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %cmp21, label %for.body4.preheader, label %for.inc12
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %inc13 = add i64 %i.04, 1
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N26:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N5:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N26]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %0 = mul nsw i64 %i.04, %n
+; CHECK-NEXT:    %i.04 = phi i64 [ %inc13, %for.inc12 ], [ 0, %test2.for.cond1.preheader.preheader ]
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N25]]
+; CHECK-NEXT:--- end of nodes in pi-block ---
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N5:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N10:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N16:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N20:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N6]]:single-instruction
+; CHECK: Node Address:[[N20]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %0
+; CHECK-NEXT:    %exitcond = icmp ne i64 %inc13, %n
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N7:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N21:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N7]]:single-instruction
+; CHECK: Node Address:[[N21]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx5 = getelementptr inbounds float, float* %arrayidx, i64 %j.02
+; CHECK-NEXT:    br i1 %exitcond, label %test2.for.cond1.preheader, label %for.end14.loopexit
+; CHECK-NEXT: Edges:none!
+
+; CHECK: Node Address:[[N16]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %4 = mul nsw i64 %i.04, %n
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N17:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N8]]:single-instruction
+; CHECK: Node Address:[[N17]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %1 = load float, float* %arrayidx5, align 4
+; CHECK-NEXT:    %arrayidx10 = getelementptr inbounds float, float* %a, i64 %4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N18]]
 
-; CHECK: Node Address:[[N10:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N18]]:single-instruction
+; CHECK-NEXT: Instructions:
+; CHECK-NEXT:    %arrayidx11 = getelementptr inbounds float, float* %arrayidx10, i64 %j.02
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N15:0x[0-9a-f]*]]
+
+; CHECK: Node Address:[[N10]]:single-instruction
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %2 = mul nsw i64 %i.04, %n
 ; CHECK-NEXT: Edges:
@@ -284,12 +318,6 @@ for.end14:                                        ; preds = %for.inc12, %entry
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %arrayidx6 = getelementptr inbounds float, float* %a, i64 %2
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N12:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N13:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %add7 = add i64 %j.02, 1
-; CHECK-NEXT: Edges:
 ; CHECK-NEXT:  [def-use] to [[N12]]
 
 ; CHECK: Node Address:[[N12]]:single-instruction
@@ -302,58 +330,47 @@ for.end14:                                        ; preds = %for.inc12, %entry
 ; CHECK-NEXT: Instructions:
 ; CHECK-NEXT:    %3 = load float, float* %arrayidx8, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N9]]
-; CHECK-NEXT:  [memory] to [[N15:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N9:0x[0-9a-f]*]]
+; CHECK-NEXT:  [memory] to [[N15]]
 
-; CHECK: Node Address:[[N9]]:single-instruction
+; CHECK: Node Address:[[N5]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %add = fadd float %1, %3
+; CHECK-NEXT:    %0 = mul nsw i64 %i.04, %n
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N15]]
+; CHECK-NEXT:  [def-use] to [[N6:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N16:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N6]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %4 = mul nsw i64 %i.04, %n
+; CHECK-NEXT:    %arrayidx = getelementptr inbounds float, float* %b, i64 %0
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N17:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N7]]
 
-; CHECK: Node Address:[[N17]]:single-instruction
+; CHECK: Node Address:[[N7]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx10 = getelementptr inbounds float, float* %a, i64 %4
+; CHECK-NEXT:    %arrayidx5 = getelementptr inbounds float, float* %arrayidx, i64 %j.02
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N18:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N8:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N18]]:single-instruction
+; CHECK: Node Address:[[N8]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %arrayidx11 = getelementptr inbounds float, float* %arrayidx10, i64 %j.02
+; CHECK-NEXT:    %1 = load float, float* %arrayidx5, align 4
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N15]]
-
-; CHECK: Node Address:[[N15]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    store float %add, float* %arrayidx11, align 4
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:  [def-use] to [[N9]]
 
-; CHECK: Node Address:[[N2]]:single-instruction
+; CHECK: Node Address:[[N9]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %cmp2 = icmp ult i64 %inc, %sub
+; CHECK-NEXT:    %add = fadd float %1, %3
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N19:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N15]]
 
-; CHECK: Node Address:[[N19]]:single-instruction
+; CHECK: Node Address:[[N15]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %cmp2, label %for.body4, label %for.inc12.loopexit
+; CHECK-NEXT:    store float %add, float* %arrayidx11, align 4
 ; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N20:0x[0-9a-f]*]]:single-instruction
-; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %exitcond = icmp ne i64 %inc13, %n
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N21:0x[0-9a-f]*]]
-
-; CHECK: Node Address:[[N21]]:single-instruction
+; CHECK: Node Address:[[N23:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br i1 %exitcond, label %test2.for.cond1.preheader, label %for.end14.loopexit
+; CHECK-NEXT:    br label %for.inc12
 ; CHECK-NEXT: Edges:none!
 
 ; CHECK: Node Address:[[N22:0x[0-9a-f]*]]:single-instruction
@@ -361,50 +378,34 @@ for.end14:                                        ; preds = %for.inc12, %entry
 ; CHECK-NEXT:    br label %for.body4
 ; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N23:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N1:0x[0-9a-f]*]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    br label %for.inc12
-; CHECK-NEXT: Edges:none!
+; CHECK-NEXT:    %sub = add i64 %n, -1
+; CHECK-NEXT: Edges:
+; CHECK-NEXT:  [def-use] to [[N2]]
+; CHECK-NEXT:  [def-use] to [[N3:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N24:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT:--- start of nodes in pi-block ---
-; CHECK: Node Address:[[N25:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N3]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc13 = add i64 %i.04, 1
+; CHECK-NEXT:    %cmp21 = icmp ult i64 1, %sub
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N26:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N4:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N26]]:single-instruction
+; CHECK: Node Address:[[N4]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %i.04 = phi i64 [ %inc13, %for.inc12 ], [ 0, %test2.for.cond1.preheader.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N25]]
-; CHECK-NEXT:--- end of nodes in pi-block ---
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N5]]
-; CHECK-NEXT:  [def-use] to [[N10]]
-; CHECK-NEXT:  [def-use] to [[N16]]
-; CHECK-NEXT:  [def-use] to [[N20]]
+; CHECK-NEXT:    br i1 %cmp21, label %for.body4.preheader, label %for.inc12
+; CHECK-NEXT: Edges:none!
 
-; CHECK: Node Address:[[N27:0x[0-9a-f]*]]:pi-block
-; CHECK-NEXT:--- start of nodes in pi-block ---
-; CHECK: Node Address:[[N28:0x[0-9a-f]*]]:single-instruction
+; CHECK: Node Address:[[N2]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %inc = add i64 %j.02, 1
+; CHECK-NEXT:    %cmp2 = icmp ult i64 %inc, %sub
 ; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N29:0x[0-9a-f]*]]
+; CHECK-NEXT:  [def-use] to [[N19:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N29]]:single-instruction
+; CHECK: Node Address:[[N19]]:single-instruction
 ; CHECK-NEXT: Instructions:
-; CHECK-NEXT:    %j.02 = phi i64 [ %inc, %for.body4 ], [ 1, %for.body4.preheader ]
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N28]]
-; CHECK-NEXT:--- end of nodes in pi-block ---
-; CHECK-NEXT: Edges:
-; CHECK-NEXT:  [def-use] to [[N7]]
-; CHECK-NEXT:  [def-use] to [[N13]]
-; CHECK-NEXT:  [def-use] to [[N18]]
-; CHECK-NEXT:  [def-use] to [[N2]]
+; CHECK-NEXT:    br i1 %cmp2, label %for.body4, label %for.inc12.loopexit
+; CHECK-NEXT: Edges:none!
 
 
 ;; This test has no cycles.
diff --git a/llvm/test/Analysis/DDG/root-node.ll b/llvm/test/Analysis/DDG/root-node.ll
index 34d6437ef9c..868fb72d452 100644
--- a/llvm/test/Analysis/DDG/root-node.ll
+++ b/llvm/test/Analysis/DDG/root-node.ll
@@ -7,12 +7,11 @@
 ; CHECK-NEXT:  [rooted] to [[N1:0x[0-9a-f]*]]
 ; CHECK-NEXT:  [rooted] to [[N2:0x[0-9a-f]*]]
 
-; CHECK: Node Address:[[N1]]:pi-block
-; CHECK: %i2.03 = phi i64 [ 0, %for.body.lr.ph ], [ %inc2, %test1.for.body ]
-
 ; CHECK: Node Address:[[N2]]:pi-block
 ; CHECK: %i1.02 = phi i64 [ 0, %for.body.lr.ph ], [ %inc, %test1.for.body ]
 
+; CHECK: Node Address:[[N1]]:pi-block
+; CHECK: %i2.03 = phi i64 [ 0, %for.body.lr.ph ], [ %inc2, %test1.for.body ]
 
 ;; // Two separate components in the graph. Root node must link to both.
 ;; void test1(unsigned long n, float * restrict a, float * restrict b) {