From 9f435740b1c652926c80529e00c92925a3196d79 Mon Sep 17 00:00:00 2001
From: Owen Anderson <resistor@mac.com>
Date: Wed, 25 Jul 2007 22:19:40 +0000
Subject: [PATCH] My last commit was not correct for nested loops.  Fix it, and
 add a testcase for it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40498 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/GVN.cpp                |  4 ++-
 test/Transforms/GVN/2007-07-25-NestedLoop.ll | 38 ++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 test/Transforms/GVN/2007-07-25-NestedLoop.ll

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index eb12abe243c..f3aa7960f66 100644
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -731,6 +731,7 @@ Value *GVN::performPHIConstruction(BasicBlock *BB, LoadInst* orig,
   } else {
     PHINode *PN = new PHINode(orig->getType(), orig->getName()+".rle", BB->begin());
     PN->reserveOperandSpace(numPreds);
+    Phis[BB] = PN;
     
     visited.insert(BB);
     // Fill in the incoming values for the block.
@@ -738,7 +739,7 @@ Value *GVN::performPHIConstruction(BasicBlock *BB, LoadInst* orig,
       if (!visited.count(*PI))
         PN->addIncoming(performPHIConstruction(*PI, orig, Phis, visited), *PI);
       else
-        PN->addIncoming(PN, *PI);
+        PN->addIncoming(Phis[*PI], *PI);
     visited.erase(BB);
     
     bool all_same = PN->getNumIncomingValues() != 1;
@@ -748,6 +749,7 @@ Value *GVN::performPHIConstruction(BasicBlock *BB, LoadInst* orig,
     
     if (all_same) {
       PN->eraseFromParent();
+      Phis[BB] = first;
       return first;
     } else {
       return PN;
diff --git a/test/Transforms/GVN/2007-07-25-NestedLoop.ll b/test/Transforms/GVN/2007-07-25-NestedLoop.ll
new file mode 100644
index 00000000000..cebaaa39be0
--- /dev/null
+++ b/test/Transforms/GVN/2007-07-25-NestedLoop.ll
@@ -0,0 +1,38 @@
+; RUN: llvm-as < %s | opt -gvn | llvm-dis
+
+	%struct.TypHeader = type { i32, %struct.TypHeader**, [3 x i8], i8 }
+
+define %struct.TypHeader* @LtRec(%struct.TypHeader* %hdL, %struct.TypHeader* %hdR) {
+entry:
+	br i1 false, label %bb556.preheader, label %bb534.preheader
+
+bb534.preheader:		; preds = %entry
+	ret %struct.TypHeader* null
+
+bb556.preheader:		; preds = %entry
+	%tmp56119 = getelementptr %struct.TypHeader* %hdR, i32 0, i32 0		; <i32*> [#uses=1]
+	%tmp56220 = load i32* %tmp56119		; <i32> [#uses=0]
+	br i1 false, label %bb.nph23, label %bb675.preheader
+
+bb.nph23:		; preds = %bb556.preheader
+	ret %struct.TypHeader* null
+
+bb656:		; preds = %bb675.outer, %bb656
+	%tmp678 = load i32* %tmp677		; <i32> [#uses=0]
+	br i1 false, label %bb684, label %bb656
+
+bb684:		; preds = %bb675.outer, %bb656
+	br i1 false, label %bb924.preheader, label %bb675.outer
+
+bb675.outer:		; preds = %bb675.preheader, %bb684
+	%tmp67812 = load i32* %tmp67711		; <i32> [#uses=0]
+	br i1 false, label %bb684, label %bb656
+
+bb675.preheader:		; preds = %bb556.preheader
+	%tmp67711 = getelementptr %struct.TypHeader* %hdR, i32 0, i32 0		; <i32*> [#uses=1]
+	%tmp677 = getelementptr %struct.TypHeader* %hdR, i32 0, i32 0		; <i32*> [#uses=1]
+	br label %bb675.outer
+
+bb924.preheader:		; preds = %bb684
+	ret %struct.TypHeader* null
+}