From 10707f3b442aa5a6cc55b899d630871f06b8ebbc Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Thu, 24 Jun 2010 22:00:37 +0000
Subject: [PATCH] It's possible that a flag is added to the SDNode that points
 back to the original SDNode. This is badness. Also, this function allows one
 SDNode to point multiple flags to another SDNode. Badness as well.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106793 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../SelectionDAG/ScheduleDAGSDNodes.cpp       | 30 ++++++++++++-------
 test/CodeGen/ARM/flag-crash.ll                | 27 +++++++++++++++++
 2 files changed, 46 insertions(+), 11 deletions(-)
 create mode 100644 test/CodeGen/ARM/flag-crash.ll

diff --git a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
index 07277b3f349..c54f36002ea 100644
--- a/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
+++ b/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
@@ -110,18 +110,25 @@ static void CheckForPhysRegDependency(SDNode *Def, SDNode *User, unsigned Op,
 static void AddFlags(SDNode *N, SDValue Flag, bool AddFlag,
                      SelectionDAG *DAG) {
   SmallVector<EVT, 4> VTs;
+  SDNode *FlagDestNode = Flag.getNode();
 
-  for (unsigned i = 0, e = N->getNumValues(); i != e; ++i)
-    VTs.push_back(N->getValueType(i));
+  // Don't add a flag from a node to itself.
+  if (FlagDestNode == N) return;
+
+  // Don't add a flag to something which already has a flag.
+  if (N->getValueType(N->getNumValues() - 1) == MVT::Flag) return;
+
+  for (unsigned I = 0, E = N->getNumValues(); I != E; ++I)
+    VTs.push_back(N->getValueType(I));
 
   if (AddFlag)
     VTs.push_back(MVT::Flag);
 
   SmallVector<SDValue, 4> Ops;
-  for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
-    Ops.push_back(N->getOperand(i));
+  for (unsigned I = 0, E = N->getNumOperands(); I != E; ++I)
+    Ops.push_back(N->getOperand(I));
 
-  if (Flag.getNode())
+  if (FlagDestNode)
     Ops.push_back(Flag);
 
   SDVTList VTList = DAG->getVTList(&VTs[0], VTs.size());
@@ -213,16 +220,17 @@ void ScheduleDAGSDNodes::ClusterNeighboringLoads(SDNode *Node) {
   // Cluster loads by adding MVT::Flag outputs and inputs. This also
   // ensure they are scheduled in order of increasing addresses.
   SDNode *Lead = Loads[0];
-  AddFlags(Lead, SDValue(0,0), true, DAG);
+  AddFlags(Lead, SDValue(0, 0), true, DAG);
+
+  SDValue InFlag = SDValue(Lead, Lead->getNumValues() - 1);
+  for (unsigned I = 1, E = Loads.size(); I != E; ++I) {
+    bool OutFlag = I < E - 1;
+    SDNode *Load = Loads[I];
 
-  SDValue InFlag = SDValue(Lead, Lead->getNumValues()-1);
-  for (unsigned i = 1, e = Loads.size(); i != e; ++i) {
-    bool OutFlag = i < e-1;
-    SDNode *Load = Loads[i];
     AddFlags(Load, InFlag, OutFlag, DAG);
 
     if (OutFlag)
-      InFlag = SDValue(Load, Load->getNumValues()-1);
+      InFlag = SDValue(Load, Load->getNumValues() - 1);
 
     ++LoadsClustered;
   }
diff --git a/test/CodeGen/ARM/flag-crash.ll b/test/CodeGen/ARM/flag-crash.ll
new file mode 100644
index 00000000000..9c61944a215
--- /dev/null
+++ b/test/CodeGen/ARM/flag-crash.ll
@@ -0,0 +1,27 @@
+; RUN: llc < %s -O3 -mtriple=thumbv7-apple-darwin10 -mcpu=cortex-a8 -relocation-model=pic
+; PR7484
+
+%struct.gs_matrix = type { float, i32, float, i32, float, i32, float, i32, float, i32, float, i32 }
+
+define fastcc void @func(%struct.gs_matrix* nocapture %pm1) nounwind {
+entry:
+  %0 = getelementptr inbounds %struct.gs_matrix* %pm1, i32 0, i32 6
+  %1 = load float* %0, align 4
+  %2 = getelementptr inbounds %struct.gs_matrix* %pm1, i32 0, i32 8
+  %3 = load float* %2, align 4
+  %4 = getelementptr inbounds %struct.gs_matrix* %pm1, i32 0, i32 2
+  %5 = bitcast float* %4 to i32*
+  %6 = load i32* %5, align 4
+  %7 = or i32 0, %6
+  %.mask = and i32 %7, 2147483647
+  %8 = icmp eq i32 %.mask, 0
+  br i1 %8, label %bb, label %bb11
+
+bb:
+  ret void
+
+bb11:
+  %9 = fmul float %1, undef
+  %10 = fmul float %3, undef
+  ret void
+}