From 0508d047fefef36d4f943ee13c82c18cf3a943ab Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Thu, 15 Dec 2011 18:21:18 +0000
Subject: [PATCH] Update DebugLoc while merging nodes at -O0.

Patch by Kyriakos Georgiou!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@146670 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/CodeGen/SelectionDAG.h           |  4 ++-
 lib/CodeGen/SelectionDAG/SelectionDAG.cpp     | 25 +++++++++++++++----
 lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp |  2 +-
 3 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/include/llvm/CodeGen/SelectionDAG.h b/include/llvm/CodeGen/SelectionDAG.h
index ccd35c4a16d..f637ea2495a 100644
--- a/include/llvm/CodeGen/SelectionDAG.h
+++ b/include/llvm/CodeGen/SelectionDAG.h
@@ -139,6 +139,7 @@ class SelectionDAG {
   const TargetSelectionDAGInfo &TSI;
   MachineFunction *MF;
   LLVMContext *Context;
+  CodeGenOpt::Level OptLevel;
 
   /// EntryNode - The starting token.
   SDNode EntryNode;
@@ -187,7 +188,7 @@ class SelectionDAG {
   SelectionDAG(const SelectionDAG&);   // Do not implement.
 
 public:
-  explicit SelectionDAG(const TargetMachine &TM);
+  explicit SelectionDAG(const TargetMachine &TM, llvm::CodeGenOpt::Level);
   ~SelectionDAG();
 
   /// init - Prepare this SelectionDAG to process code in the given
@@ -1034,6 +1035,7 @@ private:
                                void *&InsertPos);
   SDNode *FindModifiedNodeSlot(SDNode *N, const SDValue *Ops, unsigned NumOps,
                                void *&InsertPos);
+  SDNode *UpdadeDebugLocOnMergedSDNode(SDNode *N, DebugLoc loc);
 
   void DeleteNodeNotInCSEMaps(SDNode *N);
   void DeallocateNode(SDNode *N);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index e49fc7d3490..dd626e2aa10 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -840,9 +840,9 @@ unsigned SelectionDAG::getEVTAlignment(EVT VT) const {
 }
 
 // EntryNode could meaningfully have debug info if we can find it...
-SelectionDAG::SelectionDAG(const TargetMachine &tm)
+SelectionDAG::SelectionDAG(const TargetMachine &tm, CodeGenOpt::Level OL)
   : TM(tm), TLI(*tm.getTargetLowering()), TSI(*tm.getSelectionDAGInfo()),
-    EntryNode(ISD::EntryToken, DebugLoc(), getVTList(MVT::Other)),
+    OptLevel(OL), EntryNode(ISD::EntryToken, DebugLoc(), getVTList(MVT::Other)),
     Root(getEntryNode()), Ordering(0) {
   AllNodes.push_back(&EntryNode);
   Ordering = new SDNodeOrdering();
@@ -4918,6 +4918,20 @@ SDNode *SelectionDAG::SelectNodeTo(SDNode *N, unsigned MachineOpc,
   return N;
 }
 
+/// UpdadeDebugLocOnMergedSDNode - If the opt level is -O0 then it throws away
+/// the line number information on the merged node since it is not possible to
+/// preserve the information that operation is associated with multiple lines.
+/// This will make the debugger working better at -O0, were there is a higher
+/// probability having other instructions associated with that line.
+///
+SDNode *SelectionDAG::UpdadeDebugLocOnMergedSDNode(SDNode *N, DebugLoc OLoc) {
+  DebugLoc NLoc = N->getDebugLoc();
+  if (!(NLoc.isUnknown()) && (OptLevel == CodeGenOpt::None) && (OLoc != NLoc)) {
+    N->setDebugLoc(DebugLoc());
+  }
+  return N;
+}
+
 /// MorphNodeTo - This *mutates* the specified node to have the specified
 /// return type, opcode, and operands.
 ///
@@ -4939,7 +4953,7 @@ SDNode *SelectionDAG::MorphNodeTo(SDNode *N, unsigned Opc,
     FoldingSetNodeID ID;
     AddNodeIDNode(ID, Opc, VTs, Ops, NumOps);
     if (SDNode *ON = CSEMap.FindNodeOrInsertPos(ID, IP))
-      return ON;
+      return UpdadeDebugLocOnMergedSDNode(ON, N->getDebugLoc());
   }
 
   if (!RemoveNodeFromCSEMaps(N))
@@ -5143,8 +5157,9 @@ SelectionDAG::getMachineNode(unsigned Opcode, DebugLoc DL, SDVTList VTs,
     FoldingSetNodeID ID;
     AddNodeIDNode(ID, ~Opcode, VTs, Ops, NumOps);
     IP = 0;
-    if (SDNode *E = CSEMap.FindNodeOrInsertPos(ID, IP))
-      return cast<MachineSDNode>(E);
+    if (SDNode *E = CSEMap.FindNodeOrInsertPos(ID, IP)) {
+      return cast<MachineSDNode>(UpdadeDebugLocOnMergedSDNode(E, DL));
+    }
   }
 
   // Allocate a new MachineSDNode.
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 477ec807edd..3c950595b6d 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -266,7 +266,7 @@ SelectionDAGISel::SelectionDAGISel(const TargetMachine &tm,
                                    CodeGenOpt::Level OL) :
   MachineFunctionPass(ID), TM(tm), TLI(*tm.getTargetLowering()),
   FuncInfo(new FunctionLoweringInfo(TLI)),
-  CurDAG(new SelectionDAG(tm)),
+  CurDAG(new SelectionDAG(tm, OL)),
   SDB(new SelectionDAGBuilder(*CurDAG, *FuncInfo, OL)),
   GFI(),
   OptLevel(OL),