[DAG] Don't increase SDNodeOrder for dbg.value/declare.

Summary:
The SDNodeOrder is saved in the IROrder field in the SDNode, and this
field may affects scheduling. Thus, letting dbg.value/declare increase
the order numbers may in turn affect scheduling.

Because of this change we also need to update the code deciding when
dbg values should be output, in ScheduleDAGSDNodes.cpp/ProcessSDDbgValues.

Dbg values now have the same order as the SDNode they are connected to,
not the following orders.

Test cases provided by Florian Hahn.

Reviewers: bogner, aprantl, sunfish, atrick

Reviewed By: atrick

Subscribers: fhahn, probinson, andreadb, llvm-commits, MatzeB

Differential Revision: https://reviews.llvm.org/D25318

llvm-svn: 292485

2 files changed, 6 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
index 3be622f8c17..6db56d58354 100644
--- a/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/ScheduleDAGSDNodes.cpp
@@ -704,8 +704,8 @@ ProcessSDDbgValues(SDNode *N, SelectionDAG *DAG, InstrEmitter &Emitter,
   if (!N->getHasDebugValue())
     return;
 
-  // Opportunistically insert immediate dbg_value uses, i.e. those with source
-  // order number right after the N.
+  // Opportunistically insert immediate dbg_value uses, i.e. those with the same
+  // source order number as N.
   MachineBasicBlock *BB = Emitter.getBlock();
   MachineBasicBlock::iterator InsertPos = Emitter.getInsertPos();
   ArrayRef<SDDbgValue*> DVs = DAG->GetDbgValues(N);
@@ -713,7 +713,7 @@ ProcessSDDbgValues(SDNode *N, SelectionDAG *DAG, InstrEmitter &Emitter,
     if (DVs[i]->isInvalidated())
       continue;
     unsigned DVOrder = DVs[i]->getOrder();
-    if (!Order || DVOrder == ++Order) {
+    if (!Order || DVOrder == Order) {
       MachineInstr *DbgMI = Emitter.EmitDbgValue(DVs[i], VRBaseMap);
       if (DbgMI) {
         Orders.push_back(std::make_pair(DVOrder, DbgMI));
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index c1eef4dced0..277db84fded 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -937,7 +937,9 @@ void SelectionDAGBuilder::visit(const Instruction &I) {
     HandlePHINodesInSuccessorBlocks(I.getParent());
   }
 
-  ++SDNodeOrder;
+  // Increase the SDNodeOrder if dealing with a non-debug instruction.
+  if (!isa<DbgInfoIntrinsic>(I))
+    ++SDNodeOrder;
 
   CurInst = &I;