3 files changed, 63 insertions, 1 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonInstrInfo.cpp b/llvm/lib/Target/Hexagon/HexagonInstrInfo.cpp
index bcd1a5089c7..c2125bec3a5 100644
--- a/llvm/lib/Target/Hexagon/HexagonInstrInfo.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonInstrInfo.cpp
@@ -1651,8 +1651,13 @@ bool HexagonInstrInfo::areMemAccessesTriviallyDisjoint(
 bool HexagonInstrInfo::getIncrementValue(const MachineInstr &MI,
       int &Value) const {
   if (isPostIncrement(MI)) {
+    // For a post-increment, the offset is zero and the increment value is
+    // determined by the instruction's access size.
+    int Zero;
     unsigned AccessSize;
-    return getBaseAndOffset(MI, Value, AccessSize);
+    bool RetVal = getBaseAndOffset(MI, Zero, AccessSize);
+    Value = (int) AccessSize;
+    return RetVal;
   }
   if (MI.getOpcode() == Hexagon::A2_addi) {
     Value = MI.getOperand(2).getImm();
diff --git a/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp b/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp
index 0f407c2d836..2555b50f91c 100644
--- a/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.cpp
@@ -496,6 +496,48 @@ void HexagonPacketizerList::useCalleesSP(MachineInstr &MI) {
   Off.setImm(Off.getImm() + FrameSize + HEXAGON_LRFP_SIZE);
 }
 
+/// Return true if we can update the offset in MI so that MI and MJ
+/// can be packetized together.
+bool HexagonPacketizerList::updateOffset(SUnit *SUI, SUnit *SUJ) {
+  assert(SUI->getInstr() && SUJ->getInstr());
+  MachineInstr &MI = *SUI->getInstr();
+  MachineInstr &MJ = *SUJ->getInstr();
+
+  unsigned BPI, OPI;
+  if (!HII->getBaseAndOffsetPosition(MI, BPI, OPI))
+    return false;
+  unsigned BPJ, OPJ;
+  if (!HII->getBaseAndOffsetPosition(MJ, BPJ, OPJ))
+    return false;
+  unsigned Reg = MI.getOperand(BPI).getReg();
+  if (Reg != MJ.getOperand(BPJ).getReg())
+    return false;
+  // Make sure that the dependences do not restrict adding MI to the packet.
+  // That is, ignore anti dependences, and make sure the only data dependence
+  // involves the specific register.
+  for (const auto &PI : SUI->Preds)
+    if (PI.getKind() != SDep::Anti &&
+        (PI.getKind() != SDep::Data || PI.getReg() != Reg))
+      return false;
+  int Incr;
+  if (!HII->getIncrementValue(MJ, Incr))
+    return false;
+
+  int64_t Offset = MI.getOperand(OPI).getImm();
+  MI.getOperand(OPI).setImm(Offset + Incr);
+  ChangedOffset = Offset;
+  return true;
+}
+
+/// Undo the changed offset. This is needed if the instruction cannot be
+/// added to the current packet due to a different instruction.
+void HexagonPacketizerList::undoChangedOffset(MachineInstr &MI) {
+  unsigned BP, OP;
+  if (!HII->getBaseAndOffsetPosition(MI, BP, OP))
+    llvm_unreachable("Unable to find base and offset operands.");
+  MI.getOperand(OP).setImm(ChangedOffset);
+}
+
 enum PredicateKind {
   PK_False,
   PK_True,
@@ -980,6 +1022,7 @@ void HexagonPacketizerList::initPacketizerState() {
   GlueToNewValueJump = false;
   GlueAllocframeStore = false;
   FoundSequentialDependence = false;
+  ChangedOffset = INT64_MAX;
 }
 
 // Ignore bundling of pseudo instructions.
@@ -1567,6 +1610,15 @@ bool HexagonPacketizerList::isLegalToPruneDependencies(SUnit *SUI, SUnit *SUJ) {
     useCalleesSP(I);
     GlueAllocframeStore = false;
   }
+
+  if (ChangedOffset != INT64_MAX)
+    undoChangedOffset(I);
+  else if (updateOffset(SUI, SUJ)) {
+    FoundSequentialDependence = false;
+    Dependence = false;
+    return true;
+  }
+
   return false;
 }
 
diff --git a/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.h b/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.h
index 3a7bdf5101e..cbdd2367429 100644
--- a/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.h
+++ b/llvm/lib/Target/Hexagon/HexagonVLIWPacketizer.h
@@ -38,6 +38,9 @@ class HexagonPacketizerList : public VLIWPacketizerList {
   // Has the feeder instruction been glued to new value jump.
   bool GlueToNewValueJump;
 
+  // This holds the offset value, when pruning the dependences.
+  int64_t ChangedOffset;
+
   // Check if there is a dependence between some instruction already in this
   // packet and this instruction.
   bool Dependence;
@@ -117,6 +120,8 @@ protected:
   bool demoteToDotOld(MachineInstr &MI);
   bool useCallersSP(MachineInstr &MI);
   void useCalleesSP(MachineInstr &MI);
+  bool updateOffset(SUnit *SUI, SUnit *SUJ);
+  void undoChangedOffset(MachineInstr &MI);
   bool arePredicatesComplements(MachineInstr &MI1, MachineInstr &MI2);
   bool restrictingDepExistInPacket(MachineInstr&, unsigned);
   bool isNewifiable(const MachineInstr &MI, const TargetRegisterClass *NewRC);