Issue description:

SchedulerDAGInstrs::buildSchedGraph ignores dependencies between FixedStack
objects and byval parameters. So loading byval parameters from stack may be
inserted *before* it will be stored, since these operations are treated as
independent.

Fix:
Currently ARMTargetLowering::LowerFormalArguments saves byval registers with
FixedStack MachinePointerInfo. To fix the problem we need to store byval
registers with MachinePointerInfo referenced to first the "byval" parameter.

Also commit adds two new fields to the InputArg structure: Function's argument
index and InputArg's part offset in bytes relative to the start position of
Function's argument. E.g.: If function's argument is 128 bit width and it was
splitted onto 32 bit regs, then we got 4 InputArg structs with same arg index,
but different offset values. 

llvm-svn: 165616

3 files changed, 20 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index dccc2fcf25b..cdebff94e59 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -6681,7 +6681,7 @@ void SelectionDAGISel::LowerArguments(const BasicBlock *LLVMBB) {
     ISD::ArgFlagsTy Flags;
     Flags.setSRet();
     EVT RegisterVT = TLI.getRegisterType(*DAG.getContext(), ValueVTs[0]);
-    ISD::InputArg RetArg(Flags, RegisterVT, true);
+    ISD::InputArg RetArg(Flags, RegisterVT, true, 0, 0);
     Ins.push_back(RetArg);
   }
 
@@ -6729,7 +6729,8 @@ void SelectionDAGISel::LowerArguments(const BasicBlock *LLVMBB) {
       EVT RegisterVT = TLI.getRegisterType(*CurDAG->getContext(), VT);
       unsigned NumRegs = TLI.getNumRegisters(*CurDAG->getContext(), VT);
       for (unsigned i = 0; i != NumRegs; ++i) {
-        ISD::InputArg MyFlags(Flags, RegisterVT, isArgValueUsed);
+        ISD::InputArg MyFlags(Flags, RegisterVT, isArgValueUsed,
+                              Idx-1, i*RegisterVT.getStoreSize());
         if (NumRegs > 1 && i == 0)
           MyFlags.Flags.setSplit();
         // if it isn't first piece, alignment must be 1
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index d4d29f57d21..e6f0ef25d87 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -2534,6 +2534,8 @@ ARMTargetLowering::computeRegArea(CCState &CCInfo, MachineFunction &MF,
 void
 ARMTargetLowering::VarArgStyleRegisters(CCState &CCInfo, SelectionDAG &DAG,
                                         DebugLoc dl, SDValue &Chain,
+                                        const Value *OrigArg,
+                                        unsigned OffsetFromOrigArg,
                                         unsigned ArgOffset) const {
   MachineFunction &MF = DAG.getMachineFunction();
   MachineFrameInfo *MFI = MF.getFrameInfo();
@@ -2561,7 +2563,7 @@ ARMTargetLowering::VarArgStyleRegisters(CCState &CCInfo, SelectionDAG &DAG,
                                     getPointerTy());
 
     SmallVector<SDValue, 4> MemOps;
-    for (; firstRegToSaveIndex < 4; ++firstRegToSaveIndex) {
+    for (unsigned i = 0; firstRegToSaveIndex < 4; ++firstRegToSaveIndex, ++i) {
       const TargetRegisterClass *RC;
       if (AFI->isThumb1OnlyFunction())
         RC = &ARM::tGPRRegClass;
@@ -2572,7 +2574,7 @@ ARMTargetLowering::VarArgStyleRegisters(CCState &CCInfo, SelectionDAG &DAG,
       SDValue Val = DAG.getCopyFromReg(Chain, dl, VReg, MVT::i32);
       SDValue Store =
         DAG.getStore(Val.getValue(1), dl, Val, FIN,
-                 MachinePointerInfo::getFixedStack(AFI->getVarArgsFrameIndex()),
+                     MachinePointerInfo(OrigArg, OffsetFromOrigArg + 4*i),
                      false, false, 0);
       MemOps.push_back(Store);
       FIN = DAG.getNode(ISD::ADD, dl, getPointerTy(), FIN,
@@ -2606,14 +2608,16 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
   CCInfo.AnalyzeFormalArguments(Ins,
                                 CCAssignFnForNode(CallConv, /* Return*/ false,
                                                   isVarArg));
-
+  
   SmallVector<SDValue, 16> ArgValues;
   int lastInsIndex = -1;
-
   SDValue ArgValue;
+  Function::const_arg_iterator CurOrigArg = MF.getFunction()->arg_begin();
+  unsigned CurArgIdx = 0;
   for (unsigned i = 0, e = ArgLocs.size(); i != e; ++i) {
     CCValAssign &VA = ArgLocs[i];
-
+    std::advance(CurOrigArg, Ins[VA.getValNo()].OrigArgIndex - CurArgIdx);
+    CurArgIdx = Ins[VA.getValNo()].OrigArgIndex;
     // Arguments stored in registers.
     if (VA.isRegLoc()) {
       EVT RegVT = VA.getLocVT();
@@ -2709,7 +2713,8 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
           if (Flags.isByVal()) {
             unsigned VARegSize, VARegSaveSize;
             computeRegArea(CCInfo, MF, VARegSize, VARegSaveSize);
-            VarArgStyleRegisters(CCInfo, DAG, dl, Chain, 0);
+            VarArgStyleRegisters(CCInfo, DAG,
+                                 dl, Chain, CurOrigArg, Ins[VA.getValNo()].PartOffset, 0);
             unsigned Bytes = Flags.getByValSize() - VARegSize;
             if (Bytes == 0) Bytes = 1; // Don't create zero-sized stack objects.
             int FI = MFI->CreateFixedObject(Bytes,
@@ -2732,7 +2737,8 @@ ARMTargetLowering::LowerFormalArguments(SDValue Chain,
 
   // varargs
   if (isVarArg)
-    VarArgStyleRegisters(CCInfo, DAG, dl, Chain, CCInfo.getNextStackOffset());
+    VarArgStyleRegisters(CCInfo, DAG, dl, Chain, 0, 0,
+                         CCInfo.getNextStackOffset());
 
   return Chain;
 }
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.h b/llvm/lib/Target/ARM/ARMISelLowering.h
index 2b8f382c955..b5020c97108 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.h
+++ b/llvm/lib/Target/ARM/ARMISelLowering.h
@@ -466,7 +466,10 @@ namespace llvm {
                            SmallVectorImpl<SDValue> &InVals) const;
 
     void VarArgStyleRegisters(CCState &CCInfo, SelectionDAG &DAG,
-                              DebugLoc dl, SDValue &Chain, unsigned ArgOffset)
+                              DebugLoc dl, SDValue &Chain,
+                              const Value *OrigArg,
+                              unsigned OffsetFromOrigArg,
+                              unsigned ArgOffset)
       const;
 
     void computeRegArea(CCState &CCInfo, MachineFunction &MF,