Make changes to avoid creating nested CALLSEQ_START/END constructs, which aren't

yet legal according to comments in LegalizeDAG.cpp:227. 

Memcpy nodes created for copying byval arguments are inserted before
CALLSEQ_START.

The two failing tests reported in PR10876 pass after applying this patch.  


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140046 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 22 insertions, 12 deletions

diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index 56fe993e2b..ab9f464e70 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -1799,7 +1799,7 @@ static const unsigned O32IntRegs[] = {
 
 // Write ByVal Arg to arg registers and stack.
 static void
-WriteByValArg(SDValue& Chain, DebugLoc dl,
+WriteByValArg(SDValue& ByValChain, SDValue Chain, DebugLoc dl,
               SmallVector<std::pair<unsigned, SDValue>, 16>& RegsToPass,
               SmallVector<SDValue, 8>& MemOpChains, int& LastFI,
               MachineFrameInfo *MFI, SelectionDAG &DAG, SDValue Arg,
@@ -1882,19 +1882,18 @@ WriteByValArg(SDValue& Chain, DebugLoc dl,
                             DAG.getConstant(Offset, MVT::i32));
   LastFI = MFI->CreateFixedObject(RemainingSize, LocMemOffset, true);
   SDValue Dst = DAG.getFrameIndex(LastFI, PtrType);
-  Chain = DAG.getMemcpy(Chain, dl, Dst, Src,
-                        DAG.getConstant(RemainingSize, MVT::i32),
-                        std::min(ByValAlign, (unsigned)4),
-                        /*isVolatile=*/false, /*AlwaysInline=*/false,
-                        MachinePointerInfo(0), MachinePointerInfo(0));
-  MemOpChains.push_back(Chain);
+  ByValChain = DAG.getMemcpy(ByValChain, dl, Dst, Src,
+                             DAG.getConstant(RemainingSize, MVT::i32),
+                             std::min(ByValAlign, (unsigned)4),
+                             /*isVolatile=*/false, /*AlwaysInline=*/false,
+                             MachinePointerInfo(0), MachinePointerInfo(0));
 }
 
 /// LowerCall - functions arguments are copied from virtual regs to
 /// (physical regs)/(stack frame), CALLSEQ_START and CALLSEQ_END are emitted.
 /// TODO: isTailCall.
 SDValue
-MipsTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
+MipsTargetLowering::LowerCall(SDValue InChain, SDValue Callee,
                               CallingConv::ID CallConv, bool isVarArg,
                               bool &isTailCall,
                               const SmallVectorImpl<ISD::OutputArg> &Outs,
@@ -1924,8 +1923,13 @@ MipsTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
   // Get a count of how many bytes are to be pushed on the stack.
   unsigned NextStackOffset = CCInfo.getNextStackOffset();
 
-  Chain = DAG.getCALLSEQ_START(Chain, DAG.getIntPtrConstant(NextStackOffset,
-                                                            true));
+  // Chain is the output chain of the last Load/Store or CopyToReg node.
+  // ByValChain is the output chain of the last Memcpy node created for copying
+  // byval arguments to the stack.
+  SDValue Chain, CallSeqStart, ByValChain;
+  SDValue NextStackOffsetVal = DAG.getIntPtrConstant(NextStackOffset, true);
+  Chain = CallSeqStart = DAG.getCALLSEQ_START(InChain, NextStackOffsetVal);
+  ByValChain = InChain;
 
   // If this is the first call, create a stack frame object that points to
   // a location to which .cprestore saves $gp.
@@ -2019,8 +2023,8 @@ MipsTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
              "No support for ByVal args by ABIs other than O32 yet.");
       assert(Flags.getByValSize() &&
              "ByVal args of size 0 should have been ignored by front-end.");
-      WriteByValArg(Chain, dl, RegsToPass, MemOpChains, LastFI, MFI, DAG, Arg,
-                    VA, Flags, getPointerTy(), Subtarget->isLittle());
+      WriteByValArg(ByValChain, Chain, dl, RegsToPass, MemOpChains, LastFI, MFI,
+                    DAG, Arg, VA, Flags, getPointerTy(), Subtarget->isLittle());
       continue;
     }
 
@@ -2042,6 +2046,12 @@ MipsTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
   if (LastFI)
     MipsFI->extendOutArgFIRange(FirstFI, LastFI);
 
+  // If a memcpy has been created to copy a byval arg to a stack, replace the
+  // chain input of CallSeqStart with ByValChain.
+  if (InChain != ByValChain)
+    DAG.UpdateNodeOperands(CallSeqStart.getNode(), ByValChain,
+                           NextStackOffsetVal);
+
   // Transform all store nodes into one single node because all store
   // nodes are independent of each other.
   if (!MemOpChains.empty())