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Implement byval structure argument passing. The following limitations or 

deficiencies exist:

- Works only if ABI is o32.
- Zero-sized structures cannot be passed.
- There is a lot of redundancy in generated code.

llvm-svn: 131986
This commit is contained in:
Akira Hatanaka 2011-05-24 19:18:33 +00:00
parent 0a042ced97
commit 5e16c6a9b2
1 changed files with 115 additions and 5 deletions
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120
llvm/lib/Target/Mips/MipsISelLowering.cpp
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@ -959,6 +959,17 @@ static bool CC_MipsO32(unsigned ValNo, MVT ValVT,
Mips::D6, Mips::D7
};
// ByVal Args
if (ArgFlags.isByVal()) {
State.HandleByVal(ValNo, ValVT, LocVT, LocInfo,
1 /*MinSize*/, 4 /*MinAlign*/, ArgFlags);
unsigned NextReg = (State.getNextStackOffset() + 3) / 4;
for (unsigned r = State.getFirstUnallocated(IntRegs, IntRegsSize);
r < std::min(IntRegsSize, NextReg); ++r)
State.AllocateReg(IntRegs[r]);
return false;
}
// Promote i8 and i16
if (LocVT == MVT::i8 || LocVT == MVT::i16) {
LocVT = MVT::i32;
@ -1027,6 +1038,55 @@ static bool CC_MipsO32(unsigned ValNo, MVT ValVT,
// Call Calling Convention Implementation
//===----------------------------------------------------------------------===//
static const unsigned O32IntRegsSize = 4;
static const unsigned O32IntRegs[] = {
Mips::A0, Mips::A1, Mips::A2, Mips::A3
};
// Write ByVal Arg to arg registers and stack.
static void
WriteByValArg(SDValue& Chain, DebugLoc dl,
SmallVector<std::pair<unsigned, SDValue>, 16>& RegsToPass,
SmallVector<SDValue, 8>& MemOpChains, int& LastFI,
MachineFrameInfo *MFI, SelectionDAG &DAG, SDValue Arg,
const CCValAssign &VA, const ISD::ArgFlagsTy& Flags, MVT PtrType) {
unsigned FirstWord = VA.getLocMemOffset() / 4;
unsigned NumWords = (Flags.getByValSize() + 3) / 4;
unsigned LastWord = FirstWord + NumWords;
unsigned CurWord;
// copy the first 4 words of byval arg to registers A0 - A3
for (CurWord = FirstWord; CurWord < std::min(LastWord, O32IntRegsSize);
++CurWord) {
SDValue LoadPtr = DAG.getNode(ISD::ADD, dl, MVT::i32, Arg,
DAG.getConstant((CurWord - FirstWord) * 4,
MVT::i32));
SDValue LoadVal = DAG.getLoad(MVT::i32, dl, Chain, LoadPtr,
MachinePointerInfo(),
false, false, 0);
MemOpChains.push_back(LoadVal.getValue(1));
unsigned DstReg = O32IntRegs[CurWord];
RegsToPass.push_back(std::make_pair(DstReg, LoadVal));
}
// copy remaining part of byval arg to stack.
if (CurWord < LastWord) {
unsigned SizeInBytes = (LastWord - CurWord) * 4;
SDValue Src = DAG.getNode(ISD::ADD, dl, MVT::i32, Arg,
DAG.getConstant((CurWord - FirstWord) * 4,
MVT::i32));
LastFI = MFI->CreateFixedObject(SizeInBytes, CurWord * 4, true);
SDValue Dst = DAG.getFrameIndex(LastFI, PtrType);
Chain = DAG.getMemcpy(Chain, dl, Dst, Src,
DAG.getConstant(SizeInBytes, MVT::i32),
/*Align*/4,
/*isVolatile=*/false, /*AlwaysInline=*/false,
MachinePointerInfo(0), MachinePointerInfo(0));
MemOpChains.push_back(Chain);
}
}
/// LowerCall - functions arguments are copied from virtual regs to
/// (physical regs)/(stack frame), CALLSEQ_START and CALLSEQ_END are emitted.
/// TODO: isTailCall.
@ -1121,6 +1181,18 @@ MipsTargetLowering::LowerCall(SDValue Chain, SDValue Callee,
// Register can't get to this point...
assert(VA.isMemLoc());
// ByVal Arg.
ISD::ArgFlagsTy Flags = Outs[i].Flags;
if (Flags.isByVal()) {
assert(Subtarget->isABI_O32() &&
"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());
continue;
}
// Create the frame index object for this incoming parameter
// This guarantees that when allocating Local Area the firsts
// 16 bytes which are alwayes reserved won't be overwritten
@ -1299,6 +1371,29 @@ MipsTargetLowering::LowerCallResult(SDValue Chain, SDValue InFlag,
//===----------------------------------------------------------------------===//
// Formal Arguments Calling Convention Implementation
//===----------------------------------------------------------------------===//
static void ReadByValArg(MachineFunction &MF, SDValue Chain, DebugLoc dl,
std::vector<SDValue>& OutChains,
SelectionDAG &DAG, unsigned NumWords, SDValue FIN,
const CCValAssign &VA, const ISD::ArgFlagsTy& Flags) {
unsigned LocMem = VA.getLocMemOffset();
unsigned FirstWord = LocMem / 4;
// copy register A0 - A3 to frame object
for (unsigned i = 0; i < NumWords; ++i) {
unsigned CurWord = FirstWord + i;
if (CurWord >= O32IntRegsSize)
break;
unsigned SrcReg = O32IntRegs[CurWord];
unsigned Reg = AddLiveIn(MF, SrcReg, Mips::CPURegsRegisterClass);
SDValue StorePtr = DAG.getNode(ISD::ADD, dl, MVT::i32, FIN,
DAG.getConstant(i * 4, MVT::i32));
SDValue Store = DAG.getStore(Chain, dl, DAG.getRegister(Reg, MVT::i32),
StorePtr, MachinePointerInfo(), false,
false, 0);
OutChains.push_back(Store);
}
}
/// LowerFormalArguments - transform physical registers into virtual registers
/// and generate load operations for arguments places on the stack.
@ -1393,6 +1488,23 @@ MipsTargetLowering::LowerFormalArguments(SDValue Chain,
// sanity check
assert(VA.isMemLoc());
ISD::ArgFlagsTy Flags = Ins[i].Flags;
if (Flags.isByVal()) {
assert(Subtarget->isABI_O32() &&
"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.");
unsigned NumWords = (Flags.getByValSize() + 3) / 4;
LastFI = MFI->CreateFixedObject(NumWords * 4, VA.getLocMemOffset(),
true);
SDValue FIN = DAG.getFrameIndex(LastFI, getPointerTy());
InVals.push_back(FIN);
ReadByValArg(MF, Chain, dl, OutChains, DAG, NumWords, FIN, VA, Flags);
continue;
}
// The stack pointer offset is relative to the caller stack frame.
// Since the real stack size is unknown here, a negative SPOffset
// is used so there's a way to adjust these offsets when the stack
@ -1431,14 +1543,12 @@ MipsTargetLowering::LowerFormalArguments(SDValue Chain,
// Record the frame index of the first variable argument
// which is a value necessary to VASTART.
unsigned NextStackOffset = CCInfo.getNextStackOffset();
assert(NextStackOffset % 4 == 0 &&
"NextStackOffset must be aligned to 4-byte boundaries.");
LastFI = MFI->CreateFixedObject(4, NextStackOffset, true);
MipsFI->setVarArgsFrameIndex(LastFI);
const unsigned O32IntRegs[] = {
Mips::A0, Mips::A1, Mips::A2, Mips::A3
};
// Copy variable arguments passed in registers to stack.
// Copy variable arguments passed in registers to stack.
for (; NextStackOffset < 16; NextStackOffset += 4) {
TargetRegisterClass *RC = Mips::CPURegsRegisterClass;
unsigned Idx = NextStackOffset / 4;