6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-01-17 21:35:07 +00:00
Code Issues Projects Releases Wiki Activity

Turn a memcpy from string constant into a series of stores of constant values.

Browse Source 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26219 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2006-02-15 21:59:04 +00:00
parent 2f9859486a
commit 74d0aa9a4b
1 changed files with 69 additions and 47 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

116
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
View File

@ -807,36 +807,15 @@ void SelectionDAGLowering::visitAlloca(AllocaInst &I) {
/// getStringValue - Turn an LLVM constant pointer that eventually points to a
/// global into a string value. Return an empty string if we can't do it.
///
static std::string getStringValue(Value *V, unsigned Offset = 0) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
if (Init->isString()) {
std::string Result = Init->getAsString();
if (Offset < Result.size()) {
// If we are pointing INTO The string, erase the beginning...
Result.erase(Result.begin(), Result.begin()+Offset);
// Take off the null terminator, and any string fragments after it.
std::string::size_type NullPos = Result.find_first_of((char)0);
if (NullPos != std::string::npos)
Result.erase(Result.begin()+NullPos, Result.end());
return Result;
}
}
}
} else if (Constant *C = dyn_cast<Constant>(V)) {
if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
return getStringValue(GV, Offset);
else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
// Turn a gep into the specified offset.
if (CE->getNumOperands() == 3 &&
cast<Constant>(CE->getOperand(1))->isNullValue() &&
isa<ConstantInt>(CE->getOperand(2))) {
return getStringValue(CE->getOperand(0),
Offset+cast<ConstantInt>(CE->getOperand(2))->getRawValue());
}
static std::string getStringValue(GlobalVariable *GV, unsigned Offset = 0) {
if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
if (Init->isString()) {
std::string Result = Init->getAsString();
if (Offset < Result.size()) {
// If we are pointing INTO The string, erase the beginning...
Result.erase(Result.begin(), Result.begin()+Offset);
return Result;
}
}
}
@ -1523,13 +1502,10 @@ void SelectionDAGLowering::visitFrameReturnAddress(CallInst &I, bool isFrame) {
DAG.setRoot(Result.second);
}
/// getMemSetValue - Vectorized representation of the memset value
/// getMemsetValue - Vectorized representation of the memset value
/// operand.
static SDOperand getMemsetValue(SDOperand Value, MVT::ValueType VT,
SelectionDAG &DAG) {
if (VT == MVT::i8)
return Value;
SelectionDAG &DAG, TargetLowering &TLI) {
MVT::ValueType CurVT = VT;
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Value)) {
uint64_t Val = C->getValue() & 255;
@ -1556,6 +1532,24 @@ static SDOperand getMemsetValue(SDOperand Value, MVT::ValueType VT,
}
}
/// getMemsetStringVal - Similar to getMemsetValue. Except this is only
/// used when a memcpy is turned into a memset when the source is a constant
/// string ptr.
static SDOperand getMemsetStringVal(MVT::ValueType VT,
SelectionDAG &DAG, TargetLowering &TLI,
std::string &Str, unsigned Offset) {
MVT::ValueType CurVT = VT;
uint64_t Val = 0;
unsigned MSB = getSizeInBits(VT) / 8;
if (TLI.isLittleEndian())
Offset = Offset + MSB - 1;
for (unsigned i = 0; i != MSB; ++i) {
Val = (Val << 8) | Str[Offset];
Offset += TLI.isLittleEndian() ? -1 : 1;
}
return DAG.getConstant(Val, VT);
}
/// getMemBasePlusOffset - Returns base and offset node for the
static SDOperand getMemBasePlusOffset(SDOperand Base, unsigned Offset,
SelectionDAG &DAG, TargetLowering &TLI) {
@ -1640,7 +1634,7 @@ void SelectionDAGLowering::visitMemIntrinsic(CallInst &I, unsigned Op) {
for (unsigned i = 0; i < NumMemOps; i++) {
MVT::ValueType VT = MemOps[i];
unsigned VTSize = getSizeInBits(VT) / 8;
SDOperand Value = getMemsetValue(Op2, VT, DAG);
SDOperand Value = getMemsetValue(Op2, VT, DAG, TLI);
SDOperand Store = DAG.getNode(ISD::STORE, MVT::Other, getRoot(),
Value,
getMemBasePlusOffset(Op1, Offset, DAG, TLI),
@ -1655,21 +1649,49 @@ void SelectionDAGLowering::visitMemIntrinsic(CallInst &I, unsigned Op) {
if (MeetsMaxMemopRequirement(MemOps, TLI.getMaxStoresPerMemcpy(),
Size->getValue(), Align, TLI)) {
unsigned NumMemOps = MemOps.size();
unsigned Offset = 0;
unsigned SrcOff = 0, DstOff = 0;
GlobalAddressSDNode *G = NULL;
std::string Str;
if (Op2.getOpcode() == ISD::GlobalAddress)
G = cast<GlobalAddressSDNode>(Op2);
else if (Op2.getOpcode() == ISD::ADD &&
Op2.getOperand(0).getOpcode() == ISD::GlobalAddress &&
Op2.getOperand(1).getOpcode() == ISD::Constant) {
G = cast<GlobalAddressSDNode>(Op2.getOperand(0));
SrcOff += cast<ConstantSDNode>(Op2.getOperand(1))->getValue();
}
if (G) {
GlobalVariable *GV = dyn_cast<GlobalVariable>(G->getGlobal());
if (GV)
Str = getStringValue(GV);
}
for (unsigned i = 0; i < NumMemOps; i++) {
MVT::ValueType VT = MemOps[i];
unsigned VTSize = getSizeInBits(VT) / 8;
SDOperand Value =
DAG.getLoad(VT, getRoot(),
getMemBasePlusOffset(Op2, Offset, DAG, TLI),
DAG.getSrcValue(I.getOperand(2), Offset));
SDOperand Store =
DAG.getNode(ISD::STORE, MVT::Other, Value.getValue(1),
Value,
getMemBasePlusOffset(Op1, Offset, DAG, TLI),
DAG.getSrcValue(I.getOperand(1), Offset));
SDOperand Value, Chain, Store;
if (!Str.empty()) {
Value = getMemsetStringVal(VT, DAG, TLI, Str, SrcOff);
Chain = getRoot();
Store =
DAG.getNode(ISD::STORE, MVT::Other, Chain, Value,
getMemBasePlusOffset(Op1, DstOff, DAG, TLI),
DAG.getSrcValue(I.getOperand(1), DstOff));
} else {
Value = DAG.getLoad(VT, getRoot(),
getMemBasePlusOffset(Op2, SrcOff, DAG, TLI),
DAG.getSrcValue(I.getOperand(2), SrcOff));
Chain = Value.getValue(1);
Store =
DAG.getNode(ISD::STORE, MVT::Other, Chain, Value,
getMemBasePlusOffset(Op1, DstOff, DAG, TLI),
DAG.getSrcValue(I.getOperand(1), DstOff));
}
OutChains.push_back(Store);
Offset += VTSize;
SrcOff += VTSize;
DstOff += VTSize;
}
}
break;