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Add a recursive-iterative hybrid stage to attempt to reduce stack space, this

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helps but not enough.

Start pulling cases out of PPC32DAGToDAGISel::Select.  With GCC 4, this function
required 8512 bytes of stack space for each invocation (GCC 3 required less
than 700 bytes).  Pulling this first function out gets us down to 8224.  More
to come :(


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23647 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-10-06 18:45:51 +00:00
parent cf5c79b34f
commit bd937b98f4
1 changed files with 94 additions and 45 deletions
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139
lib/Target/PowerPC/PPCISelDAGToDAG.cpp
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@ -83,26 +83,70 @@ namespace {
/// InstructionSelectBasicBlock - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
virtual void InstructionSelectBasicBlock(SelectionDAG &DAG) {
DEBUG(BB->dump());
// Select target instructions for the DAG.
DAG.setRoot(Select(DAG.getRoot()));
CodeGenMap.clear();
DAG.RemoveDeadNodes();
// Emit machine code to BB.
ScheduleAndEmitDAG(DAG);
}
virtual void InstructionSelectBasicBlock(SelectionDAG &DAG);
virtual const char *getPassName() const {
return "PowerPC DAG->DAG Pattern Instruction Selection";
}
// Include the pieces autogenerated from the target description.
#include "PPC32GenDAGISel.inc"
private:
SDOperand SelectDYNAMIC_STACKALLOC(SDOperand N);
};
}
/// InstructionSelectBasicBlock - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
void PPC32DAGToDAGISel::InstructionSelectBasicBlock(SelectionDAG &DAG) {
DEBUG(BB->dump());
// The selection process is inherently a bottom-up recursive process (users
// select their uses before themselves). Given infinite stack space, we
// could just start selecting on the root and traverse the whole graph. In
// practice however, this causes us to run out of stack space on large basic
// blocks. To avoid this problem, select the entry node, then all its uses,
// iteratively instead of recursively.
std::vector<SDOperand> Worklist;
Worklist.push_back(DAG.getEntryNode());
// Note that we can do this in the PPC target (scanning forward across token
// chain edges) because no nodes ever get folded across these edges. On a
// target like X86 which supports load/modify/store operations, this would
// have to be more careful.
while (!Worklist.empty()) {
SDOperand Node = Worklist.back();
Worklist.pop_back();
if ((Node.Val->getOpcode() >= ISD::BUILTIN_OP_END &&
Node.Val->getOpcode() < PPCISD::FIRST_NUMBER) ||
CodeGenMap.count(Node)) continue;
for (SDNode::use_iterator UI = Node.Val->use_begin(),
E = Node.Val->use_end(); UI != E; ++UI) {
// Scan the values. If this use has a value that is a token chain, add it
// to the worklist.
SDNode *User = *UI;
for (unsigned i = 0, e = User->getNumValues(); i != e; ++i)
if (User->getValueType(i) == MVT::Other) {
Worklist.push_back(SDOperand(User, i));
break;
}
}
// Finally, legalize this node.
Select(Node);
}
// Select target instructions for the DAG.
DAG.setRoot(Select(DAG.getRoot()));
CodeGenMap.clear();
DAG.RemoveDeadNodes();
// Emit machine code to BB.
ScheduleAndEmitDAG(DAG);
}
/// getGlobalBaseReg - Output the instructions required to put the
/// base address to use for accessing globals into a register.
@ -632,6 +676,43 @@ SDOperand PPC32DAGToDAGISel::BuildUDIVSequence(SDNode *N) {
}
}
SDOperand PPC32DAGToDAGISel::SelectDYNAMIC_STACKALLOC(SDOperand Op) {
SDNode *N = Op.Val;
// FIXME: We are currently ignoring the requested alignment for handling
// greater than the stack alignment. This will need to be revisited at some
// point. Align = N.getOperand(2);
if (!isa<ConstantSDNode>(N->getOperand(2)) ||
cast<ConstantSDNode>(N->getOperand(2))->getValue() != 0) {
std::cerr << "Cannot allocate stack object with greater alignment than"
<< " the stack alignment yet!";
abort();
}
SDOperand Chain = Select(N->getOperand(0));
SDOperand Amt = Select(N->getOperand(1));
SDOperand R1Reg = CurDAG->getRegister(PPC::R1, MVT::i32);
SDOperand R1Val = CurDAG->getCopyFromReg(Chain, PPC::R1, MVT::i32);
Chain = R1Val.getValue(1);
// Subtract the amount (guaranteed to be a multiple of the stack alignment)
// from the stack pointer, giving us the result pointer.
SDOperand Result = CurDAG->getTargetNode(PPC::SUBF, MVT::i32, Amt, R1Val);
// Copy this result back into R1.
Chain = CurDAG->getNode(ISD::CopyToReg, MVT::Other, Chain, R1Reg, Result);
// Copy this result back out of R1 to make sure we're not using the stack
// space without decrementing the stack pointer.
Result = CurDAG->getCopyFromReg(Chain, PPC::R1, MVT::i32);
// Finally, replace the DYNAMIC_STACKALLOC with the copyfromreg.
CodeGenMap[Op.getValue(0)] = Result;
CodeGenMap[Op.getValue(1)] = Result.getValue(1);
return SDOperand(Result.Val, Op.ResNo);
}
// Select - Convert the specified operand from a target-independent to a
// target-specific node if it hasn't already been changed.
SDOperand PPC32DAGToDAGISel::Select(SDOperand Op) {
@ -718,40 +799,8 @@ SDOperand PPC32DAGToDAGISel::Select(SDOperand Op) {
CurDAG->SelectNodeTo(N, PPC::LA, MVT::i32, Tmp, GA);
return SDOperand(N, 0);
}
case ISD::DYNAMIC_STACKALLOC: {
// FIXME: We are currently ignoring the requested alignment for handling
// greater than the stack alignment. This will need to be revisited at some
// point. Align = N.getOperand(2);
if (!isa<ConstantSDNode>(N->getOperand(2)) ||
cast<ConstantSDNode>(N->getOperand(2))->getValue() != 0) {
std::cerr << "Cannot allocate stack object with greater alignment than"
<< " the stack alignment yet!";
abort();
}
SDOperand Chain = Select(N->getOperand(0));
SDOperand Amt = Select(N->getOperand(1));
SDOperand R1Reg = CurDAG->getRegister(PPC::R1, MVT::i32);
SDOperand R1Val = CurDAG->getCopyFromReg(Chain, PPC::R1, MVT::i32);
Chain = R1Val.getValue(1);
// Subtract the amount (guaranteed to be a multiple of the stack alignment)
// from the stack pointer, giving us the result pointer.
SDOperand Result = CurDAG->getTargetNode(PPC::SUBF, MVT::i32, Amt, R1Val);
// Copy this result back into R1.
Chain = CurDAG->getNode(ISD::CopyToReg, MVT::Other, Chain, R1Reg, Result);
// Copy this result back out of R1 to make sure we're not using the stack
// space without decrementing the stack pointer.
Result = CurDAG->getCopyFromReg(Chain, PPC::R1, MVT::i32);
// Finally, replace the DYNAMIC_STACKALLOC with the copyfromreg.
CodeGenMap[Op.getValue(0)] = Result;
CodeGenMap[Op.getValue(1)] = Result.getValue(1);
return SDOperand(Result.Val, Op.ResNo);
}
case ISD::DYNAMIC_STACKALLOC:
return SelectDYNAMIC_STACKALLOC(Op);
case PPCISD::FSEL: {
SDOperand Comparison = Select(N->getOperand(0));
// Extend the comparison to 64-bits.