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Completely rewrite libcall insertion by the legalizer, providing the

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following handy-dandy properties:

1. it is always correct now
2. it is much faster than before
3. it is easier to understand

This implementation builds off of the recent simplifications of the
legalizer that made it single-pass instead of iterative.

This fixes JM/lencod, JM/ldecod, and
CodeGen/Generic/2006-02-12-InsertLibcall.ll (at least on PPC).

llvm-svn: 26144
This commit is contained in:
Chris Lattner 2006-02-13 09:18:02 +00:00
parent 599b432345
commit b3fc3e3a90
1 changed files with 217 additions and 198 deletions
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415
lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -41,12 +41,24 @@ class SelectionDAGLegalize {
TargetLowering &TLI;
SelectionDAG &DAG;
// Libcall insertion helpers.
/// LastCALLSEQ_END - This keeps track of the CALLSEQ_END node that has been
/// legalized. We use this to ensure that calls are properly serialized
/// against each other, including inserted libcalls.
SDOperand LastCALLSEQ_END;
/// IsLegalizingCall - This member is used *only* for purposes of providing
/// helpful assertions that a libcall isn't created while another call is
/// being legalized (which could lead to non-serialized call sequences).
bool IsLegalizingCall;
enum LegalizeAction {
Legal, // The target natively supports this operation.
Promote, // This operation should be executed in a larger type.
Expand, // Try to expand this to other ops, otherwise use a libcall.
};
/// ValueTypeActions - This is a bitvector that contains two bits for each
/// value type, where the two bits correspond to the LegalizeAction enum.
/// This can be queried with "getTypeAction(VT)".
@ -106,6 +118,8 @@ private:
void ExpandOp(SDOperand O, SDOperand &Lo, SDOperand &Hi);
SDOperand PromoteOp(SDOperand O);
bool LegalizeAllNodesNotLeadingTo(SDNode *N, SDNode *Dest);
void LegalizeSetCCOperands(SDOperand &LHS, SDOperand &RHS, SDOperand &CC);
SDOperand ExpandLibCall(const char *Name, SDNode *Node,
@ -128,7 +142,6 @@ private:
SDOperand &Lo, SDOperand &Hi);
void ExpandShiftParts(unsigned NodeOp, SDOperand Op, SDOperand Amt,
SDOperand &Lo, SDOperand &Hi);
void SpliceCallInto(const SDOperand &CallResult, SDNode *OutChain);
SDOperand getIntPtrConstant(uint64_t Val) {
return DAG.getConstant(Val, TLI.getPointerTy());
@ -174,6 +187,9 @@ static void ComputeTopDownOrdering(SDNode *N, std::vector<SDNode*> &Order,
void SelectionDAGLegalize::LegalizeDAG() {
LastCALLSEQ_END = DAG.getEntryNode();
IsLegalizingCall = false;
// The legalize process is inherently a bottom-up recursive process (users
// legalize their uses before themselves). Given infinite stack space, we
// could just start legalizing on the root and traverse the whole graph. In
@ -230,6 +246,107 @@ void SelectionDAGLegalize::LegalizeDAG() {
DAG.RemoveDeadNodes(OldRoot.Val);
}
/// FindCallEndFromCallStart - Given a chained node that is part of a call
/// sequence, find the CALLSEQ_END node that terminates the call sequence.
static SDNode *FindCallEndFromCallStart(SDNode *Node) {
if (Node->getOpcode() == ISD::CALLSEQ_END)
return Node;
if (Node->use_empty())
return 0; // No CallSeqEnd
// The chain is usually at the end.
SDOperand TheChain(Node, Node->getNumValues()-1);
if (TheChain.getValueType() != MVT::Other) {
// Sometimes it's at the beginning.
TheChain = SDOperand(Node, 0);
if (TheChain.getValueType() != MVT::Other) {
// Otherwise, hunt for it.
for (unsigned i = 1, e = Node->getNumValues(); i != e; ++i)
if (Node->getValueType(i) == MVT::Other) {
TheChain = SDOperand(Node, i);
break;
}
// Otherwise, we walked into a node without a chain.
if (TheChain.getValueType() != MVT::Other)
return 0;
}
}
for (SDNode::use_iterator UI = Node->use_begin(),
E = Node->use_end(); UI != E; ++UI) {
// Make sure to only follow users of our token chain.
SDNode *User = *UI;
for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i)
if (User->getOperand(i) == TheChain)
if (SDNode *Result = FindCallEndFromCallStart(User))
return Result;
}
return 0;
}
/// FindCallStartFromCallEnd - Given a chained node that is part of a call
/// sequence, find the CALLSEQ_START node that initiates the call sequence.
static SDNode *FindCallStartFromCallEnd(SDNode *Node) {
assert(Node && "Didn't find callseq_start for a call??");
if (Node->getOpcode() == ISD::CALLSEQ_START) return Node;
assert(Node->getOperand(0).getValueType() == MVT::Other &&
"Node doesn't have a token chain argument!");
return FindCallStartFromCallEnd(Node->getOperand(0).Val);
}
/// LegalizeAllNodesNotLeadingTo - Recursively walk the uses of N, looking to
/// see if any uses can reach Dest. If no dest operands can get to dest,
/// legalize them, legalize ourself, and return false, otherwise, return true.
bool SelectionDAGLegalize::LegalizeAllNodesNotLeadingTo(SDNode *N,
SDNode *Dest) {
if (N == Dest) return true; // N certainly leads to Dest :)
// If the first result of this node has been already legalized, then it cannot
// reach N.
switch (getTypeAction(N->getValueType(0))) {
case Legal:
if (LegalizedNodes.count(SDOperand(N, 0))) return false;
break;
case Promote:
if (PromotedNodes.count(SDOperand(N, 0))) return false;
break;
case Expand:
if (ExpandedNodes.count(SDOperand(N, 0))) return false;
break;
}
// Okay, this node has not already been legalized. Check and legalize all
// operands. If none lead to Dest, then we can legalize this node.
bool OperandsLeadToDest = false;
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
OperandsLeadToDest |= // If an operand leads to Dest, so do we.
LegalizeAllNodesNotLeadingTo(N->getOperand(i).Val, Dest);
if (OperandsLeadToDest) return true;
// Okay, this node looks safe, legalize it and return false.
switch (getTypeAction(N->getValueType(0))) {
case Legal:
LegalizeOp(SDOperand(N, 0));
break;
case Promote:
PromoteOp(SDOperand(N, 0));
break;
case Expand: {
SDOperand X, Y;
ExpandOp(SDOperand(N, 0), X, Y);
break;
}
}
return false;
}
SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
assert(isTypeLegal(Op.getValueType()) &&
"Caller should expand or promote operands that are not legal!");
@ -586,8 +703,62 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
}
break;
case ISD::CALLSEQ_START:
case ISD::CALLSEQ_START: {
SDNode *CallEnd = FindCallEndFromCallStart(Node);
// Recursively Legalize all of the inputs of the call end that do not lead
// to this call start. This ensures that any libcalls that need be inserted
// are inserted *before* the CALLSEQ_START.
for (unsigned i = 0, e = CallEnd->getNumOperands(); i != e; ++i)
LegalizeAllNodesNotLeadingTo(CallEnd->getOperand(i).Val, Node);
// Now that we legalized all of the inputs (which may have inserted
// libcalls) create the new CALLSEQ_START node.
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Merge in the last call, to ensure that this call start after the last
// call ended.
Tmp1 = DAG.getNode(ISD::TokenFactor, MVT::Other, Tmp1, LastCALLSEQ_END);
Tmp1 = LegalizeOp(Tmp1);
// Do not try to legalize the target-specific arguments (#1+).
if (Tmp1 != Node->getOperand(0)) {
std::vector<SDOperand> Ops(Node->op_begin(), Node->op_end());
Ops[0] = Tmp1;
Result = DAG.UpdateNodeOperands(Result, Ops);
}
// Remember that the CALLSEQ_START is legalized.
AddLegalizedOperand(Op, Result);
// Now that the callseq_start and all of the non-call nodes above this call
// sequence have been legalized, legalize the call itself. During this
// process, no libcalls can/will be inserted, guaranteeing that no calls
// can overlap.
assert(!IsLegalizingCall && "Inconsistent sequentialization of calls!");
SDOperand InCallSEQ = LastCALLSEQ_END;
// Note that we are selecting this call!
LastCALLSEQ_END = SDOperand(CallEnd, 0);
IsLegalizingCall = true;
// Legalize the call, starting from the CALLSEQ_END.
LegalizeOp(LastCALLSEQ_END);
assert(!IsLegalizingCall && "CALLSEQ_END should have cleared this!");
return Result;
}
case ISD::CALLSEQ_END:
// If the CALLSEQ_START node hasn't been legalized first, legalize it. This
// will cause this node to be legalized as well as handling libcalls right.
if (LastCALLSEQ_END.Val != Node) {
LegalizeOp(SDOperand(FindCallStartFromCallEnd(Node), 0));
std::map<SDOperand, SDOperand>::iterator I = LegalizedNodes.find(Op);
assert(I != LegalizedNodes.end() &&
"Legalizing the call start should have legalized this node!");
return I->second;
}
// Otherwise, the call start has been legalized and everything is going
// according to plan. Just legalize ourselves normally here.
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Do not try to legalize the target-specific arguments (#1+), except for
// an optional flag input.
@ -607,6 +778,9 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
Result = DAG.UpdateNodeOperands(Result, Ops);
}
}
assert(IsLegalizingCall && "imbalance between START/END?");
// This finishes up call legalization.
IsLegalizingCall = false;
break;
case ISD::DYNAMIC_STACKALLOC: {
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
@ -669,12 +843,21 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
return Result.getValue(Op.ResNo);
case ISD::BR:
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Ensure that libcalls are emitted before a branch.
Tmp1 = DAG.getNode(ISD::TokenFactor, MVT::Other, Tmp1, LastCALLSEQ_END);
Tmp1 = LegalizeOp(Tmp1);
LastCALLSEQ_END = DAG.getEntryNode();
Result = DAG.UpdateNodeOperands(Result, Tmp1, Node->getOperand(1));
break;
case ISD::BRCOND:
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Ensure that libcalls are emitted before a return.
Tmp1 = DAG.getNode(ISD::TokenFactor, MVT::Other, Tmp1, LastCALLSEQ_END);
Tmp1 = LegalizeOp(Tmp1);
LastCALLSEQ_END = DAG.getEntryNode();
switch (getTypeAction(Node->getOperand(1).getValueType())) {
case Expand: assert(0 && "It's impossible to expand bools");
case Legal:
@ -719,6 +902,11 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
break;
case ISD::BR_CC:
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Ensure that libcalls are emitted before a branch.
Tmp1 = DAG.getNode(ISD::TokenFactor, MVT::Other, Tmp1, LastCALLSEQ_END);
Tmp1 = LegalizeOp(Tmp1);
LastCALLSEQ_END = DAG.getEntryNode();
Tmp2 = Node->getOperand(2); // LHS
Tmp3 = Node->getOperand(3); // RHS
Tmp4 = Node->getOperand(1); // CC
@ -798,6 +986,11 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
break;
case ISD::BRTWOWAY_CC: {
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Ensure that libcalls are emitted before a branch.
Tmp1 = DAG.getNode(ISD::TokenFactor, MVT::Other, Tmp1, LastCALLSEQ_END);
Tmp1 = LegalizeOp(Tmp1);
LastCALLSEQ_END = DAG.getEntryNode();
Tmp2 = Node->getOperand(2); // LHS
Tmp3 = Node->getOperand(3); // RHS
Tmp4 = Node->getOperand(1); // CC
@ -982,6 +1175,12 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
case ISD::RET:
Tmp1 = LegalizeOp(Node->getOperand(0)); // Legalize the chain.
// Ensure that libcalls are emitted before a return.
Tmp1 = DAG.getNode(ISD::TokenFactor, MVT::Other, Tmp1, LastCALLSEQ_END);
Tmp1 = LegalizeOp(Tmp1);
LastCALLSEQ_END = DAG.getEntryNode();
switch (Node->getNumOperands()) {
case 2: // ret val
switch (getTypeAction(Node->getOperand(1).getValueType())) {
@ -2803,169 +3002,6 @@ bool SelectionDAGLegalize::ExpandShift(unsigned Opc, SDOperand Op,SDOperand Amt,
return false;
}
/// FindLatestCallSeqStart - Scan up the dag to find the latest (highest
/// NodeDepth) node that is an CallSeqStart operation and occurs later than
/// Found.
static void FindLatestCallSeqStart(SDNode *Node, SDNode *&Found,
std::set<SDNode*> &Visited) {
if (Node->getNodeDepth() <= Found->getNodeDepth() ||
!Visited.insert(Node).second) return;
// If we found an CALLSEQ_START, we already know this node occurs later
// than the Found node. Just remember this node and return.
if (Node->getOpcode() == ISD::CALLSEQ_START) {
Found = Node;
return;
}
// Otherwise, scan the operands of Node to see if any of them is a call.
assert(Node->getNumOperands() != 0 &&
"All leaves should have depth equal to the entry node!");
for (unsigned i = 0, e = Node->getNumOperands()-1; i != e; ++i)
FindLatestCallSeqStart(Node->getOperand(i).Val, Found, Visited);
// Tail recurse for the last iteration.
FindLatestCallSeqStart(Node->getOperand(Node->getNumOperands()-1).Val,
Found, Visited);
}
/// FindEarliestCallSeqEnd - Scan down the dag to find the earliest (lowest
/// NodeDepth) node that is an CallSeqEnd operation and occurs more recent
/// than Found.
static void FindEarliestCallSeqEnd(SDNode *Node, SDNode *&Found,
std::set<SDNode*> &Visited) {
if ((Found && Node->getNodeDepth() >= Found->getNodeDepth()) ||
!Visited.insert(Node).second) return;
// If we found an CALLSEQ_END, we already know this node occurs earlier
// than the Found node. Just remember this node and return.
if (Node->getOpcode() == ISD::CALLSEQ_END) {
Found = Node;
return;
}
// Otherwise, scan the operands of Node to see if any of them is a call.
SDNode::use_iterator UI = Node->use_begin(), E = Node->use_end();
if (UI == E) return;
for (--E; UI != E; ++UI)
FindEarliestCallSeqEnd(*UI, Found, Visited);
// Tail recurse for the last iteration.
FindEarliestCallSeqEnd(*UI, Found, Visited);
}
/// FindCallSeqEnd - Given a chained node that is part of a call sequence,
/// find the CALLSEQ_END node that terminates the call sequence.
static SDNode *FindCallSeqEnd(SDNode *Node) {
if (Node->getOpcode() == ISD::CALLSEQ_END)
return Node;
if (Node->use_empty())
return 0; // No CallSeqEnd
// The chain is usually at the end.
SDOperand TheChain(Node, Node->getNumValues()-1);
if (TheChain.getValueType() != MVT::Other) {
// Sometimes it's at the beginning.
TheChain = SDOperand(Node, 0);
if (TheChain.getValueType() != MVT::Other) {
// Otherwise, hunt for it.
for (unsigned i = 1, e = Node->getNumValues(); i != e; ++i)
if (Node->getValueType(i) == MVT::Other) {
TheChain = SDOperand(Node, i);
break;
}
// Otherwise, we walked into a node without a chain.
if (TheChain.getValueType() != MVT::Other)
return 0;
}
}
for (SDNode::use_iterator UI = Node->use_begin(),
E = Node->use_end(); UI != E; ++UI) {
// Make sure to only follow users of our token chain.
SDNode *User = *UI;
for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i)
if (User->getOperand(i) == TheChain)
if (SDNode *Result = FindCallSeqEnd(User))
return Result;
}
return 0;
}
/// FindCallSeqStart - Given a chained node that is part of a call sequence,
/// find the CALLSEQ_START node that initiates the call sequence.
static SDNode *FindCallSeqStart(SDNode *Node) {
assert(Node && "Didn't find callseq_start for a call??");
if (Node->getOpcode() == ISD::CALLSEQ_START) return Node;
assert(Node->getOperand(0).getValueType() == MVT::Other &&
"Node doesn't have a token chain argument!");
return FindCallSeqStart(Node->getOperand(0).Val);
}
/// FindInputOutputChains - If we are replacing an operation with a call we need
/// to find the call that occurs before and the call that occurs after it to
/// properly serialize the calls in the block. The returned operand is the
/// input chain value for the new call (e.g. the entry node or the previous
/// call), and OutChain is set to be the chain node to update to point to the
/// end of the call chain.
static SDOperand FindInputOutputChains(SDNode *OpNode, SDNode *&OutChain,
SDOperand Entry) {
SDNode *LatestCallSeqStart = Entry.Val;
SDNode *LatestCallSeqEnd = 0;
std::set<SDNode*> Visited;
FindLatestCallSeqStart(OpNode, LatestCallSeqStart, Visited);
Visited.clear();
//std::cerr<<"Found node: "; LatestCallSeqStart->dump(); std::cerr <<"\n";
// It is possible that no ISD::CALLSEQ_START was found because there is no
// previous call in the function. LatestCallStackDown may in that case be
// the entry node itself. Do not attempt to find a matching CALLSEQ_END
// unless LatestCallStackDown is an CALLSEQ_START.
if (LatestCallSeqStart->getOpcode() == ISD::CALLSEQ_START) {
LatestCallSeqEnd = FindCallSeqEnd(LatestCallSeqStart);
//std::cerr<<"Found end node: "; LatestCallSeqEnd->dump(); std::cerr <<"\n";
} else {
LatestCallSeqEnd = Entry.Val;
}
assert(LatestCallSeqEnd && "NULL return from FindCallSeqEnd");
// Finally, find the first call that this must come before, first we find the
// CallSeqEnd that ends the call.
OutChain = 0;
FindEarliestCallSeqEnd(OpNode, OutChain, Visited);
Visited.clear();
// If we found one, translate from the adj up to the callseq_start.
if (OutChain)
OutChain = FindCallSeqStart(OutChain);
return SDOperand(LatestCallSeqEnd, 0);
}
/// SpliceCallInto - Given the result chain of a libcall (CallResult), and a
void SelectionDAGLegalize::SpliceCallInto(const SDOperand &CallResult,
SDNode *OutChain) {
// Nothing to splice it into?
if (OutChain == 0) return;
assert(OutChain->getOperand(0).getValueType() == MVT::Other);
//OutChain->dump();
// Form a token factor node merging the old inval and the new inval.
SDOperand InToken = DAG.getNode(ISD::TokenFactor, MVT::Other, CallResult,
OutChain->getOperand(0));
// Change the node to refer to the new token.
std::vector<SDOperand> Ops(OutChain->op_begin(), OutChain->op_end());
Ops[0] = InToken;
SDOperand Res = DAG.UpdateNodeOperands(SDOperand(OutChain, 0), Ops);
assert(Res.Val == OutChain && "Didn't update in place!");
}
// ExpandLibCall - Expand a node into a call to a libcall. If the result value
// does not fit into a register, return the lo part and set the hi part to the
@ -2973,12 +3009,12 @@ void SelectionDAGLegalize::SpliceCallInto(const SDOperand &CallResult,
// and leave the Hi part unset.
SDOperand SelectionDAGLegalize::ExpandLibCall(const char *Name, SDNode *Node,
SDOperand &Hi) {
SDNode *OutChain;
SDOperand InChain = FindInputOutputChains(Node, OutChain,
DAG.getEntryNode());
if (InChain.Val == 0)
InChain = DAG.getEntryNode();
assert(!IsLegalizingCall && "Cannot overlap legalization of calls!");
// The input chain to this libcall is the entry node of the function.
// Legalizing the call will automatically add the previous call to the
// dependence.
SDOperand InChain = DAG.getEntryNode();
TargetLowering::ArgListTy Args;
for (unsigned i = 0, e = Node->getNumOperands(); i != e; ++i) {
MVT::ValueType ArgVT = Node->getOperand(i).getValueType();
@ -2993,6 +3029,10 @@ SDOperand SelectionDAGLegalize::ExpandLibCall(const char *Name, SDNode *Node,
TLI.LowerCallTo(InChain, RetTy, false, CallingConv::C, false,
Callee, Args, DAG);
// Legalize the call sequence, starting with the chain. This will advance
// the LastCALLSEQ_END to the legalized version of the CALLSEQ_END node that
// was added by LowerCallTo (guaranteeing proper serialization of calls).
LegalizeOp(CallInfo.second);
SDOperand Result;
switch (getTypeAction(CallInfo.first.getValueType())) {
default: assert(0 && "Unknown thing");
@ -3003,9 +3043,6 @@ SDOperand SelectionDAGLegalize::ExpandLibCall(const char *Name, SDNode *Node,
ExpandOp(CallInfo.first, Result, Hi);
break;
}
CallInfo.second = LegalizeOp(CallInfo.second);
SpliceCallInto(CallInfo.second, OutChain);
return Result;
}
@ -3078,9 +3115,6 @@ ExpandIntToFP(bool isSigned, MVT::ValueType DestTy, SDOperand Source) {
ExpandOp(Source, SrcLo, SrcHi);
Source = DAG.getNode(ISD::BUILD_PAIR, Source.getValueType(), SrcLo, SrcHi);
SDNode *OutChain = 0;
SDOperand InChain = FindInputOutputChains(Source.Val, OutChain,
DAG.getEntryNode());
const char *FnName = 0;
if (DestTy == MVT::f32)
FnName = "__floatdisf";
@ -3088,25 +3122,10 @@ ExpandIntToFP(bool isSigned, MVT::ValueType DestTy, SDOperand Source) {
assert(DestTy == MVT::f64 && "Unknown fp value type!");
FnName = "__floatdidf";
}
SDOperand Callee = DAG.getExternalSymbol(FnName, TLI.getPointerTy());
TargetLowering::ArgListTy Args;
const Type *ArgTy = MVT::getTypeForValueType(Source.getValueType());
Args.push_back(std::make_pair(Source, ArgTy));
// We don't care about token chains for libcalls. We just use the entry
// node as our input and ignore the output chain. This allows us to place
// calls wherever we need them to satisfy data dependences.
const Type *RetTy = MVT::getTypeForValueType(DestTy);
std::pair<SDOperand,SDOperand> CallResult =
TLI.LowerCallTo(InChain, RetTy, false, CallingConv::C, true,
Callee, Args, DAG);
SpliceCallInto(CallResult.second, OutChain);
return CallResult.first;
Source = DAG.getNode(ISD::SINT_TO_FP, DestTy, Source);
SDOperand UnusedHiPart;
return ExpandLibCall("__floatdidf", Source.Val, UnusedHiPart);
}
/// ExpandLegalINT_TO_FP - This function is responsible for legalizing a