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Remove special case for SETCC opcode; add some comments explaining why

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some special cases are necessary.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72511 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eli Friedman 2009-05-28 03:56:57 +00:00
parent 2d92c71668
commit ad75460e30
1 changed files with 63 additions and 73 deletions
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136
lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@ -761,12 +761,20 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
}
case ISD::LOAD:
case ISD::STORE:
case ISD::FORMAL_ARGUMENTS:
case ISD::CALL:
// FIXME: Model these properly. LOAD and STORE are complicated, and
// STORE expects the unlegalized operand in some cases.
SimpleFinishLegalizing = false;
break;
case ISD::CALLSEQ_START:
case ISD::CALLSEQ_END:
// These instructions have properties that aren't modeled in the
// generic codepath
// FIXME: This shouldn't be necessary. These nodes have special properties
// dealing with the recursive nature of legalization. Removing this
// special case should be done as part of making LegalizeDAG non-recursive.
SimpleFinishLegalizing = false;
break;
case ISD::CALL:
// FIXME: Legalization for calls requires custom-lowering the call before
// legalizing the operands! (I haven't looked into precisely why.)
SimpleFinishLegalizing = false;
break;
case ISD::EXTRACT_ELEMENT:
@ -790,6 +798,7 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
case ISD::TRAMPOLINE:
case ISD::FRAMEADDR:
case ISD::RETURNADDR:
case ISD::FORMAL_ARGUMENTS:
// These operations lie about being legal: when they claim to be legal,
// they should actually be custom-lowered.
Action = TLI.getOperationAction(Node->getOpcode(), Node->getValueType(0));
@ -892,7 +901,6 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
#endif
assert(0 && "Do not know how to legalize this operator!");
abort();
case ISD::FORMAL_ARGUMENTS:
case ISD::CALL:
// The only option for this is to custom lower it.
Tmp3 = TLI.LowerOperation(Result.getValue(0), DAG);
@ -1534,74 +1542,6 @@ SDValue SelectionDAGLegalize::LegalizeOp(SDValue Op) {
}
break;
}
case ISD::SETCC:
Tmp1 = Node->getOperand(0);
Tmp2 = Node->getOperand(1);
Tmp3 = Node->getOperand(2);
LegalizeSetCC(Node->getValueType(0), Tmp1, Tmp2, Tmp3, dl);
// If we had to Expand the SetCC operands into a SELECT node, then it may
// not always be possible to return a true LHS & RHS. In this case, just
// return the value we legalized, returned in the LHS
if (Tmp2.getNode() == 0) {
Result = Tmp1;
break;
}
switch (TLI.getOperationAction(ISD::SETCC, Tmp1.getValueType())) {
default: assert(0 && "Cannot handle this action for SETCC yet!");
case TargetLowering::Custom:
isCustom = true;
// FALLTHROUGH.
case TargetLowering::Legal:
Result = DAG.UpdateNodeOperands(Result, Tmp1, Tmp2, Tmp3);
if (isCustom) {
Tmp4 = TLI.LowerOperation(Result, DAG);
if (Tmp4.getNode()) Result = Tmp4;
}
break;
case TargetLowering::Promote: {
// First step, figure out the appropriate operation to use.
// Allow SETCC to not be supported for all legal data types
// Mostly this targets FP
MVT NewInTy = Node->getOperand(0).getValueType();
MVT OldVT = NewInTy; OldVT = OldVT;
// Scan for the appropriate larger type to use.
while (1) {
NewInTy = (MVT::SimpleValueType)(NewInTy.getSimpleVT()+1);
assert(NewInTy.isInteger() == OldVT.isInteger() &&
"Fell off of the edge of the integer world");
assert(NewInTy.isFloatingPoint() == OldVT.isFloatingPoint() &&
"Fell off of the edge of the floating point world");
// If the target supports SETCC of this type, use it.
if (TLI.isOperationLegalOrCustom(ISD::SETCC, NewInTy))
break;
}
if (NewInTy.isInteger())
assert(0 && "Cannot promote Legal Integer SETCC yet");
else {
Tmp1 = DAG.getNode(ISD::FP_EXTEND, dl, NewInTy, Tmp1);
Tmp2 = DAG.getNode(ISD::FP_EXTEND, dl, NewInTy, Tmp2);
}
Tmp1 = LegalizeOp(Tmp1);
Tmp2 = LegalizeOp(Tmp2);
Result = DAG.UpdateNodeOperands(Result, Tmp1, Tmp2, Tmp3);
Result = LegalizeOp(Result);
break;
}
case TargetLowering::Expand:
// Expand a setcc node into a select_cc of the same condition, lhs, and
// rhs that selects between const 1 (true) and const 0 (false).
MVT VT = Node->getValueType(0);
Result = DAG.getNode(ISD::SELECT_CC, dl, VT, Tmp1, Tmp2,
DAG.getConstant(1, VT), DAG.getConstant(0, VT),
Tmp3);
break;
}
break;
}
assert(Result.getValueType() == Op.getValueType() &&
@ -3017,6 +2957,26 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
}
Results.push_back(Tmp1);
break;
case ISD::SETCC: {
Tmp1 = Node->getOperand(0);
Tmp2 = Node->getOperand(1);
Tmp3 = Node->getOperand(2);
LegalizeSetCC(Node->getValueType(0), Tmp1, Tmp2, Tmp3, dl);
// If we expanded the SETCC into an AND/OR, return the new node
if (Tmp2.getNode() == 0) {
Results.push_back(Tmp1);
break;
}
// Otherwise, SETCC for the given comparison type must be completely
// illegal; expand it into a SELECT_CC.
MVT VT = Node->getValueType(0);
Tmp1 = DAG.getNode(ISD::SELECT_CC, dl, VT, Tmp1, Tmp2,
DAG.getConstant(1, VT), DAG.getConstant(0, VT), Tmp3);
Results.push_back(Tmp1);
break;
}
case ISD::GLOBAL_OFFSET_TABLE:
case ISD::GlobalAddress:
case ISD::GlobalTLSAddress:
@ -3136,6 +3096,36 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node,
Results.push_back(Tmp1);
break;
}
case ISD::SETCC: {
// First step, figure out the appropriate operation to use.
// Allow SETCC to not be supported for all legal data types
// Mostly this targets FP
MVT NewInTy = Node->getOperand(0).getValueType();
MVT OldVT = NewInTy; OldVT = OldVT;
// Scan for the appropriate larger type to use.
while (1) {
NewInTy = (MVT::SimpleValueType)(NewInTy.getSimpleVT()+1);
assert(NewInTy.isInteger() == OldVT.isInteger() &&
"Fell off of the edge of the integer world");
assert(NewInTy.isFloatingPoint() == OldVT.isFloatingPoint() &&
"Fell off of the edge of the floating point world");
// If the target supports SETCC of this type, use it.
if (TLI.isOperationLegalOrCustom(ISD::SETCC, NewInTy))
break;
}
if (NewInTy.isInteger())
assert(0 && "Cannot promote Legal Integer SETCC yet");
else {
Tmp1 = DAG.getNode(ISD::FP_EXTEND, dl, NewInTy, Tmp1);
Tmp2 = DAG.getNode(ISD::FP_EXTEND, dl, NewInTy, Tmp2);
}
Results.push_back(DAG.getNode(ISD::SETCC, dl, Node->getValueType(0),
Tmp1, Tmp2, Node->getOperand(2)));
break;
}
}
}