maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

Lo and behold, the last bits of SelectionDAG.cpp have been moved over. 

llvm-svn: 23665
This commit is contained in:
Nate Begeman 2005-10-08 00:29:44 +00:00
parent dae96f8881
commit 2042aa5b92
1 changed files with 150 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

156
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -39,6 +39,7 @@
// is >= to that of the extend.
// FIXME: divide by zero is currently left unfolded. do we want to turn this
// into an undef?
// FIXME: select ne (select cc, 1, 0), 0, true, false -> select cc, true, false
//
//===----------------------------------------------------------------------===//
@ -1112,12 +1113,6 @@ SDOperand DAGCombiner::visitSELECT_CC(SDNode *N) {
// fold select_cc lhs, rhs, x, x, cc -> x
if (N2 == N3)
return N2;
// fold select_cc true, x, y -> x
if (SCCC && SCCC->getValue())
return N2;
// fold select_cc false, x, y -> y
if (SCCC && SCCC->getValue() == 0)
return N3;
// fold select_cc into other things, such as min/max/abs
return SimplifySelectCC(N0, N1, N2, N3, CC);
}
@ -1507,12 +1502,161 @@ SDOperand DAGCombiner::visitBRTWOWAY_CC(SDNode *N) {
}
SDOperand DAGCombiner::SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2){
assert(N0.getOpcode() ==ISD::SETCC && "First argument must be a SetCC node!");
SDOperand SCC = SimplifySelectCC(N0.getOperand(0), N0.getOperand(1), N1, N2,
cast<CondCodeSDNode>(N0.getOperand(2))->get());
// If we got a simplified select_cc node back from SimplifySelectCC, then
// break it down into a new SETCC node, and a new SELECT node, and then return
// the SELECT node, since we were called with a SELECT node.
if (SCC.Val) {
// Check to see if we got a select_cc back (to turn into setcc/select).
// Otherwise, just return whatever node we got back, like fabs.
if (SCC.getOpcode() == ISD::SELECT_CC) {
SDOperand SETCC = DAG.getNode(ISD::SETCC, N0.getValueType(),
SCC.getOperand(0), SCC.getOperand(1),
SCC.getOperand(4));
WorkList.push_back(SETCC.Val);
return DAG.getNode(ISD::SELECT, SCC.getValueType(), SCC.getOperand(2),
SCC.getOperand(3), SETCC);
}
return SCC;
}
return SDOperand();
}
SDOperand DAGCombiner::SimplifySelectCC(SDOperand N0, SDOperand N1,
SDOperand N2, SDOperand N3,
ISD::CondCode CC) {
MVT::ValueType VT = N2.getValueType();
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.Val);
ConstantSDNode *N3C = dyn_cast<ConstantSDNode>(N3.Val);
// Determine if the condition we're dealing with is constant
SDOperand SCC = SimplifySetCC(TLI.getSetCCResultTy(), N0, N1, CC, false);
ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val);
// fold select_cc true, x, y -> x
if (SCCC && SCCC->getValue())
return N2;
// fold select_cc false, x, y -> y
if (SCCC && SCCC->getValue() == 0)
return N3;
// Check to see if we can simplify the select into an fabs node
if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1)) {
// Allow either -0.0 or 0.0
if (CFP->getValue() == 0.0) {
// select (setg[te] X, +/-0.0), X, fneg(X) -> fabs
if ((CC == ISD::SETGE || CC == ISD::SETGT) &&
N0 == N2 && N3.getOpcode() == ISD::FNEG &&
N2 == N3.getOperand(0))
return DAG.getNode(ISD::FABS, VT, N0);
// select (setl[te] X, +/-0.0), fneg(X), X -> fabs
if ((CC == ISD::SETLT || CC == ISD::SETLE) &&
N0 == N3 && N2.getOpcode() == ISD::FNEG &&
N2.getOperand(0) == N3)
return DAG.getNode(ISD::FABS, VT, N3);
}
}
// Check to see if we can perform the "gzip trick", transforming
// select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A
if (N1C && N1C->isNullValue() && N3C && N3C->isNullValue() &&
MVT::isInteger(N0.getValueType()) &&
MVT::isInteger(N2.getValueType()) && CC == ISD::SETLT) {
MVT::ValueType XType = N0.getValueType();
MVT::ValueType AType = N2.getValueType();
if (XType >= AType) {
// and (sra X, size(X)-1, A) -> "and (srl X, C2), A" iff A is a
// single-bit constant. FIXME: remove once the dag combiner
// exists.
if (N2C && ((N2C->getValue() & (N2C->getValue()-1)) == 0)) {
unsigned ShCtV = Log2_64(N2C->getValue());
ShCtV = MVT::getSizeInBits(XType)-ShCtV-1;
SDOperand ShCt = DAG.getConstant(ShCtV, TLI.getShiftAmountTy());
SDOperand Shift = DAG.getNode(ISD::SRL, XType, N0, ShCt);
WorkList.push_back(Shift.Val);
if (XType > AType) {
Shift = DAG.getNode(ISD::TRUNCATE, AType, Shift);
WorkList.push_back(Shift.Val);
}
return DAG.getNode(ISD::AND, AType, Shift, N2);
}
SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
DAG.getConstant(MVT::getSizeInBits(XType)-1,
TLI.getShiftAmountTy()));
WorkList.push_back(Shift.Val);
if (XType > AType) {
Shift = DAG.getNode(ISD::TRUNCATE, AType, Shift);
WorkList.push_back(Shift.Val);
}
return DAG.getNode(ISD::AND, AType, Shift, N2);
}
}
// Check to see if this is the equivalent of setcc
// FIXME: Turn all of these into setcc if setcc if setcc is legal
// otherwise, go ahead with the folds.
if (0 && N3C && N3C->isNullValue() && N2C && (N2C->getValue() == 1ULL)) {
MVT::ValueType XType = N0.getValueType();
if (TLI.isOperationLegal(ISD::SETCC, TLI.getSetCCResultTy())) {
SDOperand Res = DAG.getSetCC(TLI.getSetCCResultTy(), N0, N1, CC);
if (Res.getValueType() != VT)
Res = DAG.getNode(ISD::ZERO_EXTEND, VT, Res);
return Res;
}
// seteq X, 0 -> srl (ctlz X, log2(size(X)))
if (N1C && N1C->isNullValue() && CC == ISD::SETEQ &&
TLI.isOperationLegal(ISD::CTLZ, XType)) {
SDOperand Ctlz = DAG.getNode(ISD::CTLZ, XType, N0);
return DAG.getNode(ISD::SRL, XType, Ctlz,
DAG.getConstant(Log2_32(MVT::getSizeInBits(XType)),
TLI.getShiftAmountTy()));
}
// setgt X, 0 -> srl (and (-X, ~X), size(X)-1)
if (N1C && N1C->isNullValue() && CC == ISD::SETGT) {
SDOperand NegN0 = DAG.getNode(ISD::SUB, XType, DAG.getConstant(0, XType),
N0);
SDOperand NotN0 = DAG.getNode(ISD::XOR, XType, N0,
DAG.getConstant(~0ULL, XType));
return DAG.getNode(ISD::SRL, XType,
DAG.getNode(ISD::AND, XType, NegN0, NotN0),
DAG.getConstant(MVT::getSizeInBits(XType)-1,
TLI.getShiftAmountTy()));
}
// setgt X, -1 -> xor (srl (X, size(X)-1), 1)
if (N1C && N1C->isAllOnesValue() && CC == ISD::SETGT) {
SDOperand Sign = DAG.getNode(ISD::SRL, XType, N0,
DAG.getConstant(MVT::getSizeInBits(XType)-1,
TLI.getShiftAmountTy()));
return DAG.getNode(ISD::XOR, XType, Sign, DAG.getConstant(1, XType));
}
}
// Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) &&
N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1)) {
if (ConstantSDNode *SubC = dyn_cast<ConstantSDNode>(N2.getOperand(0))) {
MVT::ValueType XType = N0.getValueType();
if (SubC->isNullValue() && MVT::isInteger(XType)) {
SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
DAG.getConstant(MVT::getSizeInBits(XType)-1,
TLI.getShiftAmountTy()));
SDOperand Add = DAG.getNode(ISD::ADD, XType, N0, Shift);
WorkList.push_back(Shift.Val);
WorkList.push_back(Add.Val);
return DAG.getNode(ISD::XOR, XType, Add, Shift);
}
}
}
return SDOperand();
}