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Check in some more DAGCombiner pieces 

llvm-svn: 23639
This commit is contained in:
Nate Begeman 2005-10-05 21:43:42 +00:00
parent 55149d7835
commit bd7df030d2
1 changed files with 45 additions and 23 deletions
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68
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -139,7 +139,7 @@ namespace {
SDOperand SimplifySelectCC(SDOperand N0, SDOperand N1, SDOperand N2, SDOperand SimplifySelectCC(SDOperand N0, SDOperand N1, SDOperand N2,
SDOperand N3, ISD::CondCode CC); SDOperand N3, ISD::CondCode CC);
SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1, SDOperand SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1,
ISD::CondCode Cond); ISD::CondCode Cond, bool foldBooleans = true);
public: public:
DAGCombiner(SelectionDAG &D) DAGCombiner(SelectionDAG &D)
: DAG(D), TLI(D.getTargetLoweringInfo()), AfterLegalize(false) {} : DAG(D), TLI(D.getTargetLoweringInfo()), AfterLegalize(false) {}
@ -1078,7 +1078,7 @@ SDOperand DAGCombiner::visitSELECT_CC(SDNode *N) {
ISD::CondCode CC = cast<CondCodeSDNode>(N4)->get(); ISD::CondCode CC = cast<CondCodeSDNode>(N4)->get();
// Determine if the condition we're dealing with is constant // Determine if the condition we're dealing with is constant
SDOperand SCC = SimplifySetCC(TLI.getSetCCResultTy(), N0, N1, CC); SDOperand SCC = SimplifySetCC(TLI.getSetCCResultTy(), N0, N1, CC, false);
ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val); ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val);
// fold select_cc lhs, rhs, x, x, cc -> x // fold select_cc lhs, rhs, x, x, cc -> x
@ -1404,7 +1404,7 @@ SDOperand DAGCombiner::visitBRCOND(SDNode *N) {
if (N1C && N1C->isNullValue()) if (N1C && N1C->isNullValue())
return Chain; return Chain;
// unconditional branch // unconditional branch
if (N1C && !N1C->isNullValue()) if (N1C && N1C->getValue() == 1)
return DAG.getNode(ISD::BR, MVT::Other, Chain, N2); return DAG.getNode(ISD::BR, MVT::Other, Chain, N2);
return SDOperand(); return SDOperand();
} }
@ -1432,28 +1432,49 @@ SDOperand DAGCombiner::visitBR_CC(SDNode *N) {
SDOperand CondLHS = N->getOperand(2), CondRHS = N->getOperand(3); SDOperand CondLHS = N->getOperand(2), CondRHS = N->getOperand(3);
// Use SimplifySetCC to simplify SETCC's. // Use SimplifySetCC to simplify SETCC's.
SDOperand Simp = SimplifySetCC(MVT::i1, CondLHS, CondRHS, CC->get()); SDOperand Simp = SimplifySetCC(MVT::i1, CondLHS, CondRHS, CC->get(), false);
if (Simp.Val) { ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(Simp.Val);
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Simp)) {
if (C->getValue() & 1) // Unconditional branch // fold br_cc true, dest -> br dest (unconditional branch)
return DAG.getNode(ISD::BR, MVT::Other, N->getOperand(0), if (SCCC && SCCC->getValue())
N->getOperand(4)); return DAG.getNode(ISD::BR, MVT::Other, N->getOperand(0),
else N->getOperand(4));
return N->getOperand(0); // Unconditional Fall through // fold br_cc false, dest -> unconditional fall through
} else if (Simp.Val->getOpcode() == ISD::SETCC) { if (SCCC && SCCC->isNullValue())
// Folded to a simpler setcc return N->getOperand(0);
return DAG.getNode(ISD::BR_CC, MVT::Other, N->getOperand(0), // fold to a simpler setcc
Simp.getOperand(2), Simp.getOperand(0), if (Simp.Val && Simp.getOpcode() == ISD::SETCC)
Simp.getOperand(1), N->getOperand(4)); return DAG.getNode(ISD::BR_CC, MVT::Other, N->getOperand(0),
} Simp.getOperand(2), Simp.getOperand(0),
} Simp.getOperand(1), N->getOperand(4));
return SDOperand(); return SDOperand();
} }
SDOperand DAGCombiner::visitBRTWOWAY_CC(SDNode *N) { SDOperand DAGCombiner::visitBRTWOWAY_CC(SDNode *N) {
// FIXME: come up with a common way between br_cc, brtwoway_cc, and select_cc SDOperand Chain = N->getOperand(0);
// to canonicalize the condition without calling getnode a bazillion times. SDOperand CCN = N->getOperand(1);
SDOperand LHS = N->getOperand(2);
SDOperand RHS = N->getOperand(3);
SDOperand N4 = N->getOperand(4);
SDOperand N5 = N->getOperand(5);
SDOperand SCC = SimplifySetCC(TLI.getSetCCResultTy(), LHS, RHS,
cast<CondCodeSDNode>(CCN)->get(), false);
ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val);
// fold select_cc lhs, rhs, x, x, cc -> x
if (N4 == N5)
return DAG.getNode(ISD::BR, MVT::Other, Chain, N4);
// fold select_cc true, x, y -> x
if (SCCC && SCCC->getValue())
return DAG.getNode(ISD::BR, MVT::Other, Chain, N4);
// fold select_cc false, x, y -> y
if (SCCC && SCCC->isNullValue())
return DAG.getNode(ISD::BR, MVT::Other, Chain, N5);
// fold to a simpler setcc
if (SCC.Val && SCC.getOpcode() == ISD::SETCC)
return DAG.getBR2Way_CC(Chain, SCC.getOperand(2), SCC.getOperand(0),
SCC.getOperand(1), N4, N5);
return SDOperand(); return SDOperand();
} }
@ -1468,7 +1489,8 @@ SDOperand DAGCombiner::SimplifySelectCC(SDOperand N0, SDOperand N1,
} }
SDOperand DAGCombiner::SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand DAGCombiner::SimplifySetCC(MVT::ValueType VT, SDOperand N0,
SDOperand N1, ISD::CondCode Cond) { SDOperand N1, ISD::CondCode Cond,
bool foldBooleans) {
// These setcc operations always fold. // These setcc operations always fold.
switch (Cond) { switch (Cond) {
default: break; default: break;
@ -1768,7 +1790,7 @@ SDOperand DAGCombiner::SimplifySetCC(MVT::ValueType VT, SDOperand N0,
// Fold away ALL boolean setcc's. // Fold away ALL boolean setcc's.
SDOperand Temp; SDOperand Temp;
if (N0.getValueType() == MVT::i1) { if (N0.getValueType() == MVT::i1 && foldBooleans) {
switch (Cond) { switch (Cond) {
default: assert(0 && "Unknown integer setcc!"); default: assert(0 && "Unknown integer setcc!");
case ISD::SETEQ: // X == Y -> (X^Y)^1 case ISD::SETEQ: // X == Y -> (X^Y)^1