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Relax the checking on zextload generation a bit, since as sabre pointed out

Browse Source 
you could be AND'ing with the result of a shift that shifts out all the
bits you care about, in addition to a constant.

Also, move over an add/sub_parts fold from legalize to the dag combiner,
where it works for things other than constants.  Woot!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23720 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2005-10-14 01:12:21 +00:00
parent 40f44f1f58
commit 5054f16212
2 changed files with 49 additions and 27 deletions
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52
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -147,6 +147,8 @@ namespace {
SDOperand visitSELECT(SDNode *N);
SDOperand visitSELECT_CC(SDNode *N);
SDOperand visitSETCC(SDNode *N);
SDOperand visitADD_PARTS(SDNode *N);
SDOperand visitSUB_PARTS(SDNode *N);
SDOperand visitSIGN_EXTEND(SDNode *N);
SDOperand visitZERO_EXTEND(SDNode *N);
SDOperand visitSIGN_EXTEND_INREG(SDNode *N);
@ -422,6 +424,8 @@ SDOperand DAGCombiner::visit(SDNode *N) {
case ISD::SELECT: return visitSELECT(N);
case ISD::SELECT_CC: return visitSELECT_CC(N);
case ISD::SETCC: return visitSETCC(N);
case ISD::ADD_PARTS: return visitADD_PARTS(N);
case ISD::SUB_PARTS: return visitSUB_PARTS(N);
case ISD::SIGN_EXTEND: return visitSIGN_EXTEND(N);
case ISD::ZERO_EXTEND: return visitZERO_EXTEND(N);
case ISD::SIGN_EXTEND_INREG: return visitSIGN_EXTEND_INREG(N);
@ -800,11 +804,11 @@ SDOperand DAGCombiner::visitAND(SDNode *N) {
return DAG.getNode(N0.getOpcode(), VT, ANDNode, N0.getOperand(1));
}
// fold (zext_inreg (extload x)) -> (zextload x)
if (N1C && N0.getOpcode() == ISD::EXTLOAD) {
if (N0.getOpcode() == ISD::EXTLOAD) {
MVT::ValueType EVT = cast<VTSDNode>(N0.getOperand(3))->getVT();
// If we zero all the possible extended bits, then we can turn this into
// a zextload if we are running before legalize or the operation is legal.
if (MaskedValueIsZero(SDOperand(N,0), ~0ULL<<MVT::getSizeInBits(EVT),TLI) &&
if (MaskedValueIsZero(N1, ~0ULL << MVT::getSizeInBits(EVT), TLI) &&
(!AfterLegalize || TLI.isOperationLegal(ISD::ZEXTLOAD, EVT))) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
@ -815,11 +819,11 @@ SDOperand DAGCombiner::visitAND(SDNode *N) {
}
}
// fold (zext_inreg (sextload x)) -> (zextload x) iff load has one use
if (N1C && N0.getOpcode() == ISD::SEXTLOAD && N0.Val->hasNUsesOfValue(1, 0)) {
if (N0.getOpcode() == ISD::SEXTLOAD && N0.Val->hasNUsesOfValue(1, 0)) {
MVT::ValueType EVT = cast<VTSDNode>(N0.getOperand(3))->getVT();
// If we zero all the possible extended bits, then we can turn this into
// a zextload if we are running before legalize or the operation is legal.
if (MaskedValueIsZero(SDOperand(N,0), ~0ULL<<MVT::getSizeInBits(EVT),TLI) &&
if (MaskedValueIsZero(N1, ~0ULL << MVT::getSizeInBits(EVT), TLI) &&
(!AfterLegalize || TLI.isOperationLegal(ISD::ZEXTLOAD, EVT))) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, N0.getOperand(0),
N0.getOperand(1), N0.getOperand(2),
@ -1230,6 +1234,46 @@ SDOperand DAGCombiner::visitSETCC(SDNode *N) {
cast<CondCodeSDNode>(N->getOperand(2))->get());
}
SDOperand DAGCombiner::visitADD_PARTS(SDNode *N) {
SDOperand LHSLo = N->getOperand(0);
SDOperand RHSLo = N->getOperand(2);
MVT::ValueType VT = LHSLo.getValueType();
// fold (a_Hi, 0) + (b_Hi, b_Lo) -> (b_Hi + a_Hi, b_Lo)
if (MaskedValueIsZero(LHSLo, (1ULL << MVT::getSizeInBits(VT))-1, TLI)) {
SDOperand Hi = DAG.getNode(ISD::ADD, VT, N->getOperand(1),
N->getOperand(3));
WorkList.push_back(Hi.Val);
CombineTo(N, RHSLo, Hi);
return SDOperand();
}
// fold (a_Hi, a_Lo) + (b_Hi, 0) -> (a_Hi + b_Hi, a_Lo)
if (MaskedValueIsZero(RHSLo, (1ULL << MVT::getSizeInBits(VT))-1, TLI)) {
SDOperand Hi = DAG.getNode(ISD::ADD, VT, N->getOperand(1),
N->getOperand(3));
WorkList.push_back(Hi.Val);
CombineTo(N, LHSLo, Hi);
return SDOperand();
}
return SDOperand();
}
SDOperand DAGCombiner::visitSUB_PARTS(SDNode *N) {
SDOperand LHSLo = N->getOperand(0);
SDOperand RHSLo = N->getOperand(2);
MVT::ValueType VT = LHSLo.getValueType();
// fold (a_Hi, a_Lo) - (b_Hi, 0) -> (a_Hi - b_Hi, a_Lo)
if (MaskedValueIsZero(RHSLo, (1ULL << MVT::getSizeInBits(VT))-1, TLI)) {
SDOperand Hi = DAG.getNode(ISD::SUB, VT, N->getOperand(1),
N->getOperand(3));
WorkList.push_back(Hi.Val);
CombineTo(N, LHSLo, Hi);
return SDOperand();
}
return SDOperand();
}
SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);

22
lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
View File

@ -2449,33 +2449,11 @@ ExpandByParts(unsigned NodeOp, SDOperand LHS, SDOperand RHS,
ExpandOp(LHS, LHSL, LHSH);
ExpandOp(RHS, RHSL, RHSH);
// FIXME: this should be moved to the dag combiner someday.
assert(NodeOp == ISD::ADD_PARTS || NodeOp == ISD::SUB_PARTS);
if (LHSL.getValueType() == MVT::i32) {
SDOperand LowEl = SDOperand(0,0);
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(LHSL))
if (C->getValue() == 0)
LowEl = RHSL;
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHSL))
if (C->getValue() == 0)
LowEl = LHSL;
if (LowEl.Val) {
// Turn this into an add/sub of the high part only.
SDOperand HiEl =
DAG.getNode(NodeOp == ISD::ADD_PARTS ? ISD::ADD : ISD::SUB,
LowEl.getValueType(), LHSH, RHSH);
Lo = LowEl;
Hi = HiEl;
return;
}
}
std::vector<SDOperand> Ops;
Ops.push_back(LHSL);
Ops.push_back(LHSH);
Ops.push_back(RHSL);
Ops.push_back(RHSH);
std::vector<MVT::ValueType> VTs(2, LHSL.getValueType());
Lo = DAG.getNode(NodeOp, VTs, Ops);
Hi = Lo.getValue(1);