Do not legalize large setcc with setcce, introduce setcccarry and do it with usubo/setcccarry.
Summary:
This is a continuation of the work started in D29872 . Passing the carry down as a value rather than as a glue allows for further optimizations. Introducing setcccarry makes the use of addc/subc unecessary and we can start the removal process.
This patch only introduce the optimization strictly required to get the same level of optimization as was available before nothing more.
Reviewers: jyknight, nemanjai, mkuper, spatel, RKSimon, zvi, bkramer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33374
llvm-svn: 304404
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 3008bd7..755d162 100644
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -280,6 +280,7 @@
SDValue visitSELECT_CC(SDNode *N);
SDValue visitSETCC(SDNode *N);
SDValue visitSETCCE(SDNode *N);
+ SDValue visitSETCCCARRY(SDNode *N);
SDValue visitSIGN_EXTEND(SDNode *N);
SDValue visitZERO_EXTEND(SDNode *N);
SDValue visitANY_EXTEND(SDNode *N);
@@ -1457,6 +1458,7 @@
case ISD::SELECT_CC: return visitSELECT_CC(N);
case ISD::SETCC: return visitSETCC(N);
case ISD::SETCCE: return visitSETCCE(N);
+ case ISD::SETCCCARRY: return visitSETCCCARRY(N);
case ISD::SIGN_EXTEND: return visitSIGN_EXTEND(N);
case ISD::ZERO_EXTEND: return visitZERO_EXTEND(N);
case ISD::ANY_EXTEND: return visitANY_EXTEND(N);
@@ -6838,6 +6840,19 @@
return SDValue();
}
+SDValue DAGCombiner::visitSETCCCARRY(SDNode *N) {
+ SDValue LHS = N->getOperand(0);
+ SDValue RHS = N->getOperand(1);
+ SDValue Carry = N->getOperand(2);
+ SDValue Cond = N->getOperand(3);
+
+ // If Carry is false, fold to a regular SETCC.
+ if (isNullConstant(Carry))
+ return DAG.getNode(ISD::SETCC, SDLoc(N), N->getVTList(), LHS, RHS, Cond);
+
+ return SDValue();
+}
+
/// Try to fold a sext/zext/aext dag node into a ConstantSDNode or
/// a build_vector of constants.
/// This function is called by the DAGCombiner when visiting sext/zext/aext
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
index 92b0d2a..0d5e07d 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp
@@ -2875,6 +2875,7 @@
case ISD::SELECT_CC: Res = ExpandIntOp_SELECT_CC(N); break;
case ISD::SETCC: Res = ExpandIntOp_SETCC(N); break;
case ISD::SETCCE: Res = ExpandIntOp_SETCCE(N); break;
+ case ISD::SETCCCARRY: Res = ExpandIntOp_SETCCCARRY(N); break;
case ISD::SINT_TO_FP: Res = ExpandIntOp_SINT_TO_FP(N); break;
case ISD::STORE: Res = ExpandIntOp_STORE(cast<StoreSDNode>(N), OpNo); break;
case ISD::TRUNCATE: Res = ExpandIntOp_TRUNCATE(N); break;
@@ -3009,14 +3010,16 @@
return;
}
- // Lower with SETCCE if the target supports it.
+ // Lower with SETCCE or SETCCCARRY if the target supports it.
+ EVT HiVT = LHSHi.getValueType();
+ EVT ExpandVT = TLI.getTypeToExpandTo(*DAG.getContext(), HiVT);
+ bool HasSETCCCARRY = TLI.isOperationLegalOrCustom(ISD::SETCCCARRY, ExpandVT);
+
// FIXME: Make all targets support this, then remove the other lowering.
- if (TLI.getOperationAction(
- ISD::SETCCE,
- TLI.getTypeToExpandTo(*DAG.getContext(), LHSLo.getValueType())) ==
- TargetLowering::Custom) {
- // SETCCE can detect < and >= directly. For > and <=, flip operands and
- // condition code.
+ if (HasSETCCCARRY ||
+ TLI.getOperationAction(ISD::SETCCE, ExpandVT) == TargetLowering::Custom) {
+ // SETCCE/SETCCCARRY can detect < and >= directly. For > and <=, flip
+ // operands and condition code.
bool FlipOperands = false;
switch (CCCode) {
case ISD::SETGT: CCCode = ISD::SETLT; FlipOperands = true; break;
@@ -3030,27 +3033,28 @@
std::swap(LHSHi, RHSHi);
}
// Perform a wide subtraction, feeding the carry from the low part into
- // SETCCE. The SETCCE operation is essentially looking at the high part of
- // the result of LHS - RHS. It is negative iff LHS < RHS. It is zero or
- // positive iff LHS >= RHS.
- SDVTList VTList = DAG.getVTList(LHSLo.getValueType(), MVT::Glue);
- SDValue LowCmp = DAG.getNode(ISD::SUBC, dl, VTList, LHSLo, RHSLo);
- SDValue Res =
- DAG.getNode(ISD::SETCCE, dl, getSetCCResultType(LHSLo.getValueType()),
- LHSHi, RHSHi, LowCmp.getValue(1), DAG.getCondCode(CCCode));
+ // SETCCE/SETCCCARRY. The SETCCE/SETCCCARRY operation is essentially
+ // looking at the high part of the result of LHS - RHS. It is negative
+ // iff LHS < RHS. It is zero or positive iff LHS >= RHS.
+ EVT LoVT = LHSLo.getValueType();
+ SDVTList VTList = DAG.getVTList(
+ LoVT, HasSETCCCARRY ? getSetCCResultType(LoVT) : MVT::Glue);
+ SDValue LowCmp = DAG.getNode(HasSETCCCARRY ? ISD::USUBO : ISD::SUBC, dl,
+ VTList, LHSLo, RHSLo);
+ SDValue Res = DAG.getNode(HasSETCCCARRY ? ISD::SETCCCARRY : ISD::SETCCE, dl,
+ getSetCCResultType(HiVT), LHSHi, RHSHi,
+ LowCmp.getValue(1), DAG.getCondCode(CCCode));
NewLHS = Res;
NewRHS = SDValue();
return;
}
- NewLHS = TLI.SimplifySetCC(getSetCCResultType(LHSHi.getValueType()),
- LHSHi, RHSHi, ISD::SETEQ, false,
- DagCombineInfo, dl);
+ NewLHS = TLI.SimplifySetCC(getSetCCResultType(HiVT), LHSHi, RHSHi, ISD::SETEQ,
+ false, DagCombineInfo, dl);
if (!NewLHS.getNode())
- NewLHS = DAG.getSetCC(dl, getSetCCResultType(LHSHi.getValueType()),
- LHSHi, RHSHi, ISD::SETEQ);
- NewLHS = DAG.getSelect(dl, LoCmp.getValueType(),
- NewLHS, LoCmp, HiCmp);
+ NewLHS =
+ DAG.getSetCC(dl, getSetCCResultType(HiVT), LHSHi, RHSHi, ISD::SETEQ);
+ NewLHS = DAG.getSelect(dl, LoCmp.getValueType(), NewLHS, LoCmp, HiCmp);
NewRHS = SDValue();
}
@@ -3103,8 +3107,8 @@
}
// Otherwise, update N to have the operands specified.
- return SDValue(DAG.UpdateNodeOperands(N, NewLHS, NewRHS,
- DAG.getCondCode(CCCode)), 0);
+ return SDValue(
+ DAG.UpdateNodeOperands(N, NewLHS, NewRHS, DAG.getCondCode(CCCode)), 0);
}
SDValue DAGTypeLegalizer::ExpandIntOp_SETCCE(SDNode *N) {
@@ -3125,6 +3129,24 @@
LowCmp.getValue(1), Cond);
}
+SDValue DAGTypeLegalizer::ExpandIntOp_SETCCCARRY(SDNode *N) {
+ SDValue LHS = N->getOperand(0);
+ SDValue RHS = N->getOperand(1);
+ SDValue Carry = N->getOperand(2);
+ SDValue Cond = N->getOperand(3);
+ SDLoc dl = SDLoc(N);
+
+ SDValue LHSLo, LHSHi, RHSLo, RHSHi;
+ GetExpandedInteger(LHS, LHSLo, LHSHi);
+ GetExpandedInteger(RHS, RHSLo, RHSHi);
+
+ // Expand to a SUBE for the low part and a smaller SETCCCARRY for the high.
+ SDVTList VTList = DAG.getVTList(LHSLo.getValueType(), Carry.getValueType());
+ SDValue LowCmp = DAG.getNode(ISD::SUBCARRY, dl, VTList, LHSLo, RHSLo, Carry);
+ return DAG.getNode(ISD::SETCCCARRY, dl, N->getValueType(0), LHSHi, RHSHi,
+ LowCmp.getValue(1), Cond);
+}
+
SDValue DAGTypeLegalizer::ExpandIntOp_Shift(SDNode *N) {
// The value being shifted is legal, but the shift amount is too big.
// It follows that either the result of the shift is undefined, or the
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
index 4c3b5148..8e99918 100644
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -381,6 +381,7 @@
SDValue ExpandIntOp_SELECT_CC(SDNode *N);
SDValue ExpandIntOp_SETCC(SDNode *N);
SDValue ExpandIntOp_SETCCE(SDNode *N);
+ SDValue ExpandIntOp_SETCCCARRY(SDNode *N);
SDValue ExpandIntOp_Shift(SDNode *N);
SDValue ExpandIntOp_SINT_TO_FP(SDNode *N);
SDValue ExpandIntOp_STORE(StoreSDNode *N, unsigned OpNo);
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
index c37d708..0dbd9e8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
@@ -214,6 +214,7 @@
case ISD::FPOWI: return "fpowi";
case ISD::SETCC: return "setcc";
case ISD::SETCCE: return "setcce";
+ case ISD::SETCCCARRY: return "setcccarry";
case ISD::SELECT: return "select";
case ISD::VSELECT: return "vselect";
case ISD::SELECT_CC: return "select_cc";
diff --git a/llvm/lib/CodeGen/TargetLoweringBase.cpp b/llvm/lib/CodeGen/TargetLoweringBase.cpp
index 3fc6bbc..900c031 100644
--- a/llvm/lib/CodeGen/TargetLoweringBase.cpp
+++ b/llvm/lib/CodeGen/TargetLoweringBase.cpp
@@ -927,6 +927,7 @@
// ADDCARRY operations default to expand
setOperationAction(ISD::ADDCARRY, VT, Expand);
setOperationAction(ISD::SUBCARRY, VT, Expand);
+ setOperationAction(ISD::SETCCCARRY, VT, Expand);
// These default to Expand so they will be expanded to CTLZ/CTTZ by default.
setOperationAction(ISD::CTLZ_ZERO_UNDEF, VT, Expand);