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propagate IR-level fast-math-flags to DAG nodes (NFC)

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This patch adds the minimum plumbing necessary to use IR-level
fast-math-flags (FMF) in the backend without actually using
them for anything yet. This is a follow-on to:
http://reviews.llvm.org/rL235997

...which split the existing nsw / nuw / exact flags and FMF
into their own struct.

There are 2 structural changes here:

1. The main diff is that we're preparing to extend the optimization
flags to affect more than just binary SDNodes. Eg, IR intrinsics 
( https://llvm.org/bugs/show_bug.cgi?id=21290 ) or non-binop nodes
that don't even exist in IR such as FMA, FNEG, etc.

2. The other change is that we're actually copying the FP fast-math-flags
from the IR instructions to SDNodes. 

Differential Revision: http://reviews.llvm.org/D8900

llvm-svn: 236546
This commit is contained in:
Sanjay Patel 2015-05-05 21:40:38 +00:00
parent 43ba3dfb7e
commit b7125c62c7
7 changed files with 109 additions and 99 deletions
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10
include/llvm/CodeGen/SelectionDAG.h
View File

@ -655,7 +655,7 @@ public:
SDValue getNode(unsigned Opcode, SDLoc DL, EVT VT);
SDValue getNode(unsigned Opcode, SDLoc DL, EVT VT, SDValue N);
SDValue getNode(unsigned Opcode, SDLoc DL, EVT VT, SDValue N1, SDValue N2,
bool nuw = false, bool nsw = false, bool exact = false);
const SDNodeFlags *Flags = nullptr);
SDValue getNode(unsigned Opcode, SDLoc DL, EVT VT, SDValue N1, SDValue N2,
SDValue N3);
SDValue getNode(unsigned Opcode, SDLoc DL, EVT VT, SDValue N1, SDValue N2,
@ -978,8 +978,7 @@ public:
/// Get the specified node if it's already available, or else return NULL.
SDNode *getNodeIfExists(unsigned Opcode, SDVTList VTs, ArrayRef<SDValue> Ops,
bool nuw = false, bool nsw = false,
bool exact = false);
const SDNodeFlags *Flags = nullptr);
/// Creates a SDDbgValue node.
SDDbgValue *getDbgValue(MDNode *Var, MDNode *Expr, SDNode *N, unsigned R,
@ -1236,9 +1235,8 @@ private:
void allnodes_clear();
BinarySDNode *GetBinarySDNode(unsigned Opcode, SDLoc DL, SDVTList VTs,
SDValue N1, SDValue N2, bool nuw, bool nsw,
bool exact);
SDNode *GetSDNodeWithFlags(unsigned Opcode, SDLoc DL, SDVTList VTs,
ArrayRef<SDValue> Ops, const SDNodeFlags *Flags);
/// List of non-single value types.
FoldingSet<SDVTListNode> VTListMap;

68
include/llvm/CodeGen/SelectionDAGNodes.h
View File

@ -981,6 +981,44 @@ public:
(NoSignedZeros << 6) | (AllowReciprocal << 7);
}
};
/// Returns true if the opcode is an operation with optional optimization flags.
static bool mayHaveOptimizationFlags(unsigned Opcode) {
switch (Opcode) {
case ISD::SDIV:
case ISD::UDIV:
case ISD::SRA:
case ISD::SRL:
case ISD::MUL:
case ISD::ADD:
case ISD::SUB:
case ISD::SHL:
case ISD::FADD:
case ISD::FDIV:
case ISD::FMUL:
case ISD::FREM:
case ISD::FSUB:
return true;
default:
return false;
}
}
/// This class is an extension of SDNode used from instructions that may have
/// associated extra flags.
class SDNodeWithFlags : public SDNode {
public:
SDNodeFlags Flags;
SDNodeWithFlags(unsigned Opc, unsigned Order, DebugLoc dl, SDVTList VTs,
ArrayRef<SDValue> Ops, const SDNodeFlags &NodeFlags)
: SDNode(Opc, Order, dl, VTs, Ops) {
Flags = NodeFlags;
}
// This is used to implement dyn_cast, isa, and other type queries.
static bool classof(const SDNode *N) {
return mayHaveOptimizationFlags(N->getOpcode());
}
};
/// This class is used for single-operand SDNodes. This is solely
/// to allow co-allocation of node operands with the node itself.
@ -1006,36 +1044,6 @@ public:
}
};
/// Returns true if the opcode is a binary operation with flags.
static bool isBinOpWithFlags(unsigned Opcode) {
switch (Opcode) {
case ISD::SDIV:
case ISD::UDIV:
case ISD::SRA:
case ISD::SRL:
case ISD::MUL:
case ISD::ADD:
case ISD::SUB:
case ISD::SHL:
return true;
default:
return false;
}
}
/// This class is an extension of BinarySDNode
/// used from those opcodes that have associated extra flags.
class BinaryWithFlagsSDNode : public BinarySDNode {
public:
SDNodeFlags Flags;
BinaryWithFlagsSDNode(unsigned Opc, unsigned Order, DebugLoc dl, SDVTList VTs,
SDValue X, SDValue Y)
: BinarySDNode(Opc, Order, dl, VTs, X, Y), Flags() { }
static bool classof(const SDNode *N) {
return isBinOpWithFlags(N->getOpcode());
}
};
/// This class is used for three-operand SDNodes. This is solely
/// to allow co-allocation of node operands with the node itself.
class TernarySDNode : public SDNode {

9
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -1452,12 +1452,9 @@ SDValue DAGCombiner::combine(SDNode *N) {
if (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1)) {
SDValue Ops[] = {N1, N0};
SDNode *CSENode;
if (const BinaryWithFlagsSDNode *BinNode =
dyn_cast<BinaryWithFlagsSDNode>(N)) {
CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(), Ops,
BinNode->Flags.hasNoUnsignedWrap(),
BinNode->Flags.hasNoSignedWrap(),
BinNode->Flags.hasExact());
if (auto *FlagsNode = dyn_cast<SDNodeWithFlags>(N)) {
CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(),
Ops, &FlagsNode->Flags);
} else {
CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(), Ops);
}

89
lib/CodeGen/SelectionDAG/SelectionDAG.cpp
View File

@ -400,18 +400,22 @@ static void AddNodeIDOperands(FoldingSetNodeID &ID,
}
}
static void AddBinaryNodeIDCustom(FoldingSetNodeID &ID, bool nuw, bool nsw,
bool exact) {
ID.AddBoolean(nuw);
ID.AddBoolean(nsw);
ID.AddBoolean(exact);
/// Add logical or fast math flag values to FoldingSetNodeID value.
static void AddNodeIDFlags(FoldingSetNodeID &ID, unsigned Opcode,
const SDNodeFlags *Flags) {
if (!Flags || !mayHaveOptimizationFlags(Opcode))
return;
unsigned RawFlags = Flags->getRawFlags();
// If no flags are set, do not alter the ID. This saves time and allows
// a gradual increase in API usage of the optional optimization flags.
if (RawFlags != 0)
ID.AddInteger(RawFlags);
}
/// AddBinaryNodeIDCustom - Add BinarySDNodes special infos
static void AddBinaryNodeIDCustom(FoldingSetNodeID &ID, unsigned Opcode,
bool nuw, bool nsw, bool exact) {
if (isBinOpWithFlags(Opcode))
AddBinaryNodeIDCustom(ID, nuw, nsw, exact);
static void AddNodeIDFlags(FoldingSetNodeID &ID, const SDNode *N) {
if (auto *Node = dyn_cast<SDNodeWithFlags>(N))
AddNodeIDFlags(ID, Node->getOpcode(), &Node->Flags);
}
static void AddNodeIDNode(FoldingSetNodeID &ID, unsigned short OpC,
@ -506,21 +510,6 @@ static void AddNodeIDCustom(FoldingSetNodeID &ID, const SDNode *N) {
ID.AddInteger(ST->getPointerInfo().getAddrSpace());
break;
}
case ISD::SDIV:
case ISD::UDIV:
case ISD::SRA:
case ISD::SRL:
case ISD::MUL:
case ISD::ADD:
case ISD::SUB:
case ISD::SHL: {
const BinaryWithFlagsSDNode *BinNode = cast<BinaryWithFlagsSDNode>(N);
AddBinaryNodeIDCustom(ID, N->getOpcode(),
BinNode->Flags.hasNoUnsignedWrap(),
BinNode->Flags.hasNoSignedWrap(),
BinNode->Flags.hasExact());
break;
}
case ISD::ATOMIC_CMP_SWAP:
case ISD::ATOMIC_CMP_SWAP_WITH_SUCCESS:
case ISD::ATOMIC_SWAP:
@ -564,6 +553,8 @@ static void AddNodeIDCustom(FoldingSetNodeID &ID, const SDNode *N) {
}
} // end switch (N->getOpcode())
AddNodeIDFlags(ID, N);
// Target specific memory nodes could also have address spaces to check.
if (N->isTargetMemoryOpcode())
ID.AddInteger(cast<MemSDNode>(N)->getPointerInfo().getAddrSpace());
@ -958,22 +949,22 @@ void SelectionDAG::allnodes_clear() {
DeallocateNode(AllNodes.begin());
}
BinarySDNode *SelectionDAG::GetBinarySDNode(unsigned Opcode, SDLoc DL,
SDVTList VTs, SDValue N1,
SDValue N2, bool nuw, bool nsw,
bool exact) {
if (isBinOpWithFlags(Opcode)) {
BinaryWithFlagsSDNode *FN = new (NodeAllocator) BinaryWithFlagsSDNode(
Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs, N1, N2);
FN->Flags.setNoUnsignedWrap(nuw);
FN->Flags.setNoSignedWrap(nsw);
FN->Flags.setExact(exact);
SDNode *SelectionDAG::GetSDNodeWithFlags(unsigned Opcode, SDLoc DL,
SDVTList VTs, ArrayRef<SDValue> Ops,
const SDNodeFlags *Flags) {
if (mayHaveOptimizationFlags(Opcode)) {
// If no flags were passed in, use a default flags object.
SDNodeFlags F;
if (Flags == nullptr)
Flags = &F;
return FN;
SDNodeWithFlags *NodeWithFlags = new (NodeAllocator) SDNodeWithFlags(
Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs, Ops, *Flags);
return NodeWithFlags;
}
BinarySDNode *N = new (NodeAllocator)
BinarySDNode(Opcode, DL.getIROrder(), DL.getDebugLoc(), VTs, N1, N2);
SDNode *N = new (NodeAllocator) SDNode(Opcode, DL.getIROrder(),
DL.getDebugLoc(), VTs, Ops);
return N;
}
@ -3201,7 +3192,7 @@ SDValue SelectionDAG::FoldConstantArithmetic(unsigned Opcode, SDLoc DL, EVT VT,
}
SDValue SelectionDAG::getNode(unsigned Opcode, SDLoc DL, EVT VT, SDValue N1,
SDValue N2, bool nuw, bool nsw, bool exact) {
SDValue N2, const SDNodeFlags *Flags) {
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.getNode());
ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.getNode());
switch (Opcode) {
@ -3659,24 +3650,23 @@ SDValue SelectionDAG::getNode(unsigned Opcode, SDLoc DL, EVT VT, SDValue N1,
}
// Memoize this node if possible.
BinarySDNode *N;
SDNode *N;
SDVTList VTs = getVTList(VT);
const bool BinOpHasFlags = isBinOpWithFlags(Opcode);
SDValue Ops[] = { N1, N2 };
if (VT != MVT::Glue) {
SDValue Ops[] = {N1, N2};
FoldingSetNodeID ID;
AddNodeIDNode(ID, Opcode, VTs, Ops);
if (BinOpHasFlags)
AddBinaryNodeIDCustom(ID, Opcode, nuw, nsw, exact);
AddNodeIDFlags(ID, Opcode, Flags);
void *IP = nullptr;
if (SDNode *E = CSEMap.FindNodeOrInsertPos(ID, IP))
return SDValue(E, 0);
N = GetBinarySDNode(Opcode, DL, VTs, N1, N2, nuw, nsw, exact);
N = GetSDNodeWithFlags(Opcode, DL, VTs, Ops, Flags);
CSEMap.InsertNode(N, IP);
} else {
N = GetBinarySDNode(Opcode, DL, VTs, N1, N2, nuw, nsw, exact);
N = GetSDNodeWithFlags(Opcode, DL, VTs, Ops, Flags);
}
InsertNode(N);
@ -5980,13 +5970,12 @@ SelectionDAG::getTargetInsertSubreg(int SRIdx, SDLoc DL, EVT VT,
/// getNodeIfExists - Get the specified node if it's already available, or
/// else return NULL.
SDNode *SelectionDAG::getNodeIfExists(unsigned Opcode, SDVTList VTList,
ArrayRef<SDValue> Ops, bool nuw, bool nsw,
bool exact) {
ArrayRef<SDValue> Ops,
const SDNodeFlags *Flags) {
if (VTList.VTs[VTList.NumVTs - 1] != MVT::Glue) {
FoldingSetNodeID ID;
AddNodeIDNode(ID, Opcode, VTList, Ops);
if (isBinOpWithFlags(Opcode))
AddBinaryNodeIDCustom(ID, nuw, nsw, exact);
AddNodeIDFlags(ID, Opcode, Flags);
void *IP = nullptr;
if (SDNode *E = CSEMap.FindNodeOrInsertPos(ID, IP))
return E;

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

@ -2208,6 +2208,8 @@ void SelectionDAGBuilder::visitBinary(const User &I, unsigned OpCode) {
bool nuw = false;
bool nsw = false;
bool exact = false;
FastMathFlags FMF;
if (const OverflowingBinaryOperator *OFBinOp =
dyn_cast<const OverflowingBinaryOperator>(&I)) {
nuw = OFBinOp->hasNoUnsignedWrap();
@ -2217,8 +2219,20 @@ void SelectionDAGBuilder::visitBinary(const User &I, unsigned OpCode) {
dyn_cast<const PossiblyExactOperator>(&I))
exact = ExactOp->isExact();
if (const FPMathOperator *FPOp = dyn_cast<const FPMathOperator>(&I))
FMF = FPOp->getFastMathFlags();
SDNodeFlags Flags;
Flags.setAllowReciprocal(FMF.allowReciprocal());
Flags.setExact(exact);
Flags.setNoInfs(FMF.noInfs());
Flags.setNoNaNs(FMF.noNaNs());
Flags.setNoSignedWrap(nsw);
Flags.setNoSignedZeros(FMF.noSignedZeros());
Flags.setNoUnsignedWrap(nuw);
Flags.setUnsafeAlgebra(FMF.unsafeAlgebra());
SDValue BinNodeValue = DAG.getNode(OpCode, getCurSDLoc(), Op1.getValueType(),
Op1, Op2, nuw, nsw, exact);
Op1, Op2, &Flags);
setValue(&I, BinNodeValue);
}
@ -2267,8 +2281,12 @@ void SelectionDAGBuilder::visitShift(const User &I, unsigned Opcode) {
exact = ExactOp->isExact();
}
SDNodeFlags Flags;
Flags.setExact(exact);
Flags.setNoSignedWrap(nsw);
Flags.setNoUnsignedWrap(nuw);
SDValue Res = DAG.getNode(Opcode, getCurSDLoc(), Op1.getValueType(), Op1, Op2,
nuw, nsw, exact);
&Flags);
setValue(&I, Res);
}

5
lib/CodeGen/SelectionDAG/TargetLowering.cpp
View File

@ -2660,8 +2660,9 @@ SDValue TargetLowering::BuildExactSDIV(SDValue Op1, SDValue Op2, SDLoc dl,
// TODO: For UDIV use SRL instead of SRA.
SDValue Amt = DAG.getConstant(ShAmt, dl,
getShiftAmountTy(Op1.getValueType()));
Op1 = DAG.getNode(ISD::SRA, dl, Op1.getValueType(), Op1, Amt, false, false,
true);
SDNodeFlags Flags;
Flags.setExact(true);
Op1 = DAG.getNode(ISD::SRA, dl, Op1.getValueType(), Op1, Amt, &Flags);
d = d.ashr(ShAmt);
}

5
lib/Target/X86/X86ISelLowering.cpp
View File

@ -12561,9 +12561,8 @@ SDValue X86TargetLowering::EmitTest(SDValue Op, unsigned X86CC, SDLoc dl,
case ISD::SUB:
case ISD::MUL:
case ISD::SHL: {
const BinaryWithFlagsSDNode *BinNode =
cast<BinaryWithFlagsSDNode>(Op.getNode());
if (BinNode->Flags.hasNoSignedWrap())
const SDNodeWithFlags *Node = cast<SDNodeWithFlags>(Op.getNode());
if (Node->Flags.hasNoSignedWrap())
break;
}
default: