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Fast Math Flag mapping into SDNode
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Summary: Adding support for Fast flags in the SDNode to leverage fast math sub flag usage.

Reviewers: spatel, arsenm, jbhateja, hfinkel, escha, qcolombet, echristo, wristow, javed.absar

Reviewed By: spatel

Subscribers: llvm-commits, rampitec, nhaehnle, tstellar, FarhanaAleen, nemanjai, javed.absar, jbhateja, hfinkel, wdng

Differential Revision: https://reviews.llvm.org/D45710

llvm-svn: 331547
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Michael Berg committed May 4, 2018
1 parent 0e51a12 commit 7acc81b
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Showing 8 changed files with 53 additions and 40 deletions.
31 changes: 22 additions & 9 deletions llvm/include/llvm/CodeGen/SelectionDAGNodes.h
View file
Expand Up @@ -359,21 +359,22 @@ struct SDNodeFlags {
bool NoUnsignedWrap : 1;
bool NoSignedWrap : 1;
bool Exact : 1;
bool UnsafeAlgebra : 1;
bool NoNaNs : 1;
bool NoInfs : 1;
bool NoSignedZeros : 1;
bool AllowReciprocal : 1;
bool VectorReduction : 1;
bool AllowContract : 1;
bool ApproximateFuncs : 1;
bool AllowReassociation : 1;

public:
/// Default constructor turns off all optimization flags.
SDNodeFlags()
: AnyDefined(false), NoUnsignedWrap(false), NoSignedWrap(false),
Exact(false), UnsafeAlgebra(false), NoNaNs(false), NoInfs(false),
Exact(false), NoNaNs(false), NoInfs(false),
NoSignedZeros(false), AllowReciprocal(false), VectorReduction(false),
AllowContract(false) {}
AllowContract(false), ApproximateFuncs(false), AllowReassociation(false) {}

/// Sets the state of the flags to the defined state.
void setDefined() { AnyDefined = true; }
Expand All @@ -393,10 +394,6 @@ struct SDNodeFlags {
setDefined();
Exact = b;
}
void setUnsafeAlgebra(bool b) {
setDefined();
UnsafeAlgebra = b;
}
void setNoNaNs(bool b) {
setDefined();
NoNaNs = b;
Expand All @@ -421,18 +418,32 @@ struct SDNodeFlags {
setDefined();
AllowContract = b;
}
void setApproximateFuncs(bool b) {
setDefined();
ApproximateFuncs = b;
}
void setAllowReassociation(bool b) {
setDefined();
AllowReassociation = b;
}

// These are accessors for each flag.
bool hasNoUnsignedWrap() const { return NoUnsignedWrap; }
bool hasNoSignedWrap() const { return NoSignedWrap; }
bool hasExact() const { return Exact; }
bool hasUnsafeAlgebra() const { return UnsafeAlgebra; }
bool hasNoNaNs() const { return NoNaNs; }
bool hasNoInfs() const { return NoInfs; }
bool hasNoSignedZeros() const { return NoSignedZeros; }
bool hasAllowReciprocal() const { return AllowReciprocal; }
bool hasVectorReduction() const { return VectorReduction; }
bool hasAllowContract() const { return AllowContract; }
bool hasApproximateFuncs() const { return ApproximateFuncs; }
bool hasAllowReassociation() const { return AllowReassociation; }

bool isFast() const {
return NoSignedZeros && AllowReciprocal && NoNaNs && NoInfs &&
AllowContract && ApproximateFuncs && AllowReassociation;
}

/// Clear any flags in this flag set that aren't also set in Flags.
/// If the given Flags are undefined then don't do anything.
Expand All @@ -442,13 +453,14 @@ struct SDNodeFlags {
NoUnsignedWrap &= Flags.NoUnsignedWrap;
NoSignedWrap &= Flags.NoSignedWrap;
Exact &= Flags.Exact;
UnsafeAlgebra &= Flags.UnsafeAlgebra;
NoNaNs &= Flags.NoNaNs;
NoInfs &= Flags.NoInfs;
NoSignedZeros &= Flags.NoSignedZeros;
AllowReciprocal &= Flags.AllowReciprocal;
VectorReduction &= Flags.VectorReduction;
AllowContract &= Flags.AllowContract;
ApproximateFuncs &= Flags.ApproximateFuncs;
AllowReassociation &= Flags.AllowReassociation;
}
};

Expand Down Expand Up @@ -923,6 +935,7 @@ class SDNode : public FoldingSetNode, public ilist_node<SDNode> {

const SDNodeFlags getFlags() const { return Flags; }
void setFlags(SDNodeFlags NewFlags) { Flags = NewFlags; }
bool isFast() { return Flags.isFast(); }

/// Clear any flags in this node that aren't also set in Flags.
/// If Flags is not in a defined state then this has no effect.
Expand Down
10 changes: 5 additions & 5 deletions llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View file
Expand Up @@ -9542,7 +9542,7 @@ ConstantFoldBITCASTofBUILD_VECTOR(SDNode *BV, EVT DstEltVT) {

static bool isContractable(SDNode *N) {
SDNodeFlags F = N->getFlags();
return F.hasAllowContract() || F.hasUnsafeAlgebra();
return F.hasAllowContract() || F.hasAllowReassociation();
}

/// Try to perform FMA combining on a given FADD node.
Expand Down Expand Up @@ -10567,9 +10567,9 @@ SDValue DAGCombiner::visitFMA(SDNode *N) {
return DAG.getNode(ISD::FMA, SDLoc(N), VT, N1, N0, N2);

// TODO: FMA nodes should have flags that propagate to the created nodes.
// For now, create a Flags object for use with all unsafe math transforms.
// For now, create a Flags object for use with reassociation math transforms.
SDNodeFlags Flags;
Flags.setUnsafeAlgebra(true);
Flags.setAllowReassociation(true);

if (Options.UnsafeFPMath) {
// (fma x, c1, (fmul x, c2)) -> (fmul x, c1+c2)
Expand Down Expand Up @@ -10841,9 +10841,9 @@ SDValue DAGCombiner::visitFSQRT(SDNode *N) {
return SDValue();

// TODO: FSQRT nodes should have flags that propagate to the created nodes.
// For now, create a Flags object for use with all unsafe math transforms.
// For now, create a Flags object for use with reassociation math transforms.
SDNodeFlags Flags;
Flags.setUnsafeAlgebra(true);
Flags.setAllowReassociation(true);
return buildSqrtEstimate(N0, Flags);
}

Expand Down
3 changes: 2 additions & 1 deletion llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View file
Expand Up @@ -2776,7 +2776,8 @@ void SelectionDAGBuilder::visitBinary(const User &I, unsigned OpCode) {
Flags.setNoInfs(FMF.noInfs());
Flags.setNoNaNs(FMF.noNaNs());
Flags.setNoSignedZeros(FMF.noSignedZeros());
Flags.setUnsafeAlgebra(FMF.isFast());
Flags.setApproximateFuncs(FMF.approxFunc());
Flags.setAllowReassociation(FMF.allowReassoc());

SDValue BinNodeValue = DAG.getNode(OpCode, getCurSDLoc(), Op1.getValueType(),
Op1, Op2, Flags);
Expand Down
9 changes: 6 additions & 3 deletions llvm/lib/CodeGen/SelectionDAG/SelectionDAGDumper.cpp
View file
Expand Up @@ -479,9 +479,6 @@ void SDNode::print_details(raw_ostream &OS, const SelectionDAG *G) const {
if (getFlags().hasExact())
OS << " exact";

if (getFlags().hasUnsafeAlgebra())
OS << " unsafe";

if (getFlags().hasNoNaNs())
OS << " nnan";

Expand All @@ -497,6 +494,12 @@ void SDNode::print_details(raw_ostream &OS, const SelectionDAG *G) const {
if (getFlags().hasAllowContract())
OS << " contract";

if (getFlags().hasApproximateFuncs())
OS << " afn";

if (getFlags().hasAllowReassociation())
OS << " reassoc";

if (getFlags().hasVectorReduction())
OS << " vector-reduction";

Expand Down
4 changes: 2 additions & 2 deletions llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
View file
Expand Up @@ -5145,7 +5145,7 @@ SDValue AArch64TargetLowering::getSqrtEstimate(SDValue Operand,
EVT VT = Operand.getValueType();

SDNodeFlags Flags;
Flags.setUnsafeAlgebra(true);
Flags.setAllowReassociation(true);

// Newton reciprocal square root iteration: E * 0.5 * (3 - X * E^2)
// AArch64 reciprocal square root iteration instruction: 0.5 * (3 - M * N)
Expand Down Expand Up @@ -5184,7 +5184,7 @@ SDValue AArch64TargetLowering::getRecipEstimate(SDValue Operand,
EVT VT = Operand.getValueType();

SDNodeFlags Flags;
Flags.setUnsafeAlgebra(true);
Flags.setAllowReassociation(true);

// Newton reciprocal iteration: E * (2 - X * E)
// AArch64 reciprocal iteration instruction: (2 - M * N)
Expand Down
7 changes: 3 additions & 4 deletions llvm/lib/Target/AMDGPU/SIISelLowering.cpp
View file
Expand Up @@ -5347,8 +5347,7 @@ SDValue SITargetLowering::lowerFastUnsafeFDIV(SDValue Op,
SDValue RHS = Op.getOperand(1);
EVT VT = Op.getValueType();
const SDNodeFlags Flags = Op->getFlags();
bool Unsafe = DAG.getTarget().Options.UnsafeFPMath ||
Flags.hasUnsafeAlgebra() || Flags.hasAllowReciprocal();
bool Unsafe = DAG.getTarget().Options.UnsafeFPMath || Flags.hasAllowReciprocal();

if (!Unsafe && VT == MVT::f32 && Subtarget->hasFP32Denormals())
return SDValue();
Expand Down Expand Up @@ -6698,8 +6697,8 @@ unsigned SITargetLowering::getFusedOpcode(const SelectionDAG &DAG,

const TargetOptions &Options = DAG.getTarget().Options;
if ((Options.AllowFPOpFusion == FPOpFusion::Fast || Options.UnsafeFPMath ||
(N0->getFlags().hasUnsafeAlgebra() &&
N1->getFlags().hasUnsafeAlgebra())) &&
(N0->getFlags().hasAllowContract() &&
N1->getFlags().hasAllowContract())) &&
isFMAFasterThanFMulAndFAdd(VT)) {
return ISD::FMA;
}
Expand Down
21 changes: 10 additions & 11 deletions llvm/test/CodeGen/PowerPC/fmf-propagation.ll
View file
Expand Up @@ -63,7 +63,7 @@ define float @fmul_fadd_contract2(float %x, float %y, float %z) {

; FMFDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fadd_reassoc1:'
; FMFDEBUG: fmul {{t[0-9]+}}, {{t[0-9]+}}
; FMFDEBUG: fadd {{t[0-9]+}}, {{t[0-9]+}}
; FMFDEBUG: fadd reassoc {{t[0-9]+}}, {{t[0-9]+}}
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fadd_reassoc1:'

define float @fmul_fadd_reassoc1(float %x, float %y, float %z) {
Expand All @@ -86,15 +86,14 @@ define float @fmul_fadd_reassoc1(float %x, float %y, float %z) {
; This shouldn't change anything - the intermediate fmul result is now also flagged.

; FMFDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fadd_reassoc2:'
; FMFDEBUG: fmul {{t[0-9]+}}, {{t[0-9]+}}
; FMFDEBUG: fadd {{t[0-9]+}}, {{t[0-9]+}}
; FMFDEBUG: fma {{t[0-9]+}}, {{t[0-9]+}}
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fadd_reassoc2:'

define float @fmul_fadd_reassoc2(float %x, float %y, float %z) {
; FMF-LABEL: fmul_fadd_reassoc2:
; FMF: # %bb.0:
; FMF-NEXT: xsmulsp 0, 1, 2
; FMF-NEXT: xsaddsp 1, 0, 3
; FMF-NEXT: xsmaddasp 3, 1, 2
; FMF-NEXT: fmr 1, 3
; FMF-NEXT: blr
;
; GLOBAL-LABEL: fmul_fadd_reassoc2:
Expand Down Expand Up @@ -161,7 +160,7 @@ define float @fmul_fadd_fast2(float %x, float %y, float %z) {
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_reassoc1:'

; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fma_reassoc1:'
; GLOBALDEBUG: fmul unsafe {{t[0-9]+}}
; GLOBALDEBUG: fmul reassoc {{t[0-9]+}}
; GLOBALDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_reassoc1:'

define float @fmul_fma_reassoc1(float %x) {
Expand Down Expand Up @@ -197,7 +196,7 @@ define float @fmul_fma_reassoc1(float %x) {
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_reassoc2:'

; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fma_reassoc2:'
; GLOBALDEBUG: fmul unsafe {{t[0-9]+}}
; GLOBALDEBUG: fmul reassoc {{t[0-9]+}}
; GLOBALDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_reassoc2:'

define float @fmul_fma_reassoc2(float %x) {
Expand Down Expand Up @@ -233,7 +232,7 @@ define float @fmul_fma_reassoc2(float %x) {
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_fast1:'

; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fma_fast1:'
; GLOBALDEBUG: fmul unsafe {{t[0-9]+}}
; GLOBALDEBUG: fmul reassoc {{t[0-9]+}}
; GLOBALDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_fast1:'

define float @fmul_fma_fast1(float %x) {
Expand Down Expand Up @@ -269,7 +268,7 @@ define float @fmul_fma_fast1(float %x) {
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_fast2:'

; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'fmul_fma_fast2:'
; GLOBALDEBUG: fmul unsafe {{t[0-9]+}}
; GLOBALDEBUG: fmul reassoc {{t[0-9]+}}
; GLOBALDEBUG: Type-legalized selection DAG: %bb.0 'fmul_fma_fast2:'

define float @fmul_fma_fast2(float %x) {
Expand Down Expand Up @@ -305,7 +304,7 @@ define float @fmul_fma_fast2(float %x) {
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'sqrt_afn:'

; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'sqrt_afn:'
; GLOBALDEBUG: fmul unsafe {{t[0-9]+}}
; GLOBALDEBUG: fmul reassoc {{t[0-9]+}}
; GLOBALDEBUG: Type-legalized selection DAG: %bb.0 'sqrt_afn:'

define float @sqrt_afn(float %x) {
Expand Down Expand Up @@ -345,7 +344,7 @@ define float @sqrt_afn(float %x) {
; FMFDEBUG: Type-legalized selection DAG: %bb.0 'sqrt_fast:'

; GLOBALDEBUG-LABEL: Optimized lowered selection DAG: %bb.0 'sqrt_fast:'
; GLOBALDEBUG: fmul unsafe {{t[0-9]+}}
; GLOBALDEBUG: fmul reassoc {{t[0-9]+}}
; GLOBALDEBUG: Type-legalized selection DAG: %bb.0 'sqrt_fast:'

define float @sqrt_fast(float %x) {
Expand Down
8 changes: 3 additions & 5 deletions llvm/test/CodeGen/X86/fmf-propagation.ll
View file
Expand Up @@ -3,18 +3,16 @@

; This tests the propagation of fast-math-flags from IR instructions to SDNodeFlags.

; FIXME: 'afn' and 'reassoc' were dropped. With 'fast', 'reassoc' got renamed to 'unsafe'.

; CHECK-LABEL: Initial selection DAG: %bb.0 'fmf_transfer:'

; CHECK: t5: f32 = fadd nsz t2, t4
; CHECK-NEXT: t6: f32 = fadd arcp t5, t4
; CHECK-NEXT: t7: f32 = fadd nnan t6, t4
; CHECK-NEXT: t8: f32 = fadd ninf t7, t4
; CHECK-NEXT: t9: f32 = fadd contract t8, t4
; CHECK-NEXT: t10: f32 = fadd t9, t4
; CHECK-NEXT: t11: f32 = fadd t10, t4
; CHECK-NEXT: t12: f32 = fadd unsafe nnan ninf nsz arcp contract t11, t4
; CHECK-NEXT: t10: f32 = fadd afn t9, t4
; CHECK-NEXT: t11: f32 = fadd reassoc t10, t4
; CHECK-NEXT: t12: f32 = fadd nnan ninf nsz arcp contract afn reassoc t11, t4

; CHECK: Optimized lowered selection DAG: %bb.0 'fmf_transfer:'

Expand Down

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