//===- llvm/CodeGen/GlobalISel/LegacyLegalizerInfo.h ------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
/// \file
/// Interface for Targets to specify which operations they can successfully
/// select and how the others should be expanded most efficiently.
/// This implementation has been deprecated for a long time but it still in use
/// in a few places.
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_GLOBALISEL_LEGACYLEGALIZERINFO_H
#define LLVM_CODEGEN_GLOBALISEL_LEGACYLEGALIZERINFO_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/CodeGen/TargetOpcodes.h"
#include "llvm/Support/LowLevelTypeImpl.h"
#include <unordered_map>
namespace llvm {
struct LegalityQuery;
namespace LegacyLegalizeActions {
enum LegacyLegalizeAction : std::uint8_t {
/// The operation is expected to be selectable directly by the target, and
/// no transformation is necessary.
Legal,
/// The operation should be synthesized from multiple instructions acting on
/// a narrower scalar base-type. For example a 64-bit add might be
/// implemented in terms of 32-bit add-with-carry.
NarrowScalar,
/// The operation should be implemented in terms of a wider scalar
/// base-type. For example a <2 x s8> add could be implemented as a <2
/// x s32> add (ignoring the high bits).
WidenScalar,
/// The (vector) operation should be implemented by splitting it into
/// sub-vectors where the operation is legal. For example a <8 x s64> add
/// might be implemented as 4 separate <2 x s64> adds.
FewerElements,
/// The (vector) operation should be implemented by widening the input
/// vector and ignoring the lanes added by doing so. For example <2 x i8> is
/// rarely legal, but you might perform an <8 x i8> and then only look at
/// the first two results.
MoreElements,
/// Perform the operation on a different, but equivalently sized type.
Bitcast,
/// The operation itself must be expressed in terms of simpler actions on
/// this target. E.g. a SREM replaced by an SDIV and subtraction.
Lower,
/// The operation should be implemented as a call to some kind of runtime
/// support library. For example this usually happens on machines that don't
/// support floating-point operations natively.
Libcall,
/// The target wants to do something special with this combination of
/// operand and type. A callback will be issued when it is needed.
Custom,
/// This operation is completely unsupported on the target. A programming
/// error has occurred.
Unsupported,
/// Sentinel value for when no action was found in the specified table.
NotFound,
};
} // end namespace LegacyLegalizeActions
raw_ostream &operator<<(raw_ostream &OS,
LegacyLegalizeActions::LegacyLegalizeAction Action);
/// Legalization is decided based on an instruction's opcode, which type slot
/// we're considering, and what the existing type is. These aspects are gathered
/// together for convenience in the InstrAspect class.
struct InstrAspect {
unsigned Opcode;
unsigned Idx = 0;
LLT Type;
InstrAspect(unsigned Opcode, LLT Type) : Opcode(Opcode), Type(Type) {}
InstrAspect(unsigned Opcode, unsigned Idx, LLT Type)
: Opcode(Opcode), Idx(Idx), Type(Type) {}
bool operator==(const InstrAspect &RHS) const {
return Opcode == RHS.Opcode && Idx == RHS.Idx && Type == RHS.Type;
}
};
/// The result of a query. It either indicates a final answer of Legal or
/// Unsupported or describes an action that must be taken to make an operation
/// more legal.
struct LegacyLegalizeActionStep {
/// The action to take or the final answer.
LegacyLegalizeActions::LegacyLegalizeAction Action;
/// If describing an action, the type index to change. Otherwise zero.
unsigned TypeIdx;
/// If describing an action, the new type for TypeIdx. Otherwise LLT{}.
LLT NewType;
LegacyLegalizeActionStep(LegacyLegalizeActions::LegacyLegalizeAction Action,
unsigned TypeIdx, const LLT NewType)
: Action(Action), TypeIdx(TypeIdx), NewType(NewType) {}
bool operator==(const LegacyLegalizeActionStep &RHS) const {
return std::tie(Action, TypeIdx, NewType) ==
std::tie(RHS.Action, RHS.TypeIdx, RHS.NewType);
}
};
class LegacyLegalizerInfo {
public:
using SizeAndAction =
std::pair<uint16_t, LegacyLegalizeActions::LegacyLegalizeAction>;
using SizeAndActionsVec = std::vector<SizeAndAction>;
using SizeChangeStrategy =
std::function<SizeAndActionsVec(const SizeAndActionsVec &v)>;
LegacyLegalizerInfo();
static bool needsLegalizingToDifferentSize(
const LegacyLegalizeActions::LegacyLegalizeAction Action) {
using namespace LegacyLegalizeActions;
switch (Action) {
case NarrowScalar:
case WidenScalar:
case FewerElements:
case MoreElements:
case Unsupported:
return true;
default:
return false;
}
}
/// Compute any ancillary tables needed to quickly decide how an operation
/// should be handled. This must be called after all "set*Action"methods but
/// before any query is made or incorrect results may be returned.
void computeTables();
/// More friendly way to set an action for common types that have an LLT
/// representation.
/// The LegacyLegalizeAction must be one for which
/// NeedsLegalizingToDifferentSize returns false.
void setAction(const InstrAspect &Aspect,
LegacyLegalizeActions::LegacyLegalizeAction Action) {
assert(!needsLegalizingToDifferentSize(Action));
TablesInitialized = false;
const unsigned OpcodeIdx = Aspect.Opcode - FirstOp;
if (SpecifiedActions[OpcodeIdx].size() <= Aspect.Idx)
SpecifiedActions[OpcodeIdx].resize(Aspect.Idx + 1);
SpecifiedActions[OpcodeIdx][Aspect.Idx][Aspect.Type] = Action;
}
/// The setAction calls record the non-size-changing legalization actions
/// to take on specificly-sized types. The SizeChangeStrategy defines what
/// to do when the size of the type needs to be changed to reach a legally
/// sized type (i.e., one that was defined through a setAction call).
/// e.g.
/// setAction ({G_ADD, 0, LLT::scalar(32)}, Legal);
/// setLegalizeScalarToDifferentSizeStrategy(
/// G_ADD, 0, widenToLargerTypesAndNarrowToLargest);
/// will end up defining getAction({G_ADD, 0, T}) to return the following
/// actions for different scalar types T:
/// LLT::scalar(1)..LLT::scalar(31): {WidenScalar, 0, LLT::scalar(32)}
/// LLT::scalar(32): {Legal, 0, LLT::scalar(32)}
/// LLT::scalar(33)..: {NarrowScalar, 0, LLT::scalar(32)}
///
/// If no SizeChangeAction gets defined, through this function,
/// the default is unsupportedForDifferentSizes.
void setLegalizeScalarToDifferentSizeStrategy(const unsigned Opcode,
const unsigned TypeIdx,
SizeChangeStrategy S) {
const unsigned OpcodeIdx = Opcode - FirstOp;
if (ScalarSizeChangeStrategies[OpcodeIdx].size() <= TypeIdx)
ScalarSizeChangeStrategies[OpcodeIdx].resize(TypeIdx + 1);
ScalarSizeChangeStrategies[OpcodeIdx][TypeIdx] = S;
}
/// See also setLegalizeScalarToDifferentSizeStrategy.
/// This function allows to set the SizeChangeStrategy for vector elements.
void setLegalizeVectorElementToDifferentSizeStrategy(const unsigned Opcode,
const unsigned TypeIdx,
SizeChangeStrategy S) {
const unsigned OpcodeIdx = Opcode - FirstOp;
if (VectorElementSizeChangeStrategies[OpcodeIdx].size() <= TypeIdx)
VectorElementSizeChangeStrategies[OpcodeIdx].resize(TypeIdx + 1);
VectorElementSizeChangeStrategies[OpcodeIdx][TypeIdx] = S;
}
/// A SizeChangeStrategy for the common case where legalization for a
/// particular operation consists of only supporting a specific set of type
/// sizes. E.g.
/// setAction ({G_DIV, 0, LLT::scalar(32)}, Legal);
/// setAction ({G_DIV, 0, LLT::scalar(64)}, Legal);
/// setLegalizeScalarToDifferentSizeStrategy(
/// G_DIV, 0, unsupportedForDifferentSizes);
/// will result in getAction({G_DIV, 0, T}) to return Legal for s32 and s64,
/// and Unsupported for all other scalar types T.
static SizeAndActionsVec
unsupportedForDifferentSizes(const SizeAndActionsVec &v) {
using namespace LegacyLegalizeActions;
return increaseToLargerTypesAndDecreaseToLargest(v, Unsupported,
Unsupported);
}
/// A SizeChangeStrategy for the common case where legalization for a
/// particular operation consists of widening the type to a large legal type,
/// unless there is no such type and then instead it should be narrowed to the
/// largest legal type.
static SizeAndActionsVec
widenToLargerTypesAndNarrowToLargest(const SizeAndActionsVec &v) {
using namespace LegacyLegalizeActions;
assert(v.size() > 0 &&
"At least one size that can be legalized towards is needed"
" for this SizeChangeStrategy");
return increaseToLargerTypesAndDecreaseToLargest(v, WidenScalar,
NarrowScalar);
}
static SizeAndActionsVec
widenToLargerTypesUnsupportedOtherwise(const SizeAndActionsVec &v) {
using namespace LegacyLegalizeActions;
return increaseToLargerTypesAndDecreaseToLargest(v, WidenScalar,
Unsupported);
}
static SizeAndActionsVec
narrowToSmallerAndUnsupportedIfTooSmall(const SizeAndActionsVec &v) {
using namespace LegacyLegalizeActions;
return decreaseToSmallerTypesAndIncreaseToSmallest(v, NarrowScalar,
Unsupported);
}
static SizeAndActionsVec
narrowToSmallerAndWidenToSmallest(const SizeAndActionsVec &v) {
using namespace LegacyLegalizeActions;
assert(v.size() > 0 &&
"At least one size that can be legalized towards is needed"
" for this SizeChangeStrategy");
return decreaseToSmallerTypesAndIncreaseToSmallest(v, NarrowScalar,
WidenScalar);
}
/// A SizeChangeStrategy for the common case where legalization for a
/// particular vector operation consists of having more elements in the
/// vector, to a type that is legal. Unless there is no such type and then
/// instead it should be legalized towards the widest vector that's still
/// legal. E.g.
/// setAction({G_ADD, LLT::vector(8, 8)}, Legal);
/// setAction({G_ADD, LLT::vector(16, 8)}, Legal);
/// setAction({G_ADD, LLT::vector(2, 32)}, Legal);
/// setAction({G_ADD, LLT::vector(4, 32)}, Legal);
/// setLegalizeVectorElementToDifferentSizeStrategy(
/// G_ADD, 0, moreToWiderTypesAndLessToWidest);
/// will result in the following getAction results:
/// * getAction({G_ADD, LLT::vector(8,8)}) returns
/// (Legal, vector(8,8)).
/// * getAction({G_ADD, LLT::vector(9,8)}) returns
/// (MoreElements, vector(16,8)).
/// * getAction({G_ADD, LLT::vector(8,32)}) returns
/// (FewerElements, vector(4,32)).
static SizeAndActionsVec
moreToWiderTypesAndLessToWidest(const SizeAndActionsVec &v) {
using namespace LegacyLegalizeActions;
return increaseToLargerTypesAndDecreaseToLargest(v, MoreElements,
FewerElements);
}
/// Helper function to implement many typical SizeChangeStrategy functions.
static SizeAndActionsVec increaseToLargerTypesAndDecreaseToLargest(
const SizeAndActionsVec &v,
LegacyLegalizeActions::LegacyLegalizeAction IncreaseAction,
LegacyLegalizeActions::LegacyLegalizeAction DecreaseAction);
/// Helper function to implement many typical SizeChangeStrategy functions.
static SizeAndActionsVec decreaseToSmallerTypesAndIncreaseToSmallest(
const SizeAndActionsVec &v,
LegacyLegalizeActions::LegacyLegalizeAction DecreaseAction,
LegacyLegalizeActions::LegacyLegalizeAction IncreaseAction);
LegacyLegalizeActionStep getAction(const LegalityQuery &Query) const;
unsigned getOpcodeIdxForOpcode(unsigned Opcode) const;
private:
/// Determine what action should be taken to legalize the given generic
/// instruction opcode, type-index and type. Requires computeTables to have
/// been called.
///
/// \returns a pair consisting of the kind of legalization that should be
/// performed and the destination type.
std::pair<LegacyLegalizeActions::LegacyLegalizeAction, LLT>
getAspectAction(const InstrAspect &Aspect) const;
/// The SizeAndActionsVec is a representation mapping between all natural
/// numbers and an Action. The natural number represents the bit size of
/// the InstrAspect. For example, for a target with native support for 32-bit
/// and 64-bit additions, you'd express that as:
/// setScalarAction(G_ADD, 0,
/// {{1, WidenScalar}, // bit sizes [ 1, 31[
/// {32, Legal}, // bit sizes [32, 33[
/// {33, WidenScalar}, // bit sizes [33, 64[
/// {64, Legal}, // bit sizes [64, 65[
/// {65, NarrowScalar} // bit sizes [65, +inf[
/// });
/// It may be that only 64-bit pointers are supported on your target:
/// setPointerAction(G_PTR_ADD, 0, LLT:pointer(1),
/// {{1, Unsupported}, // bit sizes [ 1, 63[
/// {64, Legal}, // bit sizes [64, 65[
/// {65, Unsupported}, // bit sizes [65, +inf[
/// });
void setScalarAction(const unsigned Opcode, const unsigned TypeIndex,
const SizeAndActionsVec &SizeAndActions) {
const unsigned OpcodeIdx = Opcode - FirstOp;
SmallVector<SizeAndActionsVec, 1> &Actions = ScalarActions[OpcodeIdx];
setActions(TypeIndex, Actions, SizeAndActions);
}
void setPointerAction(const unsigned Opcode, const unsigned TypeIndex,
const unsigned AddressSpace,
const SizeAndActionsVec &SizeAndActions) {
const unsigned OpcodeIdx = Opcode - FirstOp;
if (AddrSpace2PointerActions[OpcodeIdx].find(AddressSpace) ==
AddrSpace2PointerActions[OpcodeIdx].end())
AddrSpace2PointerActions[OpcodeIdx][AddressSpace] = {{}};
SmallVector<SizeAndActionsVec, 1> &Actions =
AddrSpace2PointerActions[OpcodeIdx].find(AddressSpace)->second;
setActions(TypeIndex, Actions, SizeAndActions);
}
/// If an operation on a given vector type (say <M x iN>) isn't explicitly
/// specified, we proceed in 2 stages. First we legalize the underlying scalar
/// (so that there's at least one legal vector with that scalar), then we
/// adjust the number of elements in the vector so that it is legal. The
/// desired action in the first step is controlled by this function.
void setScalarInVectorAction(const unsigned Opcode, const unsigned TypeIndex,
const SizeAndActionsVec &SizeAndActions) {
unsigned OpcodeIdx = Opcode - FirstOp;
SmallVector<SizeAndActionsVec, 1> &Actions =
ScalarInVectorActions[OpcodeIdx];
setActions(TypeIndex, Actions, SizeAndActions);
}
/// See also setScalarInVectorAction.
/// This function let's you specify the number of elements in a vector that
/// are legal for a legal element size.
void setVectorNumElementAction(const unsigned Opcode,
const unsigned TypeIndex,
const unsigned ElementSize,
const SizeAndActionsVec &SizeAndActions) {
const unsigned OpcodeIdx = Opcode - FirstOp;
if (NumElements2Actions[OpcodeIdx].find(ElementSize) ==
NumElements2Actions[OpcodeIdx].end())
NumElements2Actions[OpcodeIdx][ElementSize] = {{}};
SmallVector<SizeAndActionsVec, 1> &Actions =
NumElements2Actions[OpcodeIdx].find(ElementSize)->second;
setActions(TypeIndex, Actions, SizeAndActions);
}
/// A partial SizeAndActionsVec potentially doesn't cover all bit sizes,
/// i.e. it's OK if it doesn't start from size 1.
static void checkPartialSizeAndActionsVector(const SizeAndActionsVec& v) {
using namespace LegacyLegalizeActions;
#ifndef NDEBUG
// The sizes should be in increasing order
int prev_size = -1;
for(auto SizeAndAction: v) {
assert(SizeAndAction.first > prev_size);
prev_size = SizeAndAction.first;
}
// - for every Widen action, there should be a larger bitsize that
// can be legalized towards (e.g. Legal, Lower, Libcall or Custom
// action).
// - for every Narrow action, there should be a smaller bitsize that
// can be legalized towards.
int SmallestNarrowIdx = -1;
int LargestWidenIdx = -1;
int SmallestLegalizableToSameSizeIdx = -1;
int LargestLegalizableToSameSizeIdx = -1;
for(size_t i=0; i<v.size(); ++i) {
switch (v[i].second) {
case FewerElements:
case NarrowScalar:
if (SmallestNarrowIdx == -1)
SmallestNarrowIdx = i;
break;
case WidenScalar:
case MoreElements:
LargestWidenIdx = i;
break;
case Unsupported:
break;
default:
if (SmallestLegalizableToSameSizeIdx == -1)
SmallestLegalizableToSameSizeIdx = i;
LargestLegalizableToSameSizeIdx = i;
}
}
if (SmallestNarrowIdx != -1) {
assert(SmallestLegalizableToSameSizeIdx != -1);
assert(SmallestNarrowIdx > SmallestLegalizableToSameSizeIdx);
}
if (LargestWidenIdx != -1)
assert(LargestWidenIdx < LargestLegalizableToSameSizeIdx);
#endif
}
/// A full SizeAndActionsVec must cover all bit sizes, i.e. must start with
/// from size 1.
static void checkFullSizeAndActionsVector(const SizeAndActionsVec& v) {
#ifndef NDEBUG
// Data structure invariant: The first bit size must be size 1.
assert(v.size() >= 1);
assert(v[0].first == 1);
checkPartialSizeAndActionsVector(v);
#endif
}
/// Sets actions for all bit sizes on a particular generic opcode, type
/// index and scalar or pointer type.
void setActions(unsigned TypeIndex,
SmallVector<SizeAndActionsVec, 1> &Actions,
const SizeAndActionsVec &SizeAndActions) {
checkFullSizeAndActionsVector(SizeAndActions);
if (Actions.size() <= TypeIndex)
Actions.resize(TypeIndex + 1);
Actions[TypeIndex] = SizeAndActions;
}
static SizeAndAction findAction(const SizeAndActionsVec &Vec,
const uint32_t Size);
/// Returns the next action needed to get the scalar or pointer type closer
/// to being legal
/// E.g. findLegalAction({G_REM, 13}) should return
/// (WidenScalar, 32). After that, findLegalAction({G_REM, 32}) will
/// probably be called, which should return (Lower, 32).
/// This is assuming the setScalarAction on G_REM was something like:
/// setScalarAction(G_REM, 0,
/// {{1, WidenScalar}, // bit sizes [ 1, 31[
/// {32, Lower}, // bit sizes [32, 33[
/// {33, NarrowScalar} // bit sizes [65, +inf[
/// });
std::pair<LegacyLegalizeActions::LegacyLegalizeAction, LLT>
findScalarLegalAction(const InstrAspect &Aspect) const;
/// Returns the next action needed towards legalizing the vector type.
std::pair<LegacyLegalizeActions::LegacyLegalizeAction, LLT>
findVectorLegalAction(const InstrAspect &Aspect) const;
static const int FirstOp = TargetOpcode::PRE_ISEL_GENERIC_OPCODE_START;
static const int LastOp = TargetOpcode::PRE_ISEL_GENERIC_OPCODE_END;
// Data structures used temporarily during construction of legality data:
using TypeMap = DenseMap<LLT, LegacyLegalizeActions::LegacyLegalizeAction>;
SmallVector<TypeMap, 1> SpecifiedActions[LastOp - FirstOp + 1];
SmallVector<SizeChangeStrategy, 1>
ScalarSizeChangeStrategies[LastOp - FirstOp + 1];
SmallVector<SizeChangeStrategy, 1>
VectorElementSizeChangeStrategies[LastOp - FirstOp + 1];
bool TablesInitialized = false;
// Data structures used by getAction:
SmallVector<SizeAndActionsVec, 1> ScalarActions[LastOp - FirstOp + 1];
SmallVector<SizeAndActionsVec, 1> ScalarInVectorActions[LastOp - FirstOp + 1];
std::unordered_map<uint16_t, SmallVector<SizeAndActionsVec, 1>>
AddrSpace2PointerActions[LastOp - FirstOp + 1];
std::unordered_map<uint16_t, SmallVector<SizeAndActionsVec, 1>>
NumElements2Actions[LastOp - FirstOp + 1];
};
} // end namespace llvm
#endif // LLVM_CODEGEN_GLOBALISEL_LEGACYLEGALIZERINFO_H