SPIRV-Tools/source/opt/constants.h
Alan Baker 802cf053c7 Merge arithmetic with non-trivial constant operands
Adding basis of arithmetic merging

* Refactored constant collection in ConstantManager
* New rules:
 * consecutive negates
 * negate of arithmetic op with a constant
 * consecutive muls
 * reciprocal of div

* Removed IRContext::CanFoldFloatingPoint
 * replaced by Instruction::IsFloatingPointFoldingAllowed
* Fixed some bad tests
* added some header comments

Added PerformIntegerOperation

* minor fixes to constants and tests
* fixed IntMultiplyBy1 to work with 64 bit ints
* added tests for integer mul merging

Adding test for vector integer multiply merging

Adding support for merging integer add and sub through negate

* Added tests

Adding rules to merge mult with preceding divide

* Has a couple tests, but needs more
* Added more comments

Fixed bug in integer division folding

* Will no longer merge through integer division if there would be a
remainder in the division
* Added a bunch more tests

Adding rules to merge divide and multiply through divide

* Improved comments
* Added tests

Adding rules to handle mul or div of a negation

* Added tests

Changes for review

* Early exit if no constants are involved in more functions
* fixed some comments
* removed unused declaration
* clarified some logic

Adding new rules for add and subtract

* Fold adds of adds, subtracts or negates
* Fold subtracts of adds, subtracts or negates
* Added tests
2018-02-27 13:02:13 -05:00

646 lines
24 KiB
C++

// Copyright (c) 2016 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#ifndef LIBSPIRV_OPT_CONSTANTS_H_
#define LIBSPIRV_OPT_CONSTANTS_H_
#include <cinttypes>
#include <memory>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>
#include "make_unique.h"
#include "module.h"
#include "type_manager.h"
#include "types.h"
#include "util/hex_float.h"
namespace spvtools {
namespace opt {
namespace analysis {
// Class hierarchy to represent the normal constants defined through
// OpConstantTrue, OpConstantFalse, OpConstant, OpConstantNull and
// OpConstantComposite instructions.
// TODO(qining): Add class for constants defined with OpConstantSampler.
class Constant;
class ScalarConstant;
class IntConstant;
class FloatConstant;
class BoolConstant;
class CompositeConstant;
class StructConstant;
class VectorConstant;
class MatrixConstant;
class ArrayConstant;
class NullConstant;
// Abstract class for a SPIR-V constant. It has a bunch of As<subclass> methods,
// which is used as a way to probe the actual <subclass>
class Constant {
public:
Constant() = delete;
virtual ~Constant() {}
// Make a deep copy of this constant.
virtual std::unique_ptr<Constant> Copy() const = 0;
// reflections
virtual ScalarConstant* AsScalarConstant() { return nullptr; }
virtual IntConstant* AsIntConstant() { return nullptr; }
virtual FloatConstant* AsFloatConstant() { return nullptr; }
virtual BoolConstant* AsBoolConstant() { return nullptr; }
virtual CompositeConstant* AsCompositeConstant() { return nullptr; }
virtual StructConstant* AsStructConstant() { return nullptr; }
virtual VectorConstant* AsVectorConstant() { return nullptr; }
virtual MatrixConstant* AsMatrixConstant() { return nullptr; }
virtual ArrayConstant* AsArrayConstant() { return nullptr; }
virtual NullConstant* AsNullConstant() { return nullptr; }
virtual const ScalarConstant* AsScalarConstant() const { return nullptr; }
virtual const IntConstant* AsIntConstant() const { return nullptr; }
virtual const FloatConstant* AsFloatConstant() const { return nullptr; }
virtual const BoolConstant* AsBoolConstant() const { return nullptr; }
virtual const CompositeConstant* AsCompositeConstant() const {
return nullptr;
}
virtual const StructConstant* AsStructConstant() const { return nullptr; }
virtual const VectorConstant* AsVectorConstant() const { return nullptr; }
virtual const MatrixConstant* AsMatrixConstant() const { return nullptr; }
virtual const ArrayConstant* AsArrayConstant() const { return nullptr; }
virtual const NullConstant* AsNullConstant() const { return nullptr; }
// Returns the float representation of the constant. Must be a 32 bit
// Float type.
float GetFloat() const;
// Returns the double representation of the constant. Must be a 64 bit
// Float type.
double GetDouble() const;
// Returns uint32_t representation of the constant. Must be a 32 bit
// Integer type.
uint32_t GetU32() const;
// Returns uint64_t representation of the constant. Must be a 64 bit
// Integer type.
uint64_t GetU64() const;
// Returns int32_t representation of the constant. Must be a 32 bit
// Integer type.
int32_t GetS32() const;
// Returns int64_t representation of the constant. Must be a 64 bit
// Integer type.
int64_t GetS64() const;
const Type* type() const { return type_; }
protected:
Constant(const Type* ty) : type_(ty) {}
// The type of this constant.
const Type* type_;
};
// Abstract class for scalar type constants.
class ScalarConstant : public Constant {
public:
ScalarConstant() = delete;
ScalarConstant* AsScalarConstant() override { return this; }
const ScalarConstant* AsScalarConstant() const override { return this; }
// Returns a const reference of the value of this constant in 32-bit words.
virtual const std::vector<uint32_t>& words() const { return words_; }
protected:
ScalarConstant(const Type* ty, const std::vector<uint32_t>& w)
: Constant(ty), words_(w) {}
ScalarConstant(const Type* ty, std::vector<uint32_t>&& w)
: Constant(ty), words_(std::move(w)) {}
std::vector<uint32_t> words_;
};
// Integer type constant.
class IntConstant : public ScalarConstant {
public:
IntConstant(const Integer* ty, const std::vector<uint32_t>& w)
: ScalarConstant(ty, w) {}
IntConstant(const Integer* ty, std::vector<uint32_t>&& w)
: ScalarConstant(ty, std::move(w)) {}
IntConstant* AsIntConstant() override { return this; }
const IntConstant* AsIntConstant() const override { return this; }
int32_t GetS32BitValue() const {
// Relies on signed values smaller than 32-bit being sign extended. See
// section 2.2.1 of the SPIR-V spec.
assert(words().size() == 1);
return words()[0];
}
uint32_t GetU32BitValue() const {
// Relies on unsigned values smaller than 32-bit being zero extended. See
// section 2.2.1 of the SPIR-V spec.
assert(words().size() == 1);
return words()[0];
}
int64_t GetS64BitValue() const {
// Relies on unsigned values smaller than 64-bit being sign extended. See
// section 2.2.1 of the SPIR-V spec.
assert(words().size() == 2);
return static_cast<uint64_t>(words()[1]) << 32 |
static_cast<uint64_t>(words()[0]);
}
uint64_t GetU64BitValue() const {
// Relies on unsigned values smaller than 64-bit being zero extended. See
// section 2.2.1 of the SPIR-V spec.
assert(words().size() == 2);
return static_cast<uint64_t>(words()[1]) << 32 |
static_cast<uint64_t>(words()[0]);
}
bool IsZero() const {
bool is_zero = true;
for (uint32_t v : words()) {
if (v != 0) {
is_zero = false;
break;
}
}
return is_zero;
}
// Make a copy of this IntConstant instance.
std::unique_ptr<IntConstant> CopyIntConstant() const {
return MakeUnique<IntConstant>(type_->AsInteger(), words_);
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyIntConstant().release());
}
};
// Float type constant.
class FloatConstant : public ScalarConstant {
public:
FloatConstant(const Float* ty, const std::vector<uint32_t>& w)
: ScalarConstant(ty, w) {}
FloatConstant(const Float* ty, std::vector<uint32_t>&& w)
: ScalarConstant(ty, std::move(w)) {}
FloatConstant* AsFloatConstant() override { return this; }
const FloatConstant* AsFloatConstant() const override { return this; }
// Make a copy of this FloatConstant instance.
std::unique_ptr<FloatConstant> CopyFloatConstant() const {
return MakeUnique<FloatConstant>(type_->AsFloat(), words_);
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyFloatConstant().release());
}
// Returns the float value of |this|. The type of |this| must be |Float| with
// width of 32.
float GetFloatValue() const {
assert(type()->AsFloat()->width() == 32 &&
"Not a 32-bit floating point value.");
spvutils::FloatProxy<float> a(words()[0]);
return a.getAsFloat();
}
// Returns the double value of |this|. The type of |this| must be |Float|
// with width of 64.
double GetDoubleValue() const {
assert(type()->AsFloat()->width() == 64 &&
"Not a 32-bit floating point value.");
uint64_t combined_words = words()[1];
combined_words = combined_words << 32;
combined_words |= words()[0];
spvutils::FloatProxy<double> a(combined_words);
return a.getAsFloat();
}
};
// Bool type constant.
class BoolConstant : public ScalarConstant {
public:
BoolConstant(const Bool* ty, bool v)
: ScalarConstant(ty, {static_cast<uint32_t>(v)}), value_(v) {}
BoolConstant* AsBoolConstant() override { return this; }
const BoolConstant* AsBoolConstant() const override { return this; }
// Make a copy of this BoolConstant instance.
std::unique_ptr<BoolConstant> CopyBoolConstant() const {
return MakeUnique<BoolConstant>(type_->AsBool(), value_);
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyBoolConstant().release());
}
bool value() const { return value_; }
private:
bool value_;
};
// Abstract class for composite constants.
class CompositeConstant : public Constant {
public:
CompositeConstant() = delete;
CompositeConstant* AsCompositeConstant() override { return this; }
const CompositeConstant* AsCompositeConstant() const override { return this; }
// Returns a const reference of the components held in this composite
// constant.
virtual const std::vector<const Constant*>& GetComponents() const {
return components_;
}
protected:
CompositeConstant(const Type* ty) : Constant(ty), components_() {}
CompositeConstant(const Type* ty,
const std::vector<const Constant*>& components)
: Constant(ty), components_(components) {}
CompositeConstant(const Type* ty, std::vector<const Constant*>&& components)
: Constant(ty), components_(std::move(components)) {}
std::vector<const Constant*> components_;
};
// Struct type constant.
class StructConstant : public CompositeConstant {
public:
StructConstant(const Struct* ty) : CompositeConstant(ty) {}
StructConstant(const Struct* ty,
const std::vector<const Constant*>& components)
: CompositeConstant(ty, components) {}
StructConstant(const Struct* ty, std::vector<const Constant*>&& components)
: CompositeConstant(ty, std::move(components)) {}
StructConstant* AsStructConstant() override { return this; }
const StructConstant* AsStructConstant() const override { return this; }
// Make a copy of this StructConstant instance.
std::unique_ptr<StructConstant> CopyStructConstant() const {
return MakeUnique<StructConstant>(type_->AsStruct(), components_);
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyStructConstant().release());
}
};
// Vector type constant.
class VectorConstant : public CompositeConstant {
public:
VectorConstant(const Vector* ty)
: CompositeConstant(ty), component_type_(ty->element_type()) {}
VectorConstant(const Vector* ty,
const std::vector<const Constant*>& components)
: CompositeConstant(ty, components),
component_type_(ty->element_type()) {}
VectorConstant(const Vector* ty, std::vector<const Constant*>&& components)
: CompositeConstant(ty, std::move(components)),
component_type_(ty->element_type()) {}
VectorConstant* AsVectorConstant() override { return this; }
const VectorConstant* AsVectorConstant() const override { return this; }
// Make a copy of this VectorConstant instance.
std::unique_ptr<VectorConstant> CopyVectorConstant() const {
auto another = MakeUnique<VectorConstant>(type_->AsVector());
another->components_.insert(another->components_.end(), components_.begin(),
components_.end());
return another;
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyVectorConstant().release());
}
const Type* component_type() const { return component_type_; }
private:
const Type* component_type_;
};
// Matrix type constant.
class MatrixConstant : public CompositeConstant {
public:
MatrixConstant(const Matrix* ty)
: CompositeConstant(ty), component_type_(ty->element_type()) {}
MatrixConstant(const Matrix* ty,
const std::vector<const Constant*>& components)
: CompositeConstant(ty, components),
component_type_(ty->element_type()) {}
MatrixConstant(const Vector* ty, std::vector<const Constant*>&& components)
: CompositeConstant(ty, std::move(components)),
component_type_(ty->element_type()) {}
MatrixConstant* AsMatrixConstant() override { return this; }
const MatrixConstant* AsMatrixConstant() const override { return this; }
// Make a copy of this MatrixConstant instance.
std::unique_ptr<MatrixConstant> CopyMatrixConstant() const {
auto another = MakeUnique<MatrixConstant>(type_->AsMatrix());
another->components_.insert(another->components_.end(), components_.begin(),
components_.end());
return another;
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyMatrixConstant().release());
}
const Type* component_type() { return component_type_; }
private:
const Type* component_type_;
};
// Array type constant.
class ArrayConstant : public CompositeConstant {
public:
ArrayConstant(const Array* ty) : CompositeConstant(ty) {}
ArrayConstant(const Array* ty, const std::vector<const Constant*>& components)
: CompositeConstant(ty, components) {}
ArrayConstant(const Array* ty, std::vector<const Constant*>&& components)
: CompositeConstant(ty, std::move(components)) {}
ArrayConstant* AsArrayConstant() override { return this; }
const ArrayConstant* AsArrayConstant() const override { return this; }
// Make a copy of this ArrayConstant instance.
std::unique_ptr<ArrayConstant> CopyArrayConstant() const {
return MakeUnique<ArrayConstant>(type_->AsArray(), components_);
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyArrayConstant().release());
}
};
// Null type constant.
class NullConstant : public Constant {
public:
NullConstant(const Type* ty) : Constant(ty) {}
NullConstant* AsNullConstant() override { return this; }
const NullConstant* AsNullConstant() const override { return this; }
// Make a copy of this NullConstant instance.
std::unique_ptr<NullConstant> CopyNullConstant() const {
return MakeUnique<NullConstant>(type_);
}
std::unique_ptr<Constant> Copy() const override {
return std::unique_ptr<Constant>(CopyNullConstant().release());
}
};
class IRContext;
// Hash function for Constant instances. Use the structure of the constant as
// the key.
struct ConstantHash {
void add_pointer(std::u32string* h, const void* p) const {
uint64_t ptr_val = reinterpret_cast<uint64_t>(p);
h->push_back(static_cast<uint32_t>(ptr_val >> 32));
h->push_back(static_cast<uint32_t>(ptr_val));
}
size_t operator()(const Constant* const_val) const {
std::u32string h;
add_pointer(&h, const_val->type());
if (const auto scalar = const_val->AsScalarConstant()) {
for (const auto& w : scalar->words()) {
h.push_back(w);
}
} else if (const auto composite = const_val->AsCompositeConstant()) {
for (const auto& c : composite->GetComponents()) {
add_pointer(&h, c);
}
} else if (const_val->AsNullConstant()) {
h.push_back(0);
} else {
assert(
false &&
"Tried to compute the hash value of an invalid Constant instance.");
}
return std::hash<std::u32string>()(h);
}
};
// Equality comparison structure for two constants.
struct ConstantEqual {
bool operator()(const Constant* c1, const Constant* c2) const {
if (c1->type() != c2->type()) {
return false;
}
if (const auto& s1 = c1->AsScalarConstant()) {
const auto& s2 = c2->AsScalarConstant();
return s2 && s1->words() == s2->words();
} else if (const auto& composite1 = c1->AsCompositeConstant()) {
const auto& composite2 = c2->AsCompositeConstant();
return composite2 &&
composite1->GetComponents() == composite2->GetComponents();
} else if (c1->AsNullConstant())
return c2->AsNullConstant() != nullptr;
else
assert(false && "Tried to compare two invalid Constant instances.");
return false;
}
};
// This class represents a pool of constants.
class ConstantManager {
public:
ConstantManager(ir::IRContext* ctx);
ir::IRContext* context() const { return ctx_; }
// Gets or creates a unique Constant instance of type |type| and a vector of
// constant defining words |words|. If a Constant instance existed already in
// the constant pool, it returns a pointer to it. Otherwise, it creates one
// using CreateConstant. If a new Constant instance cannot be created, it
// returns nullptr.
const Constant* GetConstant(
const Type* type, const std::vector<uint32_t>& literal_words_or_ids);
// Gets or creates a Constant instance to hold the constant value of the given
// instruction. It returns a pointer to a Constant instance or nullptr if it
// could not create the constant.
const Constant* GetConstantFromInst(ir::Instruction* inst);
// Gets or creates a constant defining instruction for the given Constant |c|.
// If |c| had already been defined, it returns a pointer to the existing
// declaration. Otherwise, it calls BuildInstructionAndAddToModule. If the
// optional |pos| is given, it will insert any newly created instructions at
// the given instruction iterator position. Otherwise, it inserts the new
// instruction at the end of the current module's types section.
ir::Instruction* GetDefiningInstruction(
const Constant* c, ir::Module::inst_iterator* pos = nullptr);
// Creates a constant defining instruction for the given Constant instance
// and inserts the instruction at the position specified by the given
// instruction iterator. Returns a pointer to the created instruction if
// succeeded, otherwise returns a null pointer. The instruction iterator
// points to the same instruction before and after the insertion. This is the
// only method that actually manages id creation/assignment and instruction
// creation/insertion for a new Constant instance.
//
// |type_id| is an optional argument for disambiguating equivalent types. If
// |type_id| is specified, it is used as the type of the constant. Otherwise
// the type of the constant is derived by getting an id from the type manager
// for |c|.
ir::Instruction* BuildInstructionAndAddToModule(
const Constant* c, ir::Module::inst_iterator* pos, uint32_t type_id = 0);
// A helper function to get the result type of the given instruction. Returns
// nullptr if the instruction does not have a type id (type id is 0).
Type* GetType(const ir::Instruction* inst) const;
// A helper function to get the collected normal constant with the given id.
// Returns the pointer to the Constant instance in case it is found.
// Otherwise, it returns a null pointer.
const Constant* FindDeclaredConstant(uint32_t id) const {
auto iter = id_to_const_val_.find(id);
return (iter != id_to_const_val_.end()) ? iter->second : nullptr;
}
// A helper function to get the id of a collected constant with the pointer
// to the Constant instance. Returns 0 in case the constant is not found.
uint32_t FindDeclaredConstant(const Constant* c) const {
auto iter = const_val_to_id_.find(c);
return (iter != const_val_to_id_.end()) ? iter->second : 0;
}
// Returns the canonical constant that has the same structure and value as the
// given Constant |cst|. If none is found, it returns nullptr.
const Constant* FindConstant(const Constant* c) const {
auto it = const_pool_.find(c);
return (it != const_pool_.end()) ? *it : nullptr;
}
// Registers a new constant |cst| in the constant pool. If the constant
// existed already, it returns a pointer to the previously existing Constant
// in the pool. Otherwise, it returns |cst|.
const Constant* RegisterConstant(const Constant* cst) {
auto ret = const_pool_.insert(cst);
return *ret.first;
}
// A helper function to get a vector of Constant instances with the specified
// ids. If it can not find the Constant instance for any one of the ids,
// it returns an empty vector.
std::vector<const Constant*> GetConstantsFromIds(
const std::vector<uint32_t>& ids) const;
// Returns a vector of constants representing each in operand. If an operand
// is not constant its entry is nullptr.
std::vector<const Constant*> GetOperandConstants(ir::Instruction* inst) const;
// Records a mapping between |inst| and the constant value generated by it.
// It returns true if a new Constant was successfully mapped, false if |inst|
// generates no constant values.
bool MapInst(ir::Instruction* inst) {
if (auto cst = GetConstantFromInst(inst)) {
MapConstantToInst(cst, inst);
return true;
}
return false;
}
void RemoveId(uint32_t id) {
auto it = id_to_const_val_.find(id);
if (it != id_to_const_val_.end()) {
const_val_to_id_.erase(it->second);
id_to_const_val_.erase(it);
}
}
// Records a new mapping between |inst| and |const_value|. This updates the
// two mappings |id_to_const_val_| and |const_val_to_id_|.
void MapConstantToInst(const Constant* const_value, ir::Instruction* inst) {
const_val_to_id_[const_value] = inst->result_id();
id_to_const_val_[inst->result_id()] = const_value;
}
private:
// Creates a Constant instance with the given type and a vector of constant
// defining words. Returns a unique pointer to the created Constant instance
// if the Constant instance can be created successfully. To create scalar
// type constants, the vector should contain the constant value in 32 bit
// words and the given type must be of type Bool, Integer or Float. To create
// composite type constants, the vector should contain the component ids, and
// those component ids should have been recorded before as Normal Constants.
// And the given type must be of type Struct, Vector or Array. When creating
// VectorType Constant instance, the components must be scalars of the same
// type, either Bool, Integer or Float. If any of the rules above failed, the
// creation will fail and nullptr will be returned. If the vector is empty,
// a NullConstant instance will be created with the given type.
const Constant* CreateConstant(
const Type* type,
const std::vector<uint32_t>& literal_words_or_ids) const;
// Creates an instruction with the given result id to declare a constant
// represented by the given Constant instance. Returns an unique pointer to
// the created instruction if the instruction can be created successfully.
// Otherwise, returns a null pointer.
//
// |type_id| is an optional argument for disambiguating equivalent types. If
// |type_id| is specified, it is used as the type of the constant. Otherwise
// the type of the constant is derived by getting an id from the type manager
// for |c|.
std::unique_ptr<ir::Instruction> CreateInstruction(
uint32_t result_id, const Constant* c, uint32_t type_id = 0) const;
// Creates an OpConstantComposite instruction with the given result id and
// the CompositeConst instance which represents a composite constant. Returns
// an unique pointer to the created instruction if succeeded. Otherwise
// returns a null pointer.
//
// |type_id| is an optional argument for disambiguating equivalent types. If
// |type_id| is specified, it is used as the type of the constant. Otherwise
// the type of the constant is derived by getting an id from the type manager
// for |c|.
std::unique_ptr<ir::Instruction> CreateCompositeInstruction(
uint32_t result_id, const CompositeConstant* cc,
uint32_t type_id = 0) const;
// IR context that owns this constant manager.
ir::IRContext* ctx_;
// A mapping from the result ids of Normal Constants to their
// Constant instances. All Normal Constants in the module, either
// existing ones before optimization or the newly generated ones, should have
// their Constant instance stored and their result id registered in this map.
std::unordered_map<uint32_t, const Constant*> id_to_const_val_;
// A mapping from the Constant instance of Normal Constants to their
// result id in the module. This is a mirror map of |id_to_const_val_|. All
// Normal Constants that defining instructions in the module should have
// their Constant and their result id registered here.
std::unordered_map<const Constant*, uint32_t> const_val_to_id_;
// The constant pool. All created constants are registered here.
std::unordered_set<const Constant*, ConstantHash, ConstantEqual> const_pool_;
};
} // namespace analysis
} // namespace opt
} // namespace spvtools
#endif // LIBSPIRV_OPT_CONSTANTS_H_