src/tint/transform/array_length_from_uniform.cc - tint - Git at Google

 // Copyright 2021 The Tint Authors.
 //
 // 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.

 #include "src/tint/transform/array_length_from_uniform.h"

 #include <memory>
 #include <string>
 #include <utility>

 #include "src/tint/program_builder.h"
 #include "src/tint/sem/call.h"
 #include "src/tint/sem/function.h"
 #include "src/tint/sem/statement.h"
 #include "src/tint/sem/variable.h"
 #include "src/tint/transform/simplify_pointers.h"

 TINT_INSTANTIATE_TYPEINFO(tint::transform::ArrayLengthFromUniform);
 TINT_INSTANTIATE_TYPEINFO(tint::transform::ArrayLengthFromUniform::Config);
 TINT_INSTANTIATE_TYPEINFO(tint::transform::ArrayLengthFromUniform::Result);

 namespace tint::transform {

 namespace {

 bool ShouldRun(const Program* program) {
     for (auto* fn : program->AST().Functions()) {
         if (auto* sem_fn = program->Sem().Get(fn)) {
             for (auto* builtin : sem_fn->DirectlyCalledBuiltins()) {
                 if (builtin->Type() == sem::BuiltinType::kArrayLength) {
                     return true;
                 }
             }
         }
     }
     return false;
 }

 }  // namespace

 ArrayLengthFromUniform::ArrayLengthFromUniform() = default;
 ArrayLengthFromUniform::~ArrayLengthFromUniform() = default;

 /// PIMPL state for the transform
 struct ArrayLengthFromUniform::State {
     /// Constructor
     /// @param program the source program
     /// @param in the input transform data
     /// @param out the output transform data
     explicit State(const Program* program, const DataMap& in, DataMap& out)
         : src(program), inputs(in), outputs(out) {}

     /// Runs the transform
     /// @returns the new program or SkipTransform if the transform is not required
     ApplyResult Run() {
         auto* cfg = inputs.Get<Config>();
         if (cfg == nullptr) {
             b.Diagnostics().add_error(diag::System::Transform,
                                       "missing transform data for " +
                                           std::string(TypeInfo::Of<ArrayLengthFromUniform>().name));
             return Program(std::move(b));
         }

         if (!ShouldRun(ctx.src)) {
             return SkipTransform;
         }

         const char* kBufferSizeMemberName = "buffer_size";

         // Determine the size of the buffer size array.
         uint32_t max_buffer_size_index = 0;

         IterateArrayLengthOnStorageVar([&](const ast::CallExpression*, const sem::VariableUser*,
                                            const sem::GlobalVariable* var) {
             auto binding = var->BindingPoint();
             auto idx_itr = cfg->bindpoint_to_size_index.find(binding);
             if (idx_itr == cfg->bindpoint_to_size_index.end()) {
                 return;
             }
             if (idx_itr->second > max_buffer_size_index) {
                 max_buffer_size_index = idx_itr->second;
             }
         });

         // Get (or create, on first call) the uniform buffer that will receive the
         // size of each storage buffer in the module.
         const ast::Variable* buffer_size_ubo = nullptr;
         auto get_ubo = [&]() {
             if (!buffer_size_ubo) {
                 // Emit an array<vec4<u32>, N>, where N is 1/4 number of elements.
                 // We do this because UBOs require an element stride that is 16-byte
                 // aligned.
                 auto* buffer_size_struct = b.Structure(
                     b.Sym(), utils::Vector{
                                  b.Member(kBufferSizeMemberName,
                                           b.ty.array(b.ty.vec4(b.ty.u32()),
                                                      u32((max_buffer_size_index / 4) + 1))),
                              });
                 buffer_size_ubo =
                     b.GlobalVar(b.Sym(), b.ty.Of(buffer_size_struct), type::AddressSpace::kUniform,
                                 b.Group(AInt(cfg->ubo_binding.group)),
                                 b.Binding(AInt(cfg->ubo_binding.binding)));
             }
             return buffer_size_ubo;
         };

         std::unordered_set<uint32_t> used_size_indices;

         IterateArrayLengthOnStorageVar([&](const ast::CallExpression* call_expr,
                                            const sem::VariableUser* storage_buffer_sem,
                                            const sem::GlobalVariable* var) {
             auto binding = var->BindingPoint();
             auto idx_itr = cfg->bindpoint_to_size_index.find(binding);
             if (idx_itr == cfg->bindpoint_to_size_index.end()) {
                 return;
             }

             uint32_t size_index = idx_itr->second;
             used_size_indices.insert(size_index);

             // Load the total storage buffer size from the UBO.
             uint32_t array_index = size_index / 4;
             auto* vec_expr = b.IndexAccessor(
                 b.MemberAccessor(get_ubo()->symbol, kBufferSizeMemberName), u32(array_index));
             uint32_t vec_index = size_index % 4;
             auto* total_storage_buffer_size = b.IndexAccessor(vec_expr, u32(vec_index));

             // Calculate actual array length
             //                total_storage_buffer_size - array_offset
             // array_length = ----------------------------------------
             //                             array_stride
             const ast::Expression* total_size = total_storage_buffer_size;
             auto* storage_buffer_type = storage_buffer_sem->Type()->UnwrapRef();
             const type::Array* array_type = nullptr;
             if (auto* str = storage_buffer_type->As<sem::Struct>()) {
                 // The variable is a struct, so subtract the byte offset of the array
                 // member.
                 auto* array_member_sem = str->Members().Back();
                 array_type = array_member_sem->Type()->As<type::Array>();
                 total_size = b.Sub(total_storage_buffer_size, u32(array_member_sem->Offset()));
             } else if (auto* arr = storage_buffer_type->As<type::Array>()) {
                 array_type = arr;
             } else {
                 TINT_ICE(Transform, b.Diagnostics())
                     << "expected form of arrayLength argument to be &array_var or "
                        "&struct_var.array_member";
                 return;
             }
             auto* array_length = b.Div(total_size, u32(array_type->Stride()));

             ctx.Replace(call_expr, array_length);
         });

         outputs.Add<Result>(used_size_indices);

         ctx.Clone();
         return Program(std::move(b));
     }

   private:
     /// The source program
     const Program* const src;
     /// The transform inputs
     const DataMap& inputs;
     /// The transform outputs
     DataMap& outputs;
     /// The target program builder
     ProgramBuilder b;
     /// The clone context
     CloneContext ctx = {&b, src, /* auto_clone_symbols */ true};

     /// Iterate over all arrayLength() builtins that operate on
     /// storage buffer variables.
     /// @param functor of type void(const ast::CallExpression*, const
     /// sem::VariableUser, const sem::GlobalVariable*). It takes in an
     /// ast::CallExpression of the arrayLength call expression node, a
     /// sem::VariableUser of the used storage buffer variable, and the
     /// sem::GlobalVariable for the storage buffer.
     template <typename F>
     void IterateArrayLengthOnStorageVar(F&& functor) {
         auto& sem = src->Sem();

         // Find all calls to the arrayLength() builtin.
         for (auto* node : src->ASTNodes().Objects()) {
             auto* call_expr = node->As<ast::CallExpression>();
             if (!call_expr) {
                 continue;
             }

             auto* call = sem.Get(call_expr)->UnwrapMaterialize()->As<sem::Call>();
             auto* builtin = call->Target()->As<sem::Builtin>();
             if (!builtin || builtin->Type() != sem::BuiltinType::kArrayLength) {
                 continue;
             }

             if (auto* call_stmt = call->Stmt()->Declaration()->As<ast::CallStatement>()) {
                 if (call_stmt->expr == call_expr) {
                     // arrayLength() is used as a statement.
                     // The argument expression must be side-effect free, so just drop the statement.
                     RemoveStatement(ctx, call_stmt);
                     continue;
                 }
             }

             // Get the storage buffer that contains the runtime array.
             // Since we require SimplifyPointers, we can assume that the arrayLength()
             // call has one of two forms:
             //   arrayLength(&struct_var.array_member)
             //   arrayLength(&array_var)
             auto* param = call_expr->args[0]->As<ast::UnaryOpExpression>();
             if (TINT_UNLIKELY(!param || param->op != ast::UnaryOp::kAddressOf)) {
                 TINT_ICE(Transform, b.Diagnostics())
                     << "expected form of arrayLength argument to be &array_var or "
                        "&struct_var.array_member";
                 break;
             }
             auto* storage_buffer_expr = param->expr;
             if (auto* accessor = param->expr->As<ast::MemberAccessorExpression>()) {
                 storage_buffer_expr = accessor->structure;
             }
             auto* storage_buffer_sem = sem.Get<sem::VariableUser>(storage_buffer_expr);
             if (TINT_UNLIKELY(!storage_buffer_sem)) {
                 TINT_ICE(Transform, b.Diagnostics())
                     << "expected form of arrayLength argument to be &array_var or "
                        "&struct_var.array_member";
                 break;
             }

             // Get the index to use for the buffer size array.
             auto* var = tint::As<sem::GlobalVariable>(storage_buffer_sem->Variable());
             if (TINT_UNLIKELY(!var)) {
                 TINT_ICE(Transform, b.Diagnostics()) << "storage buffer is not a global variable";
                 break;
             }
             functor(call_expr, storage_buffer_sem, var);
         }
     }
 };

 Transform::ApplyResult ArrayLengthFromUniform::Apply(const Program* src,
                                                      const DataMap& inputs,
                                                      DataMap& outputs) const {
     return State{src, inputs, outputs}.Run();
 }

 ArrayLengthFromUniform::Config::Config(sem::BindingPoint ubo_bp) : ubo_binding(ubo_bp) {}
 ArrayLengthFromUniform::Config::Config(const Config&) = default;
 ArrayLengthFromUniform::Config& ArrayLengthFromUniform::Config::operator=(const Config&) = default;
 ArrayLengthFromUniform::Config::~Config() = default;

 ArrayLengthFromUniform::Result::Result(std::unordered_set<uint32_t> used_size_indices_in)
     : used_size_indices(std::move(used_size_indices_in)) {}
 ArrayLengthFromUniform::Result::Result(const Result&) = default;
 ArrayLengthFromUniform::Result::~Result() = default;

 }  // namespace tint::transform
	// Copyright 2021 The Tint Authors.
	//
	// 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.

	#include "src/tint/transform/array_length_from_uniform.h"

	#include <memory>
	#include <string>
	#include <utility>

	#include "src/tint/program_builder.h"
	#include "src/tint/sem/call.h"
	#include "src/tint/sem/function.h"
	#include "src/tint/sem/statement.h"
	#include "src/tint/sem/variable.h"
	#include "src/tint/transform/simplify_pointers.h"

	TINT_INSTANTIATE_TYPEINFO(tint::transform::ArrayLengthFromUniform);
	TINT_INSTANTIATE_TYPEINFO(tint::transform::ArrayLengthFromUniform::Config);
	TINT_INSTANTIATE_TYPEINFO(tint::transform::ArrayLengthFromUniform::Result);

	namespace tint::transform {

	namespace {

	bool ShouldRun(const Program* program) {
	for (auto* fn : program->AST().Functions()) {
	if (auto* sem_fn = program->Sem().Get(fn)) {
	for (auto* builtin : sem_fn->DirectlyCalledBuiltins()) {
	if (builtin->Type() == sem::BuiltinType::kArrayLength) {
	return true;
	}
	}
	}
	}
	return false;
	}

	} // namespace

	ArrayLengthFromUniform::ArrayLengthFromUniform() = default;
	ArrayLengthFromUniform::~ArrayLengthFromUniform() = default;

	/// PIMPL state for the transform
	struct ArrayLengthFromUniform::State {
	/// Constructor
	/// @param program the source program
	/// @param in the input transform data
	/// @param out the output transform data
	explicit State(const Program* program, const DataMap& in, DataMap& out)
	: src(program), inputs(in), outputs(out) {}

	/// Runs the transform
	/// @returns the new program or SkipTransform if the transform is not required
	ApplyResult Run() {
	auto* cfg = inputs.Get<Config>();
	if (cfg == nullptr) {
	b.Diagnostics().add_error(diag::System::Transform,
	"missing transform data for " +
	std::string(TypeInfo::Of<ArrayLengthFromUniform>().name));
	return Program(std::move(b));
	}

	if (!ShouldRun(ctx.src)) {
	return SkipTransform;
	}

	const char* kBufferSizeMemberName = "buffer_size";

	// Determine the size of the buffer size array.
	uint32_t max_buffer_size_index = 0;

	IterateArrayLengthOnStorageVar([&](const ast::CallExpression, const sem::VariableUser,
	const sem::GlobalVariable* var) {
	auto binding = var->BindingPoint();
	auto idx_itr = cfg->bindpoint_to_size_index.find(binding);
	if (idx_itr == cfg->bindpoint_to_size_index.end()) {
	return;
	}
	if (idx_itr->second > max_buffer_size_index) {
	max_buffer_size_index = idx_itr->second;
	}
	});

	// Get (or create, on first call) the uniform buffer that will receive the
	// size of each storage buffer in the module.
	const ast::Variable* buffer_size_ubo = nullptr;
	auto get_ubo = [&]() {
	if (!buffer_size_ubo) {
	// Emit an array<vec4<u32>, N>, where N is 1/4 number of elements.
	// We do this because UBOs require an element stride that is 16-byte
	// aligned.
	auto* buffer_size_struct = b.Structure(
	b.Sym(), utils::Vector{
	b.Member(kBufferSizeMemberName,
	b.ty.array(b.ty.vec4(b.ty.u32()),
	u32((max_buffer_size_index / 4) + 1))),
	});
	buffer_size_ubo =
	b.GlobalVar(b.Sym(), b.ty.Of(buffer_size_struct), type::AddressSpace::kUniform,
	b.Group(AInt(cfg->ubo_binding.group)),
	b.Binding(AInt(cfg->ubo_binding.binding)));
	}
	return buffer_size_ubo;
	};

	std::unordered_set<uint32_t> used_size_indices;

	IterateArrayLengthOnStorageVar([&](const ast::CallExpression* call_expr,
	const sem::VariableUser* storage_buffer_sem,
	const sem::GlobalVariable* var) {
	auto binding = var->BindingPoint();
	auto idx_itr = cfg->bindpoint_to_size_index.find(binding);
	if (idx_itr == cfg->bindpoint_to_size_index.end()) {
	return;
	}

	uint32_t size_index = idx_itr->second;
	used_size_indices.insert(size_index);

	// Load the total storage buffer size from the UBO.
	uint32_t array_index = size_index / 4;
	auto* vec_expr = b.IndexAccessor(
	b.MemberAccessor(get_ubo()->symbol, kBufferSizeMemberName), u32(array_index));
	uint32_t vec_index = size_index % 4;
	auto* total_storage_buffer_size = b.IndexAccessor(vec_expr, u32(vec_index));

	// Calculate actual array length
	// total_storage_buffer_size - array_offset
	// array_length = ----------------------------------------
	// array_stride
	const ast::Expression* total_size = total_storage_buffer_size;
	auto* storage_buffer_type = storage_buffer_sem->Type()->UnwrapRef();
	const type::Array* array_type = nullptr;
	if (auto* str = storage_buffer_type->As<sem::Struct>()) {
	// The variable is a struct, so subtract the byte offset of the array
	// member.
	auto* array_member_sem = str->Members().Back();
	array_type = array_member_sem->Type()->As<type::Array>();
	total_size = b.Sub(total_storage_buffer_size, u32(array_member_sem->Offset()));
	} else if (auto* arr = storage_buffer_type->As<type::Array>()) {
	array_type = arr;
	} else {
	TINT_ICE(Transform, b.Diagnostics())
	<< "expected form of arrayLength argument to be &array_var or "
	"&struct_var.array_member";
	return;
	}
	auto* array_length = b.Div(total_size, u32(array_type->Stride()));

	ctx.Replace(call_expr, array_length);
	});

	outputs.Add<Result>(used_size_indices);

	ctx.Clone();
	return Program(std::move(b));
	}

	private:
	/// The source program
	const Program* const src;
	/// The transform inputs
	const DataMap& inputs;
	/// The transform outputs
	DataMap& outputs;
	/// The target program builder
	ProgramBuilder b;
	/// The clone context
	CloneContext ctx = {&b, src, /* auto_clone_symbols */ true};

	/// Iterate over all arrayLength() builtins that operate on
	/// storage buffer variables.
	/// @param functor of type void(const ast::CallExpression*, const
	/// sem::VariableUser, const sem::GlobalVariable*). It takes in an
	/// ast::CallExpression of the arrayLength call expression node, a
	/// sem::VariableUser of the used storage buffer variable, and the
	/// sem::GlobalVariable for the storage buffer.
	template <typename F>
	void IterateArrayLengthOnStorageVar(F&& functor) {
	auto& sem = src->Sem();

	// Find all calls to the arrayLength() builtin.
	for (auto* node : src->ASTNodes().Objects()) {
	auto* call_expr = node->As<ast::CallExpression>();
	if (!call_expr) {
	continue;
	}

	auto* call = sem.Get(call_expr)->UnwrapMaterialize()->As<sem::Call>();
	auto* builtin = call->Target()->As<sem::Builtin>();
	if (!builtin \|\| builtin->Type() != sem::BuiltinType::kArrayLength) {
	continue;
	}

	if (auto* call_stmt = call->Stmt()->Declaration()->As<ast::CallStatement>()) {
	if (call_stmt->expr == call_expr) {
	// arrayLength() is used as a statement.
	// The argument expression must be side-effect free, so just drop the statement.
	RemoveStatement(ctx, call_stmt);
	continue;
	}
	}

	// Get the storage buffer that contains the runtime array.
	// Since we require SimplifyPointers, we can assume that the arrayLength()
	// call has one of two forms:
	// arrayLength(&struct_var.array_member)
	// arrayLength(&array_var)
	auto* param = call_expr->args[0]->As<ast::UnaryOpExpression>();
	if (TINT_UNLIKELY(!param \|\| param->op != ast::UnaryOp::kAddressOf)) {
	TINT_ICE(Transform, b.Diagnostics())
	<< "expected form of arrayLength argument to be &array_var or "
	"&struct_var.array_member";
	break;
	}
	auto* storage_buffer_expr = param->expr;
	if (auto* accessor = param->expr->As<ast::MemberAccessorExpression>()) {
	storage_buffer_expr = accessor->structure;
	}
	auto* storage_buffer_sem = sem.Get<sem::VariableUser>(storage_buffer_expr);
	if (TINT_UNLIKELY(!storage_buffer_sem)) {
	TINT_ICE(Transform, b.Diagnostics())
	<< "expected form of arrayLength argument to be &array_var or "
	"&struct_var.array_member";
	break;
	}

	// Get the index to use for the buffer size array.
	auto* var = tint::As<sem::GlobalVariable>(storage_buffer_sem->Variable());
	if (TINT_UNLIKELY(!var)) {
	TINT_ICE(Transform, b.Diagnostics()) << "storage buffer is not a global variable";
	break;
	}
	functor(call_expr, storage_buffer_sem, var);
	}
	}
	};

	Transform::ApplyResult ArrayLengthFromUniform::Apply(const Program* src,
	const DataMap& inputs,
	DataMap& outputs) const {
	return State{src, inputs, outputs}.Run();
	}

	ArrayLengthFromUniform::Config::Config(sem::BindingPoint ubo_bp) : ubo_binding(ubo_bp) {}
	ArrayLengthFromUniform::Config::Config(const Config&) = default;
	ArrayLengthFromUniform::Config& ArrayLengthFromUniform::Config::operator=(const Config&) = default;
	ArrayLengthFromUniform::Config::~Config() = default;

	ArrayLengthFromUniform::Result::Result(std::unordered_set<uint32_t> used_size_indices_in)
	: used_size_indices(std::move(used_size_indices_in)) {}
	ArrayLengthFromUniform::Result::Result(const Result&) = default;
	ArrayLengthFromUniform::Result::~Result() = default;

	} // namespace tint::transform