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// 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/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 {
ArrayLengthFromUniform::ArrayLengthFromUniform() = default;
ArrayLengthFromUniform::~ArrayLengthFromUniform() = default;
/// Iterate over all arrayLength() builtins that operate on
/// storage buffer variables.
/// @param ctx the CloneContext.
/// @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>
static void IterateArrayLengthOnStorageVar(CloneContext& ctx, F&& functor) {
auto& sem = ctx.src->Sem();
// Find all calls to the arrayLength() builtin.
for (auto* node : ctx.src->ASTNodes().Objects()) {
auto* call_expr = node->As<ast::CallExpression>();
if (!call_expr) {
continue;
}
auto* call = sem.Get(call_expr);
auto* builtin = call->Target()->As<sem::Builtin>();
if (!builtin || builtin->Type() != sem::BuiltinType::kArrayLength) {
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 (!param || param->op != ast::UnaryOp::kAddressOf) {
TINT_ICE(Transform, ctx.dst->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 (!storage_buffer_sem) {
TINT_ICE(Transform, ctx.dst->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 (!var) {
TINT_ICE(Transform, ctx.dst->Diagnostics())
<< "storage buffer is not a global variable";
break;
}
functor(call_expr, storage_buffer_sem, var);
}
}
bool ArrayLengthFromUniform::ShouldRun(const Program* program,
const DataMap&) const {
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;
}
void ArrayLengthFromUniform::Run(CloneContext& ctx,
const DataMap& inputs,
DataMap& outputs) const {
auto* cfg = inputs.Get<Config>();
if (cfg == nullptr) {
ctx.dst->Diagnostics().add_error(
diag::System::Transform,
"missing transform data for " + std::string(TypeInfo().name));
return;
}
const char* kBufferSizeMemberName = "buffer_size";
// Determine the size of the buffer size array.
uint32_t max_buffer_size_index = 0;
IterateArrayLengthOnStorageVar(
ctx, [&](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 = ctx.dst->Structure(
ctx.dst->Sym(),
{ctx.dst->Member(
kBufferSizeMemberName,
ctx.dst->ty.array(ctx.dst->ty.vec4(ctx.dst->ty.u32()),
(max_buffer_size_index / 4) + 1))});
buffer_size_ubo = ctx.dst->Global(
ctx.dst->Sym(), ctx.dst->ty.Of(buffer_size_struct),
ast::StorageClass::kUniform,
ast::AttributeList{ctx.dst->GroupAndBinding(
cfg->ubo_binding.group, cfg->ubo_binding.binding)});
}
return buffer_size_ubo;
};
std::unordered_set<uint32_t> used_size_indices;
IterateArrayLengthOnStorageVar(
ctx, [&](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 = ctx.dst->IndexAccessor(
ctx.dst->MemberAccessor(get_ubo()->symbol, kBufferSizeMemberName),
array_index);
uint32_t vec_index = size_index % 4;
auto* total_storage_buffer_size =
ctx.dst->IndexAccessor(vec_expr, 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 sem::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<sem::Array>();
total_size = ctx.dst->Sub(total_storage_buffer_size,
array_member_sem->Offset());
} else if (auto* arr = storage_buffer_type->As<sem::Array>()) {
array_type = arr;
} else {
TINT_ICE(Transform, ctx.dst->Diagnostics())
<< "expected form of arrayLength argument to be &array_var or "
"&struct_var.array_member";
return;
}
auto* array_length = ctx.dst->Div(total_size, array_type->Stride());
ctx.Replace(call_expr, array_length);
});
ctx.Clone();
outputs.Add<Result>(used_size_indices);
}
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