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// Copyright 2020 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/first_index_offset.h"
#include <memory>
#include <unordered_map>
#include <utility>
#include "src/tint/program_builder.h"
#include "src/tint/sem/function.h"
#include "src/tint/sem/member_accessor_expression.h"
#include "src/tint/sem/struct.h"
#include "src/tint/sem/variable.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::FirstIndexOffset);
TINT_INSTANTIATE_TYPEINFO(tint::transform::FirstIndexOffset::BindingPoint);
TINT_INSTANTIATE_TYPEINFO(tint::transform::FirstIndexOffset::Data);
namespace tint::transform {
namespace {
// Uniform buffer member names
constexpr char kFirstVertexName[] = "first_vertex_index";
constexpr char kFirstInstanceName[] = "first_instance_index";
bool ShouldRun(const Program* program) {
for (auto* fn : program->AST().Functions()) {
if (fn->PipelineStage() == ast::PipelineStage::kVertex) {
return true;
}
}
return false;
}
} // namespace
FirstIndexOffset::BindingPoint::BindingPoint() = default;
FirstIndexOffset::BindingPoint::BindingPoint(uint32_t b, uint32_t g) : binding(b), group(g) {}
FirstIndexOffset::BindingPoint::~BindingPoint() = default;
FirstIndexOffset::Data::Data(bool has_vtx_or_inst_index)
: has_vertex_or_instance_index(has_vtx_or_inst_index) {}
FirstIndexOffset::Data::Data(const Data&) = default;
FirstIndexOffset::Data::~Data() = default;
FirstIndexOffset::FirstIndexOffset() = default;
FirstIndexOffset::~FirstIndexOffset() = default;
Transform::ApplyResult FirstIndexOffset::Apply(const Program* src,
const DataMap& inputs,
DataMap& outputs) const {
if (!ShouldRun(src)) {
return SkipTransform;
}
ProgramBuilder b;
CloneContext ctx{&b, src, /* auto_clone_symbols */ true};
// Get the uniform buffer binding point
uint32_t ub_binding = binding_;
uint32_t ub_group = group_;
if (auto* binding_point = inputs.Get<BindingPoint>()) {
ub_binding = binding_point->binding;
ub_group = binding_point->group;
}
// Map of builtin usages
std::unordered_map<const sem::Variable*, const char*> builtin_vars;
std::unordered_map<const sem::StructMember*, const char*> builtin_members;
bool has_vertex_or_instance_index = false;
// Traverse the AST scanning for builtin accesses via variables (includes
// parameters) or structure member accesses.
for (auto* node : ctx.src->ASTNodes().Objects()) {
if (auto* var = node->As<ast::Variable>()) {
for (auto* attr : var->attributes) {
if (auto* builtin_attr = attr->As<ast::BuiltinAttribute>()) {
ast::BuiltinValue builtin = builtin_attr->builtin;
if (builtin == ast::BuiltinValue::kVertexIndex) {
auto* sem_var = ctx.src->Sem().Get(var);
builtin_vars.emplace(sem_var, kFirstVertexName);
has_vertex_or_instance_index = true;
}
if (builtin == ast::BuiltinValue::kInstanceIndex) {
auto* sem_var = ctx.src->Sem().Get(var);
builtin_vars.emplace(sem_var, kFirstInstanceName);
has_vertex_or_instance_index = true;
}
}
}
}
if (auto* member = node->As<ast::StructMember>()) {
for (auto* attr : member->attributes) {
if (auto* builtin_attr = attr->As<ast::BuiltinAttribute>()) {
ast::BuiltinValue builtin = builtin_attr->builtin;
if (builtin == ast::BuiltinValue::kVertexIndex) {
auto* sem_mem = ctx.src->Sem().Get(member);
builtin_members.emplace(sem_mem, kFirstVertexName);
has_vertex_or_instance_index = true;
}
if (builtin == ast::BuiltinValue::kInstanceIndex) {
auto* sem_mem = ctx.src->Sem().Get(member);
builtin_members.emplace(sem_mem, kFirstInstanceName);
has_vertex_or_instance_index = true;
}
}
}
}
}
if (has_vertex_or_instance_index) {
// Add uniform buffer members and calculate byte offsets
utils::Vector<const ast::StructMember*, 8> members;
members.Push(b.Member(kFirstVertexName, b.ty.u32()));
members.Push(b.Member(kFirstInstanceName, b.ty.u32()));
auto* struct_ = b.Structure(b.Sym(), std::move(members));
// Create a global to hold the uniform buffer
Symbol buffer_name = b.Sym();
b.GlobalVar(buffer_name, b.ty.Of(struct_), ast::AddressSpace::kUniform,
utils::Vector{
b.Binding(AInt(ub_binding)),
b.Group(AInt(ub_group)),
});
// Fix up all references to the builtins with the offsets
ctx.ReplaceAll([=, &ctx](const ast::Expression* expr) -> const ast::Expression* {
if (auto* sem = ctx.src->Sem().Get(expr)) {
if (auto* user = sem->As<sem::VariableUser>()) {
auto it = builtin_vars.find(user->Variable());
if (it != builtin_vars.end()) {
return ctx.dst->Add(ctx.CloneWithoutTransform(expr),
ctx.dst->MemberAccessor(buffer_name, it->second));
}
}
if (auto* access = sem->As<sem::StructMemberAccess>()) {
auto it = builtin_members.find(access->Member());
if (it != builtin_members.end()) {
return ctx.dst->Add(ctx.CloneWithoutTransform(expr),
ctx.dst->MemberAccessor(buffer_name, it->second));
}
}
}
// Not interested in this expression. Just clone.
return nullptr;
});
}
outputs.Add<Data>(has_vertex_or_instance_index);
ctx.Clone();
return Program(std::move(b));
}
} // namespace tint::transform