80 lines
2.8 KiB
C++
80 lines
2.8 KiB
C++
// Copyright 2020 The Tint Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "src/transform/emit_vertex_point_size.h"
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#include <utility>
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#include "src/ast/assignment_statement.h"
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#include "src/program_builder.h"
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namespace tint {
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namespace transform {
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namespace {
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const char kPointSizeVar[] = "tint_pointsize";
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} // namespace
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EmitVertexPointSize::EmitVertexPointSize() = default;
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EmitVertexPointSize::~EmitVertexPointSize() = default;
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Transform::Output EmitVertexPointSize::Run(const Program* in) {
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if (!in->AST().Functions().HasStage(ast::PipelineStage::kVertex)) {
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// If the module doesn't have any vertex stages, then there's nothing to do.
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return Output(Program(in->Clone()));
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}
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ProgramBuilder out;
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auto* f32 = out.create<type::F32>();
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// Declare the pointsize builtin output variable.
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auto* pointsize_var = out.create<ast::Variable>(
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Source{}, // source
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out.Symbols().Register(kPointSizeVar), // symbol
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ast::StorageClass::kOutput, // storage_class
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f32, // type
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false, // is_const
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nullptr, // constructor
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ast::DecorationList{
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out.create<ast::BuiltinDecoration>(Source{},
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ast::Builtin::kPointSize),
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});
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out.AST().AddGlobalVariable(pointsize_var);
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// Add the pointsize assignment statement to the front of all vertex stages.
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CloneContext ctx(&out, in);
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ctx.ReplaceAll([&](ast::Function* func) -> ast::Function* {
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if (func->pipeline_stage() != ast::PipelineStage::kVertex) {
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return nullptr; // Just clone func
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}
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// Build the AST expression & statement for assigning pointsize one.
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auto* one = out.create<ast::ScalarConstructorExpression>(
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Source{}, out.create<ast::FloatLiteral>(Source{}, f32, 1.0f));
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auto* pointsize_ident = out.create<ast::IdentifierExpression>(
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Source{}, out.Symbols().Register(kPointSizeVar));
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auto* pointsize_assign =
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out.create<ast::AssignmentStatement>(Source{}, pointsize_ident, one);
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return CloneWithStatementsAtStart(&ctx, func, {pointsize_assign});
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});
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ctx.Clone();
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return Output(Program(std::move(out)));
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}
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} // namespace transform
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} // namespace tint
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