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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/transform/external_texture_transform.h"
#include "src/program_builder.h"
#include "src/sem/call.h"
#include "src/sem/variable.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::ExternalTextureTransform);
namespace tint {
namespace transform {
ExternalTextureTransform::ExternalTextureTransform() = default;
ExternalTextureTransform::~ExternalTextureTransform() = default;
void ExternalTextureTransform::Run(CloneContext& ctx,
const DataMap&,
DataMap&) const {
auto& sem = ctx.src->Sem();
// Within this transform, usages of texture_external are replaced with a
// texture_2d<f32>, which will allow us perform operations on a
// texture_external without maintaining texture_external-specific code
// generation paths in the backends.
// When replacing instances of texture_external with texture_2d<f32> we must
// also modify calls to the texture_external overloads of textureLoad and
// textureSampleLevel, which unlike their texture_2d<f32> overloads do not
// require a level parameter. To do this we identify calls to textureLoad and
// textureSampleLevel that use texture_external as the first parameter and add
// a parameter for the level (which is always 0).
// Scan the AST nodes for calls to textureLoad or textureSampleLevel.
for (auto* node : ctx.src->ASTNodes().Objects()) {
if (auto* call_expr = node->As<ast::CallExpression>()) {
if (auto* intrinsic =
sem.Get(call_expr)->Target()->As<sem::Intrinsic>()) {
if (intrinsic->Type() == sem::IntrinsicType::kTextureLoad ||
intrinsic->Type() == sem::IntrinsicType::kTextureSampleLevel) {
// When a textureLoad or textureSampleLevel has been identified, check
// if the first parameter is an external texture.
if (auto* var =
sem.Get(call_expr->args[0])->As<sem::VariableUser>()) {
if (var->Variable()
->Type()
->UnwrapRef()
->Is<sem::ExternalTexture>()) {
if (intrinsic->Type() == sem::IntrinsicType::kTextureLoad &&
call_expr->args.size() != 2) {
TINT_ICE(Transform, ctx.dst->Diagnostics())
<< "expected textureLoad call with a texture_external to "
"have 2 parameters, found "
<< call_expr->args.size() << " parameters";
}
if (intrinsic->Type() ==
sem::IntrinsicType::kTextureSampleLevel &&
call_expr->args.size() != 3) {
TINT_ICE(Transform, ctx.dst->Diagnostics())
<< "expected textureSampleLevel call with a "
"texture_external to have 3 parameters, found "
<< call_expr->args.size() << " parameters";
}
// Replace the call with another that has the same parameters in
// addition to a level parameter (always zero for external
// textures).
auto* exp = ctx.Clone(call_expr->target.name);
auto* externalTextureParam = ctx.Clone(call_expr->args[0]);
ast::ExpressionList params;
if (intrinsic->Type() == sem::IntrinsicType::kTextureLoad) {
auto* coordsParam = ctx.Clone(call_expr->args[1]);
auto* levelParam = ctx.dst->Expr(0);
params = {externalTextureParam, coordsParam, levelParam};
} else if (intrinsic->Type() ==
sem::IntrinsicType::kTextureSampleLevel) {
auto* samplerParam = ctx.Clone(call_expr->args[1]);
auto* coordsParam = ctx.Clone(call_expr->args[2]);
auto* levelParam = ctx.dst->Expr(0.0f);
params = {externalTextureParam, samplerParam, coordsParam,
levelParam};
}
auto* newCall = ctx.dst->create<ast::CallExpression>(exp, params);
ctx.Replace(call_expr, newCall);
}
}
}
}
}
}
// Scan the AST nodes for external texture declarations.
for (auto* node : ctx.src->ASTNodes().Objects()) {
if (auto* var = node->As<ast::Variable>()) {
if (::tint::Is<ast::ExternalTexture>(var->type)) {
// Replace a single-plane external texture with a 2D, f32 sampled
// texture.
auto* newType = ctx.dst->ty.sampled_texture(ast::TextureDimension::k2d,
ctx.dst->ty.f32());
auto clonedSrc = ctx.Clone(var->source);
auto clonedSym = ctx.Clone(var->symbol);
auto* clonedConstructor = ctx.Clone(var->constructor);
auto clonedDecorations = ctx.Clone(var->decorations);
auto* newVar = ctx.dst->create<ast::Variable>(
clonedSrc, clonedSym, var->declared_storage_class,
var->declared_access, newType, var->is_const, clonedConstructor,
clonedDecorations);
ctx.Replace(var, newVar);
}
}
}
ctx.Clone();
}
} // namespace transform
} // namespace tint