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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/add_block_attribute.h"
#include <unordered_set>
#include <utility>
#include "src/tint/program_builder.h"
#include "src/tint/sem/variable.h"
#include "src/tint/utils/hashmap.h"
#include "src/tint/utils/hashset.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::AddBlockAttribute);
TINT_INSTANTIATE_TYPEINFO(tint::transform::AddBlockAttribute::BlockAttribute);
namespace tint::transform {
AddBlockAttribute::AddBlockAttribute() = default;
AddBlockAttribute::~AddBlockAttribute() = default;
Transform::ApplyResult AddBlockAttribute::Apply(const Program* src,
const DataMap&,
DataMap&) const {
ProgramBuilder b;
CloneContext ctx{&b, src, /* auto_clone_symbols */ true};
auto& sem = src->Sem();
// A map from a type in the source program to a block-decorated wrapper that contains it in the
// destination program.
utils::Hashmap<const sem::Type*, const ast::Struct*, 8> wrapper_structs;
// Process global 'var' declarations that are buffers.
bool made_changes = false;
for (auto* global : src->AST().GlobalVariables()) {
auto* var = sem.Get(global);
if (!ast::IsHostShareable(var->AddressSpace())) {
// Not declared in a host-sharable address space
continue;
}
made_changes = true;
auto* ty = var->Type()->UnwrapRef();
auto* str = ty->As<sem::Struct>();
// Always try to wrap the buffer type into a struct. We can not do so only if it is a struct
// but without a fixed footprint, i.e. contains a runtime-sized array as its member. Note
// that such struct type can be only used as storage buffer variables' type. Also note that
// any buffer struct type that may be nested by another type must have a fixed footprint,
// therefore will be wrapped.
bool needs_wrapping = !str || // Type is not a structure
str->HasFixedFootprint(); // Struct has a fixed footprint
if (needs_wrapping) {
const char* kMemberName = "inner";
auto* wrapper = wrapper_structs.GetOrCreate(ty, [&] {
auto* block = b.ASTNodes().Create<BlockAttribute>(b.ID(), b.AllocateNodeID());
auto wrapper_name = src->Symbols().NameFor(global->symbol) + "_block";
auto* ret = b.create<ast::Struct>(
b.Symbols().New(wrapper_name),
utils::Vector{b.Member(kMemberName, CreateASTTypeFor(ctx, ty))},
utils::Vector{block});
ctx.InsertBefore(src->AST().GlobalDeclarations(), global, ret);
return ret;
});
ctx.Replace(global->type, b.ty.Of(wrapper));
// Insert a member accessor to get the original type from the wrapper at
// any usage of the original variable.
for (auto* user : var->Users()) {
ctx.Replace(user->Declaration(),
b.MemberAccessor(ctx.Clone(global->symbol), kMemberName));
}
} else {
// Add a block attribute to this struct directly.
auto* block = b.ASTNodes().Create<BlockAttribute>(b.ID(), b.AllocateNodeID());
ctx.InsertFront(str->Declaration()->attributes, block);
}
}
if (!made_changes) {
return SkipTransform;
}
ctx.Clone();
return Program(std::move(b));
}
AddBlockAttribute::BlockAttribute::BlockAttribute(ProgramID pid, ast::NodeID nid)
: Base(pid, nid) {}
AddBlockAttribute::BlockAttribute::~BlockAttribute() = default;
std::string AddBlockAttribute::BlockAttribute::InternalName() const {
return "block";
}
const AddBlockAttribute::BlockAttribute* AddBlockAttribute::BlockAttribute::Clone(
CloneContext* ctx) const {
return ctx->dst->ASTNodes().Create<AddBlockAttribute::BlockAttribute>(
ctx->dst->ID(), ctx->dst->AllocateNodeID());
}
} // namespace tint::transform