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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/calculate_array_length.h"
#include <unordered_map>
#include <utility>
#include "src/tint/ast/call_statement.h"
#include "src/tint/ast/disable_validation_attribute.h"
#include "src/tint/program_builder.h"
#include "src/tint/sem/block_statement.h"
#include "src/tint/sem/call.h"
#include "src/tint/sem/function.h"
#include "src/tint/sem/statement.h"
#include "src/tint/sem/struct.h"
#include "src/tint/sem/variable.h"
#include "src/tint/transform/simplify_pointers.h"
#include "src/tint/utils/hash.h"
#include "src/tint/utils/map.h"
TINT_INSTANTIATE_TYPEINFO(tint::transform::CalculateArrayLength);
TINT_INSTANTIATE_TYPEINFO(
tint::transform::CalculateArrayLength::BufferSizeIntrinsic);
namespace tint::transform {
namespace {
/// ArrayUsage describes a runtime array usage.
/// It is used as a key by the array_length_by_usage map.
struct ArrayUsage {
ast::BlockStatement const* const block;
sem::Variable const* const buffer;
bool operator==(const ArrayUsage& rhs) const {
return block == rhs.block && buffer == rhs.buffer;
}
struct Hasher {
inline std::size_t operator()(const ArrayUsage& u) const {
return utils::Hash(u.block, u.buffer);
}
};
};
} // namespace
CalculateArrayLength::BufferSizeIntrinsic::BufferSizeIntrinsic(ProgramID pid)
: Base(pid) {}
CalculateArrayLength::BufferSizeIntrinsic::~BufferSizeIntrinsic() = default;
std::string CalculateArrayLength::BufferSizeIntrinsic::InternalName() const {
return "intrinsic_buffer_size";
}
const CalculateArrayLength::BufferSizeIntrinsic*
CalculateArrayLength::BufferSizeIntrinsic::Clone(CloneContext* ctx) const {
return ctx->dst->ASTNodes().Create<CalculateArrayLength::BufferSizeIntrinsic>(
ctx->dst->ID());
}
CalculateArrayLength::CalculateArrayLength() = default;
CalculateArrayLength::~CalculateArrayLength() = default;
bool CalculateArrayLength::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 CalculateArrayLength::Run(CloneContext& ctx,
const DataMap&,
DataMap&) const {
auto& sem = ctx.src->Sem();
// get_buffer_size_intrinsic() emits the function decorated with
// BufferSizeIntrinsic that is transformed by the HLSL writer into a call to
// [RW]ByteAddressBuffer.GetDimensions().
std::unordered_map<const sem::Type*, Symbol> buffer_size_intrinsics;
auto get_buffer_size_intrinsic = [&](const sem::Type* buffer_type) {
return utils::GetOrCreate(buffer_size_intrinsics, buffer_type, [&] {
auto name = ctx.dst->Sym();
auto* type = CreateASTTypeFor(ctx, buffer_type);
auto* disable_validation = ctx.dst->Disable(
ast::DisabledValidation::kIgnoreConstructibleFunctionParameter);
ctx.dst->AST().AddFunction(ctx.dst->create<ast::Function>(
name,
ast::VariableList{
// Note: The buffer parameter requires the kStorage StorageClass
// in order for HLSL to emit this as a ByteAddressBuffer.
ctx.dst->create<ast::Variable>(
ctx.dst->Sym("buffer"), ast::StorageClass::kStorage,
ast::Access::kUndefined, type, true, false, nullptr,
ast::AttributeList{disable_validation}),
ctx.dst->Param("result",
ctx.dst->ty.pointer(ctx.dst->ty.u32(),
ast::StorageClass::kFunction)),
},
ctx.dst->ty.void_(), nullptr,
ast::AttributeList{
ctx.dst->ASTNodes().Create<BufferSizeIntrinsic>(ctx.dst->ID()),
},
ast::AttributeList{}));
return name;
});
};
std::unordered_map<ArrayUsage, Symbol, ArrayUsage::Hasher>
array_length_by_usage;
// Find all the arrayLength() calls...
for (auto* node : ctx.src->ASTNodes().Objects()) {
if (auto* call_expr = node->As<ast::CallExpression>()) {
auto* call = sem.Get(call_expr);
if (auto* builtin = call->Target()->As<sem::Builtin>()) {
if (builtin->Type() == sem::BuiltinType::kArrayLength) {
// We're dealing with an arrayLength() call
// A runtime-sized array can only appear as the store type of a
// variable, or the last element of a structure (which cannot itself
// be nested). Given that we require SimplifyPointers, we can assume
// that the arrayLength() call has one of two forms:
// arrayLength(&struct_var.array_member)
// arrayLength(&array_var)
auto* arg = call_expr->args[0];
auto* address_of = arg->As<ast::UnaryOpExpression>();
if (!address_of || address_of->op != ast::UnaryOp::kAddressOf) {
TINT_ICE(Transform, ctx.dst->Diagnostics())
<< "arrayLength() expected address-of, got "
<< arg->TypeInfo().name;
}
auto* storage_buffer_expr = address_of->expr;
if (auto* accessor =
storage_buffer_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;
}
auto* storage_buffer_var = storage_buffer_sem->Variable();
auto* storage_buffer_type = storage_buffer_sem->Type()->UnwrapRef();
// Generate BufferSizeIntrinsic for this storage type if we haven't
// already
auto buffer_size = get_buffer_size_intrinsic(storage_buffer_type);
// Find the current statement block
auto* block = call->Stmt()->Block()->Declaration();
auto array_length = utils::GetOrCreate(
array_length_by_usage, {block, storage_buffer_var}, [&] {
// First time this array length is used for this block.
// Let's calculate it.
// Construct the variable that'll hold the result of
// RWByteAddressBuffer.GetDimensions()
auto* buffer_size_result = ctx.dst->Decl(
ctx.dst->Var(ctx.dst->Sym(), ctx.dst->ty.u32(),
ast::StorageClass::kNone, ctx.dst->Expr(0u)));
// Call storage_buffer.GetDimensions(&buffer_size_result)
auto* call_get_dims = ctx.dst->CallStmt(ctx.dst->Call(
// BufferSizeIntrinsic(X, ARGS...) is
// translated to:
// X.GetDimensions(ARGS..) by the writer
buffer_size, ctx.Clone(storage_buffer_expr),
ctx.dst->AddressOf(
ctx.dst->Expr(buffer_size_result->variable->symbol))));
// Calculate actual array length
// total_storage_buffer_size - array_offset
// array_length = ----------------------------------------
// array_stride
auto name = ctx.dst->Sym();
const ast::Expression* total_size =
ctx.dst->Expr(buffer_size_result->variable);
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_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 name;
}
uint32_t array_stride = array_type->Size();
auto* array_length_var = ctx.dst->Decl(
ctx.dst->Let(name, ctx.dst->ty.u32(),
ctx.dst->Div(total_size, array_stride)));
// Insert the array length calculations at the top of the block
ctx.InsertBefore(block->statements, block->statements[0],
buffer_size_result);
ctx.InsertBefore(block->statements, block->statements[0],
call_get_dims);
ctx.InsertBefore(block->statements, block->statements[0],
array_length_var);
return name;
});
// Replace the call to arrayLength() with the array length variable
ctx.Replace(call_expr, ctx.dst->Expr(array_length));
}
}
}
}
ctx.Clone();
}
} // namespace tint::transform