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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/ast/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/ast/transform/simplify_pointers.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/switch.h"
#include "src/tint/type/reference.h"
#include "src/tint/utils/hash.h"
#include "src/tint/utils/map.h"
TINT_INSTANTIATE_TYPEINFO(tint::ast::transform::CalculateArrayLength);
TINT_INSTANTIATE_TYPEINFO(tint::ast::transform::CalculateArrayLength::BufferSizeIntrinsic);
using namespace tint::number_suffixes; // NOLINT
namespace tint::ast::transform {
namespace {
bool ShouldRun(const Program* program) {
for (auto* fn : program->AST().Functions()) {
if (auto* sem_fn = program->Sem().Get(fn)) {
for (auto* builtin : sem_fn->DirectlyCalledBuiltins()) {
if (builtin->Type() == builtin::Function::kArrayLength) {
return true;
}
}
}
}
return false;
}
/// ArrayUsage describes a runtime array usage.
/// It is used as a key by the array_length_by_usage map.
struct ArrayUsage {
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, NodeID nid)
: Base(pid, nid, utils::Empty) {}
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(), ctx->dst->AllocateNodeID());
}
CalculateArrayLength::CalculateArrayLength() = default;
CalculateArrayLength::~CalculateArrayLength() = default;
Transform::ApplyResult CalculateArrayLength::Apply(const Program* src,
const DataMap&,
DataMap&) const {
if (!ShouldRun(src)) {
return SkipTransform;
}
ProgramBuilder b;
CloneContext ctx{&b, src, /* auto_clone_symbols */ true};
auto& sem = 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 type::Reference*, Symbol> buffer_size_intrinsics;
auto get_buffer_size_intrinsic = [&](const type::Reference* buffer_type) {
return utils::GetOrCreate(buffer_size_intrinsics, buffer_type, [&] {
auto name = b.Sym();
auto type = CreateASTTypeFor(ctx, buffer_type);
auto* disable_validation = b.Disable(DisabledValidation::kFunctionParameter);
b.Func(name,
utils::Vector{
b.Param("buffer",
b.ty.ptr(buffer_type->AddressSpace(), type, buffer_type->Access()),
utils::Vector{disable_validation}),
b.Param("result", b.ty.ptr(builtin::AddressSpace::kFunction, b.ty.u32())),
},
b.ty.void_(), nullptr,
utils::Vector{
b.ASTNodes().Create<BufferSizeIntrinsic>(b.ID(), b.AllocateNodeID()),
});
return name;
});
};
std::unordered_map<ArrayUsage, Symbol, ArrayUsage::Hasher> array_length_by_usage;
// Find all the arrayLength() calls...
for (auto* node : src->ASTNodes().Objects()) {
if (auto* call_expr = node->As<CallExpression>()) {
auto* call = sem.Get(call_expr)->UnwrapMaterialize()->As<sem::Call>();
if (auto* builtin = call->Target()->As<sem::Builtin>()) {
if (builtin->Type() == builtin::Function::kArrayLength) {
// We're dealing with an arrayLength() call
if (auto* call_stmt = call->Stmt()->Declaration()->As<CallStatement>()) {
if (call_stmt->expr == call_expr) {
// arrayLength() is used as a statement.
// The argument expression must be side-effect free, so just drop the
// statement.
RemoveStatement(ctx, call_stmt);
continue;
}
}
// 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<UnaryOpExpression>();
if (TINT_UNLIKELY(!address_of || address_of->op != UnaryOp::kAddressOf)) {
TINT_ICE(Transform, b.Diagnostics())
<< "arrayLength() expected address-of, got " << arg->TypeInfo().name;
}
auto* storage_buffer_expr = address_of->expr;
if (auto* accessor = storage_buffer_expr->As<MemberAccessorExpression>()) {
storage_buffer_expr = accessor->object;
}
auto* storage_buffer_sem = sem.Get<sem::VariableUser>(storage_buffer_expr);
if (TINT_UNLIKELY(!storage_buffer_sem)) {
TINT_ICE(Transform, b.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()->As<type::Reference>();
// 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 =
b.Decl(b.Var(b.Sym(), b.ty.u32(), b.Expr(0_u)));
// Call storage_buffer.GetDimensions(&buffer_size_result)
auto* call_get_dims = b.CallStmt(b.Call(
// BufferSizeIntrinsic(X, ARGS...) is
// translated to:
// X.GetDimensions(ARGS..) by the writer
buffer_size, b.AddressOf(ctx.Clone(storage_buffer_expr)),
b.AddressOf(b.Expr(buffer_size_result->variable->name->symbol))));
// Calculate actual array length
// total_storage_buffer_size - array_offset
// array_length = ----------------------------------------
// array_stride
auto name = b.Sym();
const Expression* total_size = b.Expr(buffer_size_result->variable);
const type::Array* array_type = Switch(
storage_buffer_type->StoreType(),
[&](const type::Struct* str) {
// The variable is a struct, so subtract the byte offset of
// the array member.
auto* array_member_sem = str->Members().Back();
total_size = b.Sub(total_size, u32(array_member_sem->Offset()));
return array_member_sem->Type()->As<type::Array>();
},
[&](const type::Array* arr) { return arr; });
if (TINT_UNLIKELY(!array_type)) {
TINT_ICE(Transform, b.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 = b.Decl(
b.Let(name, b.ty.u32(), b.Div(total_size, u32(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, b.Expr(array_length));
}
}
}
}
ctx.Clone();
return Program(std::move(b));
}
} // namespace tint::ast::transform