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// Copyright 2021 The Dawn & Tint Authors
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
// 1. Redistributions of source code must retain the above copyright notice, this
// list of conditions and the following disclaimer.
//
// 2. Redistributions in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// 3. Neither the name of the copyright holder nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#include "src/tint/lang/hlsl/writer/ast_raise/calculate_array_length.h"
#include <unordered_map>
#include <utility>
#include "src/tint/lang/core/type/reference.h"
#include "src/tint/lang/wgsl/ast/call_statement.h"
#include "src/tint/lang/wgsl/ast/disable_validation_attribute.h"
#include "src/tint/lang/wgsl/ast/transform/simplify_pointers.h"
#include "src/tint/lang/wgsl/program/clone_context.h"
#include "src/tint/lang/wgsl/program/program_builder.h"
#include "src/tint/lang/wgsl/resolver/resolve.h"
#include "src/tint/lang/wgsl/sem/block_statement.h"
#include "src/tint/lang/wgsl/sem/call.h"
#include "src/tint/lang/wgsl/sem/function.h"
#include "src/tint/lang/wgsl/sem/statement.h"
#include "src/tint/lang/wgsl/sem/struct.h"
#include "src/tint/lang/wgsl/sem/variable.h"
#include "src/tint/utils/containers/map.h"
#include "src/tint/utils/math/hash.h"
#include "src/tint/utils/rtti/switch.h"
TINT_INSTANTIATE_TYPEINFO(tint::hlsl::writer::CalculateArrayLength);
TINT_INSTANTIATE_TYPEINFO(tint::hlsl::writer::CalculateArrayLength::BufferSizeIntrinsic);
namespace tint::hlsl::writer {
namespace {
using namespace tint::core::fluent_types; // NOLINT
using namespace tint::core::number_suffixes; // NOLINT
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->Fn() == wgsl::BuiltinFn::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 {
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 Hash(u.block, u.buffer); }
};
};
} // namespace
CalculateArrayLength::BufferSizeIntrinsic::BufferSizeIntrinsic(GenerationID pid, ast::NodeID nid)
: Base(pid, nid, tint::Empty) {}
CalculateArrayLength::BufferSizeIntrinsic::~BufferSizeIntrinsic() = default;
std::string CalculateArrayLength::BufferSizeIntrinsic::InternalName() const {
return "intrinsic_buffer_size";
}
const CalculateArrayLength::BufferSizeIntrinsic* CalculateArrayLength::BufferSizeIntrinsic::Clone(
ast::CloneContext& ctx) const {
return ctx.dst->ASTNodes().Create<CalculateArrayLength::BufferSizeIntrinsic>(
ctx.dst->ID(), ctx.dst->AllocateNodeID());
}
CalculateArrayLength::CalculateArrayLength() = default;
CalculateArrayLength::~CalculateArrayLength() = default;
ast::transform::Transform::ApplyResult CalculateArrayLength::Apply(const Program& src,
const ast::transform::DataMap&,
ast::transform::DataMap&) const {
if (!ShouldRun(src)) {
return SkipTransform;
}
ProgramBuilder b;
program::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 core::type::Reference*, Symbol> buffer_size_intrinsics;
auto get_buffer_size_intrinsic = [&](const core::type::Reference* buffer_type) {
return tint::GetOrCreate(buffer_size_intrinsics, buffer_type, [&] {
auto name = b.Sym();
auto type = CreateASTTypeFor(ctx, buffer_type);
auto* disable_validation = b.Disable(ast::DisabledValidation::kFunctionParameter);
b.Func(name,
Vector{
b.Param("buffer",
b.ty.ptr(buffer_type->AddressSpace(), type, buffer_type->Access()),
Vector{disable_validation}),
b.Param("result", b.ty.ptr<function, u32>()),
},
b.ty.void_(), nullptr,
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<ast::CallExpression>()) {
auto* call = sem.Get(call_expr)->UnwrapMaterialize()->As<sem::Call>();
if (auto* builtin = call->Target()->As<sem::BuiltinFn>()) {
if (builtin->Fn() == wgsl::BuiltinFn::kArrayLength) {
// We're dealing with an arrayLength() call
if (auto* call_stmt = call->Stmt()->Declaration()->As<ast::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<ast::UnaryOpExpression>();
if (TINT_UNLIKELY(!address_of || address_of->op != core::UnaryOp::kAddressOf)) {
TINT_ICE()
<< "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->object;
}
auto* storage_buffer_sem = sem.Get<sem::VariableUser>(storage_buffer_expr);
if (TINT_UNLIKELY(!storage_buffer_sem)) {
TINT_ICE() << "expected form of arrayLength argument to be &array_var or "
"&struct_var.array_member";
break;
}
if (TINT_UNLIKELY(storage_buffer_sem->Type()->Is<core::type::Pointer>())) {
TINT_ICE()
<< "storage buffer variable should not be a pointer. These should have "
"been removed by the SimplifyPointers transform";
break;
}
auto* storage_buffer_var = storage_buffer_sem->Variable();
auto* storage_buffer_type =
storage_buffer_sem->Type()->As<core::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 =
tint::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 ast::Expression* total_size =
b.Expr(buffer_size_result->variable);
const core::type::Array* array_type = Switch(
storage_buffer_type->StoreType(),
[&](const core::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<core::type::Array>();
},
[&](const core::type::Array* arr) { return arr; });
if (TINT_UNLIKELY(!array_type)) {
TINT_ICE() << "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 resolver::Resolve(b);
}
} // namespace tint::hlsl::writer