| // 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/module_scope_var_to_entry_point_param.h" |
| |
| #include <unordered_map> |
| #include <unordered_set> |
| #include <utility> |
| #include <vector> |
| |
| #include "src/tint/ast/disable_validation_attribute.h" |
| #include "src/tint/program_builder.h" |
| #include "src/tint/sem/call.h" |
| #include "src/tint/sem/function.h" |
| #include "src/tint/sem/statement.h" |
| #include "src/tint/sem/variable.h" |
| |
| TINT_INSTANTIATE_TYPEINFO(tint::transform::ModuleScopeVarToEntryPointParam); |
| |
| namespace tint::transform { |
| namespace { |
| // Returns `true` if `type` is or contains a matrix type. |
| bool ContainsMatrix(const sem::Type* type) { |
| type = type->UnwrapRef(); |
| if (type->Is<sem::Matrix>()) { |
| return true; |
| } else if (auto* ary = type->As<sem::Array>()) { |
| return ContainsMatrix(ary->ElemType()); |
| } else if (auto* str = type->As<sem::Struct>()) { |
| for (auto* member : str->Members()) { |
| if (ContainsMatrix(member->Type())) { |
| return true; |
| } |
| } |
| } |
| return false; |
| } |
| } // namespace |
| |
| /// State holds the current transform state. |
| struct ModuleScopeVarToEntryPointParam::State { |
| /// The clone context. |
| CloneContext& ctx; |
| |
| /// Constructor |
| /// @param context the clone context |
| explicit State(CloneContext& context) : ctx(context) {} |
| |
| /// Clone any struct types that are contained in `ty` (including `ty` itself), |
| /// and add it to the global declarations now, so that they precede new global |
| /// declarations that need to reference them. |
| /// @param ty the type to clone |
| void CloneStructTypes(const sem::Type* ty) { |
| if (auto* str = ty->As<sem::Struct>()) { |
| if (!cloned_structs_.emplace(str).second) { |
| // The struct has already been cloned. |
| return; |
| } |
| |
| // Recurse into members. |
| for (auto* member : str->Members()) { |
| CloneStructTypes(member->Type()); |
| } |
| |
| // Clone the struct and add it to the global declaration list. |
| // Remove the old declaration. |
| auto* ast_str = str->Declaration(); |
| ctx.dst->AST().AddTypeDecl(ctx.Clone(ast_str)); |
| ctx.Remove(ctx.src->AST().GlobalDeclarations(), ast_str); |
| } else if (auto* arr = ty->As<sem::Array>()) { |
| CloneStructTypes(arr->ElemType()); |
| } |
| } |
| |
| /// Process the module. |
| void Process() { |
| // Predetermine the list of function calls that need to be replaced. |
| using CallList = std::vector<const ast::CallExpression*>; |
| std::unordered_map<const ast::Function*, CallList> calls_to_replace; |
| |
| std::vector<const ast::Function*> functions_to_process; |
| |
| // Build a list of functions that transitively reference any module-scope |
| // variables. |
| for (auto* func_ast : ctx.src->AST().Functions()) { |
| auto* func_sem = ctx.src->Sem().Get(func_ast); |
| |
| bool needs_processing = false; |
| for (auto* var : func_sem->TransitivelyReferencedGlobals()) { |
| if (var->StorageClass() != ast::StorageClass::kNone) { |
| needs_processing = true; |
| break; |
| } |
| } |
| if (needs_processing) { |
| functions_to_process.push_back(func_ast); |
| |
| // Find all of the calls to this function that will need to be replaced. |
| for (auto* call : func_sem->CallSites()) { |
| calls_to_replace[call->Stmt()->Function()->Declaration()].push_back( |
| call->Declaration()); |
| } |
| } |
| } |
| |
| // Build a list of `&ident` expressions. We'll use this later to avoid |
| // generating expressions of the form `&*ident`, which break WGSL validation |
| // rules when this expression is passed to a function. |
| // TODO(jrprice): We should add support for bidirectional SEM tree traversal |
| // so that we can do this on the fly instead. |
| std::unordered_map<const ast::IdentifierExpression*, |
| const ast::UnaryOpExpression*> |
| ident_to_address_of; |
| for (auto* node : ctx.src->ASTNodes().Objects()) { |
| auto* address_of = node->As<ast::UnaryOpExpression>(); |
| if (!address_of || address_of->op != ast::UnaryOp::kAddressOf) { |
| continue; |
| } |
| if (auto* ident = address_of->expr->As<ast::IdentifierExpression>()) { |
| ident_to_address_of[ident] = address_of; |
| } |
| } |
| |
| for (auto* func_ast : functions_to_process) { |
| auto* func_sem = ctx.src->Sem().Get(func_ast); |
| bool is_entry_point = func_ast->IsEntryPoint(); |
| |
| // Map module-scope variables onto their replacement. |
| struct NewVar { |
| Symbol symbol; |
| bool is_pointer; |
| bool is_wrapped; |
| }; |
| const char* kWrappedArrayMemberName = "arr"; |
| std::unordered_map<const sem::Variable*, NewVar> var_to_newvar; |
| |
| // We aggregate all workgroup variables into a struct to avoid hitting |
| // MSL's limit for threadgroup memory arguments. |
| Symbol workgroup_parameter_symbol; |
| ast::StructMemberList workgroup_parameter_members; |
| auto workgroup_param = [&]() { |
| if (!workgroup_parameter_symbol.IsValid()) { |
| workgroup_parameter_symbol = ctx.dst->Sym(); |
| } |
| return workgroup_parameter_symbol; |
| }; |
| |
| for (auto* var : func_sem->TransitivelyReferencedGlobals()) { |
| auto sc = var->StorageClass(); |
| auto* ty = var->Type()->UnwrapRef(); |
| if (sc == ast::StorageClass::kNone) { |
| continue; |
| } |
| if (sc != ast::StorageClass::kPrivate && |
| sc != ast::StorageClass::kStorage && |
| sc != ast::StorageClass::kUniform && |
| sc != ast::StorageClass::kHandle && |
| sc != ast::StorageClass::kWorkgroup) { |
| TINT_ICE(Transform, ctx.dst->Diagnostics()) |
| << "unhandled module-scope storage class (" << sc << ")"; |
| } |
| |
| // This is the symbol for the variable that replaces the module-scope |
| // var. |
| auto new_var_symbol = ctx.dst->Sym(); |
| |
| // Helper to create an AST node for the store type of the variable. |
| auto store_type = [&]() { return CreateASTTypeFor(ctx, ty); }; |
| |
| // Track whether the new variable is a pointer or not. |
| bool is_pointer = false; |
| |
| // Track whether the new variable was wrapped in a struct or not. |
| bool is_wrapped = false; |
| |
| if (is_entry_point) { |
| if (var->Type()->UnwrapRef()->is_handle()) { |
| // For a texture or sampler variable, redeclare it as an entry point |
| // parameter. Disable entry point parameter validation. |
| auto* disable_validation = |
| ctx.dst->Disable(ast::DisabledValidation::kEntryPointParameter); |
| auto attrs = ctx.Clone(var->Declaration()->attributes); |
| attrs.push_back(disable_validation); |
| auto* param = ctx.dst->Param(new_var_symbol, store_type(), attrs); |
| ctx.InsertFront(func_ast->params, param); |
| } else if (sc == ast::StorageClass::kStorage || |
| sc == ast::StorageClass::kUniform) { |
| // Variables into the Storage and Uniform storage classes are |
| // redeclared as entry point parameters with a pointer type. |
| auto attributes = ctx.Clone(var->Declaration()->attributes); |
| attributes.push_back(ctx.dst->Disable( |
| ast::DisabledValidation::kEntryPointParameter)); |
| attributes.push_back( |
| ctx.dst->Disable(ast::DisabledValidation::kIgnoreStorageClass)); |
| |
| auto* param_type = store_type(); |
| if (auto* arr = ty->As<sem::Array>(); |
| arr && arr->IsRuntimeSized()) { |
| // Wrap runtime-sized arrays in structures, so that we can declare |
| // pointers to them. Ideally we'd just emit the array itself as a |
| // pointer, but this is not representable in Tint's AST. |
| CloneStructTypes(ty); |
| auto* wrapper = ctx.dst->Structure( |
| ctx.dst->Sym(), |
| {ctx.dst->Member(kWrappedArrayMemberName, param_type)}); |
| param_type = ctx.dst->ty.Of(wrapper); |
| is_wrapped = true; |
| } |
| |
| param_type = ctx.dst->ty.pointer( |
| param_type, sc, var->Declaration()->declared_access); |
| auto* param = |
| ctx.dst->Param(new_var_symbol, param_type, attributes); |
| ctx.InsertFront(func_ast->params, param); |
| is_pointer = true; |
| } else if (sc == ast::StorageClass::kWorkgroup && |
| ContainsMatrix(var->Type())) { |
| // Due to a bug in the MSL compiler, we use a threadgroup memory |
| // argument for any workgroup allocation that contains a matrix. |
| // See crbug.com/tint/938. |
| // TODO(jrprice): Do this for all other workgroup variables too. |
| |
| // Create a member in the workgroup parameter struct. |
| auto member = ctx.Clone(var->Declaration()->symbol); |
| workgroup_parameter_members.push_back( |
| ctx.dst->Member(member, store_type())); |
| CloneStructTypes(var->Type()->UnwrapRef()); |
| |
| // Create a function-scope variable that is a pointer to the member. |
| auto* member_ptr = ctx.dst->AddressOf(ctx.dst->MemberAccessor( |
| ctx.dst->Deref(workgroup_param()), member)); |
| auto* local_var = |
| ctx.dst->Let(new_var_symbol, |
| ctx.dst->ty.pointer(store_type(), |
| ast::StorageClass::kWorkgroup), |
| member_ptr); |
| ctx.InsertFront(func_ast->body->statements, |
| ctx.dst->Decl(local_var)); |
| is_pointer = true; |
| } else { |
| // Variables in the Private and Workgroup storage classes are |
| // redeclared at function scope. Disable storage class validation on |
| // this variable. |
| auto* disable_validation = |
| ctx.dst->Disable(ast::DisabledValidation::kIgnoreStorageClass); |
| auto* constructor = ctx.Clone(var->Declaration()->constructor); |
| auto* local_var = |
| ctx.dst->Var(new_var_symbol, store_type(), sc, constructor, |
| ast::AttributeList{disable_validation}); |
| ctx.InsertFront(func_ast->body->statements, |
| ctx.dst->Decl(local_var)); |
| } |
| } else { |
| // For a regular function, redeclare the variable as a parameter. |
| // Use a pointer for non-handle types. |
| auto* param_type = store_type(); |
| ast::AttributeList attributes; |
| if (!var->Type()->UnwrapRef()->is_handle()) { |
| param_type = ctx.dst->ty.pointer( |
| param_type, sc, var->Declaration()->declared_access); |
| is_pointer = true; |
| |
| // Disable validation of the parameter's storage class and of |
| // arguments passed it. |
| attributes.push_back( |
| ctx.dst->Disable(ast::DisabledValidation::kIgnoreStorageClass)); |
| attributes.push_back(ctx.dst->Disable( |
| ast::DisabledValidation::kIgnoreInvalidPointerArgument)); |
| } |
| ctx.InsertBack( |
| func_ast->params, |
| ctx.dst->Param(new_var_symbol, param_type, attributes)); |
| } |
| |
| // Replace all uses of the module-scope variable. |
| // For non-entry points, dereference non-handle pointer parameters. |
| for (auto* user : var->Users()) { |
| if (user->Stmt()->Function()->Declaration() == func_ast) { |
| const ast::Expression* expr = ctx.dst->Expr(new_var_symbol); |
| if (is_pointer) { |
| // If this identifier is used by an address-of operator, just |
| // remove the address-of instead of adding a deref, since we |
| // already have a pointer. |
| auto* ident = |
| user->Declaration()->As<ast::IdentifierExpression>(); |
| if (ident_to_address_of.count(ident)) { |
| ctx.Replace(ident_to_address_of[ident], expr); |
| continue; |
| } |
| |
| expr = ctx.dst->Deref(expr); |
| } |
| if (is_wrapped) { |
| // Get the member from the wrapper structure. |
| expr = ctx.dst->MemberAccessor(expr, kWrappedArrayMemberName); |
| } |
| ctx.Replace(user->Declaration(), expr); |
| } |
| } |
| |
| var_to_newvar[var] = {new_var_symbol, is_pointer, is_wrapped}; |
| } |
| |
| if (!workgroup_parameter_members.empty()) { |
| // Create the workgroup memory parameter. |
| // The parameter is a struct that contains members for each workgroup |
| // variable. |
| auto* str = ctx.dst->Structure(ctx.dst->Sym(), |
| std::move(workgroup_parameter_members)); |
| auto* param_type = ctx.dst->ty.pointer(ctx.dst->ty.Of(str), |
| ast::StorageClass::kWorkgroup); |
| auto* disable_validation = |
| ctx.dst->Disable(ast::DisabledValidation::kEntryPointParameter); |
| auto* param = |
| ctx.dst->Param(workgroup_param(), param_type, {disable_validation}); |
| ctx.InsertFront(func_ast->params, param); |
| } |
| |
| // Pass the variables as pointers to any functions that need them. |
| for (auto* call : calls_to_replace[func_ast]) { |
| auto* target = |
| ctx.src->AST().Functions().Find(call->target.name->symbol); |
| auto* target_sem = ctx.src->Sem().Get(target); |
| |
| // Add new arguments for any variables that are needed by the callee. |
| // For entry points, pass non-handle types as pointers. |
| for (auto* target_var : target_sem->TransitivelyReferencedGlobals()) { |
| auto sc = target_var->StorageClass(); |
| if (sc == ast::StorageClass::kNone) { |
| continue; |
| } |
| |
| auto new_var = var_to_newvar[target_var]; |
| bool is_handle = target_var->Type()->UnwrapRef()->is_handle(); |
| const ast::Expression* arg = ctx.dst->Expr(new_var.symbol); |
| if (new_var.is_wrapped) { |
| // The variable is wrapped in a struct, so we need to pass a pointer |
| // to the struct member instead. |
| arg = ctx.dst->AddressOf(ctx.dst->MemberAccessor( |
| ctx.dst->Deref(arg), kWrappedArrayMemberName)); |
| } else if (is_entry_point && !is_handle && !new_var.is_pointer) { |
| // We need to pass a pointer and we don't already have one, so take |
| // the address of the new variable. |
| arg = ctx.dst->AddressOf(arg); |
| } |
| ctx.InsertBack(call->args, arg); |
| } |
| } |
| } |
| |
| // Now remove all module-scope variables with these storage classes. |
| for (auto* var_ast : ctx.src->AST().GlobalVariables()) { |
| auto* var_sem = ctx.src->Sem().Get(var_ast); |
| if (var_sem->StorageClass() != ast::StorageClass::kNone) { |
| ctx.Remove(ctx.src->AST().GlobalDeclarations(), var_ast); |
| } |
| } |
| } |
| |
| private: |
| std::unordered_set<const sem::Struct*> cloned_structs_; |
| }; |
| |
| ModuleScopeVarToEntryPointParam::ModuleScopeVarToEntryPointParam() = default; |
| |
| ModuleScopeVarToEntryPointParam::~ModuleScopeVarToEntryPointParam() = default; |
| |
| bool ModuleScopeVarToEntryPointParam::ShouldRun(const Program* program, |
| const DataMap&) const { |
| for (auto* decl : program->AST().GlobalDeclarations()) { |
| if (decl->Is<ast::Variable>()) { |
| return true; |
| } |
| } |
| return false; |
| } |
| |
| void ModuleScopeVarToEntryPointParam::Run(CloneContext& ctx, |
| const DataMap&, |
| DataMap&) const { |
| State state{ctx}; |
| state.Process(); |
| ctx.Clone(); |
| } |
| |
| } // namespace tint::transform |