// Part of the Carbon Language project, under the Apache License v2.0 with LLVM // Exceptions. See /LICENSE for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception #include "llvm/ADT/STLExtras.h" #include "llvm/ADT/Sequence.h" #include "toolchain/lower/function_context.h" #include "toolchain/sem_ir/inst.h" #include "toolchain/sem_ir/inst_kind.h" namespace Carbon::Lower { auto HandleCrossReference(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::CrossReference inst) -> void { CARBON_FATAL() << "TODO: Add support: " << inst; } auto HandleAddressOf(FunctionContext& context, SemIR::InstId inst_id, SemIR::AddressOf inst) -> void { context.SetLocal(inst_id, context.GetLocal(inst.lvalue_id)); } auto HandleArrayIndex(FunctionContext& context, SemIR::InstId inst_id, SemIR::ArrayIndex inst) -> void { auto* array_value = context.GetLocal(inst.array_id); auto* llvm_type = context.GetType(context.sem_ir().insts().Get(inst.array_id).type_id()); llvm::Value* indexes[2] = { llvm::ConstantInt::get(llvm::Type::getInt32Ty(context.llvm_context()), 0), context.GetLocal(inst.index_id)}; context.SetLocal(inst_id, context.builder().CreateInBoundsGEP(llvm_type, array_value, indexes, "array.index")); } auto HandleArrayInit(FunctionContext& context, SemIR::InstId inst_id, SemIR::ArrayInit inst) -> void { // The result of initialization is the return slot of the initializer. context.SetLocal(inst_id, context.GetLocal(context.sem_ir() .inst_blocks() .Get(inst.inits_and_return_slot_id) .back())); } auto HandleAssign(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::Assign inst) -> void { auto storage_type_id = context.sem_ir().insts().Get(inst.lhs_id).type_id(); context.FinishInitialization(storage_type_id, inst.lhs_id, inst.rhs_id); } auto HandleBinaryOperatorAdd(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::BinaryOperatorAdd inst) -> void { CARBON_FATAL() << "TODO: Add support: " << inst; } auto HandleBindName(FunctionContext& context, SemIR::InstId inst_id, SemIR::BindName inst) -> void { context.SetLocal(inst_id, context.GetLocal(inst.value_id)); } auto HandleBlockArg(FunctionContext& context, SemIR::InstId inst_id, SemIR::BlockArg inst) -> void { context.SetLocal(inst_id, context.GetBlockArg(inst.block_id, inst.type_id)); } auto HandleBoolLiteral(FunctionContext& context, SemIR::InstId inst_id, SemIR::BoolLiteral inst) -> void { llvm::Value* v = llvm::ConstantInt::get(context.builder().getInt1Ty(), inst.value.index); context.SetLocal(inst_id, v); } auto HandleBoundMethod(FunctionContext& context, SemIR::InstId inst_id, SemIR::BoundMethod inst) -> void { // Propagate just the function; the object is separately provided to the // enclosing call as an implicit argument. context.SetLocal(inst_id, context.GetLocalOrGlobal(inst.function_id)); } auto HandleBranch(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::Branch inst) -> void { // Opportunistically avoid creating a BasicBlock that contains just a branch. // TODO: Don't do this if it would remove a loop preheader block. llvm::BasicBlock* block = context.builder().GetInsertBlock(); if (block->empty() && context.TryToReuseBlock(inst.target_id, block)) { // Reuse this block as the branch target. } else { context.builder().CreateBr(context.GetBlock(inst.target_id)); } context.builder().ClearInsertionPoint(); } auto HandleBranchIf(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::BranchIf inst) -> void { llvm::Value* cond = context.GetLocal(inst.cond_id); llvm::BasicBlock* then_block = context.GetBlock(inst.target_id); llvm::BasicBlock* else_block = context.CreateSyntheticBlock(); context.builder().CreateCondBr(cond, then_block, else_block); context.builder().SetInsertPoint(else_block); } auto HandleBranchWithArg(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::BranchWithArg inst) -> void { llvm::Value* arg = context.GetLocal(inst.arg_id); SemIR::TypeId arg_type_id = context.sem_ir().insts().Get(inst.arg_id).type_id(); // Opportunistically avoid creating a BasicBlock that contains just a branch. // We only do this for a block that we know will only have a single // predecessor, so that we can correctly populate the predecessors of the // PHINode. llvm::BasicBlock* block = context.builder().GetInsertBlock(); llvm::BasicBlock* phi_predecessor = block; if (block->empty() && context.IsCurrentSyntheticBlock(block) && context.TryToReuseBlock(inst.target_id, block)) { // Reuse this block as the branch target. phi_predecessor = block->getSinglePredecessor(); CARBON_CHECK(phi_predecessor) << "Synthetic block did not have a single predecessor"; } else { context.builder().CreateBr(context.GetBlock(inst.target_id)); } context.GetBlockArg(inst.target_id, arg_type_id) ->addIncoming(arg, phi_predecessor); context.builder().ClearInsertionPoint(); } auto HandleBuiltin(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::Builtin inst) -> void { CARBON_FATAL() << "TODO: Add support: " << inst; } auto HandleCall(FunctionContext& context, SemIR::InstId inst_id, SemIR::Call inst) -> void { auto* callee = llvm::cast(context.GetLocal(inst.callee_id)); std::vector args; llvm::ArrayRef arg_ids = context.sem_ir().inst_blocks().Get(inst.args_id); if (SemIR::GetInitializingRepresentation(context.sem_ir(), inst.type_id) .has_return_slot()) { args.push_back(context.GetLocal(arg_ids.back())); arg_ids = arg_ids.drop_back(); } for (auto arg_id : arg_ids) { auto arg_type_id = context.sem_ir().insts().Get(arg_id).type_id(); if (SemIR::GetValueRepresentation(context.sem_ir(), arg_type_id).kind != SemIR::ValueRepresentation::None) { args.push_back(context.GetLocal(arg_id)); } } auto* call = context.builder().CreateCall(callee, args); context.SetLocal(inst_id, call); // Name the call's result the same as the callee. // TODO: Is this a helpful name? if (!call->getType()->isVoidTy()) { call->setName(callee->getName()); } } auto HandleClassDeclaration(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::ClassDeclaration /*inst*/) -> void { // No action to perform. } // Extracts an element of an aggregate, such as a struct, tuple, or class, by // index. Depending on the expression category and value representation of the // aggregate input, this will either produce a value or a reference. static auto GetAggregateElement(FunctionContext& context, SemIR::InstId aggr_inst_id, SemIR::MemberIndex idx, SemIR::TypeId result_type_id, llvm::Twine name) -> llvm::Value* { auto aggr_inst = context.sem_ir().insts().Get(aggr_inst_id); auto* aggr_value = context.GetLocal(aggr_inst_id); switch (SemIR::GetExpressionCategory(context.sem_ir(), aggr_inst_id)) { case SemIR::ExpressionCategory::Error: case SemIR::ExpressionCategory::NotExpression: case SemIR::ExpressionCategory::Initializing: case SemIR::ExpressionCategory::Mixed: CARBON_FATAL() << "Unexpected expression category for aggregate access"; case SemIR::ExpressionCategory::Value: { auto value_rep = SemIR::GetValueRepresentation(context.sem_ir(), aggr_inst.type_id()); CARBON_CHECK(value_rep.aggregate_kind != SemIR::ValueRepresentation::NotAggregate) << "aggregate type should have aggregate value representation"; switch (value_rep.kind) { case SemIR::ValueRepresentation::Unknown: CARBON_FATAL() << "Lowering access to incomplete aggregate type"; case SemIR::ValueRepresentation::None: return aggr_value; case SemIR::ValueRepresentation::Copy: // We are holding the values of the aggregate directly, elementwise. return context.builder().CreateExtractValue(aggr_value, idx.index, name); case SemIR::ValueRepresentation::Pointer: { // The value representation is a pointer to an aggregate that we want // to index into. auto pointee_type_id = context.sem_ir().GetPointeeType(value_rep.type_id); auto* value_type = context.GetType(pointee_type_id); auto* elem_ptr = context.builder().CreateStructGEP( value_type, aggr_value, idx.index, name); if (!value_rep.elements_are_values()) { // `elem_ptr` points to an object representation, which is our // result. return elem_ptr; } // `elem_ptr` points to a value representation. Load it. auto result_value_type_id = SemIR::GetValueRepresentation(context.sem_ir(), result_type_id) .type_id; return context.builder().CreateLoad( context.GetType(result_value_type_id), elem_ptr, name + ".load"); } case SemIR::ValueRepresentation::Custom: CARBON_FATAL() << "Aggregate should never have custom value representation"; } } case SemIR::ExpressionCategory::DurableReference: case SemIR::ExpressionCategory::EphemeralReference: { // Just locate the aggregate element. auto* aggr_type = context.GetType(aggr_inst.type_id()); return context.builder().CreateStructGEP(aggr_type, aggr_value, idx.index, name); } } } static auto GetStructFieldName(FunctionContext& context, SemIR::TypeId struct_type_id, SemIR::MemberIndex index) -> llvm::StringRef { auto fields = context.sem_ir().inst_blocks().Get( context.sem_ir() .insts() .GetAs( context.sem_ir().types().Get(struct_type_id).inst_id) .fields_id); auto field = context.sem_ir().insts().GetAs( fields[index.index]); return context.sem_ir().identifiers().Get(field.name_id); } auto HandleClassFieldAccess(FunctionContext& context, SemIR::InstId inst_id, SemIR::ClassFieldAccess inst) -> void { // Find the class that we're performing access into. auto class_type_id = context.sem_ir().insts().Get(inst.base_id).type_id(); auto class_id = context.sem_ir() .insts() .GetAs( context.sem_ir().GetTypeAllowBuiltinTypes(class_type_id)) .class_id; auto& class_info = context.sem_ir().classes().Get(class_id); // Translate the class field access into a struct access on the object // representation. context.SetLocal( inst_id, GetAggregateElement( context, inst.base_id, inst.index, inst.type_id, GetStructFieldName(context, class_info.object_representation_id, inst.index))); } auto HandleDereference(FunctionContext& context, SemIR::InstId inst_id, SemIR::Dereference inst) -> void { context.SetLocal(inst_id, context.GetLocal(inst.pointer_id)); } auto HandleField(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::Field /*inst*/) -> void { // No action to perform. } auto HandleFunctionDeclaration(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::FunctionDeclaration inst) -> void { CARBON_FATAL() << "Should not be encountered. If that changes, we may want to change " "higher-level logic to skip them rather than calling this. " << inst; } auto HandleInitializeFrom(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::InitializeFrom inst) -> void { auto storage_type_id = context.sem_ir().insts().Get(inst.dest_id).type_id(); context.FinishInitialization(storage_type_id, inst.dest_id, inst.src_id); } auto HandleIntegerLiteral(FunctionContext& context, SemIR::InstId inst_id, SemIR::IntegerLiteral inst) -> void { const llvm::APInt& i = context.sem_ir().integers().Get(inst.integer_id); // TODO: This won't offer correct semantics, but seems close enough for now. llvm::Value* v = llvm::ConstantInt::get(context.builder().getInt32Ty(), i.getZExtValue()); context.SetLocal(inst_id, v); } auto HandleNameReference(FunctionContext& context, SemIR::InstId inst_id, SemIR::NameReference inst) -> void { auto type_inst_id = context.sem_ir().GetTypeAllowBuiltinTypes(inst.type_id); if (type_inst_id == SemIR::InstId::BuiltinNamespaceType) { return; } context.SetLocal(inst_id, context.GetLocalOrGlobal(inst.value_id)); } auto HandleNamespace(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::Namespace inst) -> void { CARBON_FATAL() << "Should not be encountered. If that changes, we may want to change " "higher-level logic to skip them rather than calling this. " << inst; } auto HandleNoOp(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::NoOp /*inst*/) -> void { // No action to take. } auto HandleParameter(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::Parameter /*inst*/) -> void { CARBON_FATAL() << "Parameters should be lowered by `BuildFunctionDefinition`"; } auto HandleRealLiteral(FunctionContext& context, SemIR::InstId inst_id, SemIR::RealLiteral inst) -> void { const Real& real = context.sem_ir().reals().Get(inst.real_id); // TODO: This will probably have overflow issues, and should be fixed. double val = real.mantissa.getZExtValue() * std::pow((real.is_decimal ? 10 : 2), real.exponent.getSExtValue()); llvm::APFloat llvm_val(val); context.SetLocal(inst_id, llvm::ConstantFP::get( context.builder().getDoubleTy(), llvm_val)); } auto HandleReturn(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::Return /*inst*/) -> void { context.builder().CreateRetVoid(); } auto HandleReturnExpression(FunctionContext& context, SemIR::InstId /*inst_id*/, SemIR::ReturnExpression inst) -> void { switch (SemIR::GetInitializingRepresentation( context.sem_ir(), context.sem_ir().insts().Get(inst.expr_id).type_id()) .kind) { case SemIR::InitializingRepresentation::None: case SemIR::InitializingRepresentation::InPlace: // Nothing to return. context.builder().CreateRetVoid(); return; case SemIR::InitializingRepresentation::ByCopy: // The expression produces the value representation for the type. context.builder().CreateRet(context.GetLocal(inst.expr_id)); return; } } auto HandleSelfParameter(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::SelfParameter /*inst*/) -> void { CARBON_FATAL() << "Parameters should be lowered by `BuildFunctionDefinition`"; } auto HandleSpliceBlock(FunctionContext& context, SemIR::InstId inst_id, SemIR::SpliceBlock inst) -> void { context.LowerBlock(inst.block_id); context.SetLocal(inst_id, context.GetLocal(inst.result_id)); } auto HandleStringLiteral(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::StringLiteral inst) -> void { CARBON_FATAL() << "TODO: Add support: " << inst; } auto HandleStructAccess(FunctionContext& context, SemIR::InstId inst_id, SemIR::StructAccess inst) -> void { auto struct_type_id = context.sem_ir().insts().Get(inst.struct_id).type_id(); context.SetLocal( inst_id, GetAggregateElement( context, inst.struct_id, inst.index, inst.type_id, GetStructFieldName(context, struct_type_id, inst.index))); } auto HandleStructLiteral(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::StructLiteral /*inst*/) -> void { // A StructLiteral should always be converted to a StructInit or StructValue // if its value is needed. } // Emits the value representation for a struct or tuple whose elements are the // contents of `refs_id`. auto EmitStructOrTupleValueRepresentation(FunctionContext& context, SemIR::TypeId type_id, SemIR::InstBlockId refs_id, llvm::Twine name) -> llvm::Value* { auto value_rep = SemIR::GetValueRepresentation(context.sem_ir(), type_id); switch (value_rep.kind) { case SemIR::ValueRepresentation::Unknown: CARBON_FATAL() << "Incomplete aggregate type in lowering"; case SemIR::ValueRepresentation::None: // TODO: Add a helper to get a "no value representation" value. return llvm::PoisonValue::get(context.GetType(value_rep.type_id)); case SemIR::ValueRepresentation::Copy: { auto refs = context.sem_ir().inst_blocks().Get(refs_id); CARBON_CHECK(refs.size() == 1) << "Unexpected size for aggregate with by-copy value representation"; // TODO: Remove the LLVM StructType wrapper in this case, so we don't // need this `insert_value` wrapping. return context.builder().CreateInsertValue( llvm::PoisonValue::get(context.GetType(value_rep.type_id)), context.GetLocal(refs[0]), {0}); } case SemIR::ValueRepresentation::Pointer: { auto pointee_type_id = context.sem_ir().GetPointeeType(value_rep.type_id); auto* llvm_value_rep_type = context.GetType(pointee_type_id); // Write the value representation to a local alloca so we can produce a // pointer to it as the value representation of the struct or tuple. auto* alloca = context.builder().CreateAlloca(llvm_value_rep_type, /*ArraySize=*/nullptr, name); for (auto [i, ref] : llvm::enumerate(context.sem_ir().inst_blocks().Get(refs_id))) { context.builder().CreateStore( context.GetLocal(ref), context.builder().CreateStructGEP(llvm_value_rep_type, alloca, i)); } return alloca; } case SemIR::ValueRepresentation::Custom: CARBON_FATAL() << "Aggregate should never have custom value representation"; } } auto HandleStructInit(FunctionContext& context, SemIR::InstId inst_id, SemIR::StructInit inst) -> void { auto* llvm_type = context.GetType(inst.type_id); switch (SemIR::GetInitializingRepresentation(context.sem_ir(), inst.type_id) .kind) { case SemIR::InitializingRepresentation::None: case SemIR::InitializingRepresentation::InPlace: // TODO: Add a helper to poison a value slot. context.SetLocal(inst_id, llvm::PoisonValue::get(llvm_type)); break; case SemIR::InitializingRepresentation::ByCopy: { context.SetLocal( inst_id, EmitStructOrTupleValueRepresentation( context, inst.type_id, inst.elements_id, "struct.init")); break; } } } auto HandleStructValue(FunctionContext& context, SemIR::InstId inst_id, SemIR::StructValue inst) -> void { context.SetLocal(inst_id, EmitStructOrTupleValueRepresentation( context, inst.type_id, inst.elements_id, "struct")); } auto HandleStructTypeField(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::StructTypeField /*inst*/) -> void { // No action to take. } auto HandleTupleAccess(FunctionContext& context, SemIR::InstId inst_id, SemIR::TupleAccess inst) -> void { context.SetLocal(inst_id, GetAggregateElement(context, inst.tuple_id, inst.index, inst.type_id, "tuple.elem")); } auto HandleTupleIndex(FunctionContext& context, SemIR::InstId inst_id, SemIR::TupleIndex inst) -> void { auto index_inst = context.sem_ir().insts().GetAs(inst.index_id); auto index = context.sem_ir().integers().Get(index_inst.integer_id).getZExtValue(); context.SetLocal(inst_id, GetAggregateElement(context, inst.tuple_id, SemIR::MemberIndex(index), inst.type_id, "tuple.index")); } auto HandleTupleLiteral(FunctionContext& /*context*/, SemIR::InstId /*inst_id*/, SemIR::TupleLiteral /*inst*/) -> void { // A TupleLiteral should always be converted to a TupleInit or TupleValue if // its value is needed. } auto HandleTupleInit(FunctionContext& context, SemIR::InstId inst_id, SemIR::TupleInit inst) -> void { auto* llvm_type = context.GetType(inst.type_id); switch (SemIR::GetInitializingRepresentation(context.sem_ir(), inst.type_id) .kind) { case SemIR::InitializingRepresentation::None: case SemIR::InitializingRepresentation::InPlace: // TODO: Add a helper to poison a value slot. context.SetLocal(inst_id, llvm::PoisonValue::get(llvm_type)); break; case SemIR::InitializingRepresentation::ByCopy: { context.SetLocal( inst_id, EmitStructOrTupleValueRepresentation( context, inst.type_id, inst.elements_id, "tuple.init")); break; } } } auto HandleTupleValue(FunctionContext& context, SemIR::InstId inst_id, SemIR::TupleValue inst) -> void { context.SetLocal( inst_id, EmitStructOrTupleValueRepresentation(context, inst.type_id, inst.elements_id, "tuple")); } auto HandleUnaryOperatorNot(FunctionContext& context, SemIR::InstId inst_id, SemIR::UnaryOperatorNot inst) -> void { context.SetLocal( inst_id, context.builder().CreateNot(context.GetLocal(inst.operand_id))); } auto HandleVarStorage(FunctionContext& context, SemIR::InstId inst_id, SemIR::VarStorage inst) -> void { // TODO: Eventually this name will be optional, and we'll want to provide // something like `var` as a default. However, that's not possible right now // so cannot be tested. auto name = context.sem_ir().identifiers().Get(inst.name_id); auto* alloca = context.builder().CreateAlloca(context.GetType(inst.type_id), /*ArraySize=*/nullptr, name); context.SetLocal(inst_id, alloca); } } // namespace Carbon::Lower