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Remove caching of return slot usage. (#4163)

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The caching isn't buying us much, and is adding complexity and
divergence between the codepaths for generic and non-generic functions.

This means we no longer suppress diagnostics for the second or
subsequent time we call a function with an incomplete return type. If we
want to add that back, it might be worth considering moving the
suppression to `TryToCompleteType` and only diagnosing that a type is
incomplete once, regardless of why we're requiring it to be complete.
This commit is contained in:
Richard Smith
2024-07-25 20:29:59 +00:00
committed by GitHub
parent bf1106fc34
commit a9e835f3dc
14 changed files with 183 additions and 192 deletions
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toolchain/check/return.cpp
+23 -14
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@@ -56,10 +56,17 @@ auto CheckReturnedVar(Context& context, Parse::NodeId returned_node,
Parse::NodeId name_node, SemIR::NameId name_id,
Parse::NodeId type_node, SemIR::TypeId type_id)
-> SemIR::InstId {
// A `returned var` requires an explicit return type.
auto& function = GetCurrentFunction(context);
auto return_type_id = function.GetDeclaredReturnType(context.sem_ir());
if (!return_type_id.is_valid()) {
auto return_info = function.GetReturnInfo(context.sem_ir());
if (!return_info.is_valid()) {
// We already diagnosed this when we started defining the function. Create a
// placeholder for error recovery.
return context.AddInst<SemIR::VarStorage>(
name_node, {.type_id = type_id, .name_id = name_id});
}
// A `returned var` requires an explicit return type.
if (!return_info.type_id.is_valid()) {
CARBON_DIAGNOSTIC(ReturnedVarWithNoReturnType, Error,
"Cannot declare a `returned var` in this function.");
auto diag =
@@ -70,21 +77,21 @@ auto CheckReturnedVar(Context& context, Parse::NodeId returned_node,
}
// The declared type of the var must match the return type of the function.
if (return_type_id != type_id) {
if (return_info.type_id != type_id) {
CARBON_DIAGNOSTIC(ReturnedVarWrongType, Error,
"Type `{0}` of `returned var` does not match "
"return type of enclosing function.",
SemIR::TypeId);
auto diag =
context.emitter().Build(type_node, ReturnedVarWrongType, type_id);
NoteReturnType(diag, function, return_type_id);
NoteReturnType(diag, function, return_info.type_id);
diag.Emit();
return SemIR::InstId::BuiltinError;
}
// The variable aliases the return slot if there is one. If not, it has its
// own storage.
if (function.has_return_slot()) {
if (return_info.has_return_slot()) {
return function.return_storage_id;
}
return context.AddInst<SemIR::VarStorage>(
@@ -124,9 +131,9 @@ auto BuildReturnWithExpr(Context& context, Parse::ReturnStatementId node_id,
const auto& function = GetCurrentFunction(context);
auto returned_var_id = GetCurrentReturnedVar(context);
auto return_slot_id = SemIR::InstId::Invalid;
auto return_type_id = function.GetDeclaredReturnType(context.sem_ir());
auto return_info = function.GetReturnInfo(context.sem_ir());
if (!return_type_id.is_valid()) {
if (!return_info.type_id.is_valid()) {
CARBON_DIAGNOSTIC(
ReturnStatementDisallowExpr, Error,
"No return expression should be provided in this context.");
@@ -142,14 +149,16 @@ auto BuildReturnWithExpr(Context& context, Parse::ReturnStatementId node_id,
NoteReturnedVar(diag, returned_var_id);
diag.Emit();
expr_id = SemIR::InstId::BuiltinError;
} else if (function.has_return_slot()) {
} else if (!return_info.is_valid()) {
// We already diagnosed that the return type is invalid. Don't try to
// convert to it.
expr_id = SemIR::InstId::BuiltinError;
} else if (return_info.has_return_slot()) {
expr_id = Initialize(context, node_id, function.return_storage_id, expr_id);
return_slot_id = function.return_storage_id;
} else if (function.return_slot == SemIR::Function::ReturnSlot::Error) {
// Don't produce a second error complaining the return type is incomplete.
expr_id = SemIR::InstId::BuiltinError;
} else {
expr_id = ConvertToValueOfType(context, node_id, expr_id, return_type_id);
expr_id =
ConvertToValueOfType(context, node_id, expr_id, return_info.type_id);
}
context.AddInst<SemIR::ReturnExpr>(
@@ -169,7 +178,7 @@ auto BuildReturnVar(Context& context, Parse::ReturnStatementId node_id)
}
auto return_slot_id = function.return_storage_id;
if (!function.has_return_slot()) {
if (!function.GetReturnInfo(context.sem_ir()).has_return_slot()) {
// If we don't have a return slot, we're returning by value. Convert to a
// value expression.
returned_var_id = ConvertToValueExpr(context, returned_var_id);