From c20328e7cad2989bcdc9ff5003d6a16405c31ab5 Mon Sep 17 00:00:00 2001 From: Ian Lance Taylor Date: Thu, 19 Oct 2023 19:34:31 -0700 Subject: compiler: move lowering pass after check types pass This change moves the lowering pass after the type determination and the type checking passes. This lets us simplify some of the code that determines the type of an expression, which previously had to work correctly both before and after type determination. I'm doing this to help with future generic support. For example, with generics, we can see code like func ident[T any](v T) T { return v } func F() int32 { s := int32(1) return ident(s) } Before this change, we would type check return statements in the lowering pass (see Return_statement::do_lower). With a generic example like the above, that means we have to determine the type of s, and use that to infer the type arguments passed to ident, and use that to determine the result type of ident. That is too much to do at lowering time. Of course we can change the way that return statements work, but similar issues arise with index expressions, the types of closures for function literals, and probably other cases as well. Rather than try to deal with all those cases, we move the lowering pass after type checking. This requires a bunch of changes, notably for determining constant types. We have to add type checking for various constructs that formerly disappeared in the lowering pass. So it's a lot of shuffling. Sorry for the size of the patch. Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/536643 --- gcc/go/gofrontend/statements.h | 84 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 73 insertions(+), 11 deletions(-) (limited to 'gcc/go/gofrontend/statements.h') diff --git a/gcc/go/gofrontend/statements.h b/gcc/go/gofrontend/statements.h index 9a920ba..530011c 100644 --- a/gcc/go/gofrontend/statements.h +++ b/gcc/go/gofrontend/statements.h @@ -171,16 +171,17 @@ class Statement static Statement* make_defer_statement(Call_expression* call, Location); - // Make a return statement. + // Make a return statement. FUNCTION is a backpointer to the + // function that this statement is returning from. static Return_statement* - make_return_statement(Expression_list*, Location); + make_return_statement(Named_object* function, Expression_list*, Location); // Make a statement that returns the result of a call expression. // If the call does not return any results, this just returns the // call expression as a statement, assuming that the function will // end immediately afterward. static Statement* - make_return_from_call(Call_expression*, Location); + make_return_from_call(Named_object* function, Call_expression*, Location); // Make a break statement. static Statement* @@ -580,6 +581,11 @@ class Assignment_statement : public Statement set_omit_write_barrier() { this->omit_write_barrier_ = true; } + // Check if we can assign RHS to LHS. If we can, return true. If + // we can't, report an error and return false. + static bool + check_assignment_types(Expression* lhs, Type* rhs_type, Location); + protected: int do_traverse(Traverse* traverse); @@ -765,6 +771,9 @@ class Variable_declaration_statement : public Statement int do_traverse(Traverse*); + void + do_determine_types(Gogo*); + Statement* do_lower(Gogo*, Named_object*, Block*, Statement_inserter*); @@ -796,9 +805,11 @@ class Variable_declaration_statement : public Statement class Return_statement : public Statement { public: - Return_statement(Expression_list* vals, Location location) + Return_statement(Named_object* function, Expression_list* vals, + Location location) : Statement(STATEMENT_RETURN, location), - vals_(vals), is_lowered_(false) + function_(function), vals_(vals), types_are_determined_(false), + is_lowered_(false) { } // The list of values being returned. This may be NULL. @@ -811,6 +822,12 @@ class Return_statement : public Statement do_traverse(Traverse* traverse) { return this->traverse_expression_list(traverse, this->vals_); } + void + do_determine_types(Gogo*); + + void + do_check_types(Gogo*); + Statement* do_lower(Gogo*, Named_object*, Block*, Statement_inserter*); @@ -832,8 +849,12 @@ class Return_statement : public Statement do_dump_statement(Ast_dump_context*) const; private: + // A backpointer to the function we are returning from. + Named_object* function_; // Return values. This may be NULL. Expression_list* vals_; + // True if types have been determined. + bool types_are_determined_; // True if this statement has been lowered. bool is_lowered_; }; @@ -1185,14 +1206,14 @@ class Select_clauses private: void - lower_send(Block*, Expression*, Expression*); + lower_send(Gogo*, Block*, Expression*, Expression*); void lower_recv(Gogo*, Named_object*, Block*, Expression*, Expression*, Temporary_statement*); void - set_case(Block*, Expression*, Expression*, Expression*); + set_case(Gogo*, Block*, Expression*, Expression*, Expression*); // The channel. Expression* channel_; @@ -1655,6 +1676,12 @@ class For_statement : public Statement int do_traverse(Traverse*); + void + do_determine_types(Gogo*); + + void + do_check_types(Gogo*); + Statement* do_lower(Gogo*, Named_object*, Block*, Statement_inserter*); @@ -1715,6 +1742,12 @@ class For_range_statement : public Statement int do_traverse(Traverse*); + void + do_determine_types(Gogo*); + + void + do_check_types(Gogo*); + Statement* do_lower(Gogo*, Named_object*, Block*, Statement_inserter*); @@ -1817,7 +1850,7 @@ class Case_clauses // Lower for a nonconstant switch. void - lower(Block*, Temporary_statement*, Unnamed_label*) const; + lower(Gogo*, Block*, Temporary_statement*, Unnamed_label*) const; // Determine types of expressions. The Type parameter is the type // of the switch value. @@ -1892,7 +1925,8 @@ class Case_clauses // Lower for a nonconstant switch. void - lower(Block*, Temporary_statement*, Unnamed_label*, Unnamed_label*) const; + lower(Gogo*, Block*, Temporary_statement*, Unnamed_label*, + Unnamed_label*) const; // Determine types. void @@ -1970,6 +2004,12 @@ class Switch_statement : public Statement int do_traverse(Traverse*); + void + do_determine_types(Gogo*); + + void + do_check_types(Gogo*); + Statement* do_lower(Gogo*, Named_object*, Block*, Statement_inserter*); @@ -2028,9 +2068,17 @@ class Type_case_clauses void check_duplicates() const; + // Determine types of expressions. + void + determine_types(Gogo*); + + // Check types. + bool + check_types(Type*); + // Lower to if and goto statements. void - lower(Gogo*, Type*, Block*, Temporary_statement* descriptor_temp, + lower(Gogo*, Block*, Temporary_statement* descriptor_temp, Unnamed_label* break_label) const; // Return true if these clauses may fall through to the statements @@ -2077,9 +2125,17 @@ class Type_case_clauses int traverse(Traverse*); + // Determine types. + void + determine_types(Gogo*); + + // Check types. + bool + check_types(Type*); + // Lower to if and goto statements. void - lower(Gogo*, Type*, Block*, Temporary_statement* descriptor_temp, + lower(Gogo*, Block*, Temporary_statement* descriptor_temp, Unnamed_label* break_label, Unnamed_label** stmts_label) const; // Return true if this clause may fall through to execute the @@ -2140,6 +2196,12 @@ class Type_switch_statement : public Statement int do_traverse(Traverse*); + void + do_determine_types(Gogo*); + + void + do_check_types(Gogo*); + Statement* do_lower(Gogo*, Named_object*, Block*, Statement_inserter*); -- cgit v1.1