prune dead specializations

2026-06-12 17:27:47 +02:00
parent 4112b79c6b
commit 66e41e1d9a
4 changed files with 209 additions and 26 deletions
@@ -4,7 +4,6 @@

 # compiler hardening follow-ups

- prune unreachable function specializations before HIR construction and emission
 - support unary minus, including the signed i64 minimum literal boundary
 - move ignored example binaries into a dedicated build directory and remove `.review_tmp`

@@ -35,3 +35,8 @@ After migrating persistent compiler references and spans to compact IDs on
 `Span` is 12 bytes and `Token` is 24 bytes; AST expressions, HIR expressions,
 and IR instructions are 64, 88, and 88 bytes respectively. These sizes are
 also printed by the benchmark to catch layout regressions.
+
+After pruning stale function specializations on 2026-06-12, peak memory
+remained 8,651,659 bytes and allocations fell to 30,121. Lookup-only
+specialization resolution avoids constructing temporary signatures for
+already discovered calls.
@@ -510,16 +510,28 @@ find_infer_local :: proc(locals: []Infer_Local, name: symbol.Id) -> types.Type {
 	return types.INVALID
 }

-spec_signature_equal :: proc(spec: Spec, template: ast.Function_Id, args: []types.Type) -> bool {
-	if spec.template != template || len(spec.args) != len(args) {
-		return false
-	}
-	for arg, index in args {
-		if !types.equal(spec.args[index], arg) {
-			return false
+find_spec :: proc(checker: ^Checker, template: ast.Function_Id, actual_args: []types.Type) -> Spec_Id {
+	function := checker.ast_module.functions[template]
+	for spec, index in checker.specs {
+		if spec.template != template || len(spec.args) != len(function.params) {
+			continue
+		}
+		matches := true
+		for param, param_index in function.params {
+			actual := types.INVALID
+			if param_index < len(actual_args) {
+				actual = actual_args[param_index]
+			}
+			if !types.equal(spec.args[param_index], specialized_param_type(param.type, actual)) {
+				matches = false
+				break
+			}
+		}
+		if matches {
+			return spec_id(index)
 		}
 	}
-	return true
+	return INVALID_SPEC
 }

 specialized_param_type :: proc(syntax: ast.Type_Syntax, actual: types.Type) -> types.Type {
@@ -544,6 +556,9 @@ can_specialize :: proc(function: ast.Function, actual_args: []types.Type) -> boo
 }

 ensure_spec :: proc(checker: ^Checker, template: ast.Function_Id, actual_args: []types.Type) -> Spec_Id {
+	if existing := find_spec(checker, template, actual_args); existing != INVALID_SPEC {
+		return existing
+	}
 	function := checker.ast_module.functions[template]
 	signature: [dynamic]types.Type
 	signature.allocator = checker.allocator
@@ -554,12 +569,6 @@ ensure_spec :: proc(checker: ^Checker, template: ast.Function_Id, actual_args: [
 		}
 		append(&signature, specialized_param_type(param.type, actual))
 	}
-	for spec, index in checker.specs {
-		if spec_signature_equal(spec, template, signature[:]) {
-			delete(signature)
-			return spec_id(index)
-		}
-	}
 	result := type_from_syntax(function.result)
 	if function.pkg == 0 && function.name == checker.main_symbol && function.result == .Int {
 		result = types.I32
@@ -572,6 +581,14 @@ ensure_spec :: proc(checker: ^Checker, template: ast.Function_Id, actual_args: [
 	return index
 }

+mark_spec_demanded :: proc(checker: ^Checker, id: Spec_Id, stack: ^[dynamic]Spec_Id) {
+	if id == INVALID_SPEC || checker.specs[id].hir_id != hir.INVALID_FUNCTION {
+		return
+	}
+	checker.specs[id].hir_id = hir.Function_Id(0)
+	append(stack, id)
+}
+
 Infer_Frame :: struct {
 	expr:      ast.Expr_Id,
 	stage:     u8,
@@ -587,6 +604,7 @@ infer_expr :: proc(
 	locals: []Infer_Local,
 	pkg := ast.Package_Id(0),
 	file := ast.File_Id(0),
+	demanded: ^[dynamic]Spec_Id = nil,
 ) -> types.Type {
 	stack := checker.infer_stack
 	clear_dynamic_array(&stack)
@@ -694,8 +712,19 @@ infer_expr :: proc(
 			}
 			function := checker.ast_module.functions[frame.template]
 			if can_specialize(function, stack[frame_index].args) {
-				spec := ensure_spec(checker, frame.template, stack[frame_index].args)
-				last = checker.specs[spec].result
+				spec := INVALID_SPEC
+				if demanded == nil {
+					spec = ensure_spec(checker, frame.template, stack[frame_index].args)
+				} else if len(expr.args) == len(function.params) {
+					spec = find_spec(checker, frame.template, stack[frame_index].args)
+					mark_spec_demanded(checker, spec, demanded)
+				}
+				if spec != INVALID_SPEC {
+					last = checker.specs[spec].result
+				} else {
+					declared := type_from_syntax(function.result)
+					last = declared if declared.kind == .Concrete || declared.kind == .Void else types.INVALID
+				}
 			} else {
 				declared := type_from_syntax(function.result)
 				if function.pkg == 0 && function.name == checker.main_symbol && function.result == .Int {
@@ -712,7 +741,7 @@ infer_expr :: proc(
 	return last
 }

-infer_spec_result :: proc(checker: ^Checker, id: Spec_Id) -> types.Type {
+infer_spec_result :: proc(checker: ^Checker, id: Spec_Id, demanded: ^[dynamic]Spec_Id = nil) -> types.Type {
 	spec := checker.specs[id]
 	function := checker.ast_module.functions[spec.template]
 	declared := type_from_syntax(function.result)
@@ -736,17 +765,17 @@ infer_spec_result :: proc(checker: ^Checker, id: Spec_Id) -> types.Type {
 		statement := checker.ast_module.statements[statement_id]
 		#partial switch statement.kind {
 		case .Declaration:
-			value_type := infer_expr(checker, statement.expr, locals[:], function.pkg, function.file)
+			value_type := infer_expr(checker, statement.expr, locals[:], function.pkg, function.file, demanded)
 			declared_local := type_from_syntax(statement.type)
 			if declared_local.kind == .Concrete {
 				value_type = declared_local
 			}
 			append(&locals, Infer_Local{name = statement.name, type = value_type})
 		case .Assignment, .Expression:
-			_ = infer_expr(checker, statement.expr, locals[:], function.pkg, function.file)
+			_ = infer_expr(checker, statement.expr, locals[:], function.pkg, function.file, demanded)
 		case .Return:
 			if statement.expr != ast.INVALID_EXPR {
-				returned := infer_expr(checker, statement.expr, locals[:], function.pkg, function.file)
+				returned := infer_expr(checker, statement.expr, locals[:], function.pkg, function.file, demanded)
 				if !types.is_valid(result) {
 					result = returned
 				} else {
@@ -794,10 +823,10 @@ infer_all :: proc(checker: ^Checker) {
 		changed := false
 		spec_count := len(checker.specs)
 		for global, index in checker.ast_module.globals {
+			inferred := infer_expr(checker, global.expr, nil, global.pkg, global.file)
 			if type_from_syntax(global.type).kind == .Concrete {
 				continue
 			}
-			inferred := infer_expr(checker, global.expr, nil, global.pkg, global.file)
 			changed = merge_inferred_type(&checker.global_types[index], inferred) || changed
 		}
 		for index := 0; index < len(checker.specs); index += 1 {
@@ -814,6 +843,38 @@ infer_all :: proc(checker: ^Checker) {
 	}
 }

+prune_specs :: proc(checker: ^Checker) {
+	stack: [dynamic]Spec_Id
+	stack.allocator = checker.allocator
+	defer delete(stack)
+
+	main_template := find_template(checker, checker.main_symbol, 0)
+	if main_template != ast.INVALID_FUNCTION {
+		mark_spec_demanded(checker, find_spec(checker, main_template, nil), &stack)
+	}
+	for global in checker.ast_module.globals {
+		_ = infer_expr(checker, global.expr, nil, global.pkg, global.file, &stack)
+	}
+	for len(stack) > 0 {
+		id := pop(&stack)
+		_ = infer_spec_result(checker, id, &stack)
+	}
+
+	retained := 0
+	for spec in checker.specs {
+		if spec.hir_id == hir.INVALID_FUNCTION {
+			delete(spec.args, checker.allocator)
+			continue
+		}
+		checker.specs[retained] = spec
+		checker.specs[retained].hir_id = hir.function_id(retained)
+		retained += 1
+	}
+	for len(checker.specs) > retained {
+		_ = pop(&checker.specs)
+	}
+}
+
 add_hir_expr :: proc(checker: ^Checker, expr: hir.Expr) -> hir.Expr_Id {
 	id := hir.expr_id(len(checker.module.exprs))
 	append(&checker.module.exprs, expr)
@@ -1125,9 +1186,22 @@ build_expr :: proc(
 					continue
 				}
 			}
-			spec := ensure_spec(checker, frame.template, stack[frame_index].arg_types)
+			spec := find_spec(checker, frame.template, stack[frame_index].arg_types)
 			delete(stack[frame_index].arg_types, checker.allocator)
 			stack[frame_index].arg_types = nil
+			if spec == INVALID_SPEC {
+				id := source.addf(
+					checker.diagnostics,
+					expr.span,
+					"could not resolve specialization of '%s'",
+					symbol_text(checker, expr.name),
+				)
+				delete(stack[frame_index].built_args, checker.allocator)
+				stack[frame_index].built_args = nil
+				last = invalid_hir_expr(checker, expr.span, id)
+				_ = pop(&stack)
+				continue
+			}
 			for _, index in stack[frame_index].built_args {
 				stack[frame_index].built_args[index] = coerce_expr(
 					checker,
@@ -1997,9 +2071,7 @@ check :: proc(

 	validate_declarations(&checker)
 	infer_all(&checker)
-	for index in 0..<len(checker.specs) {
-		checker.specs[index].hir_id = hir.function_id(index)
-	}
+	prune_specs(&checker)
 	build_globals(&checker)
 	for index := 0; index < len(checker.specs); index += 1 {
 		build_function(&checker, spec_id(index))
@@ -869,6 +869,113 @@ main :: func() void {
 	testing.expect_value(t, len(hir_module.functions), 3)
 }

+@(test)
+stale_specializations_are_pruned_after_inference :: proc(t: ^testing.T) {
+	text := `derived :: identity(make())
+wide :: delayed()
+identity :: func(value int) int {
+	return value
+}
+make :: func() int {
+	return wide
+	return 1
+}
+delayed :: func() int {
+	return 128
+}
+main :: func() void {}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+	ir_module := lower.lower(&hir_module)
+	defer ir.destroy_module(&ir_module)
+	llvm_text := llvm.emit(&ir_module, &diagnostics, &symbols)
+	defer delete(llvm_text)
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	testing.expect_value(t, len(hir_module.functions), 4)
+	testing.expect(t, strings.contains(llvm_text, "@bro__p0__identity__i16"))
+	testing.expect(t, !strings.contains(llvm_text, "@bro__p0__identity__i8"))
+}
+
+@(test)
+eager_global_calls_root_specializations :: proc(t: ^testing.T) {
+	text := `make :: func() i32 {
+	return 7
+}
+unused_native :: func() i32 {
+	return 9
+}
+unused_foreign :: c func() i32
+value i32 :: make()
+main :: func() void {}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+	ir_module := lower.lower(&hir_module)
+	defer ir.destroy_module(&ir_module)
+	llvm_text := llvm.emit(&ir_module, &diagnostics, &symbols)
+	defer delete(llvm_text)
+
+	testing.expect_value(t, len(diagnostics.items), 0)
+	testing.expect_value(t, len(hir_module.functions), 2)
+	testing.expect(t, strings.contains(llvm_text, "@bro__p0__make("))
+	testing.expect(t, !strings.contains(llvm_text, "@bro__p0__unused_native("))
+	testing.expect(t, !strings.contains(llvm_text, "@unused_foreign("))
+}
+
+@(test)
+malformed_generic_calls_do_not_retain_specializations :: proc(t: ^testing.T) {
+	text := `identity :: func(value int) int {
+	return value
+}
+bad :: identity(1, 2)
+main :: func() void {}
+`
+	source_file := source.Source{path="test.bro", text=text}
+	diagnostics := source.init_diagnostics(&source_file)
+	defer source.destroy_diagnostics(&diagnostics)
+	symbols := symbol.init_table()
+	defer symbol.destroy_table(&symbols)
+	stream := lexer.lex(&source_file, &diagnostics, &symbols)
+	defer delete(stream.items)
+	ast_module := parser.parse(&stream, &source_file, &diagnostics)
+	defer ast.destroy_module(&ast_module)
+	hir_module := checker.check(&ast_module, &diagnostics, &symbols)
+	defer hir.destroy_module(&hir_module)
+	ir_module := lower.lower(&hir_module)
+	defer ir.destroy_module(&ir_module)
+	llvm_text := llvm.emit(&ir_module, &diagnostics, &symbols)
+	defer delete(llvm_text)
+
+	found_arity := false
+	for diagnostic in diagnostics.items {
+		found_arity = found_arity || strings.contains(diagnostic.message, "expects 1 arguments, got 2")
+	}
+	testing.expect(t, found_arity)
+	testing.expect_value(t, len(hir_module.functions), 1)
+	testing.expect(t, !strings.contains(llvm_text, "@bro__p0__identity"))
+	testing.expect(t, strings.contains(llvm_text, "call void @bro.trap"))
+}
+
@(test)
 long_generic_call_chain_reaches_a_fixed_point :: proc(t: ^testing.T) {
 	builder := strings.builder_make()