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fields and decls: ArrayList appending, memcpy to ast arena

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This makes fields and decl ast nodes part of the Root and ContainerDecl
AST nodes.

Surprisingly, it's a performance regression from using a singly-linked
list for these nodes:

throughput: 76.5 MiB/s => 69.4 MiB/s

However it has much better memory usage:

maxrss: 392 KB => 77 KB

It's also better API for consumers of the parser, since it is a flat
list in memory.
This commit is contained in:
Andrew Kelley
2020-05-20 16:13:02 -04:00
parent b1bcdc96ca
commit 64c149ca19
3 changed files with 137 additions and 86 deletions
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72
lib/std/zig/parse.zig
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@@ -63,16 +63,20 @@ const Parser = struct {
/// Root <- skip ContainerMembers eof
fn parseRoot(p: *Parser) Allocator.Error!*Node.Root {
const node = try p.arena.allocator.create(Node.Root);
node.* = .{
.decls = try parseContainerMembers(p, true),
// parseContainerMembers will try to skip as much
// invalid tokens as it can so this can only be the EOF
.eof_token = p.eatToken(.Eof).?,
};
const decls = try parseContainerMembers(p, true);
defer p.gpa.free(decls);
// parseContainerMembers will try to skip as much
// invalid tokens as it can so this can only be the EOF
const eof_token = p.eatToken(.Eof).?;
const node = try Node.Root.create(&p.arena.allocator, decls.len, eof_token);
std.mem.copy(*ast.Node, node.decls(), decls);
return node;
}
/// Helper function for appending elements to a singly linked list.
fn llpush(
p: *Parser,
comptime T: type,
@@ -92,9 +96,9 @@ const Parser = struct {
/// / ContainerField COMMA ContainerMembers
/// / ContainerField
/// /
fn parseContainerMembers(p: *Parser, top_level: bool) !Node.Root.DeclList {
var list = Node.Root.DeclList{};
var list_it = &list.first;
fn parseContainerMembers(p: *Parser, top_level: bool) ![]*ast.Node {
var list = std.ArrayList(*ast.Node).init(p.gpa);
defer list.deinit();
var field_state: union(enum) {
/// no fields have been seen
@@ -110,7 +114,7 @@ const Parser = struct {
while (true) {
if (try p.parseContainerDocComments()) |node| {
list_it = try p.llpush(*Node, list_it, node);
try list.append(node);
continue;
}
@@ -127,7 +131,7 @@ const Parser = struct {
field_state = .{ .end = node.firstToken() };
}
node.cast(Node.TestDecl).?.doc_comments = doc_comments;
list_it = try p.llpush(*Node, list_it, node);
try list.append(node);
continue;
}
@@ -142,7 +146,7 @@ const Parser = struct {
field_state = .{ .end = node.firstToken() };
}
node.cast(Node.Comptime).?.doc_comments = doc_comments;
list_it = try p.llpush(*Node, list_it, node);
try list.append(node);
continue;
}
@@ -173,7 +177,7 @@ const Parser = struct {
},
else => unreachable,
}
list_it = try p.llpush(*Node, list_it, node);
try list.append(node);
if (try p.parseAppendedDocComment(node.lastToken())) |appended_comment| {
switch (node.id) {
.FnProto => {},
@@ -215,7 +219,7 @@ const Parser = struct {
const field = node.cast(Node.ContainerField).?;
field.doc_comments = doc_comments;
list_it = try p.llpush(*Node, list_it, node);
try list.append(node);
const comma = p.eatToken(.Comma) orelse {
// try to continue parsing
const index = p.tok_i;
@@ -275,7 +279,7 @@ const Parser = struct {
}
}
return list;
return list.toOwnedSlice();
}
/// Attempts to find next container member by searching for certain tokens
@@ -2778,24 +2782,36 @@ const Parser = struct {
/// ContainerDeclAuto <- ContainerDeclType LBRACE ContainerMembers RBRACE
fn parseContainerDeclAuto(p: *Parser) !?*Node {
const node = (try p.parseContainerDeclType()) orelse return null;
const container_decl_type = (try p.parseContainerDeclType()) orelse return null;
const lbrace = try p.expectToken(.LBrace);
const members = try p.parseContainerMembers(false);
defer p.gpa.free(members);
const rbrace = try p.expectToken(.RBrace);
const decl_type = node.cast(Node.ContainerDecl).?;
decl_type.fields_and_decls = members;
decl_type.lbrace_token = lbrace;
decl_type.rbrace_token = rbrace;
return node;
const node = try Node.ContainerDecl.alloc(&p.arena.allocator, members.len);
node.* = .{
.layout_token = null,
.kind_token = container_decl_type.kind_token,
.init_arg_expr = container_decl_type.init_arg_expr,
.fields_and_decls_len = members.len,
.lbrace_token = lbrace,
.rbrace_token = rbrace,
};
std.mem.copy(*ast.Node, node.fieldsAndDecls(), members);
return &node.base;
}
/// Holds temporary data until we are ready to construct the full ContainerDecl AST node.
const ContainerDeclType = struct {
kind_token: TokenIndex,
init_arg_expr: ast.Node.ContainerDecl.InitArg,
};
/// ContainerDeclType
/// <- KEYWORD_struct
/// / KEYWORD_enum (LPAREN Expr RPAREN)?
/// / KEYWORD_union (LPAREN (KEYWORD_enum (LPAREN Expr RPAREN)? / Expr) RPAREN)?
fn parseContainerDeclType(p: *Parser) !?*Node {
fn parseContainerDeclType(p: *Parser) !?ContainerDeclType {
const kind_token = p.nextToken();
const init_arg_expr = switch (kind_token.ptr.id) {
@@ -2838,16 +2854,10 @@ const Parser = struct {
},
};
const node = try p.arena.allocator.create(Node.ContainerDecl);
node.* = .{
.layout_token = null,
return ContainerDeclType{
.kind_token = kind_token.index,
.init_arg_expr = init_arg_expr,
.fields_and_decls = undefined, // set by caller
.lbrace_token = undefined, // set by caller
.rbrace_token = undefined, // set by caller
};
return &node.base;
}
/// ByteAlign <- KEYWORD_align LPAREN Expr RPAREN