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add a transformation for gutting the body of a function

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This commit is contained in:
Andrew Kelley 2023-11-02 15:22:09 -07:00
parent 3263d6e6ab
commit 5f1f145199
2 changed files with 123 additions and 46 deletions
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151
lib/std/zig/render.zig
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@ -18,6 +18,11 @@ pub const Fixups = struct {
/// The key is the mut token (`var`/`const`) of the variable declaration
/// that should have a `_ = foo;` inserted afterwards.
unused_var_decls: std.AutoHashMapUnmanaged(Ast.TokenIndex, void) = .{},
/// The functions in this unordered set of indices will render with a
/// function body of `@trap()` instead, with all parameters discarded.
/// The indexes correspond to the order in which the functions appear in
/// the file.
gut_functions: std.AutoHashMapUnmanaged(u32, void) = .{},
pub fn count(f: Fixups) usize {
return f.unused_var_decls.count();
@ -34,6 +39,9 @@ const Render = struct {
ais: *Ais,
tree: Ast,
fixups: Fixups,
/// Keeps track of how many function declarations we have seen so far. Used
/// by Fixups.
function_index: u32,
};
pub fn renderTree(buffer: *std.ArrayList(u8), tree: Ast, fixups: Fixups) Error!void {
@ -47,24 +55,25 @@ pub fn renderTree(buffer: *std.ArrayList(u8), tree: Ast, fixups: Fixups) Error!v
.ais = &auto_indenting_stream,
.tree = tree,
.fixups = fixups,
.function_index = 0,
};
// Render all the line comments at the beginning of the file.
const comment_end_loc = tree.tokens.items(.start)[0];
_ = try renderComments(r, 0, comment_end_loc);
_ = try renderComments(&r, 0, comment_end_loc);
if (tree.tokens.items(.tag)[0] == .container_doc_comment) {
try renderContainerDocComments(r, 0);
try renderContainerDocComments(&r, 0);
}
if (tree.mode == .zon) {
try renderExpression(
r,
&r,
tree.nodes.items(.data)[0].lhs,
.newline,
);
} else {
try renderMembers(r, tree.rootDecls());
try renderMembers(&r, tree.rootDecls());
}
if (auto_indenting_stream.disabled_offset) |disabled_offset| {
@ -73,7 +82,7 @@ pub fn renderTree(buffer: *std.ArrayList(u8), tree: Ast, fixups: Fixups) Error!v
}
/// Render all members in the given slice, keeping empty lines where appropriate
fn renderMembers(r: Render, members: []const Ast.Node.Index) Error!void {
fn renderMembers(r: *Render, members: []const Ast.Node.Index) Error!void {
const tree = r.tree;
if (members.len == 0) return;
const container: Container = for (members) |member| {
@ -93,7 +102,7 @@ const Container = enum {
};
fn renderMember(
r: Render,
r: *Render,
container: Container,
decl: Ast.Node.Index,
space: Space,
@ -106,6 +115,8 @@ fn renderMember(
try renderDocComments(r, tree.firstToken(decl));
switch (tree.nodes.items(.tag)[decl]) {
.fn_decl => {
const this_index = r.function_index;
r.function_index += 1;
// Some examples:
// pub extern "foo" fn ...
// export fn ...
@ -150,7 +161,19 @@ fn renderMember(
}
assert(datas[decl].rhs != 0);
try renderExpression(r, fn_proto, .space);
return renderExpression(r, datas[decl].rhs, space);
const body_node = datas[decl].rhs;
if (r.fixups.gut_functions.contains(this_index)) {
ais.pushIndent();
const lbrace = tree.nodes.items(.main_token)[body_node];
try renderToken(r, lbrace, .newline);
try discardAllParams(r, fn_proto);
try ais.writer().writeAll("@trap();");
ais.popIndent();
try ais.insertNewline();
try renderToken(r, tree.lastToken(body_node), space); // rbrace
} else {
return renderExpression(r, body_node, space);
}
},
.fn_proto_simple,
.fn_proto_multi,
@ -227,7 +250,7 @@ fn renderMember(
}
/// Render all expressions in the slice, keeping empty lines where appropriate
fn renderExpressions(r: Render, expressions: []const Ast.Node.Index, space: Space) Error!void {
fn renderExpressions(r: *Render, expressions: []const Ast.Node.Index, space: Space) Error!void {
if (expressions.len == 0) return;
try renderExpression(r, expressions[0], space);
for (expressions[1..]) |expression| {
@ -236,7 +259,7 @@ fn renderExpressions(r: Render, expressions: []const Ast.Node.Index, space: Spac
}
}
fn renderExpression(r: Render, node: Ast.Node.Index, space: Space) Error!void {
fn renderExpression(r: *Render, node: Ast.Node.Index, space: Space) Error!void {
const tree = r.tree;
const ais = r.ais;
const token_tags = tree.tokens.items(.tag);
@ -815,7 +838,7 @@ fn renderExpression(r: Render, node: Ast.Node.Index, space: Space) Error!void {
}
fn renderArrayType(
r: Render,
r: *Render,
array_type: Ast.full.ArrayType,
space: Space,
) Error!void {
@ -836,7 +859,7 @@ fn renderArrayType(
return renderExpression(r, array_type.ast.elem_type, space);
}
fn renderPtrType(r: Render, ptr_type: Ast.full.PtrType, space: Space) Error!void {
fn renderPtrType(r: *Render, ptr_type: Ast.full.PtrType, space: Space) Error!void {
const tree = r.tree;
switch (ptr_type.size) {
.One => {
@ -925,7 +948,7 @@ fn renderPtrType(r: Render, ptr_type: Ast.full.PtrType, space: Space) Error!void
}
fn renderSlice(
r: Render,
r: *Render,
slice_node: Ast.Node.Index,
slice: Ast.full.Slice,
space: Space,
@ -960,7 +983,7 @@ fn renderSlice(
}
fn renderAsmOutput(
r: Render,
r: *Render,
asm_output: Ast.Node.Index,
space: Space,
) Error!void {
@ -989,7 +1012,7 @@ fn renderAsmOutput(
}
fn renderAsmInput(
r: Render,
r: *Render,
asm_input: Ast.Node.Index,
space: Space,
) Error!void {
@ -1010,7 +1033,25 @@ fn renderAsmInput(
}
fn renderVarDecl(
r: Render,
r: *Render,
var_decl: Ast.full.VarDecl,
/// Destructures intentionally ignore leading `comptime` tokens.
ignore_comptime_token: bool,
/// `comma_space` and `space` are used for destructure LHS decls.
space: Space,
) Error!void {
try renderVarDeclWithoutFixups(r, var_decl, ignore_comptime_token, space);
if (r.fixups.unused_var_decls.contains(var_decl.ast.mut_token)) {
// Discard the variable like this: `_ = foo;`
const w = r.ais.writer();
try w.writeAll("_ = ");
try w.writeAll(tokenSliceForRender(r.tree, var_decl.ast.mut_token + 1));
try w.writeAll(";\n");
}
}
fn renderVarDeclWithoutFixups(
r: *Render,
var_decl: Ast.full.VarDecl,
/// Destructures intentionally ignore leading `comptime` tokens.
ignore_comptime_token: bool,
@ -1131,7 +1172,7 @@ fn renderVarDecl(
return renderExpression(r, var_decl.ast.init_node, space); // ;
}
fn renderIf(r: Render, if_node: Ast.full.If, space: Space) Error!void {
fn renderIf(r: *Render, if_node: Ast.full.If, space: Space) Error!void {
return renderWhile(r, .{
.ast = .{
.while_token = if_node.ast.if_token,
@ -1150,7 +1191,7 @@ fn renderIf(r: Render, if_node: Ast.full.If, space: Space) Error!void {
/// Note that this function is additionally used to render if expressions, with
/// respective values set to null.
fn renderWhile(r: Render, while_node: Ast.full.While, space: Space) Error!void {
fn renderWhile(r: *Render, while_node: Ast.full.While, space: Space) Error!void {
const tree = r.tree;
const token_tags = tree.tokens.items(.tag);
@ -1214,7 +1255,7 @@ fn renderWhile(r: Render, while_node: Ast.full.While, space: Space) Error!void {
}
fn renderThenElse(
r: Render,
r: *Render,
last_prefix_token: Ast.TokenIndex,
then_expr: Ast.Node.Index,
else_token: Ast.TokenIndex,
@ -1275,7 +1316,7 @@ fn renderThenElse(
}
}
fn renderFor(r: Render, for_node: Ast.full.For, space: Space) Error!void {
fn renderFor(r: *Render, for_node: Ast.full.For, space: Space) Error!void {
const tree = r.tree;
const ais = r.ais;
const token_tags = tree.tokens.items(.tag);
@ -1346,7 +1387,7 @@ fn renderFor(r: Render, for_node: Ast.full.For, space: Space) Error!void {
}
fn renderContainerField(
r: Render,
r: *Render,
container: Container,
field_param: Ast.full.ContainerField,
space: Space,
@ -1450,7 +1491,7 @@ fn renderContainerField(
}
fn renderBuiltinCall(
r: Render,
r: *Render,
builtin_token: Ast.TokenIndex,
params: []const Ast.Node.Index,
space: Space,
@ -1588,7 +1629,7 @@ fn renderBuiltinCall(
}
}
fn renderFnProto(r: Render, fn_proto: Ast.full.FnProto, space: Space) Error!void {
fn renderFnProto(r: *Render, fn_proto: Ast.full.FnProto, space: Space) Error!void {
const tree = r.tree;
const ais = r.ais;
const token_tags = tree.tokens.items(.tag);
@ -1806,7 +1847,7 @@ fn renderFnProto(r: Render, fn_proto: Ast.full.FnProto, space: Space) Error!void
}
fn renderSwitchCase(
r: Render,
r: *Render,
switch_case: Ast.full.SwitchCase,
space: Space,
) Error!void {
@ -1869,7 +1910,7 @@ fn renderSwitchCase(
}
fn renderBlock(
r: Render,
r: *Render,
block_node: Ast.Node.Index,
statements: []const Ast.Node.Index,
space: Space,
@ -1910,7 +1951,7 @@ fn renderBlock(
}
fn renderStructInit(
r: Render,
r: *Render,
struct_node: Ast.Node.Index,
struct_init: Ast.full.StructInit,
space: Space,
@ -1975,7 +2016,7 @@ fn renderStructInit(
}
fn renderArrayInit(
r: Render,
r: *Render,
array_init: Ast.full.ArrayInit,
space: Space,
) Error!void {
@ -2095,6 +2136,7 @@ fn renderArrayInit(
.ais = &auto_indenting_stream,
.tree = r.tree,
.fixups = r.fixups,
.function_index = r.function_index,
};
// Calculate size of columns in current section
@ -2106,7 +2148,7 @@ fn renderArrayInit(
sub_expr_buffer_starts[i] = start;
if (i + 1 < section_exprs.len) {
try renderExpression(sub_render, expr, .none);
try renderExpression(&sub_render, expr, .none);
const width = sub_expr_buffer.items.len - start;
const this_contains_newline = mem.indexOfScalar(u8, sub_expr_buffer.items[start..], '\n') != null;
contains_newline = contains_newline or this_contains_newline;
@ -2126,7 +2168,7 @@ fn renderArrayInit(
column_counter = 0;
}
} else {
try renderExpression(sub_render, expr, .comma);
try renderExpression(&sub_render, expr, .comma);
const width = sub_expr_buffer.items.len - start - 2;
const this_contains_newline = mem.indexOfScalar(u8, sub_expr_buffer.items[start .. sub_expr_buffer.items.len - 1], '\n') != null;
contains_newline = contains_newline or this_contains_newline;
@ -2201,7 +2243,7 @@ fn renderArrayInit(
}
fn renderContainerDecl(
r: Render,
r: *Render,
container_decl_node: Ast.Node.Index,
container_decl: Ast.full.ContainerDecl,
space: Space,
@ -2317,7 +2359,7 @@ fn renderContainerDecl(
}
fn renderAsm(
r: Render,
r: *Render,
asm_node: Ast.full.Asm,
space: Space,
) Error!void {
@ -2476,7 +2518,7 @@ fn renderAsm(
}
fn renderCall(
r: Render,
r: *Render,
call: Ast.full.Call,
space: Space,
) Error!void {
@ -2488,7 +2530,7 @@ fn renderCall(
}
fn renderParamList(
r: Render,
r: *Render,
lparen: Ast.TokenIndex,
params: []const Ast.Node.Index,
space: Space,
@ -2557,7 +2599,7 @@ fn renderParamList(
/// Renders the given expression indented, popping the indent before rendering
/// any following line comments
fn renderExpressionIndented(r: Render, node: Ast.Node.Index, space: Space) Error!void {
fn renderExpressionIndented(r: *Render, node: Ast.Node.Index, space: Space) Error!void {
const tree = r.tree;
const ais = r.ais;
const token_starts = tree.tokens.items(.start);
@ -2617,7 +2659,7 @@ fn renderExpressionIndented(r: Render, node: Ast.Node.Index, space: Space) Error
/// Render an expression, and the comma that follows it, if it is present in the source.
/// If a comma is present, and `space` is `Space.comma`, render only a single comma.
fn renderExpressionComma(r: Render, node: Ast.Node.Index, space: Space) Error!void {
fn renderExpressionComma(r: *Render, node: Ast.Node.Index, space: Space) Error!void {
const tree = r.tree;
const token_tags = tree.tokens.items(.tag);
const maybe_comma = tree.lastToken(node) + 1;
@ -2631,7 +2673,7 @@ fn renderExpressionComma(r: Render, node: Ast.Node.Index, space: Space) Error!vo
/// Render a token, and the comma that follows it, if it is present in the source.
/// If a comma is present, and `space` is `Space.comma`, render only a single comma.
fn renderTokenComma(r: Render, token: Ast.TokenIndex, space: Space) Error!void {
fn renderTokenComma(r: *Render, token: Ast.TokenIndex, space: Space) Error!void {
const tree = r.tree;
const token_tags = tree.tokens.items(.tag);
const maybe_comma = token + 1;
@ -2645,7 +2687,7 @@ fn renderTokenComma(r: Render, token: Ast.TokenIndex, space: Space) Error!void {
/// Render an identifier, and the comma that follows it, if it is present in the source.
/// If a comma is present, and `space` is `Space.comma`, render only a single comma.
fn renderIdentifierComma(r: Render, token: Ast.TokenIndex, space: Space, quote: QuoteBehavior) Error!void {
fn renderIdentifierComma(r: *Render, token: Ast.TokenIndex, space: Space, quote: QuoteBehavior) Error!void {
const tree = r.tree;
const token_tags = tree.tokens.items(.tag);
const maybe_comma = token + 1;
@ -2678,7 +2720,7 @@ const Space = enum {
skip,
};
fn renderToken(r: Render, token_index: Ast.TokenIndex, space: Space) Error!void {
fn renderToken(r: *Render, token_index: Ast.TokenIndex, space: Space) Error!void {
const tree = r.tree;
const ais = r.ais;
const lexeme = tokenSliceForRender(tree, token_index);
@ -2686,7 +2728,7 @@ fn renderToken(r: Render, token_index: Ast.TokenIndex, space: Space) Error!void
try renderSpace(r, token_index, lexeme.len, space);
}
fn renderSpace(r: Render, token_index: Ast.TokenIndex, lexeme_len: usize, space: Space) Error!void {
fn renderSpace(r: *Render, token_index: Ast.TokenIndex, lexeme_len: usize, space: Space) Error!void {
const tree = r.tree;
const ais = r.ais;
const token_tags = tree.tokens.items(.tag);
@ -2734,7 +2776,7 @@ const QuoteBehavior = enum {
eagerly_unquote_except_underscore,
};
fn renderIdentifier(r: Render, token_index: Ast.TokenIndex, space: Space, quote: QuoteBehavior) Error!void {
fn renderIdentifier(r: *Render, token_index: Ast.TokenIndex, space: Space, quote: QuoteBehavior) Error!void {
const tree = r.tree;
const token_tags = tree.tokens.items(.tag);
assert(token_tags[token_index] == .identifier);
@ -2836,7 +2878,7 @@ fn renderIdentifier(r: Render, token_index: Ast.TokenIndex, space: Space, quote:
// Renders a @"" quoted identifier, normalizing escapes.
// Unnecessary escapes are un-escaped, and \u escapes are normalized to \x when they fit.
// If unquote is true, the @"" is removed and the result is a bare symbol whose validity is asserted.
fn renderQuotedIdentifier(r: Render, token_index: Ast.TokenIndex, space: Space, comptime unquote: bool) !void {
fn renderQuotedIdentifier(r: *Render, token_index: Ast.TokenIndex, space: Space, comptime unquote: bool) !void {
const tree = r.tree;
const ais = r.ais;
const token_tags = tree.tokens.items(.tag);
@ -2922,7 +2964,7 @@ fn hasMultilineString(tree: Ast, start_token: Ast.TokenIndex, end_token: Ast.Tok
/// Assumes that start is the first byte past the previous token and
/// that end is the last byte before the next token.
fn renderComments(r: Render, start: usize, end: usize) Error!bool {
fn renderComments(r: *Render, start: usize, end: usize) Error!bool {
const tree = r.tree;
const ais = r.ais;
@ -2985,12 +3027,12 @@ fn renderComments(r: Render, start: usize, end: usize) Error!bool {
return index != start;
}
fn renderExtraNewline(r: Render, node: Ast.Node.Index) Error!void {
fn renderExtraNewline(r: *Render, node: Ast.Node.Index) Error!void {
return renderExtraNewlineToken(r, r.tree.firstToken(node));
}
/// Check if there is an empty line immediately before the given token. If so, render it.
fn renderExtraNewlineToken(r: Render, token_index: Ast.TokenIndex) Error!void {
fn renderExtraNewlineToken(r: *Render, token_index: Ast.TokenIndex) Error!void {
const tree = r.tree;
const ais = r.ais;
const token_starts = tree.tokens.items(.start);
@ -3017,7 +3059,7 @@ fn renderExtraNewlineToken(r: Render, token_index: Ast.TokenIndex) Error!void {
/// end_token is the token one past the last doc comment token. This function
/// searches backwards from there.
fn renderDocComments(r: Render, end_token: Ast.TokenIndex) Error!void {
fn renderDocComments(r: *Render, end_token: Ast.TokenIndex) Error!void {
const tree = r.tree;
// Search backwards for the first doc comment.
const token_tags = tree.tokens.items(.tag);
@ -3049,7 +3091,7 @@ fn renderDocComments(r: Render, end_token: Ast.TokenIndex) Error!void {
}
/// start_token is first container doc comment token.
fn renderContainerDocComments(r: Render, start_token: Ast.TokenIndex) Error!void {
fn renderContainerDocComments(r: *Render, start_token: Ast.TokenIndex) Error!void {
const tree = r.tree;
const token_tags = tree.tokens.items(.tag);
var tok = start_token;
@ -3064,6 +3106,25 @@ fn renderContainerDocComments(r: Render, start_token: Ast.TokenIndex) Error!void
}
}
fn discardAllParams(r: *Render, fn_proto_node: Ast.Node.Index) Error!void {
const tree = r.tree;
const ais = r.ais;
var buf: [1]Ast.Node.Index = undefined;
const fn_proto = tree.fullFnProto(&buf, fn_proto_node).?;
const token_tags = tree.tokens.items(.tag);
const main_tokens = tree.nodes.items(.main_token);
for (fn_proto.ast.params) |param_node| {
const type_ident = main_tokens[param_node];
assert(token_tags[type_ident] == .identifier);
const name_ident = type_ident - 2;
assert(token_tags[name_ident] == .identifier);
const w = ais.writer();
try w.writeAll("_ = ");
try w.writeAll(tokenSliceForRender(r.tree, name_ident));
try w.writeAll(";\n");
}
}
fn tokenSliceForRender(tree: Ast, token_index: Ast.TokenIndex) []const u8 {
var ret = tree.tokenSlice(token_index);
switch (tree.tokens.items(.tag)[token_index]) {

18
src/reduce.zig
View File

@ -11,6 +11,15 @@ const Transformation = enum {
none,
};
// Roadmap:
// - add the main loop that checks for interestingness
// - add transformations
// - gut function
// - replace body with `@trap();`
// - discard the parameters
// - add thread pool
// - add support for `@import` detection and other files
pub fn main(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
const file_path = args[2];
const transformation = std.meta.stringToEnum(Transformation, args[3]);
@ -35,7 +44,14 @@ pub fn main(gpa: Allocator, arena: Allocator, args: []const []const u8) !void {
var rendered = std.ArrayList(u8).init(gpa);
defer rendered.deinit();
rendered.clearRetainingCapacity();
try tree.renderToArrayList(&rendered);
var gut_functions: std.AutoHashMapUnmanaged(u32, void) = .{};
try gut_functions.put(arena, 1, {});
try gut_functions.put(arena, 3, {});
try tree.renderToArrayList(&rendered, .{
.gut_functions = gut_functions,
});
const stdout = std.io.getStdOut();
try stdout.writeAll(rendered.items);