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Preprocessor: apply suggestions from code review
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Mainly changes to the control flow of the macro expansion/rescan loop

Co-authored-by: Veikka Tuominen <git@vexu.eu>
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@doppioandante @Vexu
doppioandante and Vexu committed Oct 3, 2021
1 parent 8f5c70e commit 8083895
Showing 1 changed file with 110 additions and 123 deletions.
233 changes: 110 additions & 123 deletions src/Preprocessor.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -704,20 +704,18 @@ fn collectMacroFuncArguments(pp: *Preprocessor, tokenizer: *Tokenizer, buf: *Exp
const initial_tokenizer_index = tokenizer.index;
const old_end = end_idx.*;

var lparen_found = false;
while (!lparen_found) {
const l_paren_tok = try nextBufToken(tokenizer, buf, start_idx, end_idx, extend_buf);
if (l_paren_tok.id == .nl) {
continue;
}
if (l_paren_tok.id != .l_paren) {
// Not a macro function call, go over normal identifier, rewind
tokenizer.index = initial_tokenizer_index;
end_idx.* = old_end;
return null;
while (true) {
const tok = try nextBufToken(tokenizer, buf, start_idx, end_idx, extend_buf);
switch (tok.id) {
.nl => {},
.l_paren => break,
else => {
// Not a macro function call, go over normal identifier, rewind
tokenizer.index = initial_tokenizer_index;
end_idx.* = old_end;
return null;
},
}

lparen_found = true;
}

// collect the arguments.
Expand Down Expand Up @@ -771,6 +769,22 @@ fn expandMacroExhaustive(pp: *Preprocessor, tokenizer: *Tokenizer, buf: *ExpandB
// rescan loop
var do_rescan = true;
while (do_rescan) {
// last phase before rescan: remove placeholder tokens
// NOTE: only do this if there were expansion (i.e. do_rescan is true)
if (do_rescan) {
var i: usize = start_idx;
while (i < buf.items.len) {
const tok = &buf.items[i];
switch (tok.id) {
.empty_arg => {
_ = buf.orderedRemove(i);
moving_end_idx -= 1;
},
else => i += 1,
}
}
}

do_rescan = false;
// expansion loop
var idx: usize = start_idx + advance_index;
Expand All @@ -779,132 +793,108 @@ fn expandMacroExhaustive(pp: *Preprocessor, tokenizer: *Tokenizer, buf: *ExpandB

while (idx < moving_end_idx) {
const macro_entry = pp.defines.getPtr(pp.expandedSlice(buf.items[idx]));
if (macro_entry != null and shouldExpand(buf.items[idx], macro_entry.?)) {
switch (macro_entry.?.*) {
.empty => {
if (macro_entry == null or !shouldExpand(buf.items[idx], macro_entry.?)) {
idx += 1;
continue;
}
switch (macro_entry.?.*) {
.empty => {
idx += 1;
},
.simple => |simple_macro| {
//std.debug.print("Expanding {s}\n", .{pp.expandedSlice(buf.items[idx])});
const res = try pp.expandObjMacro(&simple_macro);
defer res.deinit();
var expansion_loc = simple_macro.loc;
expansion_loc.next = buf.items[idx].loc.next;
for (res.items) |*tok| {
if (buf.items[idx].loc.next) |ln| {
try pp.markExpandedFrom(tok, ln.*);
}
try pp.markExpandedFrom(tok, simple_macro.loc);
}

try buf.replaceRange(idx, 1, res.items);
idx += res.items.len;
moving_end_idx += (res.items.len - 1);
do_rescan = true;
},
.func => |func_macro| {
var macro_scan_idx = idx;
// to be saved in case this doesn't turn out to be a call
const args = (try pp.collectMacroFuncArguments(tokenizer, buf, &macro_scan_idx, &moving_end_idx, extend_buf)) orelse {
idx += 1;
},
.simple => |simple_macro| {
//std.debug.print("Expanding {s}\n", .{pp.expandedSlice(buf.items[idx])});
const res = try pp.expandObjMacro(&simple_macro);
defer res.deinit();
var expansion_loc = simple_macro.loc;
expansion_loc.next = buf.items[idx].loc.next;
for (res.items) |*tok| {
if (buf.items[idx].loc.next) |ln| {
try pp.markExpandedFrom(tok, ln.*);
}
try pp.markExpandedFrom(tok, simple_macro.loc);
continue;
};
defer {
for (args.items) |item| {
pp.comp.gpa.free(item);
}
args.deinit();
}

try buf.replaceRange(idx, 1, res.items);
idx += res.items.len;
moving_end_idx += (res.items.len - 1);
do_rescan = true;
},
.func => |func_macro| {
var macro_scan_idx = idx;
// to be saved in case this doesn't turn out to be a call
if (try pp.collectMacroFuncArguments(tokenizer, buf, &macro_scan_idx, &moving_end_idx, extend_buf)) |args| {
defer {
for (args.items) |item| {
pp.comp.gpa.free(item);
}
args.deinit();
}
var args_count = @intCast(u32, args.items.len);
// if the macro has zero arguments g() args_count is still 1
if (args_count == 1 and func_macro.params.len == 0) args_count = 0;

var args_count = @intCast(u32, args.items.len);
// if the macro has zero arguments g() args_count is still 1
if (args_count == 1 and func_macro.params.len == 0) args_count = 0;
// Validate argument count.
const extra = Diagnostics.Message.Extra{ .arguments = .{ .expected = @intCast(u32, func_macro.params.len), .actual = args_count } };
if (func_macro.var_args and args_count < func_macro.params.len) {
try pp.comp.diag.add(.{ .tag = .expected_at_least_arguments, .loc = buf.items[idx].loc, .extra = extra });
idx += 1;
continue;
}
if (!func_macro.var_args and args_count != func_macro.params.len) {
try pp.comp.diag.add(.{ .tag = .expected_arguments, .loc = buf.items[idx].loc, .extra = extra });
idx += 1;
continue;
}
//std.debug.print("Expanding func: {s}\n", .{pp.expandedSlice(buf.items[idx])});
var expanded_args = MacroArguments.init(pp.comp.gpa);
defer expanded_args.deinit();
try expanded_args.ensureCapacity(args.items.len);
for (args.items) |arg| {
var expand_buf = ExpandBuf.init(pp.comp.gpa);
try expand_buf.appendSlice(arg);

// Validate argument count.
const extra = Diagnostics.Message.Extra{ .arguments = .{ .expected = @intCast(u32, func_macro.params.len), .actual = args_count } };
var validated = true;
if (func_macro.var_args and args_count < func_macro.params.len) {
try pp.comp.diag.add(.{ .tag = .expected_at_least_arguments, .loc = buf.items[idx].loc, .extra = extra });
validated = false;
}
if (!func_macro.var_args and args_count != func_macro.params.len) {
try pp.comp.diag.add(.{ .tag = .expected_arguments, .loc = buf.items[idx].loc, .extra = extra });
validated = false;
}
try pp.expandMacroExhaustive(tokenizer, &expand_buf, 0, expand_buf.items.len, false);

if (validated) {
//std.debug.print("Expanding func: {s}\n", .{pp.expandedSlice(buf.items[idx])});
var expanded_args = MacroArguments.init(pp.comp.gpa);
defer expanded_args.deinit();
try expanded_args.ensureCapacity(args.items.len);
for (args.items) |arg| {
var expand_buf = ExpandBuf.init(pp.comp.gpa);
try expand_buf.appendSlice(arg);

try pp.expandMacroExhaustive(tokenizer, &expand_buf, 0, expand_buf.items.len, false);

expanded_args.appendAssumeCapacity(expand_buf.toOwnedSlice());
}

var res = try pp.expandFuncMacro(&func_macro, &args, &expanded_args);
defer res.deinit();
for (expanded_args.items) |arg| {
pp.comp.gpa.free(arg);
}
var expansion_loc = func_macro.loc;
expansion_loc.next = buf.items[idx].loc.next;
for (res.items) |*tok| {
if (buf.items[idx].loc.next) |ln| {
try pp.markExpandedFrom(tok, ln.*);
}
try pp.markExpandedFrom(tok, func_macro.loc);
}

try buf.replaceRange(idx, macro_scan_idx-idx+1, res.items);
// TODO: moving_end_idx += res.items.len - (macro_scan_idx-idx+1)
// doesn't work when the RHS is negative (unsigned!)
moving_end_idx = moving_end_idx + res.items.len - (macro_scan_idx-idx+1);
idx += res.items.len;
do_rescan = true;
} else {
idx += 1;
}
} else {
idx += 1;
expanded_args.appendAssumeCapacity(expand_buf.toOwnedSlice());
}

var res = try pp.expandFuncMacro(&func_macro, &args, &expanded_args);
defer res.deinit();
for (expanded_args.items) |arg| {
pp.comp.gpa.free(arg);
}
var expansion_loc = func_macro.loc;
expansion_loc.next = buf.items[idx].loc.next;
for (res.items) |*tok| {
if (buf.items[idx].loc.next) |ln| {
try pp.markExpandedFrom(tok, ln.*);
}
},
}
}
else {
idx += 1;
}
try pp.markExpandedFrom(tok, func_macro.loc);
}

try buf.replaceRange(idx, macro_scan_idx-idx+1, res.items);
// TODO: moving_end_idx += res.items.len - (macro_scan_idx-idx+1)
// doesn't work when the RHS is negative (unsigned!)
moving_end_idx = moving_end_idx + res.items.len - (macro_scan_idx-idx+1);
idx += res.items.len;
do_rescan = true;
},
}
if (idx-start_idx == advance_index+1 and !do_rescan) {
advance_index += 1;
//std.debug.print("Advancing start index by {}\n", .{advance_index});
}

} // end of replacement phase

//if (do_rescan) {
// std.debug.print("After expansion: ", .{});
// try pp.debugTokenBuf(buf.items);
//} else {
// std.debug.print("No expansions done\n", .{});
//}

// last phase before rescan: remove placeholder tokens
// NOTE: only do this if there were expansion (i.e. do_rescan is true)
if (do_rescan) {
var i: usize = start_idx;
while (i < buf.items.len) {
const tok = &buf.items[i];
switch (tok.id) {
.empty_arg => {
_ = buf.orderedRemove(i);
moving_end_idx -= 1;
},
else => i += 1,
}
}
}
}
// end of scanning phase

Expand Down Expand Up @@ -958,9 +948,6 @@ pub fn expandedSlice(pp: *Preprocessor, tok: Token) []const u8 {

/// Concat two tokens and add the result to pp.generated
fn pasteTokens(pp: *Preprocessor, lhs: Token, rhs: Token) Error!Token {
if (lhs.id == .empty_arg and rhs.id == .empty_arg) {
return lhs;
}
if (lhs.id == .empty_arg) {
return rhs;
}
Expand Down

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