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Merge pull request #15431 from kcbanner/fix_decl_value_arena

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sema: Rework Decl.value_arena to fix another memory corruption issue
This commit is contained in:
Andrew Kelley 2023-04-28 11:43:57 -07:00 committed by GitHub
commit fd6200eda6
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3 changed files with 98 additions and 34 deletions
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73
src/Module.zig
View File

@ -411,6 +411,46 @@ pub const WipCaptureScope = struct {
}
};
const ValueArena = struct {
state: std.heap.ArenaAllocator.State,
state_acquired: ?*std.heap.ArenaAllocator.State = null,
/// If this ValueArena replaced an existing one during re-analysis, this is the previous instance
prev: ?*ValueArena = null,
/// Returns an allocator backed by either promoting `state`, or by the existing ArenaAllocator
/// that has already promoted `state`. `out_arena_allocator` provides storage for the initial promotion,
/// and must live until the matching call to release().
pub fn acquire(self: *ValueArena, child_allocator: Allocator, out_arena_allocator: *std.heap.ArenaAllocator) Allocator {
if (self.state_acquired) |state_acquired| {
return @fieldParentPtr(std.heap.ArenaAllocator, "state", state_acquired).allocator();
}
out_arena_allocator.* = self.state.promote(child_allocator);
self.state_acquired = &out_arena_allocator.state;
return out_arena_allocator.allocator();
}
/// Releases the allocator acquired by `acquire. `arena_allocator` must match the one passed to `acquire`.
pub fn release(self: *ValueArena, arena_allocator: *std.heap.ArenaAllocator) void {
if (@fieldParentPtr(std.heap.ArenaAllocator, "state", self.state_acquired.?) == arena_allocator) {
self.state = self.state_acquired.?.*;
self.state_acquired = null;
}
}
pub fn deinit(self: ValueArena, child_allocator: Allocator) void {
assert(self.state_acquired == null);
const prev = self.prev;
self.state.promote(child_allocator).deinit();
if (prev) |p| {
p.deinit(child_allocator);
}
}
};
pub const Decl = struct {
/// Allocated with Module's allocator; outlives the ZIR code.
name: [*:0]const u8,
@ -429,7 +469,7 @@ pub const Decl = struct {
@"addrspace": std.builtin.AddressSpace,
/// The memory for ty, val, align, linksection, and captures.
/// If this is `null` then there is no memory management needed.
value_arena: ?*std.heap.ArenaAllocator.State = null,
value_arena: ?*ValueArena = null,
/// The direct parent namespace of the Decl.
/// Reference to externally owned memory.
/// In the case of the Decl corresponding to a file, this is
@ -607,7 +647,7 @@ pub const Decl = struct {
variable.deinit(gpa);
gpa.destroy(variable);
}
if (decl.value_arena) |arena_state| {
if (decl.value_arena) |value_arena| {
if (decl.owns_tv) {
if (decl.val.castTag(.str_lit)) |str_lit| {
mod.string_literal_table.getPtrContext(str_lit.data, .{
@ -615,7 +655,7 @@ pub const Decl = struct {
}).?.* = .none;
}
}
arena_state.promote(gpa).deinit();
value_arena.deinit(gpa);
decl.value_arena = null;
decl.has_tv = false;
decl.owns_tv = false;
@ -624,9 +664,9 @@ pub const Decl = struct {
pub fn finalizeNewArena(decl: *Decl, arena: *std.heap.ArenaAllocator) !void {
assert(decl.value_arena == null);
const arena_state = try arena.allocator().create(std.heap.ArenaAllocator.State);
arena_state.* = arena.state;
decl.value_arena = arena_state;
const value_arena = try arena.allocator().create(ValueArena);
value_arena.* = .{ .state = arena.state };
decl.value_arena = value_arena;
}
/// This name is relative to the containing namespace of the decl.
@ -4537,15 +4577,20 @@ fn semaDecl(mod: *Module, decl_index: Decl.Index) !bool {
// We need the memory for the Type to go into the arena for the Decl
var decl_arena = std.heap.ArenaAllocator.init(gpa);
const decl_arena_allocator = decl_arena.allocator();
const decl_arena_state = blk: {
const decl_value_arena = blk: {
errdefer decl_arena.deinit();
const s = try decl_arena_allocator.create(std.heap.ArenaAllocator.State);
const s = try decl_arena_allocator.create(ValueArena);
s.* = .{ .state = undefined };
break :blk s;
};
defer {
decl_arena_state.* = decl_arena.state;
decl.value_arena = decl_arena_state;
if (decl.value_arena) |value_arena| {
assert(value_arena.state_acquired == null);
decl_value_arena.prev = value_arena;
}
decl_value_arena.state = decl_arena.state;
decl.value_arena = decl_value_arena;
}
var analysis_arena = std.heap.ArenaAllocator.init(gpa);
@ -5493,9 +5538,9 @@ pub fn analyzeFnBody(mod: *Module, func: *Fn, arena: Allocator) SemaError!Air {
const decl = mod.declPtr(decl_index);
// Use the Decl's arena for captured values.
var decl_arena = decl.value_arena.?.promote(gpa);
defer decl.value_arena.?.* = decl_arena.state;
const decl_arena_allocator = decl_arena.allocator();
var decl_arena: std.heap.ArenaAllocator = undefined;
const decl_arena_allocator = decl.value_arena.?.acquire(gpa, &decl_arena);
defer decl.value_arena.?.release(&decl_arena);
var sema: Sema = .{
.mod = mod,

38
src/Sema.zig
View File

@ -2856,9 +2856,9 @@ fn zirEnumDecl(
const decl_val = try sema.analyzeDeclVal(block, src, new_decl_index);
done = true;
var decl_arena = new_decl.value_arena.?.promote(gpa);
defer new_decl.value_arena.?.* = decl_arena.state;
const decl_arena_allocator = decl_arena.allocator();
var decl_arena: std.heap.ArenaAllocator = undefined;
const decl_arena_allocator = new_decl.value_arena.?.acquire(gpa, &decl_arena);
defer new_decl.value_arena.?.release(&decl_arena);
extra_index = try mod.scanNamespace(&enum_obj.namespace, extra_index, decls_len, new_decl);
@ -26999,13 +26999,12 @@ const ComptimePtrMutationKit = struct {
fn beginArena(self: *ComptimePtrMutationKit, mod: *Module) Allocator {
const decl = mod.declPtr(self.decl_ref_mut.decl_index);
self.decl_arena = decl.value_arena.?.promote(mod.gpa);
return self.decl_arena.allocator();
return decl.value_arena.?.acquire(mod.gpa, &self.decl_arena);
}
fn finishArena(self: *ComptimePtrMutationKit, mod: *Module) void {
const decl = mod.declPtr(self.decl_ref_mut.decl_index);
decl.value_arena.?.* = self.decl_arena.state;
decl.value_arena.?.release(&self.decl_arena);
self.decl_arena = undefined;
}
};
@ -27036,6 +27035,7 @@ fn beginComptimePtrMutation(
.elem_ptr => {
const elem_ptr = ptr_val.castTag(.elem_ptr).?.data;
var parent = try sema.beginComptimePtrMutation(block, src, elem_ptr.array_ptr, elem_ptr.elem_ty);
switch (parent.pointee) {
.direct => |val_ptr| switch (parent.ty.zigTypeTag()) {
.Array, .Vector => {
@ -30653,10 +30653,9 @@ fn resolveStructLayout(sema: *Sema, ty: Type) CompileError!void {
try sema.perm_arena.alloc(u32, struct_obj.fields.count())
else blk: {
const decl = sema.mod.declPtr(struct_obj.owner_decl);
var decl_arena = decl.value_arena.?.promote(sema.mod.gpa);
defer decl.value_arena.?.* = decl_arena.state;
const decl_arena_allocator = decl_arena.allocator();
var decl_arena: std.heap.ArenaAllocator = undefined;
const decl_arena_allocator = decl.value_arena.?.acquire(sema.mod.gpa, &decl_arena);
defer decl.value_arena.?.release(&decl_arena);
break :blk try decl_arena_allocator.alloc(u32, struct_obj.fields.count());
};
@ -30700,9 +30699,9 @@ fn semaBackingIntType(mod: *Module, struct_obj: *Module.Struct) CompileError!voi
const decl_index = struct_obj.owner_decl;
const decl = mod.declPtr(decl_index);
var decl_arena = decl.value_arena.?.promote(gpa);
defer decl.value_arena.?.* = decl_arena.state;
const decl_arena_allocator = decl_arena.allocator();
var decl_arena: std.heap.ArenaAllocator = undefined;
const decl_arena_allocator = decl.value_arena.?.acquire(gpa, &decl_arena);
defer decl.value_arena.?.release(&decl_arena);
const zir = struct_obj.namespace.file_scope.zir;
const extended = zir.instructions.items(.data)[struct_obj.zir_index].extended;
@ -31394,9 +31393,9 @@ fn semaStructFields(mod: *Module, struct_obj: *Module.Struct) CompileError!void
}
const decl = mod.declPtr(decl_index);
var decl_arena = decl.value_arena.?.promote(gpa);
defer decl.value_arena.?.* = decl_arena.state;
const decl_arena_allocator = decl_arena.allocator();
var decl_arena: std.heap.ArenaAllocator = undefined;
const decl_arena_allocator = decl.value_arena.?.acquire(gpa, &decl_arena);
defer decl.value_arena.?.release(&decl_arena);
var analysis_arena = std.heap.ArenaAllocator.init(gpa);
defer analysis_arena.deinit();
@ -31734,10 +31733,9 @@ fn semaUnionFields(mod: *Module, union_obj: *Module.Union) CompileError!void {
extra_index += body.len;
const decl = mod.declPtr(decl_index);
var decl_arena = decl.value_arena.?.promote(gpa);
defer decl.value_arena.?.* = decl_arena.state;
const decl_arena_allocator = decl_arena.allocator();
var decl_arena: std.heap.ArenaAllocator = undefined;
const decl_arena_allocator = decl.value_arena.?.acquire(gpa, &decl_arena);
defer decl.value_arena.?.release(&decl_arena);
var analysis_arena = std.heap.ArenaAllocator.init(gpa);
defer analysis_arena.deinit();

21
test/cases/decl_value_arena.zig Normal file
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@ -0,0 +1,21 @@
pub const Protocols: struct {
list: *const fn(*Connection) void = undefined,
handShake: type = struct {
const stepStart: u8 = 0;
},
} = .{};
pub const Connection = struct {
streamBuffer: [0]u8 = undefined,
__lastReceivedPackets: [0]u8 = undefined,
handShakeState: u8 = Protocols.handShake.stepStart,
};
pub fn main() void {
var conn: Connection = undefined;
_ = conn;
}
// run
//