archives/zig
1
0
Fork 0
mirror of https://codeberg.org/ziglang/zig.git synced 2026-03-08 01:24:49 +01:00
Code Issues Projects Releases Packages Wiki Activity Actions

std.heap.BrkAllocator: fix incorrect assumptions

Browse source
This commit is contained in:
Andrew Kelley 2026-02-12 14:58:49 -08:00
parent 6296924214
commit 0957761d5c
1 changed files with 12 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

26
lib/std/heap/BrkAllocator.zig
View file

@ -10,7 +10,6 @@ const Allocator = std.mem.Allocator;
const Alignment = std.mem.Alignment;
const assert = std.debug.assert;
const math = std.math;
const page_size_max = std.heap.page_size_max;
comptime {
if (!builtin.single_threaded) @compileError("unsupported");
@ -36,14 +35,9 @@ pub const Error = Allocator.Error;
const max_usize = math.maxInt(usize);
const ushift = math.Log2Int(usize);
const bigpage_size = 64 * 1024;
const pages_per_bigpage = bigpage_size / page_size_max;
const bigpage_size: comptime_int = @max(64 * 1024, std.heap.page_size_max);
const bigpage_count = max_usize / bigpage_size;
comptime {
assert(bigpage_size >= page_size_max);
}
/// Because of storing free list pointers, the minimum size class is 3.
const min_class = math.log2(math.ceilPowerOfTwoAssert(usize, 1 + @sizeOf(usize)));
const size_class_count = math.log2(bigpage_size) - min_class;
@ -70,7 +64,7 @@ fn alloc(ctx: *anyopaque, len: usize, alignment: Alignment, return_address: usiz
}
const next_addr = global.next_addrs[class];
if (next_addr % page_size_max == 0) {
if (next_addr % bigpage_size == 0) {
const addr = allocBigPages(1);
if (addr == 0) return null;
//std.debug.print("allocated fresh slot_size={d} class={d} addr=0x{x}\n", .{
@ -172,15 +166,19 @@ fn allocBigPages(n: usize) usize {
}
if (builtin.cpu.arch.isWasm()) {
comptime assert(std.heap.page_size_max == std.heap.page_size_min);
const page_size = std.heap.page_size_max;
const pages_per_bigpage = bigpage_size / page_size;
const page_index = @wasmMemoryGrow(0, pow2_pages * pages_per_bigpage);
if (page_index == -1) return 0;
return @as(usize, @intCast(page_index)) * page_size_max;
return @as(usize, @intCast(page_index)) * page_size;
} else if (builtin.os.tag == .linux) {
const start_brk = s: {
const start_brk = global.prev_brk;
break :s if (start_brk == 0) std.os.linux.brk(0) else start_brk;
};
const end_brk = start_brk + pow2_pages * pages_per_bigpage * page_size_max;
const prev_brk = global.prev_brk;
const start_brk = if (prev_brk == 0)
std.mem.alignForward(usize, std.os.linux.brk(0), bigpage_size)
else
prev_brk;
const end_brk = start_brk + pow2_pages * bigpage_size;
const new_prev_brk = std.os.linux.brk(end_brk);
global.prev_brk = new_prev_brk;
if (new_prev_brk != end_brk) return 0;