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std.heap.GeneralPurposeAllocator: reduce page size to 512K

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and fix compilation on 32-bit targets
This commit is contained in:
Andrew Kelley 2025-02-05 01:04:44 -08:00
parent 00b723dc9d
commit b14a350430
1 changed files with 7 additions and 6 deletions
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13
lib/std/heap/general_purpose_allocator.zig
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@ -104,12 +104,13 @@ const StackTrace = std.builtin.StackTrace;
const page_size: usize = @max(std.heap.page_size_max, switch (builtin.os.tag) {
.windows => 64 * 1024, // Makes `std.heap.PageAllocator` take the happy path.
.wasi => 64 * 1024, // Max alignment supported by `std.heap.WasmAllocator`.
else => 2 * 1024 * 1024, // Avoids too many active mappings when `page_size_max` is low.
else => 512 * 1024, // Avoids too many active mappings when `page_size_max` is low.
});
const page_align: mem.Alignment = .fromByteUnits(page_size);
/// Integer type for pointing to slots in a small allocation
const SlotIndex = std.meta.Int(.unsigned, math.log2(page_size) + 1);
const Log2USize = std.math.Log2Int(usize);
const default_test_stack_trace_frames: usize = if (builtin.is_test) 10 else 6;
const default_sys_stack_trace_frames: usize = if (std.debug.sys_can_stack_trace) default_test_stack_trace_frames else 0;
@ -383,7 +384,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
/// This is executed only at compile-time to prepopulate a lookup table.
fn calculateSlotCount(size_class_index: usize) SlotIndex {
const size_class = @as(usize, 1) << @as(u6, @intCast(size_class_index));
const size_class = @as(usize, 1) << @as(Log2USize, @intCast(size_class_index));
var lower: usize = 8;
var upper: usize = (page_size - bucketSize(lower)) / size_class;
while (upper > lower) {
@ -408,7 +409,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
}
fn detectLeaksInBucket(bucket: *BucketHeader, size_class_index: usize, used_bits_count: usize) bool {
const size_class = @as(usize, 1) << @as(u6, @intCast(size_class_index));
const size_class = @as(usize, 1) << @as(Log2USize, @intCast(size_class_index));
const slot_count = slot_counts[size_class_index];
var leaks = false;
var used_bits_byte: usize = 0;
@ -745,7 +746,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
const used_bits_byte = bucket.usedBits(slot_index / 8);
const used_bit_index: u3 = @intCast(slot_index % 8);
used_bits_byte.* |= (@as(u8, 1) << used_bit_index);
const size_class = @as(usize, 1) << @as(u6, @intCast(size_class_index));
const size_class = @as(usize, 1) << @as(Log2USize, @intCast(size_class_index));
if (config.stack_trace_frames > 0) {
bucket.captureStackTrace(ret_addr, slot_count, slot_index, .alloc);
}
@ -858,7 +859,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
const bucket: *BucketHeader = .fromPage(page_addr, slot_count);
if (bucket.canary != config.canary) @panic("Invalid free");
const page_offset = freed_addr - page_addr;
const size_class = @as(usize, 1) << @as(u6, @intCast(size_class_index));
const size_class = @as(usize, 1) << @as(Log2USize, @intCast(size_class_index));
const slot_index: SlotIndex = @intCast(page_offset / size_class);
const used_byte_index = slot_index / 8;
const used_bit_index: u3 = @intCast(slot_index % 8);
@ -953,7 +954,7 @@ pub fn GeneralPurposeAllocator(comptime config: Config) type {
const bucket: *BucketHeader = .fromPage(page_addr, slot_count);
if (bucket.canary != config.canary) @panic("Invalid free");
const page_offset = memory_addr - page_addr;
const size_class = @as(usize, 1) << @as(u6, @intCast(size_class_index));
const size_class = @as(usize, 1) << @as(Log2USize, @intCast(size_class_index));
const slot_index: SlotIndex = @intCast(page_offset / size_class);
const used_byte_index = slot_index / 8;
const used_bit_index: u3 = @intCast(slot_index % 8);