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Implement block-based skipping

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This commit is contained in:
Benjamin Feng 2019-12-03 17:24:50 -06:00
parent 45e0441278
commit b33211ed51
1 changed files with 29 additions and 18 deletions
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47
lib/std/heap.zig
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@ -254,43 +254,54 @@ extern fn @"llvm.wasm.memory.grow.i32"(u32, u32) i32;
const WasmPageAllocator = struct {
// TODO: figure out why __heap_base cannot be found
var heap_base_wannabe: [256]u8 = undefined;
var heap_base_wannabe: [256]u8 align(16) = undefined;
const FreeBlock = struct {
offset: usize = 0,
packed_data: std.PackedIntSlice(u1) = std.PackedIntSlice(u1).init(&[_]u8{}, 0),
block_data: []u128 = &[_]u128{},
fn initData(self: *FreeBlock, data: []u8) void {
fn initData(self: *FreeBlock, data: []align(16) u8) void {
// 0 == used, 1 == free
std.mem.set(u8, data, 0);
self.packed_data = std.PackedIntSlice(u1).init(data, data.len * 8);
self.block_data = @bytesToSlice(u128, data);
}
fn totalPages(self: FreeBlock) usize {
return self.packed_data.int_count;
}
// TODO: optimize this terribleness
fn useRecycled(self: *FreeBlock, num_pages: usize) ?[*]u8 {
var found_idx: usize = 0;
var found_size: usize = 0;
var i: usize = 0;
while (i < self.packed_data.int_count) : (i += 1) {
if (self.packed_data.get(i) == 0) {
found_size = 0;
} else {
if (found_size == 0) {
found_idx = i;
}
found_size += 1;
for (self.block_data) |segment, i| {
const spills_into_next = @bitCast(i128, segment) < 0;
const has_enough_bits = @popCount(u128, segment) >= num_pages;
if (found_size >= num_pages) {
while (found_size > 0) {
found_size -= 1;
self.packed_data.set(found_idx + found_size, 0);
if (!spills_into_next and !has_enough_bits) continue;
var j: usize = i * 128;
while (j < self.packed_data.int_count) : (j += 1) {
if (self.packed_data.get(j) == 0) {
found_size = 0;
if (j > (i + 1) * 128) {
break;
}
} else {
if (found_size == 0) {
found_idx = j;
}
found_size += 1;
if (found_size >= num_pages) {
while (found_size > 0) {
found_size -= 1;
self.packed_data.set(found_idx + found_size, 0);
}
return @intToPtr([*]u8, (found_idx + self.offset) * std.mem.page_size);
}
return @intToPtr([*]u8, (found_idx + self.offset) * std.mem.page_size);
}
}
}
@ -365,7 +376,7 @@ const WasmPageAllocator = struct {
// Steal the last page from the memory currently being recycled
free_end -= 1;
extended.initData(@intToPtr([*]u8, free_end * std.mem.page_size)[0..std.mem.page_size]);
extended.initData(@intToPtr([*]align(16) u8, free_end * std.mem.page_size)[0..std.mem.page_size]);
}
extended.recycle(free_start, free_end);
}