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Strip out an unnecessary memset

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This commit is contained in:
Benjamin Feng 2019-12-04 21:41:01 -06:00
parent 5784985bb8
commit 86ae75363e
1 changed files with 18 additions and 15 deletions
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33
lib/std/heap.zig
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@ -254,31 +254,30 @@ 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 align(16) = undefined;
var heap_base_wannabe align(16) = [_]u8{0} ** 256;
const FreeBlock = struct {
const Io = std.packed_int_array.PackedIntIo(u1, .Little);
bytes: []align(16) u8,
fn initData(self: *FreeBlock, bytes: []align(16) u8) void {
// 0 == used, 1 == free
std.mem.set(u8, bytes, 0);
self.bytes = bytes;
}
const Io = std.packed_int_array.PackedIntIo(u1, .Little);
const used = 0;
const free = 1;
fn totalPages(self: FreeBlock) usize {
return self.bytes.len * 8;
}
fn getBit(self: *FreeBlock, idx: usize) u1 {
return Io.get(self.bytes, idx, 0);
const bit_offset = 0;
return Io.get(self.bytes, idx, bit_offset);
}
fn setBits(self: *FreeBlock, start_idx: usize, len: usize, val: u1) void {
const bit_offset = 0;
var i: usize = 0;
while (i < len) : (i += 1) {
Io.set(self.bytes, start_idx + i, 0, val);
Io.set(self.bytes, start_idx + i, bit_offset, val);
}
}
@ -306,7 +305,7 @@ const WasmPageAllocator = struct {
while (j + count < self.totalPages() and self.getBit(j + count) == 1) {
count += 1;
if (count >= num_pages) {
self.setBits(j, num_pages, 0);
self.setBits(j, num_pages, used);
return j;
}
}
@ -317,7 +316,7 @@ const WasmPageAllocator = struct {
}
fn recycle(self: *FreeBlock, start_idx: usize, len: usize) void {
self.setBits(start_idx, len, 1);
self.setBits(start_idx, len, free);
}
};
@ -375,8 +374,8 @@ const WasmPageAllocator = struct {
if (free_end > free_start) {
if (conventional.totalPages() == 0) {
//conventional.initData(__heap_base[0..@intCast(usize, @"llvm.wasm.memory.size.i32"(0) * std.mem.page_size)]);
conventional.initData(heap_base_wannabe[0..]);
//conventional.bytes = __heap_base[0..@intCast(usize, @"llvm.wasm.memory.size.i32"(0) * std.mem.page_size)];
conventional.bytes = heap_base_wannabe[0..];
}
if (free_start < extendedOffset()) {
@ -384,8 +383,12 @@ const WasmPageAllocator = struct {
} else {
if (extended.totalPages() == 0) {
// Steal the last page from the memory currently being recycled
// TODO: would it be better if we use the first page instead?
free_end -= 1;
extended.initData(@intToPtr([*]align(16) u8, free_end * std.mem.page_size)[0..std.mem.page_size]);
extended.bytes = @intToPtr([*]align(16) u8, free_end * std.mem.page_size)[0..std.mem.page_size];
// Since this is the first page being freed and we consume it, assume *nothing* is free.
std.mem.set(u8, extended.bytes, FreeBlock.used);
}
extended.recycle(free_start - extendedOffset(), free_end - free_start);
}