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WasmAllocator: cleanup

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This commit is contained in:
Shritesh Bhattarai 2019-04-16 12:23:45 -05:00
parent 4235982fe6
commit 0c28a18d96
1 changed files with 10 additions and 10 deletions
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20
std/heap.zig
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@ -318,9 +318,10 @@ pub const FixedBufferAllocator = struct {
} }
}; };
// FIXME: Exposed LLVM intrinsics is a bug
// See: https://github.com/ziglang/zig/issues/2291
extern fn @"llvm.wasm.memory.size.i32"(u32) u32; extern fn @"llvm.wasm.memory.size.i32"(u32) u32;
extern fn @"llvm.wasm.memory.grow.i32"(u32, u32) i32; extern fn @"llvm.wasm.memory.grow.i32"(u32, u32) i32;
const WASM_PAGE_SIZE = 64 * 1024; // 64 kilobytes
pub const wasm_allocator = &wasm_allocator_state.allocator; pub const wasm_allocator = &wasm_allocator_state.allocator;
var wasm_allocator_state = WasmAllocator{ var wasm_allocator_state = WasmAllocator{
@ -333,7 +334,7 @@ var wasm_allocator_state = WasmAllocator{
.end_index = 0, .end_index = 0,
}; };
pub const WasmAllocator = struct { const WasmAllocator = struct {
allocator: Allocator, allocator: Allocator,
start_ptr: [*]u8, start_ptr: [*]u8,
num_pages: usize, num_pages: usize,
@ -347,11 +348,11 @@ pub const WasmAllocator = struct {
const adjusted_index = self.end_index + (adjusted_addr - addr); const adjusted_index = self.end_index + (adjusted_addr - addr);
const new_end_index = adjusted_index + size; const new_end_index = adjusted_index + size;
const required_memory = new_end_index - (self.num_pages * WASM_PAGE_SIZE); if (new_end_index > self.num_pages * os.page_size) {
const required_memory = new_end_index - (self.num_pages * os.page_size);
if (required_memory > 0) { var num_pages: u32 = required_memory / os.page_size;
var num_pages: u32 = @divTrunc(required_memory, WASM_PAGE_SIZE); if (required_memory % os.page_size != 0) {
if (@rem(required_memory, WASM_PAGE_SIZE) != 0) {
num_pages += 1; num_pages += 1;
} }
@ -369,7 +370,7 @@ pub const WasmAllocator = struct {
return result; return result;
} }
// Check if memory is the last "item" and it aligns. That lets us expand or reclaim memory // Check if memory is the last "item" and is aligned correctly
fn is_last_item(allocator: *Allocator, memory: []u8, alignment: u29) bool { fn is_last_item(allocator: *Allocator, memory: []u8, alignment: u29) bool {
const self = @fieldParentPtr(WasmAllocator, "allocator", allocator); const self = @fieldParentPtr(WasmAllocator, "allocator", allocator);
return memory.ptr == self.start_ptr + self.end_index - memory.len and mem.alignForward(@ptrToInt(memory.ptr), alignment) == @ptrToInt(memory.ptr); return memory.ptr == self.start_ptr + self.end_index - memory.len and mem.alignForward(@ptrToInt(memory.ptr), alignment) == @ptrToInt(memory.ptr);
@ -380,14 +381,14 @@ pub const WasmAllocator = struct {
// Initialize start_ptr at the first realloc // Initialize start_ptr at the first realloc
if (self.num_pages == 0) { if (self.num_pages == 0) {
self.start_ptr = @intToPtr([*]u8, @intCast(usize, @"llvm.wasm.memory.size.i32"(0)) * WASM_PAGE_SIZE); self.start_ptr = @intToPtr([*]u8, @intCast(usize, @"llvm.wasm.memory.size.i32"(0)) * os.page_size);
} }
if (is_last_item(allocator, old_mem, new_align)) { if (is_last_item(allocator, old_mem, new_align)) {
const start_index = self.end_index - old_mem.len; const start_index = self.end_index - old_mem.len;
const new_end_index = start_index + new_size; const new_end_index = start_index + new_size;
if (new_end_index > self.num_pages * WASM_PAGE_SIZE) { if (new_end_index > self.num_pages * os.page_size) {
_ = try alloc(allocator, new_end_index - self.end_index, new_align); _ = try alloc(allocator, new_end_index - self.end_index, new_align);
} }
const result = self.start_ptr[start_index..new_end_index]; const result = self.start_ptr[start_index..new_end_index];
@ -404,7 +405,6 @@ pub const WasmAllocator = struct {
} }
fn shrink(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 { fn shrink(allocator: *Allocator, old_mem: []u8, old_align: u29, new_size: usize, new_align: u29) []u8 {
// TODO: Use is_last_item or other heuristic here
return old_mem[0..new_size]; return old_mem[0..new_size];
} }
}; };