mirror/zig
1
0
Fork 0
mirror of https://github.com/ziglang/zig.git synced 2026-02-21 16:54:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

Merge pull request #2312 from squeek502/heap-shrink-large-align

Browse Source 
fix heap allocators when shrinking an object but growing its alignment
This commit is contained in:
Andrew Kelley 2019-04-24 23:44:28 -04:00 committed by GitHub
commit 56e07622c6
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 63 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
std/heap.zig
View File

@ -139,7 +139,11 @@ pub const DirectAllocator = struct {
return shrink(allocator, old_mem, old_align, new_size, new_align);
}
const result = try alloc(allocator, new_size, new_align);
mem.copy(u8, result, old_mem);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
_ = os.posix.munmap(@ptrToInt(old_mem.ptr), old_mem.len);
return result;
},
@ -152,9 +156,8 @@ pub const DirectAllocator = struct {
const root_addr = @intToPtr(*align(1) usize, old_record_addr).*;
const old_ptr = @intToPtr(*c_void, root_addr);
if(new_size == 0)
{
if(os.windows.HeapFree(self.heap_handle.?, 0, old_ptr) == 0) unreachable;
if(new_size == 0) {
if (os.windows.HeapFree(self.heap_handle.?, 0, old_ptr) == 0) unreachable;
return old_mem[0..0];
}
@ -167,8 +170,17 @@ pub const DirectAllocator = struct {
) orelse return error.OutOfMemory;
const offset = old_adjusted_addr - root_addr;
const new_root_addr = @ptrToInt(new_ptr);
const new_adjusted_addr = new_root_addr + offset;
assert(new_adjusted_addr % new_align == 0);
const adjusted_addr = new_root_addr + offset;
const new_adjusted_addr = mem.alignForward(new_root_addr, new_align);
// If HeapReAlloc didn't happen to move the memory to the new alignment
// then we need to copy it
if (new_adjusted_addr != adjusted_addr) {
@memcpy(
@intToPtr([*]u8, new_adjusted_addr),
@intToPtr([*]u8, adjusted_addr),
std.math.min(old_mem.len, new_size),
);
}
const new_record_addr = new_adjusted_addr + new_size;
@intToPtr(*align(1) usize, new_record_addr).* = new_root_addr;
return @intToPtr([*]u8, new_adjusted_addr)[0..new_size];
@ -258,7 +270,11 @@ pub const ArenaAllocator = struct {
return error.OutOfMemory;
} else {
const result = try alloc(allocator, new_size, new_align);
mem.copy(u8, result, old_mem);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
return result;
}
}
@ -316,7 +332,11 @@ pub const FixedBufferAllocator = struct {
return error.OutOfMemory;
} else {
const result = try alloc(allocator, new_size, new_align);
mem.copy(u8, result, old_mem);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
return result;
}
}
@ -459,7 +479,11 @@ pub const ThreadSafeFixedBufferAllocator = blk: {
return error.OutOfMemory;
} else {
const result = try alloc(allocator, new_size, new_align);
mem.copy(u8, result, old_mem);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
return result;
}
}
@ -569,6 +593,7 @@ test "DirectAllocator" {
try testAllocator(allocator);
try testAllocatorAligned(allocator, 16);
try testAllocatorLargeAlignment(allocator);
try testAllocatorAlignedShrink(allocator);
}
test "ArenaAllocator" {
@ -581,15 +606,17 @@ test "ArenaAllocator" {
try testAllocator(&arena_allocator.allocator);
try testAllocatorAligned(&arena_allocator.allocator, 16);
try testAllocatorLargeAlignment(&arena_allocator.allocator);
try testAllocatorAlignedShrink(&arena_allocator.allocator);
}
var test_fixed_buffer_allocator_memory: [30000 * @sizeOf(usize)]u8 = undefined;
var test_fixed_buffer_allocator_memory: [40000 * @sizeOf(usize)]u8 = undefined;
test "FixedBufferAllocator" {
var fixed_buffer_allocator = FixedBufferAllocator.init(test_fixed_buffer_allocator_memory[0..]);
try testAllocator(&fixed_buffer_allocator.allocator);
try testAllocatorAligned(&fixed_buffer_allocator.allocator, 16);
try testAllocatorLargeAlignment(&fixed_buffer_allocator.allocator);
try testAllocatorAlignedShrink(&fixed_buffer_allocator.allocator);
}
test "FixedBufferAllocator Reuse memory on realloc" {
@ -627,6 +654,7 @@ test "ThreadSafeFixedBufferAllocator" {
try testAllocator(&fixed_buffer_allocator.allocator);
try testAllocatorAligned(&fixed_buffer_allocator.allocator, 16);
try testAllocatorLargeAlignment(&fixed_buffer_allocator.allocator);
try testAllocatorAlignedShrink(&fixed_buffer_allocator.allocator);
}
fn testAllocator(allocator: *mem.Allocator) !void {
@ -709,3 +737,28 @@ fn testAllocatorLargeAlignment(allocator: *mem.Allocator) mem.Allocator.Error!vo
allocator.free(slice);
}
fn testAllocatorAlignedShrink(allocator: *mem.Allocator) mem.Allocator.Error!void {
var debug_buffer: [1000]u8 = undefined;
const debug_allocator = &FixedBufferAllocator.init(&debug_buffer).allocator;
const alloc_size = os.page_size * 2 + 50;
var slice = try allocator.alignedAlloc(u8, 16, alloc_size);
defer allocator.free(slice);
var stuff_to_free = std.ArrayList([]align(16) u8).init(debug_allocator);
while (@ptrToInt(slice.ptr) == mem.alignForward(@ptrToInt(slice.ptr), os.page_size * 2)) {
try stuff_to_free.append(slice);
slice = try allocator.alignedAlloc(u8, 16, alloc_size);
}
while (stuff_to_free.popOrNull()) |item| {
allocator.free(item);
}
slice[0] = 0x12;
slice[60] = 0x34;
// realloc to a smaller size but with a larger alignment
slice = try allocator.alignedRealloc(slice, os.page_size * 2, alloc_size / 2);
testing.expect(slice[0] == 0x12);
testing.expect(slice[60] == 0x34);
}