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fix heap allocators when shrinking an object but growing its alignment

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This commit is contained in:
Ryan Liptak 2019-04-19 17:54:53 -07:00
parent bb25f212b3
commit 66020856b2
1 changed files with 49 additions and 4 deletions
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53
std/heap.zig
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@ -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;
},
@ -258,7 +262,11 @@ 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 +324,11 @@ 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 +471,11 @@ 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 +585,7 @@ test "DirectAllocator" {
try testAllocator(allocator);
try testAllocatorAligned(allocator, 16);
try testAllocatorLargeAlignment(allocator);
try testAllocatorAlignedShrink(allocator);
}
test "ArenaAllocator" {
@ -581,6 +598,7 @@ 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;
@ -590,6 +608,7 @@ test "FixedBufferAllocator" {
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 +646,7 @@ 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 +729,28 @@ 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);
}