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Added DirectAllocator support for alignments > os.page_size on posix systems

master
tgschultz 2018-04-21 20:41:49 -05:00
parent 7186e92c86
commit a1083b019c
1 changed files with 59 additions and 8 deletions
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67
std/heap.zig
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@ -79,19 +79,38 @@ pub const DirectAllocator = struct {
switch (builtin.os) {
Os.linux, Os.macosx, Os.ios => {
assert(alignment <= os.page_size);
const p = os.posix;
const addr = p.mmap(null, n, p.PROT_READ|p.PROT_WRITE,
p.MAP_PRIVATE|p.MAP_ANONYMOUS, -1, 0);
if (addr == p.MAP_FAILED) {
return error.OutOfMemory;
}
return @intToPtr(&u8, addr)[0..n];
const alloc_size = if(alignment <= os.page_size) n else n + alignment;
const addr = p.mmap(null, alloc_size, p.PROT_READ|p.PROT_WRITE,
p.MAP_PRIVATE|p.MAP_ANONYMOUS, -1, 0);
if(addr == p.MAP_FAILED) return error.OutOfMemory;
if(alloc_size == n) return @intToPtr(&u8, addr)[0..n];
var aligned_addr = addr & ~usize(alignment - 1);
aligned_addr += alignment;
//We can unmap the unused portions of our mmap, but we must only
// pass munmap bytes that exist outside our allocated pages or it
// will happily eat us too
//Since alignment > page_size, we are by definition on a page boundry
const unused_start = addr;
const unused_len = aligned_addr - 1 - unused_start;
var err = p.munmap(@intToPtr(&u8, unused_start), unused_len);
debug.assert(p.getErrno(err) == 0);
//It is impossible that there is an unoccupied page at the top of our
// mmap.
return @intToPtr(&u8, aligned_addr)[0..n];
},
Os.windows => {
const amt = n + alignment + @sizeOf(usize);
const heap_handle = self.heap_handle ?? blk: {
const hh = os.windows.HeapCreate(os.windows.HEAP_NO_SERIALIZE, amt, 0) ?? return error.OutOfMemory;
const hh = os.windows.HeapCreate(os.windows.HEAP_NO_SERIALIZE, amt, 0)
?? return error.OutOfMemory;
self.heap_handle = hh;
break :blk hh;
};
@ -322,6 +341,7 @@ test "DirectAllocator" {
const allocator = &direct_allocator.allocator;
try testAllocator(allocator);
try testAllocatorLargeAlignment(allocator);
}
test "ArenaAllocator" {
@ -332,6 +352,7 @@ test "ArenaAllocator" {
defer arena_allocator.deinit();
try testAllocator(&arena_allocator.allocator);
try testAllocatorLargeAlignment(&arena_allocator.allocator);
}
var test_fixed_buffer_allocator_memory: [30000 * @sizeOf(usize)]u8 = undefined;
@ -339,6 +360,7 @@ test "FixedBufferAllocator" {
var fixed_buffer_allocator = FixedBufferAllocator.init(test_fixed_buffer_allocator_memory[0..]);
try testAllocator(&fixed_buffer_allocator.allocator);
try testAllocatorLargeAlignment(&fixed_buffer_allocator.allocator);
}
fn testAllocator(allocator: &mem.Allocator) !void {
@ -360,3 +382,32 @@ fn testAllocator(allocator: &mem.Allocator) !void {
allocator.free(slice);
}
fn testAllocatorLargeAlignment(allocator: &mem.Allocator) mem.Allocator.Error!void {
//Maybe a platform's page_size is actually the same as or
// very near usize?
if(os.page_size << 2 > @maxValue(usize)) return;
const USizeShift = @IntType(false, std.math.log2(usize.bit_count));
const large_align = u29(os.page_size << 2);
var align_mask: usize = undefined;
_ = @shlWithOverflow(usize, ~usize(0), USizeShift(@ctz(large_align)), &align_mask);
var slice = try allocator.allocFn(allocator, 500, large_align);
debug.assert(@ptrToInt(slice.ptr) & align_mask == @ptrToInt(slice.ptr));
slice = try allocator.reallocFn(allocator, slice, 100, large_align);
debug.assert(@ptrToInt(slice.ptr) & align_mask == @ptrToInt(slice.ptr));
slice = try allocator.reallocFn(allocator, slice, 5000, large_align);
debug.assert(@ptrToInt(slice.ptr) & align_mask == @ptrToInt(slice.ptr));
slice = try allocator.reallocFn(allocator, slice, 10, large_align);
debug.assert(@ptrToInt(slice.ptr) & align_mask == @ptrToInt(slice.ptr));
slice = try allocator.reallocFn(allocator, slice, 20000, large_align);
debug.assert(@ptrToInt(slice.ptr) & align_mask == @ptrToInt(slice.ptr));
allocator.free(slice);
}