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Merge pull request #2357 from squeek502/heap-shrink-large-align 

DirectAllocator: reduce the amount of redundant memcpy calls on Windows
master
Andrew Kelley 2019-04-26 19:34:24 -04:00 committed by GitHub
parent efc5122fb6 afc33f00ee
commit ac3946620c
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 14 additions and 26 deletions
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40
std/heap.zig
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@ -139,11 +139,7 @@ pub const DirectAllocator = struct {
return shrink(allocator, old_mem, old_align, new_size, new_align);
}
const result = try alloc(allocator, new_size, new_align);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
@memcpy(result.ptr, old_mem.ptr, std.math.min(old_mem.len, result.len));
_ = os.posix.munmap(@ptrToInt(old_mem.ptr), old_mem.len);
return result;
},
@ -170,16 +166,20 @@ pub const DirectAllocator = struct {
) orelse return error.OutOfMemory;
const offset = old_adjusted_addr - root_addr;
const new_root_addr = @ptrToInt(new_ptr);
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) {
var new_adjusted_addr = new_root_addr + offset;
const offset_is_valid = new_adjusted_addr + new_size + @sizeOf(usize) <= new_root_addr + amt;
const offset_is_aligned = new_adjusted_addr % new_align == 0;
if (!offset_is_valid or !offset_is_aligned) {
// If HeapReAlloc didn't happen to move the memory to the new alignment,
// or the memory starting at the old offset would be outside of the new allocation,
// then we need to copy the memory to a valid aligned address and use that
const new_aligned_addr = mem.alignForward(new_root_addr, new_align);
@memcpy(
@intToPtr([*]u8, new_aligned_addr),
@intToPtr([*]u8, new_adjusted_addr),
@intToPtr([*]u8, adjusted_addr),
std.math.min(old_mem.len, new_size),
);
new_adjusted_addr = new_aligned_addr;
}
const new_record_addr = new_adjusted_addr + new_size;
@intToPtr(*align(1) usize, new_record_addr).* = new_root_addr;
@ -270,11 +270,7 @@ pub const ArenaAllocator = struct {
return error.OutOfMemory;
} else {
const result = try alloc(allocator, new_size, new_align);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
@memcpy(result.ptr, old_mem.ptr, std.math.min(old_mem.len, result.len));
return result;
}
}
@ -332,11 +328,7 @@ pub const FixedBufferAllocator = struct {
return error.OutOfMemory;
} else {
const result = try alloc(allocator, new_size, new_align);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
@memcpy(result.ptr, old_mem.ptr, std.math.min(old_mem.len, result.len));
return result;
}
}
@ -479,11 +471,7 @@ pub const ThreadSafeFixedBufferAllocator = blk: {
return error.OutOfMemory;
} else {
const result = try alloc(allocator, new_size, new_align);
if (result.len >= old_mem.len) {
mem.copy(u8, result, old_mem);
} else {
@memcpy(result.ptr, old_mem.ptr, new_size);
}
@memcpy(result.ptr, old_mem.ptr, std.math.min(old_mem.len, result.len));
return result;
}
}