srctree

Андрей Краевский parent 4fac5bd6 7cc0e6d4
std: fix big int llshr to respect aliasing (#19612)

lib/std/math/big/int.zig added: 21, removed: 8, total 13

@@ -3776,19 +3776,19 @@ fn llshr(r: []Limb, a: []const Limb, shift: usize) void {

const limb_shift = shift / limb_bits;

const interior_limb_shift = @as(Log2Limb, @truncate(shift));

var carry: Limb = 0;

var i: usize = 0;

while (i < a.len - limb_shift) : (i += 1) {

const src_i = a.len - i - 1;

const dst_i = src_i - limb_shift;

const dst_i = i;

const src_i = dst_i + limb_shift;

const src_digit = a[src_i];

r[dst_i] = carry | (src_digit >> interior_limb_shift);

carry = @call(.always_inline, math.shl, .{

const src_digit_next = if (src_i + 1 < a.len) a[src_i + 1] else 0;

const carry = @call(.always_inline, math.shl, .{

Limb,

src_digit,

src_digit_next,

limb_bits - @as(Limb, @intCast(interior_limb_shift)),

});

r[dst_i] = carry | (src_digit >> interior_limb_shift);

}

lib/std/math/big/int_test.zig added: 21, removed: 8, total 13

@@ -2019,6 +2019,19 @@ test "shift-right multi" {

try a.shiftRight(&a, 63);

try a.shiftRight(&a, 2);

try testing.expect(a.eqlZero());

try a.set(0xffff0000eeee1111dddd2222cccc3333000000000000000000000);

try a.shiftRight(&a, 84);

const string = try a.toString(

testing.allocator,

16,

.lower,

);

defer testing.allocator.free(string);

try std.testing.expectEqualStrings(

string,

"ffff0000eeee1111dddd2222cccc3333",

);

}

test "shift-left single" {