Skip to content

Commit

Permalink
update uses of overflow arithmetic builtins
Browse files Browse the repository at this point in the history
  • Loading branch information
@Vexu
Vexu committed Dec 21, 2022
1 parent 3e39cd5 commit d81a68c
Show file tree
Hide file tree
Showing 28 changed files with 540 additions and 403 deletions.
14 changes: 8 additions & 6 deletions lib/compiler_rt/trunctfxf2.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -49,14 +49,16 @@ pub fn __trunctfxf2(a: f128) callconv(.C) f80 {
const round_bits = a_abs & round_mask;
if (round_bits > halfway) {
// Round to nearest
const carry = @boolToInt(@addWithOverflow(u64, res.fraction, 1, &res.fraction));
res.exp += carry;
res.fraction |= @as(u64, carry) << 63; // Restore integer bit after carry
const ov = @addWithOverflow(res.fraction, 1);
res.fraction = ov[0];
res.exp += ov[1];
res.fraction |= @as(u64, ov[1]) << 63; // Restore integer bit after carry
} else if (round_bits == halfway) {
// Ties to even
const carry = @boolToInt(@addWithOverflow(u64, res.fraction, res.fraction & 1, &res.fraction));
res.exp += carry;
res.fraction |= @as(u64, carry) << 63; // Restore integer bit after carry
const ov = @addWithOverflow(res.fraction, res.fraction & 1);
res.fraction = ov[0];
res.exp += ov[1];
res.fraction |= @as(u64, ov[1]) << 63; // Restore integer bit after carry
}
if (res.exp == 0) res.fraction &= ~@as(u64, integer_bit); // Remove integer bit for de-normals
}
Expand Down
4 changes: 1 addition & 3 deletions lib/std/compress/deflate/compressor_test.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -172,9 +172,7 @@ test "deflate/inflate" {
defer testing.allocator.free(large_data_chunk);
// fill with random data
for (large_data_chunk) |_, i| {
var mul: u8 = @truncate(u8, i);
_ = @mulWithOverflow(u8, mul, mul, &mul);
large_data_chunk[i] = mul;
large_data_chunk[i] = @truncate(u8, i) *% @truncate(u8, i);
}
try testToFromWithLimit(large_data_chunk, limits);
}
Expand Down
16 changes: 8 additions & 8 deletions lib/std/crypto/pcurves/p256/p256_64.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -75,10 +75,10 @@ pub const NonMontgomeryDomainFieldElement = [4]u64;
inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @addWithOverflow(u64, arg2, arg3, &t);
const carry2 = @addWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @addWithOverflow(arg2, arg3);
const ov2 = @addWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function subborrowxU64 is a subtraction with borrow.
Expand All @@ -97,10 +97,10 @@ inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) vo
inline fn subborrowxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @subWithOverflow(u64, arg2, arg3, &t);
const carry2 = @subWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @subWithOverflow(arg2, arg3);
const ov2 = @subWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function mulxU64 is a multiplication, returning the full double-width result.
Expand Down
16 changes: 8 additions & 8 deletions lib/std/crypto/pcurves/p256/p256_scalar_64.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -75,10 +75,10 @@ pub const NonMontgomeryDomainFieldElement = [4]u64;
inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @addWithOverflow(u64, arg2, arg3, &t);
const carry2 = @addWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @addWithOverflow(arg2, arg3);
const ov2 = @addWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function subborrowxU64 is a subtraction with borrow.
Expand All @@ -97,10 +97,10 @@ inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) vo
inline fn subborrowxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @subWithOverflow(u64, arg2, arg3, &t);
const carry2 = @subWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @subWithOverflow(arg2, arg3);
const ov2 = @subWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function mulxU64 is a multiplication, returning the full double-width result.
Expand Down
16 changes: 8 additions & 8 deletions lib/std/crypto/pcurves/p384/p384_64.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,10 @@ pub const NonMontgomeryDomainFieldElement = [6]u64;
inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @addWithOverflow(u64, arg2, arg3, &t);
const carry2 = @addWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @addWithOverflow(arg2, arg3);
const ov2 = @addWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function subborrowxU64 is a subtraction with borrow.
Expand All @@ -66,10 +66,10 @@ inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) vo
inline fn subborrowxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @subWithOverflow(u64, arg2, arg3, &t);
const carry2 = @subWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @subWithOverflow(arg2, arg3);
const ov2 = @subWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function mulxU64 is a multiplication, returning the full double-width result.
Expand Down
16 changes: 8 additions & 8 deletions lib/std/crypto/pcurves/p384/p384_scalar_64.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,10 @@ pub const NonMontgomeryDomainFieldElement = [6]u64;
inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @addWithOverflow(u64, arg2, arg3, &t);
const carry2 = @addWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @addWithOverflow(arg2, arg3);
const ov2 = @addWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function subborrowxU64 is a subtraction with borrow.
Expand All @@ -66,10 +66,10 @@ inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) vo
inline fn subborrowxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @subWithOverflow(u64, arg2, arg3, &t);
const carry2 = @subWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @subWithOverflow(arg2, arg3);
const ov2 = @subWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function mulxU64 is a multiplication, returning the full double-width result.
Expand Down
16 changes: 8 additions & 8 deletions lib/std/crypto/pcurves/secp256k1/secp256k1_64.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,10 @@ pub const NonMontgomeryDomainFieldElement = [4]u64;
inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @addWithOverflow(u64, arg2, arg3, &t);
const carry2 = @addWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @addWithOverflow(arg2, arg3);
const ov2 = @addWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function subborrowxU64 is a subtraction with borrow.
Expand All @@ -66,10 +66,10 @@ inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) vo
inline fn subborrowxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @subWithOverflow(u64, arg2, arg3, &t);
const carry2 = @subWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @subWithOverflow(arg2, arg3);
const ov2 = @subWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function mulxU64 is a multiplication, returning the full double-width result.
Expand Down
16 changes: 8 additions & 8 deletions lib/std/crypto/pcurves/secp256k1/secp256k1_scalar_64.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -44,10 +44,10 @@ pub const NonMontgomeryDomainFieldElement = [4]u64;
inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @addWithOverflow(u64, arg2, arg3, &t);
const carry2 = @addWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @addWithOverflow(arg2, arg3);
const ov2 = @addWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function subborrowxU64 is a subtraction with borrow.
Expand All @@ -66,10 +66,10 @@ inline fn addcarryxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) vo
inline fn subborrowxU64(out1: *u64, out2: *u1, arg1: u1, arg2: u64, arg3: u64) void {
@setRuntimeSafety(mode == .Debug);

var t: u64 = undefined;
const carry1 = @subWithOverflow(u64, arg2, arg3, &t);
const carry2 = @subWithOverflow(u64, t, arg1, out1);
out2.* = @boolToInt(carry1) | @boolToInt(carry2);
const ov1 = @subWithOverflow(arg2, arg3);
const ov2 = @subWithOverflow(ov1[0], arg1);
out1.* = ov2[0];
out2.* = ov1[1] | ov2[1];
}

/// The function mulxU64 is a multiplication, returning the full double-width result.
Expand Down
4 changes: 3 additions & 1 deletion lib/std/crypto/salsa20.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -263,7 +263,9 @@ fn SalsaNonVecImpl(comptime rounds: comptime_int) type {
while (j < 64) : (j += 1) {
xout[j] ^= buf[j];
}
ctx[9] += @boolToInt(@addWithOverflow(u32, ctx[8], 1, &ctx[8]));
const ov = @addWithOverflow(ctx[8], 1);
ctx[8] = ov[0];
ctx[9] += ov[1];
}
if (i < in.len) {
salsaCore(x[0..], ctx, true);
Expand Down
24 changes: 16 additions & 8 deletions lib/std/crypto/utils.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -87,15 +87,19 @@ pub fn timingSafeAdd(comptime T: type, a: []const T, b: []const T, result: []T,
if (endian == .Little) {
var i: usize = 0;
while (i < len) : (i += 1) {
const tmp = @boolToInt(@addWithOverflow(u8, a[i], b[i], &result[i]));
carry = tmp | @boolToInt(@addWithOverflow(u8, result[i], carry, &result[i]));
const ov1 = @addWithOverflow(a[i], b[i]);
const ov2 = @addWithOverflow(ov1[0], carry);
result[i] = ov2[0];
carry = ov1[1] | ov2[1];
}
} else {
var i: usize = len;
while (i != 0) {
i -= 1;
const tmp = @boolToInt(@addWithOverflow(u8, a[i], b[i], &result[i]));
carry = tmp | @boolToInt(@addWithOverflow(u8, result[i], carry, &result[i]));
const ov1 = @addWithOverflow(a[i], b[i]);
const ov2 = @addWithOverflow(ov1[0], carry);
result[i] = ov2[0];
carry = ov1[1] | ov2[1];
}
}
return @bitCast(bool, carry);
Expand All @@ -110,15 +114,19 @@ pub fn timingSafeSub(comptime T: type, a: []const T, b: []const T, result: []T,
if (endian == .Little) {
var i: usize = 0;
while (i < len) : (i += 1) {
const tmp = @boolToInt(@subWithOverflow(u8, a[i], b[i], &result[i]));
borrow = tmp | @boolToInt(@subWithOverflow(u8, result[i], borrow, &result[i]));
const ov1 = @subWithOverflow(a[i], b[i]);
const ov2 = @subWithOverflow(ov1[0], borrow);
result[i] = ov2[0];
borrow = ov1[1] | ov2[1];
}
} else {
var i: usize = len;
while (i != 0) {
i -= 1;
const tmp = @boolToInt(@subWithOverflow(u8, a[i], b[i], &result[i]));
borrow = tmp | @boolToInt(@subWithOverflow(u8, result[i], borrow, &result[i]));
const ov1 = @subWithOverflow(a[i], b[i]);
const ov2 = @subWithOverflow(ov1[0], borrow);
result[i] = ov2[0];
borrow = ov1[1] | ov2[1];
}
}
return @bitCast(bool, borrow);
Expand Down
2 changes: 1 addition & 1 deletion lib/std/heap.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -789,7 +789,7 @@ pub fn testAllocatorLargeAlignment(base_allocator: mem.Allocator) !void {
const large_align: usize = mem.page_size / 2;

var align_mask: usize = undefined;
_ = @shlWithOverflow(usize, ~@as(usize, 0), @as(Allocator.Log2Align, @ctz(large_align)), &align_mask);
align_mask = @shlWithOverflow(~@as(usize, 0), @as(Allocator.Log2Align, @ctz(large_align)))[0];

var slice = try allocator.alignedAlloc(u8, large_align, 500);
try testing.expect(@ptrToInt(slice.ptr) & align_mask == @ptrToInt(slice.ptr));
Expand Down
16 changes: 8 additions & 8 deletions lib/std/leb128.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,11 +15,11 @@ pub fn readULEB128(comptime T: type, reader: anytype) !T {

while (group < max_group) : (group += 1) {
const byte = try reader.readByte();
var temp = @as(U, byte & 0x7f);

if (@shlWithOverflow(U, temp, group * 7, &temp)) return error.Overflow;
const ov = @shlWithOverflow(@as(U, byte & 0x7f), group * 7);
if (ov[1] != 0) return error.Overflow;

value |= temp;
value |= ov[0];
if (byte & 0x80 == 0) break;
} else {
return error.Overflow;
Expand Down Expand Up @@ -65,13 +65,13 @@ pub fn readILEB128(comptime T: type, reader: anytype) !T {

while (group < max_group) : (group += 1) {
const byte = try reader.readByte();
var temp = @as(U, byte & 0x7f);

const shift = group * 7;
if (@shlWithOverflow(U, temp, shift, &temp)) {
const ov = @shlWithOverflow(@as(U, byte & 0x7f), shift);
if (ov[1] != 0) {
// Overflow is ok so long as the sign bit is set and this is the last byte
if (byte & 0x80 != 0) return error.Overflow;
if (@bitCast(S, temp) >= 0) return error.Overflow;
if (@bitCast(S, ov[0]) >= 0) return error.Overflow;

// and all the overflowed bits are 1
const remaining_shift = @intCast(u3, @typeInfo(U).Int.bits - @as(u16, shift));
Expand All @@ -80,14 +80,14 @@ pub fn readILEB128(comptime T: type, reader: anytype) !T {
} else {
// If we don't overflow and this is the last byte and the number being decoded
// is negative, check that the remaining bits are 1
if ((byte & 0x80 == 0) and (@bitCast(S, temp) < 0)) {
if ((byte & 0x80 == 0) and (@bitCast(S, ov[0]) < 0)) {
const remaining_shift = @intCast(u3, @typeInfo(U).Int.bits - @as(u16, shift));
const remaining_bits = @bitCast(i8, byte | 0x80) >> remaining_shift;
if (remaining_bits != -1) return error.Overflow;
}
}

value |= temp;
value |= ov[0];
if (byte & 0x80 == 0) {
const needs_sign_ext = group + 1 < max_group;
if (byte & 0x40 != 0 and needs_sign_ext) {
Expand Down
23 changes: 15 additions & 8 deletions lib/std/math.zig
View file
Original file line number Diff line number Diff line change
Expand Up @@ -468,21 +468,26 @@ test "clamp" {

/// Returns the product of a and b. Returns an error on overflow.
pub fn mul(comptime T: type, a: T, b: T) (error{Overflow}!T) {
var answer: T = undefined;
return if (@mulWithOverflow(T, a, b, &answer)) error.Overflow else answer;
if (T == comptime_int) return a * b;
const ov = @mulWithOverflow(a, b);
if (ov[1] != 0) return error.Overflow;
return ov[0];
}

/// Returns the sum of a and b. Returns an error on overflow.
pub fn add(comptime T: type, a: T, b: T) (error{Overflow}!T) {
if (T == comptime_int) return a + b;
var answer: T = undefined;
return if (@addWithOverflow(T, a, b, &answer)) error.Overflow else answer;
const ov = @addWithOverflow(a, b);
if (ov[1] != 0) return error.Overflow;
return ov[0];
}

/// Returns a - b, or an error on overflow.
pub fn sub(comptime T: type, a: T, b: T) (error{Overflow}!T) {
var answer: T = undefined;
return if (@subWithOverflow(T, a, b, &answer)) error.Overflow else answer;
if (T == comptime_int) return a - b;
const ov = @subWithOverflow(a, b);
if (ov[1] != 0) return error.Overflow;
return ov[0];
}

pub fn negate(x: anytype) !@TypeOf(x) {
Expand All @@ -492,8 +497,10 @@ pub fn negate(x: anytype) !@TypeOf(x) {
/// Shifts a left by shift_amt. Returns an error on overflow. shift_amt
/// is unsigned.
pub fn shlExact(comptime T: type, a: T, shift_amt: Log2Int(T)) !T {
var answer: T = undefined;
return if (@shlWithOverflow(T, a, shift_amt, &answer)) error.Overflow else answer;
if (T == comptime_int) return a << shift_amt;
const ov = @shlWithOverflow(a, shift_amt);
if (ov[1] != 0) return error.Overflow;
return ov[0];
}

/// Shifts left. Overflowed bits are truncated.
Expand Down
Loading

0 comments on commit d81a68c

Please sign in to comment.