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Fix tautological big_int tests.

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IntegratedQuantum 2022-12-14 01:29:25 +01:00 committed by GitHub
parent f1b536c44c
commit 0b4461d97b
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5 changed files with 68 additions and 37 deletions
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28
lib/std/math/big/int.zig
View File

@ -1176,15 +1176,26 @@ pub const Mutable = struct {
/// `a.limbs.len - (shift / (@sizeOf(Limb) * 8))`.
pub fn shiftRight(r: *Mutable, a: Const, shift: usize) void {
if (a.limbs.len <= shift / limb_bits) {
r.len = 1;
r.positive = true;
r.limbs[0] = 0;
// Shifting negative numbers converges to -1 instead of 0
if (a.positive) {
r.len = 1;
r.positive = true;
r.limbs[0] = 0;
} else {
r.len = 1;
r.positive = false;
r.limbs[0] = 1;
}
return;
}
llshr(r.limbs[0..], a.limbs[0..a.limbs.len], shift);
r.normalize(a.limbs.len - (shift / limb_bits));
r.positive = a.positive;
// Shifting negative numbers converges to -1 instead of 0
if (!r.positive and r.len == 1 and r.limbs[0] == 0) {
r.limbs[0] = 1;
}
}
/// r = ~a under 2s complement wrapping semantics.
@ -2974,8 +2985,15 @@ pub const Managed = struct {
/// r and a may alias.
pub fn shiftRight(r: *Managed, a: *const Managed, shift: usize) !void {
if (a.len() <= shift / limb_bits) {
r.metadata = 1;
r.limbs[0] = 0;
// Shifting negative numbers converges to -1 instead of 0
if (a.isPositive()) {
r.metadata = 1;
r.limbs[0] = 0;
} else {
r.metadata = 1;
r.setSign(false);
r.limbs[0] = 1;
}
return;
}

63
lib/std/math/big/int_test.zig
View File

@ -516,8 +516,8 @@ test "big.int add multi-single" {
}
test "big.int add multi-multi" {
const op1 = 0xefefefef7f7f7f7f;
const op2 = 0xfefefefe9f9f9f9f;
var op1: u128 = 0xefefefef7f7f7f7f;
var op2: u128 = 0xfefefefe9f9f9f9f;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
var b = try Managed.initSet(testing.allocator, op2);
@ -830,8 +830,8 @@ test "big.int sub multi-single" {
}
test "big.int sub multi-multi" {
const op1 = 0xefefefefefefefefefefefef;
const op2 = 0xabababababababababababab;
var op1: u128 = 0xefefefefefefefefefefefef;
var op2: u128 = 0xabababababababababababab;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
@ -914,8 +914,8 @@ test "big.int mul multi-single" {
}
test "big.int mul multi-multi" {
const op1 = 0x998888efefefefefefefef;
const op2 = 0x333000abababababababab;
var op1: u256 = 0x998888efefefefefefefef;
var op2: u256 = 0x333000abababababababab;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
var b = try Managed.initSet(testing.allocator, op2);
@ -1033,8 +1033,8 @@ test "big.int mulWrap single-single signed" {
}
test "big.int mulWrap multi-multi unsigned" {
const op1 = 0x998888efefefefefefefef;
const op2 = 0x333000abababababababab;
var op1: u256 = 0x998888efefefefefefefef;
var op2: u256 = 0x333000abababababababab;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
var b = try Managed.initSet(testing.allocator, op2);
@ -1044,7 +1044,7 @@ test "big.int mulWrap multi-multi unsigned" {
defer c.deinit();
try c.mulWrap(&a, &b, .unsigned, 65);
try testing.expect((try c.to(u128)) == (op1 * op2) & ((1 << 65) - 1));
try testing.expect((try c.to(u256)) == (op1 * op2) & ((1 << 65) - 1));
}
test "big.int mulWrap multi-multi signed" {
@ -1150,8 +1150,8 @@ test "big.int div single-single with rem" {
}
test "big.int div multi-single no rem" {
const op1 = 0xffffeeeeddddcccc;
const op2 = 34;
var op1: u128 = 0xffffeeeeddddcccc;
var op2: u128 = 34;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
@ -1169,8 +1169,8 @@ test "big.int div multi-single no rem" {
}
test "big.int div multi-single with rem" {
const op1 = 0xffffeeeeddddcccf;
const op2 = 34;
var op1: u128 = 0xffffeeeeddddcccf;
var op2: u128 = 34;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
@ -1188,8 +1188,8 @@ test "big.int div multi-single with rem" {
}
test "big.int div multi>2-single" {
const op1 = 0xfefefefefefefefefefefefefefefefe;
const op2 = 0xefab8;
var op1: u128 = 0xfefefefefefefefefefefefefefefefe;
var op2: u128 = 0xefab8;
var a = try Managed.initSet(testing.allocator, op1);
defer a.deinit();
@ -1981,22 +1981,22 @@ test "big.int shift-right negative" {
var arg = try Managed.initSet(testing.allocator, -20);
defer arg.deinit();
try a.shiftRight(&arg, 2);
try testing.expect((try a.to(i32)) == -20 >> 2);
try testing.expect((try a.to(i32)) == -5); // -20 >> 2 == -5
var arg2 = try Managed.initSet(testing.allocator, -5);
defer arg2.deinit();
try a.shiftRight(&arg2, 10);
try testing.expect((try a.to(i32)) == -5 >> 10);
try testing.expect((try a.to(i32)) == -1); // -5 >> 10 == -1
}
test "big.int shift-left negative" {
test "big.int shift-right negative" {
var a = try Managed.init(testing.allocator);
defer a.deinit();
var arg = try Managed.initSet(testing.allocator, -10);
defer arg.deinit();
try a.shiftRight(&arg, 1232);
try testing.expect((try a.to(i32)) == -10 >> 1232);
try testing.expect((try a.to(i32)) == -1); // -10 >> 1232 == -1
}
test "big.int sat shift-left simple unsigned" {
@ -2064,34 +2064,35 @@ test "big.int sat shift-left signed simple positive" {
}
test "big.int sat shift-left signed multi positive" {
const x = 1;
var x: SignedDoubleLimb = 1;
const shift = @bitSizeOf(SignedDoubleLimb) - 1;
var a = try Managed.initSet(testing.allocator, x);
defer a.deinit();
try a.shiftLeftSat(&a, shift, .signed, @bitSizeOf(SignedDoubleLimb));
try testing.expect((try a.to(SignedDoubleLimb)) == @as(SignedDoubleLimb, x) <<| shift);
try testing.expect((try a.to(SignedDoubleLimb)) == x <<| shift);
}
test "big.int sat shift-left signed multi negative" {
const x = -1;
var x: SignedDoubleLimb = -1;
const shift = @bitSizeOf(SignedDoubleLimb) - 1;
var a = try Managed.initSet(testing.allocator, x);
defer a.deinit();
try a.shiftLeftSat(&a, shift, .signed, @bitSizeOf(SignedDoubleLimb));
try testing.expect((try a.to(SignedDoubleLimb)) == @as(SignedDoubleLimb, x) <<| shift);
try testing.expect((try a.to(SignedDoubleLimb)) == x <<| shift);
}
test "big.int bitNotWrap unsigned simple" {
var a = try Managed.initSet(testing.allocator, 123);
var x: u10 = 123;
var a = try Managed.initSet(testing.allocator, x);
defer a.deinit();
try a.bitNotWrap(&a, .unsigned, 10);
try testing.expect((try a.to(u10)) == ~@as(u10, 123));
try testing.expect((try a.to(u10)) == ~x);
}
test "big.int bitNotWrap unsigned multi" {
@ -2104,12 +2105,13 @@ test "big.int bitNotWrap unsigned multi" {
}
test "big.int bitNotWrap signed simple" {
var x: i11 = -456;
var a = try Managed.initSet(testing.allocator, -456);
defer a.deinit();
try a.bitNotWrap(&a, .signed, 11);
try testing.expect((try a.to(i11)) == ~@as(i11, -456));
try testing.expect((try a.to(i11)) == ~x);
}
test "big.int bitNotWrap signed multi" {
@ -2232,14 +2234,16 @@ test "big.int bitwise xor simple" {
}
test "big.int bitwise xor multi-limb" {
var a = try Managed.initSet(testing.allocator, maxInt(Limb) + 1);
var x: DoubleLimb = maxInt(Limb) + 1;
var y: DoubleLimb = maxInt(Limb);
var a = try Managed.initSet(testing.allocator, x);
defer a.deinit();
var b = try Managed.initSet(testing.allocator, maxInt(Limb));
var b = try Managed.initSet(testing.allocator, y);
defer b.deinit();
try a.bitXor(&a, &b);
try testing.expect((try a.to(DoubleLimb)) == (maxInt(Limb) + 1) ^ maxInt(Limb));
try testing.expect((try a.to(DoubleLimb)) == x ^ y);
}
test "big.int bitwise xor single negative simple" {
@ -2327,7 +2331,6 @@ test "big.int bitwise or multi-limb" {
try a.bitOr(&a, &b);
// TODO: big.int.cpp or is wrong on multi-limb.
try testing.expect((try a.to(DoubleLimb)) == (maxInt(Limb) + 1) + maxInt(Limb));
}

8
src/value.zig
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@ -4194,8 +4194,12 @@ pub const Value = extern union {
const result_limbs = lhs_bigint.limbs.len -| (shift / (@sizeOf(std.math.big.Limb) * 8));
if (result_limbs == 0) {
// The shift is enough to remove all the bits from the number, which means the
// result is zero.
return Value.zero;
// result is 0 or -1 depending on the sign.
if (lhs_bigint.positive) {
return Value.zero;
} else {
return Value.negative_one;
}
}
const limbs = try allocator.alloc(

1
test/behavior.zig
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@ -125,6 +125,7 @@ test {
_ = @import("behavior/bugs/13159.zig");
_ = @import("behavior/bugs/13164.zig");
_ = @import("behavior/bugs/13171.zig");
_ = @import("behavior/bugs/13209.zig");
_ = @import("behavior/bugs/13285.zig");
_ = @import("behavior/bugs/13435.zig");
_ = @import("behavior/bugs/13664.zig");

5
test/behavior/bugs/13209.zig Normal file
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@ -0,0 +1,5 @@
const std = @import("std");
test {
try std.testing.expect(-1 == @as(i8, -3) >> 2);
try std.testing.expect(-1 == -3 >> 2000);
}