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[test/Prototypes] Fix DoubleWidth think-os #70289

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merged 1 commit into from
Dec 7, 2023
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[test/Prototypes] Fix DoubleWidth think-os #70289

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37 changes: 28 additions & 9 deletions test/Prototypes/DoubleWidth.swift.gyb
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Original file line number Diff line number Diff line change
Expand Up @@ -393,8 +393,10 @@ extension DoubleWidth : FixedWidthInteger {

let low =
DoubleWidth<Low>(mid1.partial, a.partial)
let (sum_, overflow_) =
mid1.carry.addingReportingOverflow(mid2.partial)
let high =
DoubleWidth(High(mid2.carry + d.carry), mid1.carry + mid2.partial)
DoubleWidth(High(mid2.carry + d.carry + (overflow_ ? 1 : 0)), sum_)

if isNegative {
let (lowComplement, overflow) = (~low).addingReportingOverflow(1)
Expand Down Expand Up @@ -595,10 +597,14 @@ extension DoubleWidth : UnsignedInteger where Base : UnsignedInteger {
) -> (quotient: Low, remainder: Magnitude) {
// The following invariants are guaranteed to hold by dividingFullWidth or
// quotientAndRemainder before this method is invoked:
assert(lhs.high != (0 as Low))
assert(rhs.leadingZeroBitCount == 0)
assert(Magnitude(lhs.high, lhs.mid) < rhs)

guard lhs.high != (0 as Low) else {
let lhs_ = Magnitude(lhs.mid, lhs.low)
return lhs_ < rhs ? (0, lhs_) : (1, lhs_ &- rhs)
}

// Estimate the quotient.
var quotient = lhs.high == rhs.high
? Low.max
Expand Down Expand Up @@ -699,12 +705,13 @@ extension DoubleWidth : UnsignedInteger where Base : UnsignedInteger {

// Left shift both rhs and lhs, then divide and right shift the remainder.
let shift = rhs.leadingZeroBitCount
// Note the use of `>>` instead of `&>>` below,
// as `high` should be zero if `shift` is zero.
let high = (lhs >> (Magnitude.bitWidth &- shift)).low
let rhs = rhs &<< shift
let lhs = lhs &<< shift
let (quotient, remainder) = high == (0 as Low)
? (1, lhs &- rhs)
: Magnitude._divide((high, lhs.high, lhs.low), by: rhs)
let (quotient, remainder) =
Magnitude._divide((high, lhs.high, lhs.low), by: rhs)
return (Magnitude(0, quotient), remainder &>> shift)
}
}
Expand Down Expand Up @@ -813,15 +820,27 @@ dwTests.test("Arithmetic/unsigned") {
expectEqual(lhs % rhs, 4096)
}
do {
let lhs = DoubleWidth<UInt64>((high: 0xa0c7d7165cf01386, low: 0xbf3f66a93056143f))
let rhs = DoubleWidth<UInt64>((high: 0x9ac3a19b1e7d6b83, low: 0x513929792d588736))
let lhs = UInt128((high: 0xa0c7d7165cf01386, low: 0xbf3f66a93056143f))
let rhs = UInt128((high: 0x9ac3a19b1e7d6b83, low: 0x513929792d588736))
expectEqual(String(lhs % rhs), "7997221894243298914179865336050715913")
}
do {
let lhs = DoubleWidth<UInt64>((high: 0xea8a9116b7af33b7, low: 0x3d9d6779ddd22ca3))
let rhs = DoubleWidth<UInt64>((high: 0xc3673efc7f1f37cc, low: 0x312f661057d0ba94))
let lhs = UInt128((high: 0xea8a9116b7af33b7, low: 0x3d9d6779ddd22ca3))
let rhs = UInt128((high: 0xc3673efc7f1f37cc, low: 0x312f661057d0ba94))
expectEqual(String(lhs % rhs), "52023287460685389410162512181093036559")
}
do {
let lhs = UInt256("2369676578372158364766242369061213561181961479062237766620")!
let rhs = UInt256("102797312405202436815976773795958969482")!
expectEqual(String(lhs / rhs), "23051931251193218442")
}
do {
let lhs = UInt256("96467201117289166187766181030232879447148862859323917044548749804018359008044")!
let rhs = UInt256("4646260627574879223760172113656436161581617773435991717024")!
expectEqual(String(lhs / rhs), "20762331011904583253")
}

expectTrue((0xff01 as DoubleWidth<UInt8>).multipliedFullWidth(by: 0x101) == (high: 256, low: 1))
}

dwTests.test("Arithmetic/signed") {
Expand Down