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Merged
merged 1 commit into from
Aug 15, 2020
Merged

Improve overflow error message #214

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23 changes: 20 additions & 3 deletions src/FixedPointNumbers.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -200,9 +200,19 @@ saturating_sub(x::X, y::X) where {X <: FixedPoint} =
saturating_sub(x::X, y::X) where {X <: FixedPoint{<:Unsigned}} = X(x.i - min(x.i, y.i), 0)

# checked arithmetic
checked_neg(x::X) where {X <: FixedPoint} = X(checked_neg(x.i), 0)
checked_add(x::X, y::X) where {X <: FixedPoint} = X(checked_add(x.i, y.i), 0)
checked_sub(x::X, y::X) where {X <: FixedPoint} = X(checked_sub(x.i, y.i), 0)
checked_neg(x::X) where {X <: FixedPoint} = checked_sub(zero(X), x)
function checked_add(x::X, y::X) where {X <: FixedPoint}
r, f = Base.Checked.add_with_overflow(x.i, y.i)
z = X(r, 0) # store first
f && throw_overflowerror(:+, x, y)
z
end
function checked_sub(x::X, y::X) where {X <: FixedPoint}
r, f = Base.Checked.sub_with_overflow(x.i, y.i)
z = X(r, 0) # store first
f && throw_overflowerror(:-, x, y)
z
end

# default arithmetic
const DEFAULT_ARITHMETIC = :wrapping
Expand Down Expand Up @@ -424,6 +434,13 @@ scaledual(::Type{Tdual}, x::AbstractArray{T}) where {Tdual, T <: FixedPoint} =
throw(ArgumentError(String(take!(io))))
end

@noinline function throw_overflowerror(op::Symbol, @nospecialize(x), @nospecialize(y))
io = IOBuffer()
print(io, x, ' ', op, ' ', y, " overflowed for type ")
showtype(io, typeof(x))
throw(OverflowError(String(take!(io))))
end

function Random.rand(r::AbstractRNG, ::SamplerType{X}) where X <: FixedPoint
X(rand(r, rawtype(X)), 0)
end
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8 changes: 4 additions & 4 deletions test/fixed.jl
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Expand Up @@ -275,8 +275,8 @@ end
xs = typemin(F):eps(F):typemax(F)
fneg(x) = -float(x)
@test all(x -> wrapping_neg(wrapping_neg(x)) === x, xs)
@test all(x -> saturating_neg(x) == clamp(fneg(x), F), xs)
@test all(x -> !(typemin(F) < fneg(x) < typemax(F)) ||
@test all(x -> saturating_neg(x) === clamp(fneg(x), F), xs)
@test all(x -> !(typemin(F) <= fneg(x) <= typemax(F)) ||
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I had excluded typemin and typemax with the intention of writing generic code for 100% testing. They have a risk of causing inconsistencies due to the rounding errors in floating point operations.
However, I decided against supporting non-8-bit types in 100% tests for multiplication. So we can safely include typemin and typemax for 8-bit types.

wrapping_neg(x) === checked_neg(x) === fneg(x) % F, xs)
end
end
Expand All @@ -301,8 +301,8 @@ end
xys = ((x, y) for x in xs, y in xs)
fadd(x, y) = float(x) + float(y)
@test all(((x, y),) -> wrapping_sub(wrapping_add(x, y), y) === x, xys)
@test all(((x, y),) -> saturating_add(x, y) == clamp(fadd(x, y), F), xys)
@test all(((x, y),) -> !(typemin(F) < fadd(x, y) < typemax(F)) ||
@test all(((x, y),) -> saturating_add(x, y) === clamp(fadd(x, y), F), xys)
@test all(((x, y),) -> !(typemin(F) <= fadd(x, y) <= typemax(F)) ||
wrapping_add(x, y) === checked_add(x, y) === fadd(x, y) % F, xys)
end
end
Expand Down
6 changes: 3 additions & 3 deletions test/normed.jl
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Expand Up @@ -303,7 +303,7 @@ end
fneg(x) = -float(x)
@test all(x -> wrapping_neg(wrapping_neg(x)) === x, xs)
@test all(x -> saturating_neg(x) === clamp(fneg(x), N), xs)
@test all(x -> !(typemin(N) < fneg(x) < typemax(N)) ||
@test all(x -> !(typemin(N) <= fneg(x) <= typemax(N)) ||
wrapping_neg(x) === checked_neg(x) === fneg(x) % N, xs)
end
end
Expand All @@ -329,7 +329,7 @@ end
fadd(x, y) = float(x) + float(y)
@test all(((x, y),) -> wrapping_sub(wrapping_add(x, y), y) === x, xys)
@test all(((x, y),) -> saturating_add(x, y) === clamp(fadd(x, y), N), xys)
@test all(((x, y),) -> !(typemin(N) < fadd(x, y) < typemax(N)) ||
@test all(((x, y),) -> !(typemin(N) <= fadd(x, y) <= typemax(N)) ||
wrapping_add(x, y) === checked_add(x, y) === fadd(x, y) % N, xys)
end
end
Expand All @@ -354,7 +354,7 @@ end
fsub(x, y) = float(x) - float(y)
@test all(((x, y),) -> wrapping_add(wrapping_sub(x, y), y) === x, xys)
@test all(((x, y),) -> saturating_sub(x, y) === clamp(fsub(x, y), N), xys)
@test all(((x, y),) -> !(typemin(N) < fsub(x, y) < typemax(N)) ||
@test all(((x, y),) -> !(typemin(N) <= fsub(x, y) <= typemax(N)) ||
wrapping_sub(x, y) === checked_sub(x, y) === fsub(x, y) % N, xys)
end
end
Expand Down