Closed
Description
openedon Feb 25, 2021
julia> function f(n)
(n_positive, neg) = Base.split_sign(n); ccall(:jl_breakpoint, Cvoid, ())
Base.dec(n_positive, 1, neg)
end
LLVM IR:
; @ REPL[9]:2 within `f'
; ┌ @ intfuncs.jl:743 within `split_sign'
; │┌ @ int.jl:172 within `abs'
; ││┌ @ int.jl:132 within `flipsign'
%7 = ashr i32 %0, 31
%8 = add i32 %0, %7
%9 = xor i32 %8, %7
; │└└
; │┌ @ promotion.jl:360 within `<'
; ││┌ @ promotion.jl:291 within `promote'
; │││┌ @ promotion.jl:268 within `_promote'
; ││││┌ @ number.jl:7 within `convert'
; │││││┌ @ boot.jl:757 within `Int64'
; ││││││┌ @ boot.jl:676 within `toInt64'
%10 = sext i32 %0 to i64
Assembly:
; │┌ @ intfuncs.jl:743 within `split_sign'
; ││┌ @ int.jl:172 within `abs'
; │││┌ @ int.jl:132 within `flipsign'
asr w10, w9, #31
add w11, w9, w10
eor w0, w11, w10
; ││└└
; ││┌ @ promotion.jl:360 within `<'
; │││┌ @ promotion.jl:291 within `promote'
; ││││┌ @ promotion.jl:268 within `_promote'
; │││││┌ @ number.jl:7 within `convert'
; ││││││┌ @ boot.jl:757 within `Int64'
; │││││││┌ @ boot.jl:676 within `toInt64'
mov x8, x9
; │││└└└└└
; │││ @ promotion.jl:360 within `<' @ int.jl:83
cmp x8, #0 ; =0
cset w10, lt
w9 is not sign extended in the x9 register
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