[Vm-dev] Sign-bit bug in character literals > 16r7FFF ... related to SistaV1?
nicolas.cellier.aka.nice at gmail.com
Tue Mar 8 17:45:23 UTC 2022
which OS ?
I cannot reproduce on macos 64,
Cog[Spur] VM [CoInterpreterPrimitives VMMaker.oscog-eem.3172]
Mac OS X built on Mar 6 2022 15:31:16 CET Compiler: 4.2.1 Compatible Apple
LLVM 10.0.1 (clang-1001.0.46.4)
platform sources revision VM: 202110232003
Le mar. 8 mars 2022 à 17:57, Marcel Taeumel <marcel.taeumel at hpi.de> a
> Hi Eliot, hi all --
> I think we have an sign-bit bug for character literals with code points >
> Steps to reproduce:
> 1. Print it: "Character value: 16r8000"
> 2. Inspect the result by evaluating the character literal or send
> #asInteger to it. It will most likely not render in a standard Squeak and
> show up like "$? asInteger".
> In a 32-bit VM, I will get the (positive) integer value 16r3FFF8000.
> In a 64-bit VM, I will get the (negative) integer value '-16r8000'.
> Somehow, starting at bit 0, the bits 16 to 29 flip from 0 to 1. In 64-bit,
> this means a negative number. Not sure about bits 30 and 31 here.
> Is there a bug in the upper tag bits of immediate characters?
> Is this related to the 2-byte or 3-byte byte codes in SistaV1?
> Works fine up to 16r7FFF. (This is unrelated to #leadingChar. Mine was 0
> in this experiment.)
> VM: 202112201228 (VMMaker.oscog-eem.3116)
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