[rust-dev] Integer overflow, round -2147483648

Daniel Micay danielmicay at gmail.com
Sat Jun 21 16:10:57 PDT 2014


On 21/06/14 06:26 PM, comex wrote:
> On Sat, Jun 21, 2014 at 6:02 PM, Daniel Micay <danielmicay at gmail.com> wrote:
>> It's not possible to add new instructions to x86_64 that are not large
>> and hard to decode. It's too late, nothing short of breaking backwards
>> compatibility by introducing a new architecture will provide trapping on
>> overflow without a performance hit. To repeat what I said elsewhere,
>> Rust's baseline would still be obsolete if it failed on overflow because
>> there's no indication that we can sanely / portably implement failure on
>> overflow via trapping. It's certainly not possible in LLVM right now.
> 
> Er... since when?  Many single-byte opcodes in x86-64 corresponding to
> deprecated x86 instructions are currently undefined.

http://ref.x86asm.net/coder64.html

I don't see enough gaps here for the necessary instructions.

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