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digitalmars.D - Did you know that inline assembly is safe?

reply Dany12L <dany12719l gmail.com> writes:
Hi,

I found that in D for some reason it is possible to declare the 
assembly inline as  safe, this honestly seems crazy to me... The 
compiler can't do any checks on the assembly code to ensure it's 
 safe and it's certainly up to the developer to check it but D is 
 trusted to do this.

     void main()  safe {
         asm  safe {
             mov [RIP], 0;
         }
     }

This code simply compiles and of course then you get SIGSEGV when 
you run it..

I believe inline assembly should only be allowed  system and 
 trusted, and under no circumstances should it allowed be  safe
May 06 2023
next sibling parent reply Quirin Schroll <qs.il.paperinik gmail.com> writes:
On Saturday, 6 May 2023 at 14:55:08 UTC, Dany12L wrote:

 Hi,

 I found that in D for some reason it is possible to declare the 
 assembly inline as  safe, this honestly seems crazy to me... 
 The compiler can't do any checks on the assembly code to ensure 
 it's  safe and it's certainly up to the developer to check it 
 but D is  trusted to do this.

     void main()  safe {
         asm  safe {
             mov [RIP], 0;
         }
     }

 This code simply compiles and of course then you get SIGSEGV 
 when you run it..

 I believe inline assembly should only be allowed  system and 
  trusted, and under no circumstances should it allowed be  safe


` safe` should be immediately disallowed for `asm`. I guess, 
theoretically, assembly code can be ` safe` under very specific 
circumstances, e.g. code that writes no memory. Useful? I don’t 
think so.
May 06 2023
parent Dany12L <dany12719l gmail.com> writes:
On Saturday, 6 May 2023 at 16:23:22 UTC, Quirin Schroll wrote:

I guess,
 theoretically, assembly code can be ` safe` under very specific 
 circumstances, e.g. code that writes no memory. Useful? I don’t 
 think so.


Of course, for example this:

     void main()  safe {
         asm  safe {
             nop;
         }
     }

Technically it would be right to mark it as  safe, but it must be 
the compiler to evaluate whether it is safe or not.

Until we have a technology to do this (and honestly it would be 
useless in my opinion for the use of inline asm) we should not 
allow  safe in inline assembly
May 06 2023
prev sibling parent Nick Treleaven <nick geany.org> writes:
On Saturday, 6 May 2023 at 14:55:08 UTC, Dany12L wrote:

 I believe inline assembly should only be allowed  system and 
  trusted, and under no circumstances should it allowed be  safe


https://github.com/dlang/dmd/pull/15192
May 06 2023