Re: Sythetic registers: modrm/gas question.

[Tom Lord <lord at emf dot net>]

       > How do I tell gas to assemble an operand as a one-byte offset
       > instead of a four-byte offset?
       > 
       > e.g. 
       > 
       > MOV     eax,[ebp + 4]
       > 
       > Does it "just know?"
  

       Yes, of course it "just knows", that's why your guess that gcc
       is generating poor code seems ill-informed. It is inconceivable
       that *any* compiler would use four byte offsets to access the
       local stack frame.


_That's_ rude.

The question since it could almost certainly have been answered with a
five-minute experiment (what, you don't have the necessary platform
around?)

The caustic reply (beginning at "that's why...") because it is
illogical and prejudicial:  the synthregs proposal is argued for 
at a much higher level than would require that close an examination
of GCC's generated code -- and by-eye examination of that code 
doesn't at all easily help us decide if/when synthregs is a win.
Or are you good at simulating complex caches in your head based
on disassembly listings and demand that we all are as well?

-t