Re : Re : Re : Re : [PATCH] Compressed ia32 ELF file generation for loading by Gujin 1/3

Re : Re : Re : Re : [PATCH] Compressed ia32 ELF file generation for loading by Gujin 1/3

[Etienne Lorrain]

H. Peter Anvin wrote:
> I've long wished that someone would do a proper 16-bit x86 port of gcc; 

> however, the .code16gcc is usually good enough, although it produces 
> code which is a lot bigger than it needs to be.

  It is only that much bigger if you compare to 16 bits integer compilers,

 but once you deal with 32 bits integers in real mode you have one extra byte

 out of the two - which is still better than dealing with dx:ax.

 Last time I compiled (long time ago) some piece of code with and without

 .code16gcc it was approx 15% bigger - approx what you get when optimising.


 Etienne.




	

	
		
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Re: Re : Re : Re : Re : [PATCH] Compressed ia32 ELF file generation for loading by Gujin 1/3

[H. Peter Anvin]

Etienne Lorrain wrote:
> H. Peter Anvin wrote:
>> I've long wished that someone would do a proper 16-bit x86 port of gcc; 
> 
>> however, the .code16gcc is usually good enough, although it produces 
>> code which is a lot bigger than it needs to be.
> 
>   It is only that much bigger if you compare to 16 bits integer compilers,
>  but once you deal with 32 bits integers in real mode you have one extra byte
>  out of the two - which is still better than dealing with dx:ax.
> 
>  Last time I compiled (long time ago) some piece of code with and without
>  .code16gcc it was approx 15% bigger - approx what you get when optimising.
> 

That's not a valid comparison, because you're using 32-bit registers to 
hold 16-bit pointers, and then sticking 67 prefixes on completely 
unnecessarily.

	-hpa

Re: Re : Re : Re : Re : [PATCH] Compressed ia32 ELF file generation for loading by Gujin 1/3

[Eric W. Biederman]

"H. Peter Anvin" <hpa@zytor.com> writes:

> Etienne Lorrain wrote:
>> H. Peter Anvin wrote:
>>> I've long wished that someone would do a proper 16-bit x86 port of gcc;
>>
>>> however, the .code16gcc is usually good enough, although it produces code
>>> which is a lot bigger than it needs to be.
>>
>>   It is only that much bigger if you compare to 16 bits integer compilers,
>>  but once you deal with 32 bits integers in real mode you have one extra byte
>>  out of the two - which is still better than dealing with dx:ax.
>>
>>  Last time I compiled (long time ago) some piece of code with and without
>>  .code16gcc it was approx 15% bigger - approx what you get when optimising.
>>
>
> That's not a valid comparison, because you're using 32-bit registers to hold
> 16-bit pointers, and then sticking 67 prefixes on completely unnecessarily.

Regardless if the size is good enough we can use it :)

For romcc I had a 3x code bloat over had crafted assembler, because I
had no memory and had to inline every single function call because I
didn't have someplace to put a return register.  So I have the
scenario with the most code bloat.  I win!

Eric