stack frame optimization problem

[downs]

sprucely wrote:
> To try to be sure I had the correct syntax I tried the -S option of g++ along with a switch for intel syntax to output the assembly. However the portion corresponding to the inline assembly was still in ATT syntax.
> 
> For my resulting D executable I tried using hte, but it would abort after mentioning something about a nonexistent htcfg file. I didn't find much info after a cursory search. I gave up easily because I wasn't sure if I would be able to make proper use of it. Maybe I should take an x86 assembly course.
> 
> Vladimir Panteleev Wrote:
> 
>> On Tue, 20 Oct 2009 18:45:50 +0300, sprucely <timberdig at gmail.com> wrote:
>>
>>> This works with g++ and inline ATT assembly, but I have had no such luck  
>>> in D. I have many simple functions that need to be executed sequentially  
>>> and have identical stack frames. To avoid the overhead of setting up and  
>>> tearing down the stack frames I want to jmp from the body of one  
>>> function to the body of the next. A simplified example...
>>>
>>> extern(C) byte jumpHere;
>>>
>>> byte* jumpTo = &jumpHere;
>>>
>>> void f1()
>>> {
>>> 	asm
>>> 	{
>>> 		//jmp dword ptr jumpTo;
>>> 		mov EAX, jumpTo;
>>> 		jmp EAX;
>>> 		//jmp [EAX]
>>> 	}
>>> }
>>>
>>> void f2()
>>> {
>>> 	asm{jumpHere:;}
>>> }
>>>
>>> No matter what I try I get a segfault. My assembly skills are very  
>>> limited. I'm not using the naked keyword yet, because I want to get a  
>>> proof-of-concept working first. Anyone see anything wrong with this? Any  
>>> suggestions?
>> Just disassemble the resulting machine code and look at what's going on.
>>
>> -- 
>> Best regards,
>>   Vladimir                          mailto:thecybershadow at gmail.com
> 

Try dropping an "int 3" before and after, then running it in gdb and using the "disassemble" and "info registers" commands.