Re: Why does gas put a stop bit in a bundle?

["H. J. Lu" <hjl at lucon dot org>]

On Wed, Apr 30, 2003 at 11:37:03AM -0400, Jim Wilson wrote:
> H. J. Lu wrote:
> > GAS adds a stop bit at the last bundle in the current section
> > automatically.
> > Why does gas do that? I'd like to turn it off.
> 
> Because we can't do dependency violation checking across section 
> switches.  Thus, in order to be safe, we must emit a stop bit when 
> exiting the text section.  Doing otherwise will result in code that 
> silently fails at run time.  Consider what happens if someone has C code 
> with an extended asm that switches to an alternate code section and then 
> back to text.
> 
> Section switching also causes problems for generation of unwind info. 
> It also used to cause trouble for dwarf2 compaction, but I think Richard 
> Henderson fixed that problem.

Intel ia64 assembler doesn't add a stop bit. I consider it unfortunate
for gas. Can you create a testcase which shows dependency violation
doesn't with section switch? I'd like to add it to gas and I will take
a look at it when I find time.

Thanks.


H.J.