Re: [SH][PATCH] Disable ABI frame sniffer

[Daniel Jacobowitz <drow@false.org>]

On Wed, Nov 09, 2005 at 05:12:15PM +0000, Andrew STUBBS wrote:
> Hi,
> 
> The attached patch adds a new sh-specific command:
> 
> set backtrace abi-sniffer
> 
> This command allows the ABI frame sniffer to be disabled. The default 
> state remains 'on', as it is now.

I had to look up what you meant by "ABI frame sniffer"; we normally
call this the prologue analyzer.

> With the ABI sniffer 'off' it is not possible to backtrace through code 
> that does not have CFI. On sh-elf, at least, there is always CFI when 
> there is debug info, so it is relatively rare that the ABI sniffer is 
> actually required.
> 
> I have not set the default to 'off' because that causes quite a number 
> of FAILs in the testsuite.

That should be a hint...

Obviously the SH maintainers have final say, but I strongly discourage
any patch along these lines.  If you want to improve the fallback
unwinder, go ahead.  If you want to add more generic tests to terminate
backtraces without annoying messages, we can discuss that.  But turning
it off is not viable.

-- 
Daniel Jacobowitz
CodeSourcery, LLC