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Date: Sat, 02 Apr 2005 09:54:00 -0000
From: "Eli Zaretskii" <eliz@gnu.org>
To: GDB <gdb@sources.redhat.com>
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In-reply-to: <20050401141105.GB29152@nevyn.them.org> (message from Daniel
	Jacobowitz on Fri, 1 Apr 2005 09:11:05 -0500)
Subject: Re: [mi] watchpoint-scope exec async command
Reply-to: Eli Zaretskii <eliz@gnu.org>
References: <20050329013634.GB6373@nevyn.them.org> <20050329024945.GC3957@white> <20050329020123.GA7266@nevyn.them.org> <01c534a6$Blat.v2.4$944e44a0@zahav.net.il> <20050329214414.GA3498@nevyn.them.org> <01c53564$Blat.v2.4$1da3c140@zahav.net.il> <20050331014749.GA264@white> <01c535ab$Blat.v2.4$c21baac0@zahav.net.il> <20050331205826.GA1590@white> <01c5369a$Blat.v2.4$2f0a6100@zahav.net.il> <20050401141105.GB29152@nevyn.them.org>
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> Date: Fri, 1 Apr 2005 09:11:05 -0500
> From: Daniel Jacobowitz <drow@false.org>
> Cc: GDB <gdb@sources.redhat.com>
> 
> Actually, I don't think software watchpoints need it at all.  A
> software watchpoint is implemented primarily by single-stepping the
> inferior, right?  Well, after every single-step we know whether or not
> the breakpoint is still in scope...

That's true, but running the code that checks whether the watchpoint
is still in scope after each instruction would slow down GDB even
more, while the scope breakpoint doesn't add any slowdown.

Of course, this is all based on speculative arguments, at least from
my side, so it could be 100% wrong.  If someone who reads this knows
for a fact why scope breakpoints were introduced, please speak up.