[DTrace-devel] [PATCH 14/14] Fix string disasm due to new code path

[Eugene Loh]

On 5/2/23 12:31, Nick Alcock wrote:

> I guess this is identifying the null check in string load/store and
> correctly recognizing that it is indeed a string?

No.  Nothing specifically related to strings.  The update to the 
comments was supposed to make clear what was going on.  The change to 
the actual code was unfortunately a little more complicated.

Anyhow, we look for access to gvars or lvars.  We used to assume a reg 
would be reused, and so the detection was overly narrow.  Since now we 
do a trial load (to check DT_NULL_STRING), a different reg is used.  So 
the disasm algorithm is now a little broader.  It looks for gvar/lvar 
access without also requiring that a reg is being reused.  It's still 
robust, though.  If we're reading dctx->gvar, we know we're accessing a 
gvar.

> If so, it looks like
> it does what it's meant to:
> Reviewed-by: Nick Alcock <nick.alcock at oracle.com>