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Re: [PATCH] strlenopt improvements

> Can you please explain this stmt_set_p stuff?  dont_invalidate should be
> only set on strinfos that will be seen by the immediately following
> maybe_invalidate call (at the end of handle_builtin_strcpy caller -
> strlen_optimize_stmt).  If you set it on which unshare_strinfo is called,
> if there is no unsharing, it is obviously fine, but if there is unsharing,
> then dont_invalidate will be set on some strinfo that won't be seen by the
> next may_invalidate.  It might trigger in some other basic block and might
> cause wrong code.

It's not needed.  I've retested it with the following loop instead. No
regressions on s390x and x86_64.  Ok to apply?

+       if (dsi->prev != 0 && (chainsi = verify_related_strinfos (dsi)) != NULL)
+ 	{
+ 	  for (; chainsi && chainsi != dsi; chainsi = get_strinfo (chainsi->next))
+ 	    {
+ 	      /* When setting a stmt for delayed length computation
+ 		 prevent all strinfos through dsi from being
+ 		 invalidated.  */
+ 	      chainsi = unshare_strinfo (chainsi);
+ 	      chainsi->stmt = stmt;
+ 	      chainsi->length = NULL_TREE;
+ 	      chainsi->endptr = NULL_TREE;
+ 	      chainsi->dont_invalidate = true;
+ 	    }
+ 	}



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