On Wed, 4 Sep 2013, Xinliang David Li wrote: > > This patch submission still fails to pay attention to various of my > > comments. > > > > If you can provide inlined comments in the patch, that will be more > useful and productive.
I have explained things several times in this thread already. I see no point in repeating things when what I would say has already been said and ignored. As far as I can tell, this latest patch submission has taken one line from the message it is in response to, and largely ignored the following two paragraphs (including where I explicitly say that said line should not appear literally in the source code at all). But, repeating what I said before yet again: (but you should be referring to the relevant types The patch does not do properly that. It refers explicitly to long_double_type_node and double_type_node. - "type", the type being converted to, "itype", the type of the function being called in the source code, "TREE_TYPE (arg0)", the type of the argument after extensions have been removed, and "newtype", computed from those The patch only engages with "type". I suspect "newtype" is what it really means there when using "type". When it uses long_double_type_node and double_type_node, those should be "itype". - so you should have expressions like the above with two or more of those four types, but not with long_double_type_node directly). See above. The patch uses long_double_type_node directly, contrary to what I explicitly said. You are free to disagree with something I say in a review - but in that case you need to reply specifically to the review comment explaining your rationale for disagreeing with it. Just ignoring the comment and not mentioning the disagreement wastes the time of reviewers. The patch submission will need to include a proper analysis to justify to the reader why the particular inequality with particular types from those four is correct in all cases where the relevant code may be executed. The comments only refer to "T1" and "T2" without explaining how they relate to the original expression (three types) or the variables within GCC dealing with various types (four types, because newtype gets involved). I said back in <http://gcc.gnu.org/ml/gcc-patches/2013-09/msg00161.html> and <http://gcc.gnu.org/ml/gcc-patches/2013-08/msg01384.html> that three types are involved - when I say "the patch submission needs to include its own analysis for the full generality of three types", again, it's inappropriate for a patch to omit such an analysis without justification. The patch submission needs to include an analysis that properly explains the transformation involved and the conditions under which it is safe. Maybe starting along the lines of: We have an expression of the form (T1) sqrtT2 ((T2) exprT3), where exprT3 has type T3 (TREE_TYPE (ARG0)), T2 is the type of the floating-point square root function being used (ITYPE), T1 is TYPE and all these types are binary floating-point types. We wish to optimize if possible to an expression of the form (T1) sqrtT4 ((T4) exprT3), where T4 (NEWTYPE) is narrower than T2. (Then explain the choice of T4 and the conditions under which the transformation is safe, with appropriate references.) I suggest that for the next patch submission you (the patch submitter) make sure you spend at least an hour properly understanding the issues and all the previous messages in the thread and writing up the detailed, coherent explanation of the transformation and analysis of the issues that I asked for some time ago, as if for a reader who hasn't read any of this thread or looked at this transformation in GCC before. I've certainly spent longer than that on review in this thread. It's normal for a patch involving anything at all tricky to take hours to write up (and also normal for one to discover, in the course of writing the detailed coherent analysis for people who aren't familiar with the code and the issues involved, that there's in fact something wrong with the patch and it needs revisiting before submission). -- Joseph S. Myers jos...@codesourcery.com
