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[PATCH GCC]Try to fold (long)(A-B) into (long)A - (long)B for canonicalization in tree affine

From: "Bin Cheng" <bin dot cheng at arm dot com>
To: <gcc-patches at gcc dot gnu dot org>
Date: Wed, 2 Sep 2015 11:48:19 +0800
Subject: [PATCH GCC]Try to fold (long)(A-B) into (long)A - (long)B for canonicalization in tree affine
Authentication-results: sourceware.org; auth=none

Hi,
Generally we don't try to fold (long)(A-B) into (long)A - (long)B because it
results in more operations.  On the other hand, this fold is wanted when we
want to explore as many canonical opportunities as possible.  Tree affine is
definitely such a place.  This patch supports this in
tree_to_aff_combination, so it can produce canonical affines rather than
stupid expressions like "&arr + (sizetype) (t_4(D) + t_4(D)) * 4 -
(sizetype)t_4(D) * 8".  

Bootstrap and test on x86_64 and aarch64 along with other patches.  Is it
OK?

2015-08-31  Bin Cheng  <bin.cheng@arm.com>

	* tree-affine.c (tree_to_aff_combination): Try to fold (long)(A-B)
	by adding CASE_CONVERT support.

Attachment: pr66388_2-20150824.txt
Description: Text document

Follow-Ups:
- Re: [PATCH GCC]Try to fold (long)(A-B) into (long)A - (long)B for canonicalization in tree affine
  - From: Richard Biener

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