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[RFC][PR68217] Improve value range for signed & sign-bit-CST

From: kugan <kugan dot vivekanandarajah at linaro dot org>
To: "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>, Richard Biener <richard dot guenther at gmail dot com>
Date: Fri, 15 Apr 2016 20:44:27 +1000
Subject: [RFC][PR68217] Improve value range for signed & sign-bit-CST
Authentication-results: sourceware.org; auth=none

As pointed out by Richard, for signed & sign-bit-CST value range shouldbe [-INF, 0] range, not a [-INF, INF] range as happens now.

This patch fixes this. I bootstrapped and regression tested forx86-64-linux-gnu with no new regression. Is this OK for statege-1.


Thanks,
Kugan


gcc/ChangeLog:

2016-04-14  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR middle-end/68217

* tree-vrp.c (extract_range_from_binary_expr_1): In case of signed &sign-bit-CST,

	 generate [-INF, 0] instead of [-INF, INF].


gcc/testsuite/ChangeLog:

2016-04-14  Kugan Vivekanandarajah  <kuganv@linaro.org>

	PR middle-end/68217
	* gcc.dg/pr68217.c: New test.

Attachment: pr68217.txt
Description: Text document

Follow-Ups:
- Re: [RFC][PR68217] Improve value range for signed & sign-bit-CST
  - From: Richard Biener

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