3 Commits

Author	SHA1	Message	Date
Sanjay Patel	a96468b9ad	transform obscured FP sign bit ops into a fabs/fneg using TLI hook ... This is effectively a revert of: http://reviews.llvm.org/rL249702 - [InstCombine] transform masking off of an FP sign bit into a fabs() intrinsic call (PR24886) and: http://reviews.llvm.org/rL249701 - [ValueTracking] teach computeKnownBits that a fabs() clears sign bits and a reimplementation as a DAG combine for targets that have IEEE754-compliant fabs/fneg instructions. This is intended to resolve the objections raised on the dev list: http://lists.llvm.org/pipermail/llvm-dev/2016-April/098154.html and: https://llvm.org/bugs/show_bug.cgi?id=24886#c4 In the interest of patch minimalism, I've only partly enabled AArch64. PowerPC, MIPS, x86 and others can enable later. Differential Revision: http://reviews.llvm.org/D19391 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@271573 91177308-0d34-0410-b5e6-96231b3b80d8	2016-06-02 20:01:37 +00:00
Sanjay Patel	1938c39ce4	[ValueTracking] teach computeKnownBits that a fabs() clears sign bits ... This was requested in D13076: if we're going to canonicalize to fabs(), ValueTracking should know that fabs() clears sign bits. In this patch (as in D13076), we're not handling vectors yet even though computeKnownBits' fabs() case itself should be vector-ready via the splat in this patch. Fixing this will require follow-on patches to correct other logic that uses 'getScalarType'. Differential Revision: http://reviews.llvm.org/D13222 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@249701 91177308-0d34-0410-b5e6-96231b3b80d8	2015-10-08 16:56:55 +00:00
Sanjay Patel	3f349b2ba8	Optimize away fabs() calls when input is squared (known positive). ... Eliminate library calls and intrinsic calls to fabs when the input is a squared value. Note that no unsafe-math / fast-math assumptions are needed for this optimization. Differential Revision: http://reviews.llvm.org/D5777 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219717 91177308-0d34-0410-b5e6-96231b3b80d8	2014-10-14 20:43:11 +00:00