Commit Graph

7 Commits

Author SHA1 Message Date
Matt Arsenault 7233344c28 SimplifyLibCalls: Replace fabs libcalls with intrinsics
Add missing fabs(fpext) optimzation that worked with the call,
and also fixes it creating a second fpext when there were multiple
uses.

llvm-svn: 292172
2017-01-17 00:10:40 +00:00
Matt Arsenault 1e0edbf03c InstSimplify: Eliminate fabs on known positive
llvm-svn: 291624
2017-01-11 00:33:24 +00:00
Matt Arsenault a7d2194168 SimplifyLibCalls: Remove incorrect optimization of fabs
fabs(x * x) is not generally safe to assume x is positive if x is a NaN.
This is also less general than it could be, so this will be replaced
with a transformation on the intrinsic.

llvm-svn: 291359
2017-01-07 19:55:12 +00:00
Matt Arsenault 56ff4839ae InstCombine: Fold fabs on select of constants
llvm-svn: 290913
2017-01-03 22:40:34 +00:00
Sanjay Patel dba8b4c04d 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

llvm-svn: 271573
2016-06-02 20:01:37 +00:00
Sanjay Patel 9115cf8c9d [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

llvm-svn: 249701
2015-10-08 16:56:55 +00:00
Sanjay Patel 0ca42bb5a8 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

llvm-svn: 219717
2014-10-14 20:43:11 +00:00