commit 01f4bc2efa85d9ccd84d5b355597d861603fac82
author Nikita Popov <nikita.ppv@gmail.com> Fri Jan 11 21:18:00 2019 +0000
committer Nikita Popov <nikita.ppv@gmail.com> Fri Jan 11 21:18:00 2019 +0000
tree 34570a0c86857860a63dcca96d0bd839fa46080a
parent d5cc99d571fa89054537e1a88d9feac7e4250f54

[ConstantFolding] Fold undef for integer intrinsics

This fixes https://bugs.llvm.org/show_bug.cgi?id=40110.

This implements handling of undef operands for integer intrinsics in
ConstantFolding, in particular for the bitcounting intrinsics (ctpop,
cttz, ctlz), the with.overflow intrinsics, the saturating math
intrinsics and the funnel shift intrinsics.

The undef behavior follows what InstSimplify does for the general cas
e of non-constant operands. For the bitcount intrinsics (where
InstSimplify doesn't do undef handling -- there cannot be a combination
of an undef + non-constant operand) I'm using a 0 result if the intrinsic
is defined for zero and undef otherwise.

Differential Revision: https://reviews.llvm.org/D55950

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350971 91177308-0d34-0410-b5e6-96231b3b80d8