Summary:
Fold
or(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X)
into
X s> Y ? -1 : X
https://rise4fun.com/Alive/d8Ab
clamp255 is a common operator in image processing, can be implemented
in a shifty way "(255 - X) >> 31 | X & 255". Fold shift into select
enables more optimization, e.g., vmin generation for ARM target.
Reviewers: lebedev.ri, efriedma, spatel, kparzysz, bcahoon
Reviewed By: lebedev.ri
Subscribers: kristof.beyls, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67800
llvm-svn: 372678
Summary:
Clamp negative to zero and clamp positive to allOnes are common
operation in image saturation.
Add tests for shifty implementation of clamping, as prepare work for
folding:
and(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X) --> X s> 0 ? X : 0;
or(ashr(subNSW(Y, X), ScalarSizeInBits(Y)-1), X) --> X s> Y ? allOnes : X.
Reviewers: lebedev.ri, efriedma, spatel, kparzysz, bcahoon
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67798
llvm-svn: 372671
Huihui Zhang