[LoopIdiomRecognize] Support for converting loops that use LSHR to CTLZ.
In the 'detectCTLZIdiom' function support for loops that use LSHR instruction instead of ASHR has been added.
This supports creating ctlz from the following code.
int lzcnt(int x) {
int count = 0;
while (x > 0) {
count++;
x = x >> 1;
}
return count;
}
Patch by Olga Moldovanova
Differential Revision: https://reviews.llvm.org/D48354
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336509
91177308-0d34-0410-b5e6-
96231b3b80d8