commit d59827deefbcee8dcd6b6584f8eb925b22a7564a
author Zhaoshi Zheng <zhaoshiz@coduaurora.org> Thu Mar 23 18:06:09 2017 +0000
committer Zhaoshi Zheng <zhaoshiz@coduaurora.org> Thu Mar 23 18:06:09 2017 +0000
tree f7a48cb52e7f3b585e9cb4d576de6baf0c70e606
parent c4fa083a1dd268a634b2e53a83e94c947664c93f

Model ashr(shl(x, n), m) as mul(x, 2^(n-m)) when n > m

Given below case:

  %y = shl %x, n
  %z = ashr %y, m

when n = m, SCEV models it as sext(trunc(x)). This patch tries to handle
the case where n > m by using sext(mul(trunc(x), 2^(n-m)))) as the SCEV
expression.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@298631 91177308-0d34-0410-b5e6-96231b3b80d8