[InstCombine] Add tests to show missing fold opportunity for "icmp and shift" (nfc).

Summary:
For icmp pred (and (sh X, Y), C), 0

  When C is signbit, expect to fold (X << Y) & signbit ==/!= 0 into (X << Y) >=/< 0,
  rather than (X & (signbit >> Y)) != 0.

  When C+1 is power of 2, expect to fold (X << Y) & ~C ==/!= 0 into (X << Y) </>= C+1,
  rather than (X & (~C >> Y)) == 0.

For icmp pred (and X, (sh signbit, Y)), 0

  Expect to fold (X & (signbit l>> Y)) ==/!= 0 into (X << Y) >=/< 0
  Expect to fold (X & (signbit << Y)) ==/!= 0 into (X l>> Y) >=/< 0

  Reviewers: lebedev.ri, efriedma, spatel, craig.topper

  Reviewed By: lebedev.ri

  Subscribers: llvm-commits

  Tags: #llvm

  Differential Revision: https://reviews.llvm.org/D63025

llvm-svn: 363479
6 files changed
tree: 0e51c4b1e339273ce5e516cf02c5346085259fa1
  1. .arcconfig
  2. .clang-format
  3. .clang-tidy
  4. .gitignore
  5. README.md
  6. clang-tools-extra/
  7. clang/
  8. compiler-rt/
  9. debuginfo-tests/
  10. libclc/
  11. libcxx/
  12. libcxxabi/
  13. libunwind/
  14. lld/
  15. lldb/
  16. llgo/
  17. llvm/
  18. openmp/
  19. parallel-libs/
  20. polly/
  21. pstl/
README.md

The LLVM Compiler Infrastructure

This directory and its subdirectories contain source code for LLVM, a toolkit for the construction of highly optimized compilers, optimizers, and runtime environments.