Revert "Limit the symbol search in DynamicLibrary to the module that was opened."

This reverts commit r216563, which breaks lli's dynamic symbol resolution.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216569 91177308-0d34-0410-b5e6-96231b3b80d8
InstSimplify: Compute comparison ranges for left shift instructions

'shl nuw CI, x' produces [CI, CI << CLZ(CI)]
'shl nsw CI, x' produces [CI << CLO(CI)-1, CI] if CI is negative
'shl nsw CI, x' produces [CI, CI << CLZ(CI)-1] if CI is non-negative

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216570 91177308-0d34-0410-b5e6-96231b3b80d8
Fix some semantic usability issues with DynamicLibrary.

This patch allows invalid DynamicLibrary instances to be
constructed, and fixes the const-correctness of the isValid()
method.

No functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216571 91177308-0d34-0410-b5e6-96231b3b80d8