Rewrite SCEV's backedge taken count computation.

Patch by Michele Scandale!

Rewrite of the functions used to compute the backedge taken count of a
loop on LT and GT comparisons.

I decided to split the handling of LT and GT cases becasue the trick
"a > b == -a < -b" in some cases prevents the trip count computation
due to the multiplication by -1 on the two operands of the
comparison. This issue comes from the conservative computation of
value range of SCEVs: taking the negative SCEV of an expression that
have a small positive range (e.g. [0,31]), we would have a SCEV with a
fullset as value range.

Indeed, in the new rewritten function I tried to better handle the
maximum backedge taken count computation when MAX/MIN expression are
used to handle the cases where no entry guard is found.

Some test have been modified in order to check the new value correctly
(I manually check them and reasoning on possible overflow the new
values seem correct).

I finally added a new test case related to the multiplication by -1
issue on GT comparisons.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194116 91177308-0d34-0410-b5e6-96231b3b80d8
Implement AArch64 Neon instruction set Bitwise Extract.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194118 91177308-0d34-0410-b5e6-96231b3b80d8
Implement AArch64 Neon instruction set Perm.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194123 91177308-0d34-0410-b5e6-96231b3b80d8
Fix definition for Mips16 pc relative load word instructions.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194126 91177308-0d34-0410-b5e6-96231b3b80d8
[llvm-c] Implement LLVMPrintValueToString

Original patch by Chris Wailes

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194135 91177308-0d34-0410-b5e6-96231b3b80d8
[OCaml] Implement Llvm.string_of_llvalue

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194136 91177308-0d34-0410-b5e6-96231b3b80d8
[llvm-c] Expose IRReader interface

Original patch by Chris Wailes

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194137 91177308-0d34-0410-b5e6-96231b3b80d8
[OCaml] Impement Llvm_irreader, bindings to LLVM assembly parser

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194138 91177308-0d34-0410-b5e6-96231b3b80d8
[llvm-c] Expose LLVMLoadLibraryPermanently

Original patch by Chris Wailes

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194139 91177308-0d34-0410-b5e6-96231b3b80d8
[llvm-c] Add functions for initializing native AsmPrinter, AsmParser & Disassembler

Original patch by Chris Wailes

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194140 91177308-0d34-0410-b5e6-96231b3b80d8
[llvm-c] Correctly check for existence of native AsmParser, AsmPrinter, Disassembler

Also, properly name the functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194141 91177308-0d34-0410-b5e6-96231b3b80d8
[llvm-c] Specify explicit namespace in LLVMLoadLibraryPermanently

Presence of using namespace llvm depended on several #ifdef's, and
this broke the build on mswin32.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194142 91177308-0d34-0410-b5e6-96231b3b80d8