Use the LLVM_GNUC_PREREQ macro instead of the longhand version check

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221219 91177308-0d34-0410-b5e6-96231b3b80d8
[Support][Program] Add findProgramByName(Name, OptionalPaths)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221220 91177308-0d34-0410-b5e6-96231b3b80d8
Use findProgramByName.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221221 91177308-0d34-0410-b5e6-96231b3b80d8
Remove setPreservesCFG from instcombine.  The pass, in particular, does not
preserve LoopSimplify because instcombine may replace branch predicates
with undef which loop simplify then replaces with always exit.  Replace
setPreservesCFG with the more constrained preservation of DomTree and
LoopInfo.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221223 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "Transforms: reapply SVN r219899"

This reverts commit r220811 and r220839. It made an incorrect change to
musttail handling.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221226 91177308-0d34-0410-b5e6-96231b3b80d8
Docs: give binutils/gold instructions for CMake too.

Patch by Steve King.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221227 91177308-0d34-0410-b5e6-96231b3b80d8