Remove dead code.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213963 91177308-0d34-0410-b5e6-96231b3b80d8
Fix arc4random detection.

Patch by Pascal Stumpf.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213966 91177308-0d34-0410-b5e6-96231b3b80d8
[stack protector] Fix a potential security bug in stack protector where the
address of the stack guard was being spilled to the stack.

Previously the address of the stack guard would get spilled to the stack if it
was impossible to keep it in a register. This patch introduces a new target
independent node and pseudo instruction which gets expanded post-RA to a
sequence of instructions that load the stack guard value. Register allocator
can now just remat the value when it can't keep it in a register. 

<rdar://problem/12475629>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213967 91177308-0d34-0410-b5e6-96231b3b80d8
[stack protector] Add test cases for thumb and thumb2.

<rdar://problem/12475629>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213970 91177308-0d34-0410-b5e6-96231b3b80d8