LeakDetector: Simplify code and fix comments, NFC

Rather than requiring overloads in the wrapper and the impl, just
overload the impl and use templates in the wrapper.  This makes it less
error prone to add more overloads (`void *` defeats any chance the
compiler has at noticing bugs, so the easier the better).

At the same time, correct the comment that was lying about not changing
functionality for `Value`.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224058 91177308-0d34-0410-b5e6-96231b3b80d8
[CodeGen] Add print and verify pass after each MachineFunctionPass by default

Previously print+verify passes were added in a very unsystematic way, which is
annoying when debugging as you miss intermediate steps and allows bugs to stay
unnotice when no verification is performed.

To make this change practical I added the possibility to explicitely disable
verification. I used this option on all places where no verification was
performed previously (because alot of places actually don't pass the
MachineVerifier).
In the long term these problems should be fixed properly and verification
enabled after each pass. I'll enable some more verification in subsequent
commits.

This is the 2nd attempt at this after realizing that PassManager::add() may
actually delete the pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224059 91177308-0d34-0410-b5e6-96231b3b80d8
IR: Store MDNodes in a separate LeakDetector container

This gives us better leak detection messages, like `Value` has.

This also has the side effect of papering over a problem where
`MachineInstr`s are added as garbage to the leak detector and then
deleted without being removed.  If `MDNode::getTemporary()` allocates an
`MDNodeFwdDecl` in the same spot, the leak detector asserts.  By
separating `MDNode`s into their own container we lose that assertion.

Since `MachineInstr` is required to have a trivial destructor, its usage
of `LeakDetector` at all is pretty suspect.  I'll be sending a patch
soon to strip that out.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224060 91177308-0d34-0410-b5e6-96231b3b80d8
CodeGen: Stop using LeakDetector for MachineInstr

Since `MachineInstr` is required to have a trivial destructor, it cannot
remove itself from `LeakDetection`.  Remove the calls.

As it happens, this requirement is because `MachineFunction` allocates
all `MachineInstr`s in a custom allocator; when the `MachineFunction` is
destroyed they're dropped of the edge.  There's no benefit to detecting
leaks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224061 91177308-0d34-0410-b5e6-96231b3b80d8
[ASan] Change fake stack and local variables handling.

This commit changes the way we get fake stack from ASan runtime
(to find use-after-return errors) and the way we represent local
variables:
  - __asan_stack_malloc function now returns pointer to newly allocated
    fake stack frame, or NULL if frame cannot be allocated. It doesn't
    take pointer to real stack as an input argument, it is calculated
    inside the runtime.
  - __asan_stack_free function doesn't take pointer to real stack as
    an input argument. Now this function is never called if fake stack
    frame wasn't allocated.
  - __asan_init version is bumped to reflect changes in the ABI.
  - new flag "-asan-stack-dynamic-alloca" allows to store all the
    function local variables in a dynamic alloca, instead of the static
    one. It reduces the stack space usage in use-after-return mode
    (dynamic alloca will not be called if the local variables are stored
    in a fake stack), and improves the debug info quality for local
    variables (they will not be described relatively to %rbp/%rsp, which
    are assumed to be clobbered by function calls). This flag is turned
    off by default for now, but I plan to turn it on after more
    testing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224062 91177308-0d34-0410-b5e6-96231b3b80d8