[asan-assembly-instrumentation] Prologue and epilogue are moved out from InstrumentMemOperand().

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216869 91177308-0d34-0410-b5e6-96231b3b80d8
Small refactor on VectorizerHint for deduplication

Previously, the hint mechanism relied on clean up passes to remove redundant
metadata, which still showed up if running opt at low levels of optimization.
That also has shown that multiple nodes of the same type, but with different
values could still coexist, even if temporary, and cause confusion if the
next pass got the wrong value.

This patch makes sure that, if metadata already exists in a loop, the hint
mechanism will never append a new node, but always replace the existing one.
It also enhances the algorithm to cope with more metadata types in the future
by just adding a new type, not a lot of code.

Re-applying again due to MSVC 2013 being minimum requirement, and this patch
having C++11 that MSVC 2012 didn't support.

Fixes PR20655.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216870 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a really bad miscompile introduced in r216865 - the else-if logic
chain became completely broken here as *all* intrinsic users ended up
being skipped, and the ones that seemed to be singled out were actually
the exact wrong set.

This is a great example of why long else-if chains can be easily
confusing. Switch the entire code to use early exits and early continues
to have simpler (and more importantly, correct) logic here, as well as
fixing the reversed logic for detecting and continuing on lifetime
intrinsics.

I've also significantly cleaned up the test case and added another test
case demonstrating an example where the optimization is not (trivially)
safe to perform.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216871 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "[asan-assembly-instrumentation] Prologue and epilogue are moved out from InstrumentMemOperand()."

This reverts commit 895aa397038b8de86d83ac0997a70949a486e112.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216872 91177308-0d34-0410-b5e6-96231b3b80d8