Chandler Carruth 59fff99fc0 [PM] Introduce a PoisoningVH as a (more expensive) alternative to ... AssertingVH that delays any reported error until the handle is *used*. This allows data structures to contain handles which become dangling provided the data structure is cleaned up afterward rather than used for anything interesting. The implementation is moderately horrible in part because it works to leave AssertingVH in place, undisturbed. If at some point there is consensus that this is simply how AssertingVH should be used, it can be substantially simplified. This remains a boring pointer in a non-asserts build as you would expect. The only place we pay cost is in asserts builds. I plan to use this as a basis for replacing the asserting VHs that currently dangle in the new PM until invalidation occurs in both LVI and SCEV. Differential Revision: https://reviews.llvm.org/D29061 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@292925 91177308-0d34-0410-b5e6-96231b3b80d8		2017-01-24 12:34:47 +00:00
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llvm	[PM] Introduce a PoisoningVH as a (more expensive) alternative to	2017-01-24 12:34:47 +00:00
llvm-c	[GVN] Initial check-in of a new global value numbering algorithm.	2016-12-22 16:03:48 +00:00