[IR] Add support for empty tokens

Description

[IR] Add support for empty tokens

When working with tokens, it is often the case that one has instructions
which consume a token and produce a new token. Currently, we have no
mechanism to represent an initial token state.

Instead, we can create a notional "empty token" by inventing a new
constant which captures the semantics we would like. This new constant
is called ConstantTokenNone and is written textually as "token none".

Differential Revision: http://reviews.llvm.org/D14581

Details

Committed
majnemerNov 11 2015, 1:57 PM
Differential Revision
D14581: [IR] Add support for empty tokens
Parents
rL252810: [CMake] Fixing passthrough for variables starting with the sub-project name
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