For years, optimizer engineers have been hitting a common bug caused by passes
assuming all SILValues have a parent function only to be surprised by SILUndef.
Generally we see SILUndef not that often so we see this come up later in
testing. This patch eliminates that problem by making SILUndef uniqued at the
function level instead of the module level. This ensures that it makes sense for
SILUndef to have a parent function, eliminating this possibility since we can
define an API to get its parent function.
rdar://123484595
This fixes all analyses that use AccessUtils in the presence of new
forwarding instructions. This is also needed for consistency with the
C++ source base. And for general sanity.
Utilities that walk the use-def chain should never hard-code a list of
opcodes that happened to work with some specific pass. Passes should
never assume that a basic SIL utility handles specific SIL operations
a certain way. Instead, the utility needs to be defined in terms of
SIL semantics. In this case, the utility is supposed to handle all
instructions that semantically forward ownership of a reference.
Mirror isIdentityPreservingRefCase.
I don't know why this does not apply to boxes and existentials, but am convervatively staying consistent with the
current behavior.
These instructions carry lifetime dependence from a single operand to a single result. They are not forwarding
instructions because we use them to indicate the boundaries of a forwarded lifetime.
* add ForwardingInstruction conformances to missing forwarding instruction classes
* move all the forwarding instruction conformance definitions into ForwardingInstructions.swift
* remove the default implementations of the requirements, so that every instruction needs to specify them
These were always redundant. And there is no way to emit them
correctly for valid OSA when the original dependence scope is in the
caller.
NFC without:
-enable-experimental-feature NonescapableTypes
-enable-lifetime-dependence-diagnostics
Improve noescape function handling. Use the mayEscape API.
Improve handling of @_unsafeNonescapableResult.
Improve handling of initialized scopes. Use findSingleInitializer.
Provide APIs needed by lifetime dependence diagnostics, namely LifetimeDependenceConvention.
Reorganize the APIs so it's easy to find related functionality which
API is responsible for which functionality.
Remove the originalFunctionConvention complexity. It is no longer
needed for lifetime dependence inference, and generally should be
avoided in SIL.
Add some placeholder FIXMEs because this not a good PR in which to
change existing functionality.
