The reason why I am introducing special instructions is so I can maintain the
qualified ownership API wedge in between qualified SIL and the rest of the ARC
instructions that are pervasively used in the compiler.
These instructions in the future /could/ be extended to just take @sil_unmanaged
operands directly, but I want to maintain flexibility to take regular
non-trivial operands in the short term.
rdar://29791263
This commit makes the following changes:
1. guaranteed arguments will trip the verifier if they have a lifetime ending
use.
2. owned arguments must have a lifetime ending use in a function. We already
would have exposed this as a leak via the dataflow, but exiting early gives us a
better clearer error message.
The way SILResultInfo::getOwnershipKind(SILModule &) was implemented before was
incorrect, resulting in getTypeLowering being called on a lowered type without a
proper generic signature being pushed on the type lowering stack. This commit
fixes that issue locally.
The real fix is in a PR that Slava is preparing that provides a getTypeLowering
that takes a SILType and a GenericSignature so that the user does not need to
perform a push/pop.
rdar://29791263
This is dead code and can be re-added if it is needed. Right now though there
really isnt a ValueOwnershipKind that corresponds to deallocating and I do not
want to add a new ValueOwnershipKind for dead code.
This commit includes the dataflow verifier and plugs in the use checker into the
dataflow verifier.
Some specific checks in the use checker need revision, but I for today
this is good enough. As I go through SILGen I am going to fix them.
rdar://29671437
This is the first verifier for SemanticSIL. The verifier is very simple and
verifies that given a SILValue V, V->getOwnershipKind() returns an ownership
kind compatible with all of V's user instructions.
This is implemented by adding a new method to SILInstruction:
SILInstruction::verifyOperandOwnership()
This method creates an instance of the visitor OwnershipCompatibilityUseChecker
and then has the instance visit this.
The OwnershipCompatibilityUseChecker is a SILInstructionVisitor that for a given
instruction verifies that the given SILInstruction's operand SILValue's produce
ValueOwnershipKind that are compatible with the SILInstruction. The reason why
it is implemented as a visitor is to ensure that a warning is produced if a new
instruction is added and a method on the OwnershipCompatibleUseChecker isn't
added.
Keep in mind that this is just the first verifier and the full verifier (that
also verifies dataflow) is built on top of it. The reason why this separate API
to the use verifier is exposed is that exposing the checker enables us to place
an assert in SILBuilder to diagnose any places where SIL ownership is violated
immediately when the violation occurs allowing for an easy debugging experience
for compiler writers. This assert is a key tool that I am going to be using to
make SILGen conform to the SIL Ownership Model.
Again, this will be behind the -enable-semantic-sil flag, so normal development
will be unaffected by this change.
rdar://29671437
