evaluator to precisely evaluate Builtin.assert_configuration.
Unify UnknownReason::Trap and UnknownReason::AssertionFailure error
values in the constant evaluator, now that we have 'condfail_message'
SIL instruction, which provides an error message for the traps.
With the advent of dynamic_function_ref the actual callee of such a ref
my vary. Optimizations should not assume to know the content of a
function referenced by dynamic_function_ref. Introduce
getReferencedFunctionOrNull which will return null for such function
refs. And getInitialReferencedFunction to return the referenced
function.
Use as appropriate.
rdar://50959798
(also referred to as flow-sensitive mode) so that the evaluator
can be used by clients to constant evaluate instructions in a
SILFunction body one by one following the flow of control.
