Rewrite ForEachStmt SILGen to use the Optional intrinsics with the Generator.next method to iterate through sequences, and kill off the Enumerator path in Sema. Cut over 'EnumeratorType.Element' requirements to instead require 'GeneratorType.Element' in the stdlib.
There are a couple of bugs remaining that need follow-up work. There appears to be a bug in nested enum layout (e.g. T??) that's causing test/Interpreter/enum to break; I'll investigate and fix. There's also a lingering type-checker bug with inferred associated types that causes them to fail requirement checks <rdar://problem/15172101>, which I think Doug needs to look into.
Swift SVN r9017
Also, change the location of "looping back to head" branch to point to the closing brace of the body, which is a more natural source location than the beginning of the enclosing loop statement.
Swift SVN r7989
Tuple exploding happens during RValue construction, so changed the constructor and addElement() method to take the location parameter. The imploding happens on RValue::forwardAsSingleValue and RValue::getAsSingleValue(). Make sure the right SIL locations are passed to all of these
Also, added some missing locations in pattern matching code.
Swift SVN r7916
I've decided to keep only the location of the scope AST node that corresponds to the cleanup. (Currently, there is no user that needs the originator expression, which caused the cleanup. So keeping things simple.)
Added the cleanup location to the Scope and JumpDest classes, which gets assigned on construction of those. The Scope's and JumpDest locations are used when we emit the cleanup instructions.
We now give better location info for 2 existing tests for definitive initialization.
(+ Rather sparse testing of all this.)
Swift SVN r7764
We mark the branch instructions leading into single epilog code with ReturnLocation/ImplicitReturnLocation. If SIL Gen simplifies the code and merges the code representing the return into the epilog block, the terminator of the epilog block (the ReturnInst) will have the return location info on it. Otherwise, the ReturnInst has the RegularLocation, which represents the enclosing FunctionExpr or Constructor/Destructor Decls.
(I've discussed dropping the optimization from SILGen, and keeping the epilog code canonical, with Adrian; but he said that there might not be any wins in doing so, so keeping it for now.)
Added AutoGeneratedLocation to represent segments of code generated by SILGen. This will be used for thunks and other auto-generated segments.
Swift SVN r7634
ForStmt::Cond is already a NullablePtr<>. This patch changes
ForStmt::Initializer and ForStmt::Increment to be NullablePtr. Otherwise it
looks like Cond can be null, while Initializer and Increment can not.
Swift SVN r7265
