Type annotations for instruction operands are omitted, e.g.
```
%3 = struct $S(%1, %2)
```
Operand types are redundant anyway and were only used for sanity checking in the SIL parser.
But: operand types _are_ printed if the definition of the operand value was not printed yet.
This happens:
* if the block with the definition appears after the block where the operand's instruction is located
* if a block or instruction is printed in isolation, e.g. in a debugger
The old behavior can be restored with `-Xllvm -sil-print-types`.
This option is added to many existing test files which check for operand types in their check-lines.
The initial version of the debugger testing transform instruments
assignments in a way that allows the debugger to sanity-check its
expression evaluator.
Given an assignment expression of the form:
```
a = b
```
The transform rewrites the relevant bits of the AST to look like this:
```
{ () -> () in
a = b
checkExpect("a", stringForPrintObject(a))
}()
```
The purpose of the rewrite is to make it easier to exercise the
debugger's expression evaluator in new contexts. This can be automated
by having the debugger set a breakpoint on checkExpect, running `expr
$Varname`, and comparing the result to the expected value generated by
the runtime.
While the initial version of this testing transform only supports
instrumenting assignments, it should be simple to teach it to do more
interesting rewrites.
There's a driver script available in SWIFT_BIN_DIR/lldb-check-expect to
simplfiy the process of launching and testing instrumented programs.
rdar://36032055
