--trace_channels should delineate channel instantiations across multiply-instantiated procs

What's hard to do? (limit 100 words)

When using interpreter_main with the flag --trace_channels, the info message reports sends and receives with the proc identifier + channel name, e.g. for sends at

xls/xls/dslx/bytecode/bytecode_interpreter.cc

Line 1145 in 6e48d19

channel_data->channel_name(), formatted_data));

which is populated from

xls/xls/dslx/bytecode/bytecode_emitter.cc

Line 109 in 6e48d19

absl::StrFormat("%s::%s", proc_name, channel->ToString()),

).

For example:

I0819 13:13:57.195329  141589 foo.x:42]] Sent data on channel `Foo::x_in`:

The problem is, when we spawn the same proc multiple times, it still reports the same thing, so we can't tell which sub-proc the message is logged against.

Current best alternative workaround (limit 100 words)

I'm not aware of a workaround.

Your view of the "best case XLS enhancement" (limit 100 words)

The logged info should show something like:

I0819 13:13:57.195329  141589 foo.x:42]] Sent data on channel `Foo::x_in(foo_0_x_in)`:
I0819 13:13:57.195329  141589 foo.x:42]] Sent data on channel `Foo(foo_0)::x_in`:

If spawned procs were named, it could be used to differentiate the channels, since channel members within a proc are unique by construction.

Alternatively, channel declarations are named, so retaining this metadata when one end is passed into a spawned proc could perhaps be used to disambiguate multiply-instantiated channels as well.

somewhat related: #1438