dtrace(1): add -d flag to dump D script post-dt_sugar

[christos]

Summary

By specifying the -d flag, libdtrace will dump the D script after it has applied
syntactical sugar transformations (e.g if/else). This is useful for both understanding
what dt_sugar does, as well as debugging it.

[markj]

cddl/contrib/opensolaris/cmd/dtrace/dtrace.1

199

Probably clarify that it dumps to stdout.

cddl/contrib/opensolaris/lib/libdtrace/common/dt_sugar.c

521 ↗

(On Diff #117771)

Do we actually need to do this here? Why not have the compiler dump the output script after calling dt_compile_sugar()? That seems somewhat simpler.

[christos]

Move dump code to dt_cc.c.

[0mp]

Would it be wiser to implement this as an extension to the -x flag?

[markj]

cddl/contrib/opensolaris/cmd/dtrace/dtrace.1

199

cddl/contrib/opensolaris/cmd/dtrace/dtrace.c

155

[markj]

In D38732#881808, @0mp wrote:

Would it be wiser to implement this as an extension to the -x flag?

This option is in the same vein as -S, whereas -x is used to set runtime parameters for the dtrace script. So, -x feels like the wrong place to me, but maybe I'm missing something?

[0mp]

In D38732#881813, @markj wrote:

In D38732#881808, @0mp wrote:

Would it be wiser to implement this as an extension to the -x flag?

This option is in the same vein as -S, whereas -x is used to set runtime parameters for the dtrace script. So, -x feels like the wrong place to me, but maybe I'm missing something?

I don't think you are missing anything :) I just wonder if there is a way to avoid taking up a whole flag for a debug feature.

OTOH, I checked macOS DTrace implementation and they are not using -d for anything, so it seems it is fine if we dedicate -d to dumping D scripts post dt_sugar.

[christos]

s/stdout/standard output/

[christos]

Print dnp as well.

[christos]

Typo fixes.

[christos]

remove if/else comment in dt_cc as dt_sugar now also performs transformations
on kinst probes.

[christos]

I don't think there are any pending changes for this PR, it can get through.