llc debug info

I can generate debug info using opt like this:
opt < a.bc > /dev/null -mypass -debug

But I don’t know how to do it using llc.
I check http://llvm.org/docs/CommandGuide/llc.html
there are not any information about debug flags.

Purpose
EX:
I want to print all the DEBUG(dbgs()…) in llvm/lib/CodeGen/RegAllocGreedy.cpp .
What should I do?

Have you tried passing -debug?

Because llvm/lib/CodeGen/RegAllocGreedy.cpp has this line:

    #define DEBUG_TYPE "regalloc"

You can also pass -debug-only=regalloc to only evaluate the DEBUG()
statements in that file. So you may want to similarly define:

    #define DEBUG_TYPE “mypass"

If your pass is called -mypass.

Then I suspect that code isn¡¦t being executed. Try running through
a debugger (like lldb or gdb), and step through the statements.