Hi,
Currently debugging Cmm is a bit painful because we don't have enough debug
information to map assembly to Cmm lines, so I have do the mapping manually.
However I realized that when building .cmm files we actually generates some
debug information, in form of "ticks":
//tick src<rts/Apply.cmm:631:9-37>
_c2e::I64 = I64[R1 + 32];
Here the tick says that this assignment is for this Cmm line in Apply.cmm:
Words = StgAP_STACK_size(ap);
I was wondering what needs to be done to generate DWARF information from those
so that gdb can show Cmm line we're executing, and gdb commands like `next`,
`break` etc. work.
I also realize that we don't consistently generate these ticks for all Cmm
lines, for example, in the same Cmm dump there isn't a tick before this line:
(_c2j::I64) = call MO_Cmpxchg W64(R1, stg_AP_STACK_info,
stg_WHITEHOLE_info);
It's actually for Apply.cmm:646.
So there are two problems:
- Generate ticks for _all_ Cmm lines
- Generate DWARF information from those so that gdb can show current Cmm line,
and commands like `next` and `break` work.
Anyone know how hard would this be to implement? I'm wondering if we could turn
this into a SoC project. It's a very well defined task, and given that we have
some DWARF support already, perhaps it's not too hard for a SoC.
Ömer
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