[LLVMdev] debug stoppoint nodes with -fast option
vasudev.negi at microchip.com
Tue Apr 7 21:52:38 PDT 2009
Thanks for the info regarding DebugLoc field. Another related question
that I have is regarding debug info for local variables. With -fast
option, ISD::DECLARE nodes are created in DAG for debug info of local
variables. I am planning to custom handle these nodes, get the required
info from llvm.dbg.variable global address and emit it in ISel. But
without -fast option ISD::DECLARE nodes are not created. How can i
access the debug info for local variables in that case? Is it available
directly somewhere in AsmPrinter like the debug info for global variables?
Dale Johannesen wrote:
> On Apr 5, 2009, at 11:54 PMPDT, vasudev wrote:
>> I need to generate line number debug information for PIC16 target.
>> PIC16 does not support dwarf format. It supports coff format. So I
>> to custom handle the STOPPOINT nodes. Without -fast option the
>> nodes are not created in dag because of the below check in
>> if (Fast)
>> If I give -fast option then the Fast flag is true, but the dag doesn't
>> contain STOPPOINT nodes.
> Right. Currently, the way we tell whether optimization was requested
> at the command line level is to look at -fast; -O0 == -fast.
> The stoppoint nodes enforce an ordering of loads and stores
> corresponding to the original source, which means that putting them in
> without -fast would lead to codegen (scheduling) differences between -
> O and -O -g. We don't want that.
> Instead, the debug info is transferred at this point from stoppoint
> nodes to the DebugLoc field in each MachineInstr node. You should
> probably use that.
> (The current state of debug info with -O is that we think -g never
> affects codegen; violations of that should be reported as bugs. The
> quality of the debug info has not been worked on much and is
>> If I have simple loads and stores in source
>> code, the dag doesn't contain them too. Why are these nodes not being
> I don't know. Something to do with your target, they appear for me.
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