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 >> need >> to custom handle the STOPPOINT nodes. Without -fast option the >> STOPPOINT >> nodes are not created in dag because of the below check in >> SelectionDAGBuild.cpp >> if (Fast) >> DAG.setRoot(DAG.getDbgStopPoint(getRoot(), >> 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 > problematic.) > > >> If I have simple loads and stores in source >> code, the dag doesn't contain them too. Why are these nodes not being >> created? >> > > > I don't know. Something to do with your target, they appear for me. > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
On Apr 7, 2009, at 9:52 PMPDT, vasudev wrote:> 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?Not yet. The Declare nodes interfere with optimizations, as do the Stoppoint nodes: they count as an extra Use, which affects many optimizations that are looking for a single Use (of the alloca node, or whatever). Rather than try to hunt these all down, the plan is to reimplement declarations in a way that isn't represented as a Use. This is in the early stages yet and I can't give you a date when it will work, sorry.> 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 >>> need >>> to custom handle the STOPPOINT nodes. Without -fast option the >>> STOPPOINT >>> nodes are not created in dag because of the below check in >>> SelectionDAGBuild.cpp >>> if (Fast) >>> DAG.setRoot(DAG.getDbgStopPoint(getRoot(), >>> 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 >> problematic.) >> >> >>> If I have simple loads and stores in source >>> code, the dag doesn't contain them too. Why are these nodes not >>> being >>> created? >>> >> >> >> I don't know. Something to do with your target, they appear for me. >> >> _______________________________________________ >> LLVM Developers mailing list >> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >> > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
Can we help in local variable debug info work. Dale Johannesen wrote:> On Apr 7, 2009, at 9:52 PMPDT, vasudev wrote: > > >> 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? >> > > Not yet. The Declare nodes interfere with optimizations, as do the > Stoppoint nodes: they count as an extra Use, which affects many > optimizations that are looking for a single Use (of the alloca node, > or whatever). Rather than try to hunt these all down, the plan is to > reimplement declarations in a way that isn't represented as a Use. > This is in the early stages yet and I can't give you a date when it > will work, sorry. > > >> 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 >>>> need >>>> to custom handle the STOPPOINT nodes. Without -fast option the >>>> STOPPOINT >>>> nodes are not created in dag because of the below check in >>>> SelectionDAGBuild.cpp >>>> if (Fast) >>>> DAG.setRoot(DAG.getDbgStopPoint(getRoot(), >>>> 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 >>> problematic.) >>> >>> >>> >>>> If I have simple loads and stores in source >>>> code, the dag doesn't contain them too. Why are these nodes not >>>> being >>>> created? >>>> >>>> >>> I don't know. Something to do with your target, they appear for me. >>> >>> _______________________________________________ >>> LLVM Developers mailing list >>> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >>> >>> >> _______________________________________________ >> LLVM Developers mailing list >> LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu >> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >> > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >
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