similar to: Notes from dbg.value coffee chat

On Fri, Oct 9, 2020 at 9:38 AM Cazalet-Hyams, Orlando < orlando.hyams at sony.com> wrote: > Hi Reid, > > > > Thanks for sharing this. I plan to work on improving debug-info for > variables > > living in memory as my next "project" so I am very interested to hear with > what > > others have to say about "Idea 1". > > > > There

Debug info today handles two cases reasonably well: 1. At -O0, dbg.declare does a good job describing variables that live at some known stack offset 2. With optimizations, variables promoted to SSA can be described with dbg.value This leaves behind a large hole in our optimized debug info: variables that cannot be promoted, typically because they are address-taken. This is

It's worth remembering that there are two syntactically similar but semantically different kinds of "expression" in DWARF. A DWARF expression computes a value; if the available value is a pointer, you add DW_OP_deref to express the pointed-to value. A DWARF location expression computes a location, and adds various operators to express locations that a (value) expression cannot, such

Hi! I have a small issue with the JumpThreading pass (in opt). As described in the code (JumpThreading.cpp), the pass may if certain criteria are fulfilled duplicate the content of a block. If the duplicated block contain a call to @llvm.dbg.declare() you will end up with invalid code as the intrinsic @llvm.dbg.declare() only should occur once for each variable. I think the JumpThreading

Hi Reid, Thanks for taking this on, I'm very pleased to see improvements related to debug info for optimized code. (You can cc me on code reviews, although I'm sure a lot of the patches will be in areas I am not very familiar with.) While I have a really good handle on the DWARF standard, and have done a bunch of work with the type stuff, my understanding of IR mechanics is pretty naïve,

> On Apr 1, 2020, at 2:56 AM, Sourabh Singh Tomar <sourav0311 at gmail.com> wrote: > > > Do you mean documenting the desired frontend behavior, or adding some verifier in > LLVM? A warning for the latter is that SROA may currently emit IR that contains a > mix of declares and values for different fragments of an aggregate variable, so I > assume that is something that

Hi Xiang, On Wed, Nov 11, 2020 at 1:59 AM Zhang, Xiang1 <xiang1.zhang at intel.com> wrote: > Jeremy wrote: > > ... The value %0 is live up to and including the ADD64ri but not past it, meaning LLVM today will drop the DBG_VALUE ... > > Just a little puzzle about the " drop the DBG_VALUE ", maybe I didn't get your key point, >

> On Mar 30, 2020, at 11:57 PM, Sourabh Singh Tomar <sourav0311 at gmail.com> wrote: > >> > My understanding is that this isn't correct: dbg.declare specifies the >> memory address of a variable for the whole lifetime of the function, >> whereas dbg.value (and dbg.addr) specify the value/address until the >> next debug intrinsic. Mixing these two kinds

> > On Mar 27, 2018, at 7:41 PM, Hsiangkai Wang via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hello all, > > I would like to enhance LLVM debug info that supports setting > breakpoint on labels in function. > > Generally, if users use GDB as their debugger, they could set > breakpoints on labels in function. Following is an example. > > // C

>> There are a couple of references made to %llvm.dbg.variable, which >> isn't defined anywhere. It it an intrinsic? A global? Could it be a >> relic from the old debug info docs (where it *is* defined?). The same >> goes for llvm.dbg.derivedtype and llvm.dbg.subrange which are also >> referenced but not defined. > > It was a stale reference. I fixed the

On Feb 1, 2011, at 3:58 AM, Eli Bendersky wrote: > Hello > I'm reading http://llvm.org/docs/SourceLevelDebugging.html and some > things aren't clear. > > There are a couple of references made to %llvm.dbg.variable, which > isn't defined anywhere. It it an intrinsic? A global? Could it be a > relic from the old debug info docs (where it *is* defined?). The same

Hello I'm reading http://llvm.org/docs/SourceLevelDebugging.html and some things aren't clear. There are a couple of references made to %llvm.dbg.variable, which isn't defined anywhere. It it an intrinsic? A global? Could it be a relic from the old debug info docs (where it *is* defined?). The same goes for llvm.dbg.derivedtype and llvm.dbg.subrange which are also referenced but not

Hi, I had a problem with LLVM not emitting local variable info, even though I had calls to llvm.dbg.define. After some tracking I found that the llvm.dbg.declare (and probably value too) have to have a !dbg !nr after them to get emitted at all. maybe someone can adjust http://llvm.org/docs/SourceLevelDebugging.html#format_common_declare that the two llvm.dbg. functions need a !dbg line info

Hi all, Thanks for the answers! I feel like I've hijacked your thread now though Björn, sorry for that. But from the answers it sounds like there is agreement that it's reasonable to remove the duplicates as done in Björn's patch? --- A couple of more things around the problem I saw. On 09/19/2017 05:40 PM, Adrian Prantl wrote: > A dbg.declare describes a stack-allocated

> On Mar 30, 2020, at 4:13 AM, Jeremy Morse via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi Sourabh, > > On Mon, Mar 30, 2020 at 8:09 AM Sourabh Singh Tomar via llvm-dev > <llvm-dev at lists.llvm.org> wrote: >> Under what circumstances should a frontend choose to emit(at -O0(No optimization)) llvm.dbg.value for a local variable. >> >> I

> On Sep 19, 2017, at 6:33 AM, Mikael Holmén via llvm-dev <llvm-dev at lists.llvm.org> wrote: > > Hi Björn, > > I don't have any answers, just more confusion. Hopefully someone else can bring some light to this. > > I'm also interested in dbg.declares and what the rules are regarding them since it's not very clear to me at the moment. A dbg.declare

Hello Everyone, I have general question WRT llvm.dbg.value intrinsic function semantics. Under what circumstances should a frontend choose to emit(at -O0(No optimization)) llvm.dbg.value for a local variable. I saw some debuginfo code in flang(older one), sort of it choose to emit *llvm.dbg.value* for *every load operation* happening on a *local variable*. And as noted below in IR snippet it

Hi Devang, >> I use llvm and llvm-gcc as a C-to-C transformation tool using a >> modified version of the c backend, and rely on llvm debug instructions >> to link back to the original source code. >> >> Does anyone know how to get detailed line number and variable debug >> information at optimization levels beyond O0? >> >> Currently, I extract this

> I don't see how this is a meaningful distinction in LLVM IR. In LLVM IR we only have SSA values. An SSA value could be an alloca, or a gep into an alloca, or spilled onto the stack at the MIR level, in which case the dbg.value should get lowered into a memory location (if it isn't explicitly a DW_OP_stack_value). I think the distinction is still important; even at the IR level, if we

Hi Martijn On Fri, Nov 13, 2009 at 4:52 AM, Martijn <martijn at martijnrutten.com> wrote: > Hello, > > I use llvm and llvm-gcc as a C-to-C transformation tool using a > modified version of the c backend, and rely on llvm debug instructions > to link back to the original source code. > > Does anyone know how to get detailed line number and variable debug > information