jhuber6 marked an inline comment as done.
jhuber6 added inline comments.
================
Comment at: openmp/runtime/test/tasking/kmp_taskloop.c:100
th_counter[i] = 0;
- #pragma omp parallel num_threads(N)
+ #pragma omp parallel // num_threads(N)
{
----------------
jdoerfert wrote:
> jhuber6 wrote:
> > jdoerfert wrote:
> > > jhuber6 wrote:
> > > > jdoerfert wrote:
> > > > > jhuber6 wrote:
> > > > > > AndreyChurbanov wrote:
> > > > > > > jhuber6 wrote:
> > > > > > > > jhuber6 wrote:
> > > > > > > > > jdoerfert wrote:
> > > > > > > > > > jhuber6 wrote:
> > > > > > > > > > > I am not entirely sure why, but commenting this out
> > > > > > > > > > > causes the problem to go away. I tried adding proper
> > > > > > > > > > > names to the forward-declared functions but since clang
> > > > > > > > > > > already knew I had something called ident_t, I couldn't
> > > > > > > > > > > declare a new struct with the same name.
> > > > > > > > > > This is not good. The difference should only be that the
> > > > > > > > > > `kmpc_fork_call` has a different argument, right? Does the
> > > > > > > > > > segfault happen at compile or runtime?
> > > > > > > > > >
> > > > > > > > > > You can just use the ident_t clang created, right? Did you
> > > > > > > > > > print the function names requested by clang as we discussed?
> > > > > > > > > I added an assertion and debug statements. If I try to
> > > > > > > > > declare a struct named "Ident_t" I get the following error
> > > > > > > > > message in the seg-fault. I think the seg-fault is
> > > > > > > > > compile-time.
> > > > > > > > >
> > > > > > > > > Found OpenMP runtime function __kmpc_global_thread_num with
> > > > > > > > > type i32 (%struct.ident_t.0*). Expected type is i32
> > > > > > > > > (%struct.ident_t*)
> > > > > > > > > clang:
> > > > > > > > > /home/jhuber/Documents/llvm-project/llvm/lib/Frontend/OpenMP/OMPIRBuilder.cpp:124:
> > > > > > > > > static llvm::Function*
> > > > > > > > > llvm::OpenMPIRBuilder::getOrCreateRuntimeFunction(llvm::Module&,
> > > > > > > > > llvm::omp::RuntimeFunction): Assertion `FnTy ==
> > > > > > > > > Fn->getFunctionType() && "Found OpenMP runtime function has
> > > > > > > > > mismatched types"' failed.
> > > > > > > > I'm not sure if there's a way around this without changing the
> > > > > > > > getOrCreateRuntimeFunction method to return a FunctionCallee
> > > > > > > > and removing the assertion. Clang doesn't know about the
> > > > > > > > ident_t struct when it's compiling the file, but when its doing
> > > > > > > > the codegen it sees two structs with the same name and creates
> > > > > > > > a new name. So when it gets the types it says that ident_t and
> > > > > > > > ident_t.0 don't match. As you said the old version got around
> > > > > > > > this by adding a bitcasting instruction so it knew how to turn
> > > > > > > > it into an ident_t pointer.
> > > > > > > Note that this change breaks the test on any system with more
> > > > > > > that 4 procs. Because array th_counter[4] is indexed by thread
> > > > > > > number which can easily be greater than 3 if number of threads is
> > > > > > > not limited.
> > > > > > The problem was that the num_threads clause required an implicit
> > > > > > call to kmpc_global_thread_num so it could be passed to
> > > > > > kmpc_push_num_threads. The types of the implicit function and the
> > > > > > forward declaration then wouldn't match up. I added another forward
> > > > > > declaration to explicitly call kmpc_push_num_threads. Is this a
> > > > > > sufficient solution?
> > > > > We need this to work with num_threads(8).
> > > > >
> > > > > > Clang doesn't know about the ident_t struct when it's compiling the
> > > > > > file, but when its doing the codegen it sees two structs with the
> > > > > > same name and creates a new name.
> > > > >
> > > > > Where are the two structs coming from? We should have one. If clang
> > > > > introduces one it needs to use the one from OMPKindes.def instead. Is
> > > > > that a fix?
> > > > The first struct is the one that I'm assuming comes from the OpenMP
> > > > CodeGen that places the Ident_t struct in the IR file. if I declare a
> > > > struct also named ident_t in the C source file it most likely will see
> > > > that there's two structs with the same name and call the second one
> > > > "ident_t.0" internally. The other ident_t struct is only known once
> > > > clang generates the LLVM IR so I can't just use "ident_t" nor can I
> > > > declare a struct with the same name.
> > > 1) Either Clang needs to use the `llvm::omp::types::Ident` *or* Clang
> > > needs to define `llvm::omp::types::Ident` and we do not do it via
> > > `__OMP_STRUCT_TYPE(Ident, ident_t, Int32, Int32, Int32, Int32, Int8Ptr)`.
> > > I would prefer the first solution.
> > >
> > > 2) `OMPConstants.cpp` does pick up an existing struct type with the same
> > > name if present. That is, probably not what we want because it clashes
> > > with user types.
> > >
> > > 3) We can still return a `FunctionCallee` with the Function* and the
> > > expected type (as defined by OMPKinds.def) to mimic the old behavior for
> > > now.
> > > Either Clang needs to use the `llvm::omp::types::Ident` *or* Clang needs
> > > to define `llvm::omp::types::Ident` and we do not do it via
> > > `__OMP_STRUCT_TYPE(Ident, ident_t, Int32, Int32, Int32, Int32, Int8Ptr)`.
> > > I would prefer the first solution.
> > I'm probably not understanding something correctly here. There's already an
> > ident_t type declared in `CGOpenMPRuntime:1065` which it uses for
> > generating the types for the runtime functions, but this isn't used until
> > code generation so it can't be used while compiling the file. If we declare
> > it up front then wouldn't that make ident_t a reserved keyword?
> >
> > > We can still return a `FunctionCallee` with the `Function*` and the
> > > expected type (as defined by OMPKinds.def) to mimic the old behavior for
> > > now.
> > A FunctionCallee can be generated from a Function * but not vice-versa,
> > right? This would require changing the code in OpenMPIRBuilder.
> In CGOpenMPRuntime.cpp there is:
> `IdentTy = CGM.getTypes().ConvertRecordDeclType(RD);`
> what happens if you replace that with:
> `IdentTy = llvm::omp::types::Ident;`
> ?
>
> ---
>
> FunctionCallee is just a Function* and the "expected type". You can go from
> FunctionCallee to Function by just picking the proper member. You'd need to
> change the Builder in two ways: 1) return FunctionCallee(Fn, ExpectedType);
> 2) where it is used extract the Function * from the FunctionCallee. You might
> want to use a helper if you go this route.
It causes all the OpenMP tests to fail, not sure why exactly. I'll look into it
more tomorrow.
Repository:
rG LLVM Github Monorepo
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https://reviews.llvm.org/D80222/new/
https://reviews.llvm.org/D80222
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