[LLVMdev] Trying to use patchpoint in MCJIT

[Gaël Thomas]

Ok I see. Of course, at runtime, it's enough for dynamic linking or for
deoptimization. However, wmkit acts both as a jit and as an aot. For the
aot, it means that I can not use patchpoint and that I should have two
different compilation strategy. It's not so difficult, but in this case, I
can not use patchpoints to generate gc's stackmap for the aot (basically, I
think that I could use a patchpoint to generate a safepoint where I know
the locations of my roots by ysing them as arguments of the patchpoint?)?

Do you think that using a symbol for my targets is easy to implement? Or
maybe that there is a conceptual problem for symbols in this case?

By the way, were can I find the metadata at the end of the compilation?
They are generated in a special symbol/section?

Anyway, thank you for your answer,
Gaël
Le 18 déc. 2013 02:17, "Filip Pizlo" <fpizlo at apple.com> a écrit :

> patchpoint is intended to be used in VMs that do their own linking, and so
> you wouldn't expect the function parameter to be resolved by LLVM.
>
> Presumably, in VMKit, you could just plant a pointer constant to the
> function you wish to call initially?
>
> -Filip
>
>
> On Dec 17, 2013, at 2:42 PM, Gaël Thomas <gael.thomas00 at gmail.com> wrote:
>
> Hi all,
>
> I'm trying to play with patchoint (with MCJIT and VMKit) and I don't
> understand something. I generate this call for my first patch point.
> Basically, I want to call f(0).
>
> %5 = call i64 (i64, i32, i8*, i32, ...)* @llvm.experimental.patchpoint.i64(
>  i64 42, ;; patch point id is 42
>  i32 0,   ;; 0 bytes for the padding
>  i8* bitcast (i32 (i32)* @f to i8*), ;; my function f
>  i32 1,   ;; 1 argument
>  i32 0)   ;; the argument
>
> I think that the types are correct (at least, the compiler seems happy
> with that:)). But when I'm trying to compile the code (that I generate
> from C++, it's not a bitcode file), I have this message:
>
> Assertion failed: (isa<X>(Val) && "cast<Ty>() argument of incompatible
> type!"), function cast, file
> /Users/gthomas/research/vmkit4/llvm-src/include/llvm/Support/Casting.h,
> line 232.
>
> With this stack (I only give the relevant part):
>
>    frame #5: 0x000000010092ed44
> libjvm.dylib`llvm::SelectionDAGBuilder::visitPatchpoint() + 3780 at
> SelectionDAGNodes.h:610
>    frame #6: 0x000000010091f511
>
> libjvm.dylib`llvm::SelectionDAGBuilder::visitIntrinsicCall(this=0x0000000106ff4d20,
> I=0x0000000106fea460) + 10961 at SelectionDAGBuilder.cpp:5349
>    frame #7: 0x0000000100904c4a
> libjvm.dylib`llvm::SelectionDAGBuilder::visitCall(this=0x0000000106ff4d20,
> I=0x0000000106fea460) + 234 at SelectionDAGBuilder.cpp:5870
>    frame #8: 0x00000001008fc9ea
> libjvm.dylib`llvm::SelectionDAGBuilder::visit(this=0x0000000106ff4d20,
> I=0x0000000106fea460) + 74 at SelectionDAGBuilder.cpp:971
>    frame #9: 0x0000000100947e98
>
> libjvm.dylib`llvm::SelectionDAGISel::SelectBasicBlock(this=0x0000000106ff40d0,
> HadTailCall=0x00007fff5fbfe31e) + 40 at SelectionDAGISel.cpp:579
>    frame #10: 0x0000000100947aee
>
> libjvm.dylib`llvm::SelectionDAGISel::SelectAllBasicBlocks(this=0x0000000106ff40d0,
> Fn=0x0000000106fe7020) + 8174 at SelectionDAGISel.cpp:1192
>    frame #11: 0x0000000100944b94
>
> libjvm.dylib`llvm::SelectionDAGISel::runOnMachineFunction(this=0x0000000106ff40d0)
> + 1588 at SelectionDAGISel.cpp:434
>    frame #12: 0x0000000100afefc0
> libjvm.dylib`llvm::MachineFunctionPass::runOnFunction() + 128 at
> MachineFunctionPass.cpp:33
>    frame #13: 0x00000001010837fb
> libjvm.dylib`llvm::FPPassManager::runOnFunction(this=0x0000000106fedf20,
> F=0x0000000106fe7020) + 331 at LegacyPassManager.cpp:1538
>    frame #14: 0x0000000101083abb
> libjvm.dylib`llvm::FPPassManager::runOnModule(this=0x0000000106fedf20)
> + 59 at LegacyPassManager.cpp:1558
>    frame #15: 0x000000010108402d
> libjvm.dylib`llvm::legacy::PassManagerImpl::run(llvm::Module&)
> [inlined] llvm::legacy::PassManagerImpl::getContainedManager(N=0,
> this=0x0000000106feb9f0) + 429 at LegacyPassManager.cpp:1616
>    frame #16: 0x0000000101083e80
> libjvm.dylib`llvm::legacy::PassManagerImpl::run(this=0x0000000106feb9f0,
> M=0x0000000106fe6f30) + 544 at LegacyPassManager.cpp:1711
>    frame #17: 0x000000010108466d
> libjvm.dylib`llvm::legacy::PassManager::run() + 13 at
> LegacyPassManager.cpp:1746
>    frame #18: 0x0000000100eeaf8c
> libjvm.dylib`llvm::MCJIT::emitObject(this=0x0000000106fa69a0,
> M=0x0000000106fe6f30) + 236 at MCJIT.cpp:131
>    frame #19: 0x0000000100eeb2d3
> libjvm.dylib`llvm::MCJIT::generateCodeForModule(this=0x0000000106fa69a0,
> M=0x0000000106fe6f30) + 323 at MCJIT.cpp:169
>    frame #20: 0x0000000100eec022
> libjvm.dylib`llvm::MCJIT::getFunctionAddress(std::string const&)
> [inlined] llvm::MCJIT::getSymbolAddress(this=0x0000000106fa69a0,
> CheckFunctionsOnly=true) + 58 at MCJIT.cpp:279
>    frame #21: 0x0000000100eebfe8
> libjvm.dylib`llvm::MCJIT::getFunctionAddress(this=0x0000000106fa69a0,
> Name=0x00007fff5fbfe7b0) + 40 at MCJIT.cpp:295
> ...
>
> So, I don't understand where could be my mistake?
>
> Thank you in advance,
> Gaël
>
>
>
> --
> -------------------------------------------------------------------
> Gaël Thomas, Associate Professor, UPMC
> http://pagesperso-systeme.lip6.fr/Gael.Thomas/
> -------------------------------------------------------------------
>
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