[llvm-dev] LLVMGetBitcodeModuleInContext2 problem

[Friedman, Eli via llvm-dev]

You're going to have to read the C++ headers for a lot of things to make 
sense; the C headers don't really have much documentation.

In this case:

   /// getFunctionAddress - Return the address of the specified function.
   /// This may involve code generation.
   virtual uint64_t getFunctionAddress(const std::string &Name) {
     // Default implementation for the interpreter.  MCJIT will override 
this.
     // Interpreter clients should use getPointerToFunction instead.
     return 0;
   }

I would suggest using MCJIT (LLVMCreateMCJITCompilerForModule).

-Eli

On 3/8/2017 5:25 PM, Toshiyasu Morita wrote:
> Oops, missed initializing some stuff. Added:
>
>         LLVMLinkInMCJIT();
>         LLVMInitializeNativeTarget();
>         LLVMInitializeNativeAsmPrinter();
>         LLVMInitializeNativeAsmParser();
>
> Now it crashes in LLVMGetFunctionAddress().
>
> Hmm.
>
>
> On Wed, Mar 8, 2017 at 5:14 PM, Toshiyasu Morita <toshi at tensyr.com 
> <mailto:toshi at tensyr.com>> wrote:
>
>     Made it a bit further. Here's the current code:
>
>     void llvm_load_IR_library(char *path)
>     {
>             char *error;
>             LLVMExecutionEngineRef engine;
>             object0_t* (*func)(void), *output;
>             LLVMContextRef global_context;
>             LLVMMemoryBufferRef module;
>             LLVMModuleRef ir_lib_module;
>             bool flag;
>
>             printf("loading IR library from path: %s\n", path);
>
>             LLVMCreateMemoryBufferWithContentsOfFile(path, &module,
>     &error);
>
>             global_context = LLVMGetGlobalContext();
>
>             flag = LLVMGetBitcodeModuleInContext2(global_context,
>     module, &ir_lib_module);
>
>             printf("LLVMGetBitcodeModuleInContext2() returned %d\n",
>     flag);
>
>             LLVMVerifyModule(ir_lib_module, LLVMAbortProcessAction,
>     &error);
>             LLVMDumpModule(ir_lib_module);
>
>             if (LLVMCreateExecutionEngineForModule(&engine,
>     ir_lib_module, &error) != 0) {
>                     fprintf(stderr, "failed to create execution
>     engine\n");
>                     abort();
>             }
>
>             // Call the function
>             func = (object0_t *
>     (*)(void))LLVMGetFunctionAddress(engine, "test");
>             output = (*func)();
>     }
>
>     when this code is executed, i see:
>
>     ...
>     LLVMGetBitcodeModuleInContext2() returned 0
>     ; ModuleID = '/home/toshi/tensyr/debug_build/test.bc'
>     source_filename = "test.c"
>     target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
>     target triple = "x86_64-unknown-linux-gnu"
>
>     @str = private unnamed_addr constant [16 x i8] c"test successful\00"
>
>     ; Materializable
>     ; Function Attrs: nounwind uwtable
>     define void @test() local_unnamed_addr #0 {}
>
>     ; Function Attrs: nounwind
>     declare i32 @puts(i8* nocapture readonly) #1
>
>     attributes #0 = { nounwind uwtable "disable-tail-calls"="false"
>     "less-precise-fpmad"="false" "no-frame-pointer-elim"="false"
>     "no-infs-fp-math"="false" "no-jump-tables"="false"
>     "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false"
>     "stack-protector-buffer-size"="8" "target-cpu"="x86-64"
>     "target-features"="+fxsr,+mmx,+sse,+sse2,+x87"
>     "unsafe-fp-math"="false" "use-soft-float"="false" }
>     attributes #1 = { nounwind }
>
>     !llvm.ident = !{!0}
>
>     !0 = !{!"clang version 3.9.1 (tags/RELEASE_391/final)"}
>     failed to create execution engine
>     Aborted (core dumped)
>
>     Not sure why LLVMCreateExecutionEngineForModule is failing.
>     Any help appreciated.
>
>     Toshi
>
>
>     On Wed, Mar 8, 2017 at 3:56 PM, Toshiyasu Morita <toshi at tensyr.com
>     <mailto:toshi at tensyr.com>> wrote:
>
>>         Or do you mean I need to load the module into memory before
>>         calling LLVMGetBitcodeModuleInContext2?
>
>         > Yes, you need to load the module into memory first.
>         > LLVMCreateMemoryBufferWithContentsOfFile will do that for you.
>
>         Thanks!
>
>
>         On Wed, Mar 8, 2017 at 3:48 PM, Friedman, Eli
>         <efriedma at codeaurora.org <mailto:efriedma at codeaurora.org>> wrote:
>
>             On 3/8/2017 3:44 PM, Toshiyasu Morita wrote:
>>
>>
>>                         module_path =
>>                 LLVMCreateMemoryBufferWithMemoryRange(path,
>>                 strlen(path), "path", 1);
>>
>>
>>             LLVMCreateMemoryBufferWithContentsOfFile takes a path.
>>
>>             Erm...no...the code is calling
>>             LLVMCreateMemoryBufferWithMemoryRange, not
>>             LLVMCreateMemoryBufferWithContentsOfFile...
>>
>>             Or do you mean I need to load the module into memory
>>             before calling LLVMGetBitcodeModuleInContext2?
>
>             Yes, you need to load the module into memory first.
>             LLVMCreateMemoryBufferWithContentsOfFile will do that for you.
>
>             -Eli
>
>             -- 
>             Employee of Qualcomm Innovation Center, Inc.
>             Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
>
>
>
>


-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project

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