[llvm-dev] mcjit C interface problems

[Toshiyasu Morita via llvm-dev]

Thanks for the tip - getting closer:

$ ./capi_test 5 6
args[0]: 5
args[1]: 6
result: 4294959200

Here's the code I changed:

  printf("args[0]: %d\n", (int)LLVMGenericValueToInt(args[0], 0));
  printf("args[1]: %d\n", (int)LLVMGenericValueToInt(args[1], 0));

  uint64_t (*func)();
  func = (uint64_t (*)())LLVMGetFunctionAddress(engine, "sum");
  printf("result: %lu\n", (*func)());

Anything else I should look at?

Toshi



On Wed, Jan 25, 2017 at 5:20 PM, Andres Freund <andres at anarazel.de> wrote:

> Hi,
>
> On 2017-01-25 15:17:04 -0800, Toshiyasu Morita via llvm-dev wrote:
> >   long long x = strtoll(argv[1], NULL, 10);
> >   long long y = strtoll(argv[2], NULL, 10);
> >
> >   LLVMGenericValueRef args[] =
> > {LLVMCreateGenericValueOfInt(LLVMInt32Type(), x, 0),
> >
> > LLVMCreateGenericValueOfInt(LLVMInt32Type(), y, 0)};
> >
> >   printf("args[0]: %d\n", (int)LLVMGenericValueToInt(args[0], 0));
> >   printf("args[1]: %d\n", (int)LLVMGenericValueToInt(args[1], 0));
> >
> >   LLVMGenericValueRef res = LLVMRunFunction(engine, sum, 2, args);
> >
> >   printf("result: %d\n", (int)LLVMGenericValueToInt(res, 0));
>
> > It seems to fail to add, and always returns the first argument.
> > Any help greatly appreciated.
>
> I don't think LLVMGenericValueToInt / LLVMRunFunction really work with
> mcjit.  I'd bet you'd see better results if you'd use
> LLVMGetFunctionAddress, cast the returned pointer to the correc type,
> and then call the function via that.
>
> Greetings,
>
> Andres Freund
>
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