waxiadao@gmail.com
2014-Apr-04 05:48 UTC
[LLVMdev] Weird problems on calling an external function from MCJIT on Windows(mingw)
Hi, I have a IR file generated by Clang: ; ModuleID = 'test_load_lib.c' target datalayout "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f80:128:128-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S32" target triple = "i686-pc-mingw32" declare i32 @a_outside_func(i32) define i32 @test_func() { entry: %call = call i32 @a_outside_func(i32 15) ret i32 %call } where a_outside_func is a function defined on my code: extern "C" int a_outside_func(int a) { return a + 50; } and following code is to get MCJIT work: #define prt(x) if(x) { cout << x << endl; } LLVMInitializeAllTargets(); LLVMInitializeAllTargetMCs(); LLVMInitializeAllTargetInfos(); LLVMInitializeAllAsmParsers(); LLVMInitializeAllAsmPrinters(); LLVMInitializeAllDisassemblers(); // just initialize them all.... prt(a_outside_func(50)); // afraid of linker optmize it out char *err = 0; LLVMMemoryBufferRef ll_f = 0; LLVMModuleRef m = 0; LLVMCreateMemoryBufferWithContentsOfFile("test_load_lib.ll",&ll_f,&err); //read .ll prt(err); LLVMParseIRInContext(LLVMGetGlobalContext(),ll_f,&m,&err); // ll_f doesnt need freeing prt(err); LLVMDumpModule(m); LLVMLinkInMCJIT(); LLVMExecutionEngineRef ee = 0; LLVMCreateMCJITCompilerForModule(&ee,m,0,0,&err); prt(err); using tf_t = int (); tf_t *f (tf_t*)LLVMGetPointerToGlobal(ee,LLVMGetNamedFunction(m,"test_func")); At first i got "LLVM ERROR: Incompatible object format! " But by reading some articles I append LLVMSetTarget(m,"i686-pc-mingw32"); and it's fixed. Then I got "LLVM ERROR: Program used external function 'a_outside_func' which could not be resolved!". I assumed my program didn't export the symbol properly.Thus,I use nm to check my program's export and I found "a_outside_func" was renamed to "_a_outside_func" . For it I rename the function name in the IR to "_a_outside_func".But it seemed to make no difference: "LLVM ERROR: Program used external function '_a_outside_func' which could not be resolved!". ............. After a day's wasting I unconsciously packed my external function "a_outside_func" into a shared object,called llvm::sys::DynamicLibrary::LoadLibraryPermanently("ext_func.so"); at the beginning of the program and named the function "_a_outside_func" in the IR. OMG IT WORKS THEN?! So I'd like to ask why llvm cant resolve my external function from the program itself(in fact i dont get such problems on linux)? -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20140404/67d616fb/attachment.html>
Anton Korobeynikov
2014-Apr-04 08:10 UTC
[LLVMdev] Weird problems on calling an external function from MCJIT on Windows(mingw)
Hello While there is a symbol in the object file, there is nothing like this in the final executable (well, you can try to export functions from PE/COFF executable, but this is pretty non-standard technique). This is the biggest difference wrt linux, where all the visible symbols are exported by default from the binary. Most probably, the best way here is to create an explicit mapping between a GlobalValue which represents your external function and the address of your function. ExecutionEngine::addGlobalMapping() is your friend here. On Fri, Apr 4, 2014 at 9:48 AM, waxiadao at gmail.com <waxiadao at gmail.com> wrote:> Hi, > I have a IR file generated by Clang: > > ; ModuleID = 'test_load_lib.c' > target datalayout > "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f80:128:128-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S32" > target triple = "i686-pc-mingw32" > > declare i32 @a_outside_func(i32) > > define i32 @test_func() { > entry: > %call = call i32 @a_outside_func(i32 15) > ret i32 %call > } > > where a_outside_func is a function defined on my code: > > extern "C" int a_outside_func(int a) > { > return a + 50; > } > > and following code is to get MCJIT work: > > #define prt(x) if(x) { cout << x << endl; } > LLVMInitializeAllTargets(); > LLVMInitializeAllTargetMCs(); > LLVMInitializeAllTargetInfos(); > LLVMInitializeAllAsmParsers(); > LLVMInitializeAllAsmPrinters(); > LLVMInitializeAllDisassemblers(); // just initialize them all.... > prt(a_outside_func(50)); // afraid of linker optmize it out > > char *err = 0; > LLVMMemoryBufferRef ll_f = 0; > LLVMModuleRef m = 0; > LLVMCreateMemoryBufferWithContentsOfFile("test_load_lib.ll",&ll_f,&err); > //read .ll > prt(err); > LLVMParseIRInContext(LLVMGetGlobalContext(),ll_f,&m,&err); // ll_f doesnt > need freeing > prt(err); > LLVMDumpModule(m); > > LLVMLinkInMCJIT(); > LLVMExecutionEngineRef ee = 0; > LLVMCreateMCJITCompilerForModule(&ee,m,0,0,&err); > prt(err); > using tf_t = int (); > tf_t *f > (tf_t*)LLVMGetPointerToGlobal(ee,LLVMGetNamedFunction(m,"test_func")); > > At first i got "LLVM ERROR: Incompatible object format! " > But by reading some articles I append LLVMSetTarget(m,"i686-pc-mingw32"); > and it's fixed. > Then I got "LLVM ERROR: Program used external function 'a_outside_func' > which could not be resolved!". > I assumed my program didn't export the symbol properly.Thus,I use nm to > check my program's export and I found "a_outside_func" was renamed to > "_a_outside_func" > . > For it I rename the function name in the IR to "_a_outside_func".But it > seemed to make no difference: "LLVM ERROR: Program used external function > '_a_outside_func' which could not be resolved!". > ............. > After a day's wasting I unconsciously packed my external function > "a_outside_func" into a shared object,called > llvm::sys::DynamicLibrary::LoadLibraryPermanently("ext_func.so"); at the > beginning of the program and named the function "_a_outside_func" in the IR. > OMG IT WORKS THEN?! > So I'd like to ask why llvm cant resolve my external function from the > program itself(in fact i dont get such problems on linux)? > > _______________________________________________ > LLVM Developers mailing list > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev >-- With best regards, Anton Korobeynikov Faculty of Mathematics and Mechanics, Saint Petersburg State University
waxiadao@gmail.com
2014-Apr-04 08:25 UTC
[LLVMdev] Weird problems on calling an external function from MCJIT on Windows(mingw)
Hello I quite thank you for your advice,but I have to tell that it made no difference too calling "LLVMAddGlobalMapping(ee,LLVMGetNamedFunction(m,"_a_outside_func"),(void*)(&a_outside_func));". 2014-04-04 16:10 GMT+08:00 Anton Korobeynikov <anton at korobeynikov.info>:> Hello > > While there is a symbol in the object file, there is nothing like this > in the final executable (well, you can try to export functions from > PE/COFF executable, but this is pretty non-standard technique). This > is the biggest difference wrt linux, where all the visible symbols are > exported by default from the binary. > > Most probably, the best way here is to create an explicit mapping > between a GlobalValue which represents your external function and the > address of your function. ExecutionEngine::addGlobalMapping() is your > friend here. > > On Fri, Apr 4, 2014 at 9:48 AM, waxiadao at gmail.com <waxiadao at gmail.com> > wrote: > > Hi, > > I have a IR file generated by Clang: > > > > ; ModuleID = 'test_load_lib.c' > > target datalayout > > > "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f80:128:128-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S32" > > target triple = "i686-pc-mingw32" > > > > declare i32 @a_outside_func(i32) > > > > define i32 @test_func() { > > entry: > > %call = call i32 @a_outside_func(i32 15) > > ret i32 %call > > } > > > > where a_outside_func is a function defined on my code: > > > > extern "C" int a_outside_func(int a) > > { > > return a + 50; > > } > > > > and following code is to get MCJIT work: > > > > #define prt(x) if(x) { cout << x << endl; } > > LLVMInitializeAllTargets(); > > LLVMInitializeAllTargetMCs(); > > LLVMInitializeAllTargetInfos(); > > LLVMInitializeAllAsmParsers(); > > LLVMInitializeAllAsmPrinters(); > > LLVMInitializeAllDisassemblers(); // just initialize them all.... > > prt(a_outside_func(50)); // afraid of linker optmize it > out > > > > char *err = 0; > > LLVMMemoryBufferRef ll_f = 0; > > LLVMModuleRef m = 0; > > > LLVMCreateMemoryBufferWithContentsOfFile("test_load_lib.ll",&ll_f,&err); > > //read .ll > > prt(err); > > LLVMParseIRInContext(LLVMGetGlobalContext(),ll_f,&m,&err); // ll_f > doesnt > > need freeing > > prt(err); > > LLVMDumpModule(m); > > > > LLVMLinkInMCJIT(); > > LLVMExecutionEngineRef ee = 0; > > LLVMCreateMCJITCompilerForModule(&ee,m,0,0,&err); > > prt(err); > > using tf_t = int (); > > tf_t *f > > (tf_t*)LLVMGetPointerToGlobal(ee,LLVMGetNamedFunction(m,"test_func")); > > > > At first i got "LLVM ERROR: Incompatible object format! " > > But by reading some articles I append LLVMSetTarget(m,"i686-pc-mingw32"); > > and it's fixed. > > Then I got "LLVM ERROR: Program used external function 'a_outside_func' > > which could not be resolved!". > > I assumed my program didn't export the symbol properly.Thus,I use nm to > > check my program's export and I found "a_outside_func" was renamed to > > "_a_outside_func" > > . > > For it I rename the function name in the IR to "_a_outside_func".But it > > seemed to make no difference: "LLVM ERROR: Program used external function > > '_a_outside_func' which could not be resolved!". > > ............. > > After a day's wasting I unconsciously packed my external function > > "a_outside_func" into a shared object,called > > llvm::sys::DynamicLibrary::LoadLibraryPermanently("ext_func.so"); at the > > beginning of the program and named the function "_a_outside_func" in the > IR. > > OMG IT WORKS THEN?! > > So I'd like to ask why llvm cant resolve my external function from the > > program itself(in fact i dont get such problems on linux)? > > > > _______________________________________________ > > LLVM Developers mailing list > > LLVMdev at cs.uiuc.edu http://llvm.cs.uiuc.edu > > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev > > > > > > -- > With best regards, Anton Korobeynikov > Faculty of Mathematics and Mechanics, Saint Petersburg State University >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20140404/586e917e/attachment.html>
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