C++/Fortran 混合编程：对"_gfortran_reshape_r8"的未定义引用

Question

我正在编译一个c++代码和Fortran子程序。c++ cpp代码如下:

#include "Calculate.h"
extern "C" double SolveEq_(double *Gvalue, double *GvalueU, double *GvalueV, double *Gnodex, double *Gnodey, double *GtimeInc, double *Glfs);
template <class T1, class T2>
void Calculate(vector<Element<T1, T2> > &elm, GParameter &GeqPm, GmeshInfo &Gmesh)
{
    // Solving Equation using Fortran code
    SolveEq_(&Gmesh.Gvalue[0], &Gmesh.GvalueU[0], &Gmesh.GvalueV[0], &Gmesh.Gnodex[0], &Gmesh.Gnodey[0], &GeqPm.GtimeInc, &GeqPm.Glfs);
    return;
}

Fortran代码是这样的:

!==========================================================================
Module Inputpar
Implicit None
Integer,parameter :: Numx = 200, Numy = 200
End Module
!======================================== PROGRAM =============================================
Subroutine SolveEq(Gvalue, GvalueU, GvalueV, Gnodex, Gnodey, Deltat, Lfs);
Use Inputpar
Implicit None
Real*8 Deltat, Lfs, Dt, Su
Real*8 Gvalue(1, (Numx+1)*(Numy+1)), GvalueU(1, (Numx+1)*(Numy+1)), GvalueV(1, (Numx+1)*(Numy+1))
Real*8 Gnodex(0:Numx), Gnodey(0:Numy)
Real*8 DX, DY
Real*8 X(-3:Numx+3), Y(-3:Numy+3)
Real*8 VelX(-3:Numx+3,-3:Numy+3), VelY(-3:Numx+3,-3:Numy+3)
Real*8 G(-3:Numx+3,-3:Numy+3)
Common /CommonData/ X, Y, DX, DY, VelX, VelY, G, Dt, Su
!============================= Data Transfer ============================
Dt                  = Deltat
Su                  = Lfs
X          (0:Numx) = Gnodex(0:Numx)
Y          (0:Numy) = Gnodey(0:Numy)
VelX(0:Numx,0:Numy) = transpose(reshape(GvalueU,(/Numy+1,Numx+1/)))
VelY(0:Numx,0:Numy) = transpose(reshape(GvalueV,(/Numy+1,Numx+1/)))
G   (0:Numx,0:Numy) = transpose(reshape(Gvalue ,(/Numy+1,Numx+1/)))
!==========Some other lines neglected here=================
End
!======================================== END PROGRAM =========================================

首先使用命令编译Fortran代码:

      gfortran SolveEq.f90 -c -o SolveEq.o

然后使用makefile编译c++/Fortran代码:

# Compiler
CC = g++
# Debug option
DEBUG = false
# Source directory of codes
SRC1 = /home
SRC2 = $(SRC1)/Resources
SRC3 = $(SRC1)/Resources/Classes
OPT=-fopenmp -O2
ifdef $(DEBUG)
  PROG=test.out
else
  PROG=i.out
endif
# Linker
#LNK=-I$(MPI)/include -L$(MPI)/lib -lmpich -lopa -lmpl -lpthread
OBJS = libtseutil.a Calculate.o SolveEq.o
OBJS_F=$(OBJS)
SUF_OPTS1=$(OBJS_F)
SUF_OPTS2=-I$(SRC2)/
SUF_OPTS3=-I$(SRC3)/
SUF_OPTS4=
# Details of compiling
$(PROG): $(OBJS_F)
    $(CC) $(OPT) -o $@ $(SUF_OPTS1)
%.o: $(SRC1)/%.cpp
    $(CC) $(OPT) -c $< $(SUF_OPTS2)
%.o: $(SRC2)/%.cpp
    $(CC) $(OPT) -c $< $(SUF_OPTS3)
%.o: $(SRC3)/%.cpp
    $(CC) $(OPT) -c $< $(SUF_OPTS4)
# Clean
.PHONY: clean
clean:
    @rm -rf *.o *.oo *.log

但是，错误显示:

g++ -fopenmp -O2 -o libtseutil.a Calculate.o SolveEq.o
Calculate.o: In function `void Calculate<CE_Tri, SolElm2d>(std::vector<Element<CE_Tri, SolElm2d>, std::allocator<Element<CE_Tri, SolElm2d> > >&, GParameter&, GmeshInfo&)':
Calculate.cpp:(.text._Z10CalculateGI6CE_Tri8SolElm2dEvRSt6vectorI7ElementIT_T0_ESaIS6_EER10GParameterR9GmeshInfo[_Z10CalculateGI6CE_Tri8SolElm2dEvRSt6vectorI7ElementIT_T0_ESaIS6_EER10GParameterR9GmeshInfo]+0x3c): undefined reference to `SolveEq_'
SolveEq.o: In function `solveeq_':
SolveEq.f90:(.text+0x2b8e): undefined reference to `_gfortran_reshape_r8'
SolveEq.f90:(.text+0x2d2a): undefined reference to `_gfortran_reshape_r8'
SolveEq.f90:(.text+0x2ec6): undefined reference to `_gfortran_reshape_r8'
SolveEq.f90:(.text+0x31fa): undefined reference to `_gfortran_reshape_r8'
collect2: error: ld returned 1 exit status

这是怎么发生的?

我用了一个简单的案例来测试混合编译。c++代码是:

#include <stdlib.h>
#include <stdio.h>
#include <iostream>
#include <vector>
using namespace std;
extern "C" double fortran_sum_(double *sum, double *su2m, double *vec, double* vec2, int *size);
int main(int argc, char ** argv)
{
    int size;
    double sum, sum2;
    double aa,bb,cc,dd;
    vector<double> vec;
    vector<double> vec2;
    size=2;
    aa=1.0;
    bb=2.0;
    sum=0.0;
    sum2=0.0;
    vec.push_back(aa);
    vec.push_back(bb);
    vec2.push_back(aa*2.0);
    vec2.push_back(bb*2.0);
    fortran_sum_(&sum, &sum2, &vec[0], &vec2[0], &size);
    cout << "Calling a Fortran function" << endl;
    cout << "============================" << endl;
    cout << "size = " << size << endl;
    cout << "sum = " << sum << endl;
    cout << "sum2 = " << sum2 << endl << endl;
}

Fortran代码是:

Subroutine fortran_sum(gsum, gsum2, gvec, gvec2, gsize2)
  integer gsize,gsize2
  real*8 gvec(0:gsize2-1), gvec2(0:1)
  real*8 gsum, gsum2
  gsum = gvec(0)+gvec(1);
  gsum2 = gvec2(0)+gvec2(1);
  gsize = gsize*2;
end 

然后用命令编译:

gfortran fortran_sum.f90 -c -o fortran_sum.o
g++ fortran_sum.o call_fortran.cpp -o a.out
./a.out

效果很好:

Calling a Fortran function
============================
size = 2
sum = 3
sum2 = 6

Answer 1

函数_gfortran_reshape_r8是gfortran编译的代码所使用的库的一部分。当您使用单一语言进行编译时，这些库会自动链接，因为用于链接的任何程序都知道它们。在链接混合代码时，需要找到与所选择的链接器不对应的语言的库，并显式地将其放在命令行中。通常你链接c++语法，就像你在这里所做的那样，并显式地添加fortran编译器的库。

Answer 2

我对Fortran语言有点弱。当我编译你的fortran代码并将其通过nm时，它给了我以下内容。没有"SolveEq_"符号。只有"solveeq_"。

0000000000000020 r A.15.3480
0000000000000000 r A.3.3436
0000000000000010 r A.9.3463
                 U _gfortran_reshape_r8
00000000000fbe28 C commondata_
                 U free
                 U malloc
0000000000000000 T solveeq_

---

编辑:当我使用"solveeq_"时，它为我编译。下面是demo (main.cpp)的简化代码:

extern "C" double solveeq_(
              double *Gvalue, double *GvalueU, 
              double *GvalueV, double *Gnodex, 
              double *Gnodey, double *GtimeInc, double *Glfs
           );
template <typename T>
void Calculate(T *one, T *two, T *three,
               T *four, T *five, T *six, T *seven) {
    solveeq_(one,two,three,four,five,six,seven);
}
int main(int argc, char ** argv) {
     double one,two,three,four,five,six,seven;
     Calculate<double>(&one,&two,&three,&four,&five,&six,&seven);
}

编译为(f.f90有fortran代码):

gfortran -c f.f90
g++ f.o main.cpp -lgfortran

---

似乎，自2003年以来，如果你想从C/c++调用fortran函数，你可以使用BIND(它可能不是fortran/fortran，尽管没有一些额外的努力)。

子程序SolveEq(F) BIND(C,NAME="SolveMyEquation")Real Gvalue, GvalueU, GvalueV, Gnodex, Gnodey, delta, Lfs  

Answer 3

感谢大家，尤其是@Brick和@blackpen。问题已解决。

1)，将-lgfortran添加到命令行中，否则将显示:未定义引用' _gfortran_shape_r8 '

2)，将。f90函数的名称改为小写字母"solveeq"，否则它将显示:undefined reference to ' SolveGeq_'

最后我的。cpp变成了:

#include "Calculate.h"
extern "C" void solveeq_(double *Gvalue, double *GvalueU, double *GvalueV, double *Gnodex, double *Gnodey, double *GtimeInc, double *Glfs);
template <class T1, class T2>
void Calculate(vector<Element<T1, T2> > &elm, GParameter &GeqPm, GmeshInfo &Gmesh)
{
    // Solving Equation using Fortran code
    solveeq_(&Gmesh.Gvalue[0], &Gmesh.GvalueU[0], &Gmesh.GvalueV[0], &Gmesh.Gnodex[0], &Gmesh.Gnodey[0], &GeqPm.GtimeInc, &GeqPm.Glfs);
    return;
}

fortran代码。f90类似于:

!==========================================================================
Module Inputpar
Implicit None
Integer,parameter :: Numx = 200, Numy = 200
End Module
!======================================== PROGRAM =============================================
Subroutine SolveEq(Gvalue, GvalueU, GvalueV, Gnodex, Gnodey, Deltat, Lfs);
Use Inputpar
Implicit None
Real*8 Deltat, Lfs, Dt, Su
Real*8 Gvalue(1, (Numx+1)*(Numy+1)), GvalueU(1, (Numx+1)*(Numy+1)), GvalueV(1, (Numx+1)*(Numy+1))
Real*8 Gnodex(0:Numx), Gnodey(0:Numy)
Real*8 DX, DY
Real*8 X(-3:Numx+3), Y(-3:Numy+3)
Real*8 VelX(-3:Numx+3,-3:Numy+3), VelY(-3:Numx+3,-3:Numy+3)
Real*8 G(-3:Numx+3,-3:Numy+3)
Common /CommonData/ X, Y, DX, DY, VelX, VelY, G, Dt, Su
!============================= Data Transfer ============================
Dt                  = Deltat
Su                  = Lfs
X          (0:Numx) = Gnodex(0:Numx)
Y          (0:Numy) = Gnodey(0:Numy)
VelX(0:Numx,0:Numy) = transpose(reshape(GvalueU,(/Numy+1,Numx+1/)))
VelY(0:Numx,0:Numy) = transpose(reshape(GvalueV,(/Numy+1,Numx+1/)))
G   (0:Numx,0:Numy) = transpose(reshape(Gvalue ,(/Numy+1,Numx+1/)))
!==========Some other lines neglected here=================
End
!======================================== END PROGRAM =========================================

makefile是这样的

# Compiler
CC = g++
# Debug option
DEBUG = false
# Source directory of codes
SRC1 = /home
SRC2 = $(SRC1)/Resources
SRC3 = $(SRC1)/Resources/Classes
OPT=-fopenmp -O2
ifdef $(DEBUG)
  PROG=test.out
else
  PROG=i.out
endif
# Linker
#LNK=-I$(MPI)/include -L$(MPI)/lib -lmpich -lopa -lmpl -lpthread
OBJS = libtseutil.a Calculate.o solveeq.o
OBJS_F=$(OBJS)
SUF_OPTS1=$(OBJS_F)
SUF_OPTS2=-I$(SRC2)/
SUF_OPTS3=-I$(SRC3)/
SUF_OPTS4=
# Details of compiling
$(PROG): $(OBJS_F)
    $(CC) $(OPT) -o $@ $(SUF_OPTS1)
%.o: $(SRC1)/%.cpp
    $(CC) $(OPT) -c $< $(SUF_OPTS2)
%.o: $(SRC2)/%.cpp
    $(CC) $(OPT) -c $< $(SUF_OPTS3)
%.o: $(SRC3)/%.cpp
    $(CC) $(OPT) -c $< $(SUF_OPTS4)
solveeq.o: $(SRC1)/solveeq.f90
    gfortran -c $<
# Clean
.PHONY: clean
clean:
    @rm -rf *.o *.oo *.log