Re: [microblaze-uclinux] microblaze c++ linker issue with new and delete operators

[John Williams <jwilliams@xxxxxxxxxxxxxx>]

Hi Gianluca,

C++ apps are not currently supported for MicroBlaze / uClinux.  While it
may be possible (as you have seen) to get simple apps going, the STL,
iostreams libraries etc will not build properly.

PetaLogix will be releasing a new toolchain soon with full C++ support
for uClinux apps - if you have an urgent need please contact me directly.

Regards,

John

Gianluca wrote:

> Hello.
> I am facing some big problems using c++ compilers on microblaze target and new and delete operator.
> 
> My simple c++ programs is the following code snippet:
> 
> class Prova
> {
>     public:
>         Prova();
> 	Prova(int p1, int p2);
> 	~Prova();
>         int somma( int a, int b );
> 	int uno;
> 	int due;
> };
> 
> Prova::Prova()
> {
> 	uno = 7;
> 	due = 3;
> }
> 
> Prova::Prova(int p1, int p2)
> {
> 	if( p1 )
> 		uno = p1;
> 	if ( p2 )
> 		due = p2;
> }
> 
> Prova::~Prova(void)
> {
> }
> 
> int Prova::somma( int a, int b )
> {
> 	uno = a;
> 	due = b;
> 	return uno + due;
> }
> 
> int main()
> {
> 	Prova * pippo = new( Prova );
> 	int a, b;
> 	
> 	a = 7;
> 	b = 3;
> 	int c = pippo->somma(a,b);
> 	
> 	delete pippo;
> 	
> 	return c;
> }
> 
> When launching compile command line:
> $ ucfront-g++ mb-g++  -c -Os -g -fomit-frame-pointer -fno-common -fno-builtin -Wall   -msoft-float -mno-xl-soft-mul -mxl-barrel-shift -mno-xl-soft-div  -DEMBED -Dlinux -D__linux__ -Dunix -D__uClinux__   -W -Wall -Wredundant-decls -Wshadow -Wpointer-arith -Wpacked -Wcast-qual main.cpp -o main.o
> everything was compiled fine.
> 
> But when I try to link this program, here it is the first problem:
> 
> ucfront-g++ mb-g++  -Wl,-elf2flt  -o appmain main.o
> appmain.elf2flt: In function `main':
> /home/gianluca/main.cpp(.text+0xc8): undefined reference to `operator new(unsigned long)'
> /home/gianluca/main.cpp(.text+0x100): undefined reference to `operator delete(void*)'
> collect2: ld returned 1 exit status
> make: *** [appmain] Error 1
> 
> But, if I change the main() function to:
> 
> int main()
> {
> 	Prova pippo;
> 	int a, b;
> 	
> 	a = 7;
> 	b = 3;
> 	int c = pippo.somma(a,b);
> 	
> 	return c;
> }
> 
> Everything is working (and linking) as expected.
> Why?
> It looks like the linker/compiler doesn't complain about dynamic memory allocation of pointers with new and delete operators.
> 
> Another issue is about the linker command line:
> if using the first code snippet and OMIT the (ucfront-g++) environment system, such as:
> mb-g++ -o appmain main.o
> Everything is finishing without any error!!!
> 
> Something related to syscall and gcc function call for memory allocation???
> 
> Any help, clue, hint will be appreciated.
> 
> Kind Regards,


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