llvm dev - Oct 2011 - [LLVMdev] There are compiling errors when converting bytecode to c by LLC

I convert C to bytecode by LLVM, and then convert the bytecode back to C by
LLC, but the generated C code cannot be compiled. Could anyone give me some
suggestions? Thanks!

The initial C file is rather simple (hello world):

#include <stdio.h>

int main() {

        printf("hello world\n");

        printf("hello world1\n");

        return 0;

}


The two commands:

llvm-gcc -emit-llvm -c -o hello.bc hello.c

llc -march=c hello.bc

Version of LLVM: 2.9


The source of error in generated c file:

/* Global Variable Declarations */

static _OC_str { unsigned char array[12]; };

static _OC_str1 { unsigned char array[13]; };




/* Global Variable Definitions and Initialization */

static _OC_str { unsigned char array[12]; } = { "hello world" };

static _OC_str1 { unsigned char array[13]; } = { "hello world1" };


It seems that _OC_str, and _OC_str1 are structure variables, but I have
never seen such way of declarations, definitions, and initialization of
structure in C code. I guess it may be supported in some standards of C.
Could anyone please give me some information about the problem? Thanks!

--
Best Regards,
Fei Jia
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Hi Fei Jia,

What revision are you using? I suggest you to try C backend with the
most recent LLVM version, if possible. I recall I had some similar C
backend breakages in July-August: structs definitions were lost
somewhere. To my understanding, the correct result should look like
this:

/* Typedefs */
typedef struct l_unnamed_0 l_unnamed_0;
typedef struct l_unnamed_1 l_unnamed_1;

/* Structure contents */
struct l_unnamed_0 {
  unsigned char array[12];
};

struct l_unnamed_1 {
  unsigned char array[13];
};

/* Global Variable Declarations */
static l_unnamed_0 _OC_cst;
static l_unnamed_1 _OC_cst1;

/* Global Variable Definitions and Initialization */
extern static l_unnamed_0 _OC_cst = { "hello world" };
extern static l_unnamed_1 _OC_cst1 = { "hello world1" };

- D.

2011/10/11 Fei Jia <j.jiafei at gmail.com>:
> I convert C to bytecode by LLVM, and then convert the bytecode back to C by
> LLC, but the generated C code cannot be compiled. Could anyone give me some
> suggestions? Thanks!
> The initial C file is rather simple (hello world):
>
> #include <stdio.h>
>
> int main() {
>
>         printf("hello world\n");
>
>         printf("hello world1\n");
>
>         return 0;
>
> }
>
> The two commands:
>
> llvm-gcc -emit-llvm -c -o hello.bc hello.c
>
> llc -march=c hello.bc
>
> Version of LLVM: 2.9
>
> The source of error in generated c file:
>
> /* Global Variable Declarations */
>
> static _OC_str { unsigned char array[12]; };
>
> static _OC_str1 { unsigned char array[13]; };
>
>
>
> /* Global Variable Definitions and Initialization */
>
> static _OC_str { unsigned char array[12]; } = { "hello world" };
>
> static _OC_str1 { unsigned char array[13]; } = { "hello world1"
};
>
> It seems that _OC_str, and _OC_str1 are structure variables, but I have
> never seen such way of declarations, definitions, and initialization of
> structure in C code. I guess it may be supported in some standards of C.
> Could anyone please give me some information about the problem? Thanks!
> --
> Best Regards,
> Fei Jia
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
>

Dear Dmitry,

Thanks for your reply. I have just updated my version from svn sever and
it's perfect now. The previous version is from the svn server several days
before Oct 10, and I guess the code related with gcc might not be updated
at that time.

Thanks a lot!

--
Best Regards,
Fei Jia




On Sat, Oct 29, 2011 at 4:43 PM, Dmitry N. Mikushin <maemarcus at
gmail.com>wrote:
> Hi Fei Jia,
>
> What revision are you using? I suggest you to try C backend with the
> most recent LLVM version, if possible. I recall I had some similar C
> backend breakages in July-August: structs definitions were lost
> somewhere. To my understanding, the correct result should look like
> this:
>
> /* Typedefs */
> typedef struct l_unnamed_0 l_unnamed_0;
> typedef struct l_unnamed_1 l_unnamed_1;
>
> /* Structure contents */
> struct l_unnamed_0 {
>  unsigned char array[12];
> };
>
> struct l_unnamed_1 {
>  unsigned char array[13];
> };
>
> /* Global Variable Declarations */
> static l_unnamed_0 _OC_cst;
> static l_unnamed_1 _OC_cst1;
>
> /* Global Variable Definitions and Initialization */
> extern static l_unnamed_0 _OC_cst = { "hello world" };
> extern static l_unnamed_1 _OC_cst1 = { "hello world1" };
>
> - D.
>
> 2011/10/11 Fei Jia <j.jiafei at gmail.com>:
> > I convert C to bytecode by LLVM, and then convert the bytecode back to
C
> by
> > LLC, but the generated C code cannot be compiled. Could anyone give me
> some
> > suggestions? Thanks!
> > The initial C file is rather simple (hello world):
> >
> > #include <stdio.h>
> >
> > int main() {
> >
> >         printf("hello world\n");
> >
> >         printf("hello world1\n");
> >
> >         return 0;
> >
> > }
> >
> > The two commands:
> >
> > llvm-gcc -emit-llvm -c -o hello.bc hello.c
> >
> > llc -march=c hello.bc
> >
> > Version of LLVM: 2.9
> >
> > The source of error in generated c file:
> >
> > /* Global Variable Declarations */
> >
> > static _OC_str { unsigned char array[12]; };
> >
> > static _OC_str1 { unsigned char array[13]; };
> >
> >
> >
> > /* Global Variable Definitions and Initialization */
> >
> > static _OC_str { unsigned char array[12]; } = { "hello
world" };
> >
> > static _OC_str1 { unsigned char array[13]; } = { "hello
world1" };
> >
> > It seems that _OC_str, and _OC_str1 are structure variables, but I
have
> > never seen such way of declarations, definitions, and initialization
of
> > structure in C code. I guess it may be supported in some standards of
C.
> > Could anyone please give me some information about the problem?
Thanks!
> > --
> > Best Regards,
> > Fei Jia
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> >
> >
>
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