[LLVMdev] using GCC LTO files as a frontend to dragonegg?

[Marcus Daniels]

  Hello,

With GCC, it is possible to compile GIMPLE from an object file back to 
assembly.  With Dragonegg, it seems to be a NOP.  (See below for a 
comparison.)

This appears it could be a nice way to mix the strengths of GCC and 
LLVM.  If it worked..  Should it?

Thanks,

Marcus

[mdaniels at dn002 dragonegg]$ cat hello.c
#include <stdio.h>
int hello () { printf ("Hello World\n"); }
[mdaniels at dn002 dragonegg]$ gcc-4.5 -flto -c hello.c[mdaniels at dn002 
dragonegg]$ gcc-4.5 -S -x lto hello.o
[mdaniels at dn002 dragonegg]$ cat hello.s
     .file    "hello.o"
     .section    .rodata
.LC0:
     .string    "Hello World"
     .text
.globl hello
     .type    hello, @function
hello:
.LFB0:
     .cfi_startproc
     pushq    %rbp
     .cfi_def_cfa_offset 16
     movq    %rsp, %rbp
     .cfi_offset 6, -16
     .cfi_def_cfa_register 6
     movl    $.LC0, %edi
     call    puts
     leave
     .cfi_def_cfa 7, 8
     ret
     .cfi_endproc
.LFE0:
     .size    hello, .-hello
     .ident    "GCC: (GNU) 4.5.1"
     .section    .note.GNU-stack,"", at progbits
[mdaniels at dn002 dragonegg]$ cat hello.c
#include <stdio.h>
int hello () { printf ("Hello World\n"); }
[mdaniels at dn002 dragonegg]$ gcc-4.5 -flto -c hello.c
[mdaniels at dn002 dragonegg]$ rm -f hello.s
[mdaniels at dn002 dragonegg]$ gcc-4.5 -O0 -c -x lto -S hello.o
[mdaniels at dn002 dragonegg]$ cat hello.s
     .file    "hello.o"
     .section    .rodata
.LC0:
     .string    "Hello World"
     .text
.globl hello
     .type    hello, @function
hello:
.LFB0:
     .cfi_startproc
     pushq    %rbp
     .cfi_def_cfa_offset 16
     movq    %rsp, %rbp
     .cfi_offset 6, -16
     .cfi_def_cfa_register 6
     movl    $.LC0, %edi
     call    puts
     leave
     .cfi_def_cfa 7, 8
     ret
     .cfi_endproc
.LFE0:
     .size    hello, .-hello
     .ident    "GCC: (GNU) 4.5.1"
     .section    .note.GNU-stack,"", at progbits
[mdaniels at dn002 dragonegg]$ rm -f hello.s
[mdaniels at dn002 dragonegg]$ gcc-4.5 -fplugin=./dragonegg.so -c -x lto 
-flto -S hello.o
[mdaniels at dn002 dragonegg]$ cat hello.s
     .file    "hello.o"

     .ident    "GCC: (GNU) 4.5.1 LLVM: 113541"


     .section    .note.GNU-stack,"", at progbits