Re: Create binary from GCJ generated assembly

[Andrew Haley <aph@redhat.com>]

isuru herath wrote:

 > I want to add two assembly instructions to my Java program. Earlier
 > I was doing it in C with "asm volatile". To get the same behavior in
 > Java I used JNI. I used GCJ with -fjni flat to crate the binary. It
 > executed and gave the correct output. But when I checked the memory
 > references between two assembly instructions it is very high
 > compared to the C program.  Thereafter I got the assembly version of
 > both C and Java codes with -S option. In C version, assembly
 > instructions are directly inserted in the proper places. But in Java
 > version library calls are placed in the places where assembly should
 > be inserted. I doubt this may be the case for larger memory
 > references. So my question is is there a way to edit the gcj
 > generated assembly and insert assembly instructions and compile it
 > to a binary. I tried two different ways(trial and error). Nothing
 > worked.
 >
 > [1]
 > gcj --main=new_shared_counter -o new_shared_counter new_shared_counter.s
 >
 > [2]
 > gcc shared_counter.s
 >

gcj can't handle inline asm.

There are a few ways to do this:

* Write the code with the asm in C++ using CNI.  This is the easiest
   way, and gives you results identical to using asm volatile in C.

* Add a compiler intrinsic.  This requires specialist knowledge.

* Post-process the assembler output from gcj to replace a call with
   some assembly instructions.  Nasty, but it'd work.  Again, this
   requires specialist knowledge.

 > Any help on how to compile a gcj generated assembly to binary would
 > be greatly appreciated.

Use the assembler, "as".

Andrew.