llvm dev - Sep 2005 - [LLVMdev] bytecode

Hi,
   I'm changing bytecode format a little bit, i.e. for 2 operands
Instructions, the original is like this:
    01-00:Opcode type
    07-02:Opcode
    15-08: Instruction type
    23-16: Operand#1
    31-24: Operand#2
My change is like this:
    01-00:Opcode type
    07-02:Opcode
    15-08: Instruction type
    16: myflag1
    17: myflag2
    24-18: Operand#1
    31-25: Operand#2
    I do the corresponding changes in both Writer.cpp and Reader.cpp.But
when I compile, errors take place when "linking comp_genericeh.bc
component..". comp_genericeh.bc is some bytecode in
/runtime/GCCLibrary.
    I wonder is it because the comp_genericeh.bc is produced by orignal
bytecode format so that the changed bytecode read& write lib cann't
encode and decode it correctly?

-- 
Shuhan

Yes, that's right.  If you change the bytecode format, you need to 
rebuild your LLVM tree (which will rebuild the runtime libraries), and 
then reinstall the libraries.  To do this, run

make -C runtime install-bytecode

from your LLVM object directory.

Rob

On Sep 9, 2005, at 11:19 AM, shding at mtu.edu wrote:
> Hi,
>    I'm changing bytecode format a little bit, i.e. for 2 operands
> Instructions, the original is like this:
>     01-00:Opcode type
>     07-02:Opcode
>     15-08: Instruction type
>     23-16: Operand#1
>     31-24: Operand#2
> My change is like this:
>     01-00:Opcode type
>     07-02:Opcode
>     15-08: Instruction type
>     16: myflag1
>     17: myflag2
>     24-18: Operand#1
>     31-25: Operand#2
>     I do the corresponding changes in both Writer.cpp and 
> Reader.cpp.But
> when I compile, errors take place when "linking comp_genericeh.bc
> component..". comp_genericeh.bc is some bytecode in
> /runtime/GCCLibrary.
>     I wonder is it because the comp_genericeh.bc is produced by orignal
> bytecode format so that the changed bytecode read& write lib cann't
> encode and decode it correctly?
>
> -- 
> Shuhan
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>
Robert L. Bocchino Jr.
Ph.D. Student, Computer Science
University of Illinois, Urbana-Champaign
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On Fri, 9 Sep 2005 shding at mtu.edu wrote:
> Hi,
>   I'm changing bytecode format a little bit, i.e. for 2 operands
> Instructions, the original is like this:
>    01-00:Opcode type
>    07-02:Opcode
>    15-08: Instruction type
>    23-16: Operand#1
>    31-24: Operand#2
> My change is like this:
>    01-00:Opcode type
>    07-02:Opcode
>    15-08: Instruction type
>    16: myflag1
>    17: myflag2
>    24-18: Operand#1
>    31-25: Operand#2
>    I do the corresponding changes in both Writer.cpp and Reader.cpp.But
> when I compile, errors take place when "linking comp_genericeh.bc
> component..". comp_genericeh.bc is some bytecode in
> /runtime/GCCLibrary.
>    I wonder is it because the comp_genericeh.bc is produced by orignal
> bytecode format so that the changed bytecode read& write lib cann't
> encode and decode it correctly?
Yup, that's the problem.  The best way to handle this is invent a new 
bytecode version number, and parse the old format when reading a .bc file 
older than the current version.  This is how we handle backwards 
compatibility when we change the .bc format.

-Chris

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