[LLVMdev] Does LLVM 3.5 works with IR from LLVM 3.0?

[Gaoyao Xiao]

On Tue, Jul 15, 2014 at 5:12 PM, Reid Kleckner <rnk at google.com> wrote:

> On Tue, Jul 15, 2014 at 2:00 PM, Gaoyao Xiao <windxing2007 at gmail.com>
> wrote:
>
>> On Tue, Jul 15, 2014 at 10:46 AM, John Criswell <jtcriswel at gmail.com>
>> wrote:
>>
>>>  On 7/15/14, 9:32 AM, Gaoyao Xiao wrote:
>>>
>>> Hi,
>>>
>>>
>>>  I have some IR files which can  be compiled using llc-3.0 and
>>> gcc-4.6.3. I want to instrument these IR files. My instrumentation pass is
>>> implemented under LLVM-3.5 and some data structures in LLVM-3.5 are not
>>> available on LLVM-3.0, such as *AttributeSet* in *Attribute.h*. I tried
>>> to compile my instrumentation pass under LLVM-3.0 and it failed due to
>>> missing data types. So I am asking whether it is possible to use LLVM-3.5
>>> to instrument the IR files?  If not, is there any walk around?
>>>
>>>
>>> I believe LLVM 3.5 is supposed to be able to read bitcode files from
>>> LLVM 3.0.  It is possible, though, that bugs may prevent this from
>>> working.  If it doesn't work, you should probably file a bug report with
>>> (if possible) a reduced test case.
>>>
>>> If reading the old bitcode files directly into opt/clang/whatever
>>> doesn't work, try disassembling the bitcode into an assembly file with
>>> llvm-dis from LLVM 3.0 and re-assembling the output using llvm-as from LLVM
>>> 3.5:
>>>
>> opt and clang can read the bitcode but the produced binary cannot run.
>>
>>>
>>> llvm-dis-3.0 -f -o - file.bc | llvm-as-3.5 -f -o newfile.bc
>>>
>> I tried this and the newfile.bc is incorrect. newfile.bc can be compiled
>> to binary but cannot run.
>>
>
> This would be good to debug.  There isn't enough info here to know what
> went wrong.
>
The only error from the compiled bzip2 binary is:
*Could not translate address: 0xa0048000*

 I tried several other spec2006 programs and the error is similar with
different addresses. Since my instrumentation is quite simple, I am
thinking rewrite it for llvm-3.0 and that might be quicker. Do you have any
hint based on the short error message?

>
>
>> I also tried to this:
>>
>> *llvm-dis-3.0 -f -o - file.bc | llvm-as-3.5 -f -o newfile.bcllvm-dis-3.5
>> -f -o newfile.bc | llvm-as-3.0 -o newnewfile.bc*
>>
>
> This obviously won't work.  We will generate newer LLVM assembly than the
> old llvm-as can read.
>
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