[LLVMdev] whether these transformations are doable and how?
Zheng Wang
jason.wangz at gmail.com
Fri Apr 9 08:12:31 PDT 2010
Hi Ning,
The easy way is to check some examples in lib/Transformation or lib/Analysis.
You may also write some simple c programs, then you can use "llc
-march=cpp x.bc" to see how you can declare variables using LLVM APIs.
For example, you can simply write a c program named test.c as:
#include <stdio.h>
int global_1;
float global_2;
int main()
{
int stack_1, stack_2;
...
return 0;
}
You can translate it to LLVM Bytecode by:
llvm-gcc -emit-llvm -c test.c
opt -mem2reg -f < test.o > test.new.o
then, convert it c++ formation by:
llc -march=cpp test.new.o
You should be able to get some hints about how to declare global
variables from generated file --- test.new.o.cpp.
On 9 April 2010 12:29, Ning Wang <neal.wang at gmail.com> wrote:
> Hi folk,
>
> I'm a newbie to llvm, please first forgive my naive questions. I want to
> instrument llvm code to do some run-time monitoring work. After reading
> some of the llvm documentation, it begins clear to me that I can do the
> instrumentation in a transformation pass. There are several things I want
> to do in the transformation pass, but I'm not sure whether they are doable
> and how to do them even after I read the documentation. I would be very
> appreciate if anyone can answer my questions or give me hints of how to do
> them.
>
> 1. can I add more global memory objects to a module? any hint how to do
> it? do I need to derive a pass from ModulePass?
> 2. can I add more stack allocated memory objects to a function? the answer
> seems yes, any hint how to do it?
> 3. can I modify a function to take extra formal parameters? can I update
> all calls of the original function to take extra actual paramters? The
> function might be called across multiple modules. It seems this has to be
> done at both ModulePass and FunctionPass levels.
>
> Thanks,
> Neal
>
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>
Cheers,
Zheng
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