llvm dev - Apr 2011 - [LLVMdev] [Fwd: Re: [Fwd: Regarding Inter Procedural Constant Propagation]]

Hi,
I used the following commands on the program attached below:

 llvm-gcc --emit-llvm main.c -c -o main.bc
 opt -ipconstprop main.bc -o main1.bc
 diff main.bc main1.bc

 no difference was o/p :(

 The Program Segment is as shown below:
 #include <stdio.h>
 void f1(int a)
 {
 	a=a+1;
 	printf("%d",a);
 }

 void f2()
 {
        int b;
 	b=1;
        f1(b);
 }

int main()
 {
	int a=1;
 	f2();
 	f1(a);
}


 Also,when i use the following command:
 opt -print-after-all main.bc

The dumps generated dont include IPCP or Intraprocedural Const Propagation
dumps.Why so?

Is there any other way to see the effect of a pass on the i/p bitcode file?
Kindly let me know where i am going wrong.

 Netra,
>> ---------------------------- Original Message
----------------------------
>> Subject: Regarding Inter Procedural Constant Propagation
>> From:    netra at cse.iitb.ac.in<mailto:netra at cse.iitb.ac.in>
>> Date:    Wed, April 13, 2011 1:29 am
>> To:      llvmdev at cs.illinois.edu<mailto:llvmdev at
cs.illinois.edu>
>>
--------------------------------------------------------------------------
>>
>> Hi,
>> I want to see the output of a InterProcedural Constant Propagation Pass
>> IPCP in llvm.
>> I have llvm 2.8 installed.And i used opt -print-after-all command to
see
>> the .bc output generated after each pass.
>> However,this does not include dump produced by IPCP  :( why?
>> Kindly tell me how to view dump produced by IPCP.
>>
>> P.S: i have tried opt -ipcp src.bc -o src1.bc
>> However the src.bc and src1.bc both files r identical. :(
>>
>> Kindly help me regarding this.
>>
>> Regards,
>> Netra
>>
Regards,
Netra

Hi Netra,
> I used the following commands on the program attached below:
>
>   llvm-gcc --emit-llvm main.c -c -o main.bc
>   opt -ipconstprop main.bc -o main1.bc
almost all LLVM optimization passes work poorly if you haven't run the
mem2reg pass first, so try at least
   opt -mem2reg -ipconstprop main.bc -o main1.bc
>   Also,when i use the following command:
>   opt -print-after-all main.bc
>
> The dumps generated dont include IPCP or Intraprocedural Const Propagation
> dumps.Why so?
Because you didn't tell opt to run that pass.

Ciao, Duncan.