llvm dev - Mar 2009 - [LLVMdev] Machine dependent dead-instruction elimination

I have a pass that modifies my machine dependent instructions and I have
ran into a situation where I want to remove all instructions that an
instruction is dependent on when I remove an instruction.

Is there a way to do this using the API calls?

 

For example, I have a sequence of instructions

a = b + c

d = c * c

store d, *a

load e, *a

f = e + d

 

 

since the store and load are pointless I want to turn them into a simple
move turning the code into

a = b + c

d = c * c

tmp = d

e = tmp

f = e + d

 

however I also want to remove the `a = b + c` instruction.

 

Any idea's?


Thanks,

 

Micah Villmow

Systems Engineer

Advanced Technology & Performance

Advanced Micro Devices Inc.

S1-609 One AMD Place

Sunnyvale, CA. 94085

P: 408-749-3966

 

 

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On Mar 23, 2009, at 11:48 AM, Villmow, Micah wrote:
> I have a pass that modifies my machine dependent instructions and I  
> have ran into a situation where I want to remove all instructions  
> that an instruction is dependent on when I remove an instruction.
> Is there a way to do this using the API calls?
No. See DeadMachineInstructionElim.cpp.

Evan
>
> For example, I have a sequence of instructions
> a = b + c
> d = c * c
> store d, *a
> load e, *a
> f = e + d
>
>
> since the store and load are pointless I want to turn them into a  
> simple move turning the code into
> a = b + c
> d = c * c
> tmp = d
> e = tmp
> f = e + d
>
> however I also want to remove the `a = b + c` instruction.
>
> Any idea’s?
>
> Thanks,
>
> Micah Villmow
> Systems Engineer
> Advanced Technology & Performance
> Advanced Micro Devices Inc.
> S1-609 One AMD Place
> Sunnyvale, CA. 94085
> P: 408-749-3966
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
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