[LLVMdev] Dead Store Elimination

[Vinayak Borkar]

Hi Duncan,


The mem2reg pass did not help. Moving the alloca instructions into the 
entry block did the trick.

One other thing I noticed is that if there was only one alloca, the dead 
store is eliminated. Having the second one (does not matter which of the 
two) prevents the elimination. Is this a bug?

Thanks,
Vinayak


On 9/10/12 8:16 AM, Duncan Sands wrote:
> Hi Vinayak,
>
>> Here is the result of optimization using the following passes:
>>
>> llvm::createBasicAliasAnalysisPass()
>> llvm::createInstructionCombiningPass()
>> llvm::createReassociatePass()
>> llvm::createGVNPass()
>> llvm::createCFGSimplificationPass()
>>
>
> you should run the mem2reg pass too, and first.
>
>> ; <label>:7                                       ; preds =
>> %openSuccessBB
>>    %8 = alloca i64, align 8
>
> Put alloca instructions in the entry block if possible.
>
> Ciao, Duncan.
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