llvm dev - Jul 2004 - [LLVMdev] Stack alignment problem

Hello,
it seems the Prolog/Epilog insertion does not correctly align stack for me. 
Consider the PEI::calculateFrameObjectOffsets method. It only aligns the 
stack if 

   FFI->hasCalls()

is true. The only place where 

   MachineFrameInfo::setHasCalls 

is invoked is

   PEI::saveCallerSavedRegisters

and the value 'true' is only passed when there are instructions with
opcodes
equal to either RegInfo->getCallFrameSetupOpcode() or  
RegInfo->getCallFrameDestroyOpcode(). I don't have such special opcode,
so
hasCalls returns false and the stack is not aligned.

Any ideas?

- Volodya

On Thu, 1 Jul 2004, Vladimir Prus wrote:
>
> Hello,
> it seems the Prolog/Epilog insertion does not correctly align stack for me.
> Consider the PEI::calculateFrameObjectOffsets method. It only aligns the
> stack if
>    FFI->hasCalls()
> is true. The only place where
Yup, the idea is that you dno't need to align the outgoign stack for a
leaf function.
>    MachineFrameInfo::setHasCalls
> is invoked is
>    PEI::saveCallerSavedRegisters
> and the value 'true' is only passed when there are instructions
with opcodes
> equal to either RegInfo->getCallFrameSetupOpcode() or
> RegInfo->getCallFrameDestroyOpcode(). I don't have such special
opcode, so
> hasCalls returns false and the stack is not aligned.
Okay, if you don't want to use this functionality, just call setHasCalls()
on the MFI in your instruction selector.  That should prevent this from
happening on any functions.

-Chris

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