llvm dev - Dec 2008 - [LLVMdev] Controlling the stack layout

Hi Anton,

Anton Korobeynikov wrote:
> I don't see any huge problems with writing such pass: just create
> stack frame objects at fixed offsets inside your MF pass - and you'll
> done. The only problem is that you need to do this early - before
> prologue / epilogue inserter code runs, since afterwards stack frame
> layout is almostly finalized (at "high level") and you'd deal
with
> much low-level and target-specific stuff.
>
>   
OK.
> I believe you can even use on of prologue-epilogue inserter hooks in
> order to do this...
>   
Could you point me where those hooks are in the llvm code? I didn't find 
any.

Thanks!
Nicolas

Hi, Nicolas
> Could you point me where those hooks are in the llvm code? I didn't
find
> any.
Look into PrologEpilogInserter.cpp::PEI::runOnMachineFunction(). There
are calls to hooks inside TargetRegisterInfo:
TargetRegisterInfo::processFunctionBeforeCalleeSavedScan() and
TargetRegisterInfo::processFunctionBeforeFrameFinalized().

Maybe they are not so convenient when working via JIT but at least
you'll know the place, where all stack-related stuff is being cooked
:)

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

Anton Korobeynikov wrote:
> Hi, Nicolas
>
>   
>> Could you point me where those hooks are in the llvm code? I didn't
find
>> any.
>>     
> Look into PrologEpilogInserter.cpp::PEI::runOnMachineFunction(). There
> are calls to hooks inside TargetRegisterInfo:
> TargetRegisterInfo::processFunctionBeforeCalleeSavedScan() and
> TargetRegisterInfo::processFunctionBeforeFrameFinalized().
>
>   
Doesn't that involve modifying the target? eg modifying 
X86RegisterInfo.cpp to allocate the stack entry?