[LLVMdev] Problem of stack slot coloring (original) (raw)

Qingan Li ww345ww at gmail.com
Mon Oct 13 06:29:38 PDT 2014


Hi,

Can anyone help me with the stack slot coloring optimization? This corresponding file is /lib/codegen/stackslotcoloring.cpp.

It is said this optimization was for stack slot overlay for frame size reduction, after register allocation phase. And this transformation pass relies on the LiveStack analysis pass.

How, when checking the source code, it seems the LiveStack analysis has not been implemented, since the code was found in LiveStackAnalysis.cpp:

bool LiveStacks::runOnMachineFunction(MachineFunction &MF) {

And I found the greedy register allocator did nothing to fill the LiveStackAnalysis::*S2IMap, *which is critical for the stack slot coloring. Furthermore, the LiveInterval analysis only computes live intervals for virtual registers, but not for stack slots which has frame indexes. Does it mean this optimization has not been implemented yet ? And any advice for me to do it by myself? Or am I misunderstanding the implementation?

I really need some advice eagerly! Any help is greatly appreciated!

-- Best regards,

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