Double spills with Greedy regalloc

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1

Hello,

I noticed the following interesting code sequence while compiling a piece of code with the backend I’m developing. Probably this issue is for Jakob, but anyways this is what I’m getting:

STDWPtrQRr <fi#12>, 0, %R25R24; mem:ST2FixedStack12
STDWPtrQRr <fi#12>, 0, %R25R24; mem:ST2FixedStack12
STDWPtrQRr <fi#13>, 0, %R23R22; mem:ST2FixedStack13
STDWPtrQRr <fi#13>, 0, %R23R22; mem:ST2FixedStack13
STDWPtrQRr <fi#14>, 0, %R21R20; mem:ST2FixedStack14
STDWPtrQRr <fi#14>, 0, %R21R20; mem:ST2FixedStack14
STDWPtrQRr <fi#15>, 0, %R19R18; mem:ST2FixedStack15
STDWPtrQRr <fi#15>, 0, %R19R18; mem:ST2FixedStack15

Each STDWPtrQRr is a spill instruction, but notice that it’s spilling everything twice to each frame index. I’m only getting this with the Greedy regalloc, PBQP will not duplicate the spills.
Is there something here that I’m missing or could it be a bug? I haven’t attached the C code now to not spam the message or the huge debug output of the regalloc, but I will supply any information as requested.

Thanks

2

Did you implement isStoreToStackSlot() ?

3

No, but after doing it that fixed it, thanks Jakob!

2012/1/27 Jakob Stoklund Olesen <stoklund@2pi.dk>