[llvm-commits] [llvm] r121197 - in /llvm/trunk: lib/Target/ARM/ARMFrameInfo.cpp lib/Target/ARM/ARMFrameInfo.h test/CodeGen/ARM/2010-12-07-PEIBug.ll

[Eric Christopher]

On Dec 7, 2010, at 3:08 PM, Evan Cheng wrote:

> Fix a bad prologue / epilogue codegen bug where the compiler would emit illegal
> vpush instructions to save / restore VFP / NEON registers like this:
> vpush {d8,d10,d11}
> vpop {d8,d10,d11}
> 
> vpush and vpop do not allow gaps in the register list.
> rdar://8728956
> 

Thanks for fixing this!

This was somewhat hard to follow, I had to read it a couple of times to make sure I knew the looping order. It could use a couple of comments as to what's going on, something like:

"If NoGap is enabled then split up the pushes to ensure that the registers are adjacent, e.g.
 vpush {d8, d10, d11} becomes the two pushes vpush {d8 } ; vpush { d10, d11 }"

Might be clearer what's going on if we just did a second pass through the Regs vector after grabbing all of the matching registers?

while (!Regs.empty())
 …

and then just pop regs as we iterate through?

Thoughts?

-eric
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