[LLVMdev] Void values

Chris Lattner clattner at apple.com
Sat Jun 12 08:45:00 PDT 2010

On Jun 12, 2010, at 5:37 AM, Kenneth Uildriks wrote:

> Are there any platforms where it wouldn't Just Work if the code
> generator generated a {} return everywhere it presently generates a
> void return?  I'm not saying make those changes to the code generator,
> I'm just asking if VMCore replaced void with {} would any code
> generators need changing?  I don't think X86 would be affected - EAX
> is not preserved even if the function returns void.

I don't think so, but noone has done the experiment to see the fallout.  The biggest issue is that in code like this:

  %1 = add i32 ...
  store ...
  %2 = mul i32 %1, ...

That the numbering gets broken because store now produces a (unit) value.  For this issue alone, it may be an "llvm 3.0" sort of change.


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