llvm dev - Oct 2006 - [LLVMdev] Number of spills/stores

Dear guys,

     After compiling 188.ammp, one of spec floating point benchmarks,
using the linear scan register allocator, I got 34 spills, but only
28 store instructions. These data were given by -stats. Is this number
correct? I mean, the number of stores should be equal or greater than
the number of spills, shouldn't it?

Best regards,

Fernando

On Wed, 4 Oct 2006, Fernando Magno Quintao Pereira
wrote:
>     After compiling 188.ammp, one of spec floating point benchmarks,
> using the linear scan register allocator, I got 34 spills, but only
> 28 store instructions. These data were given by -stats. Is this number
> correct? I mean, the number of stores should be equal or greater than
> the number of spills, shouldn't it?
Some spill code gets folded into instructions.  For example, if you have:

   vreg1234 += 7

they can be spilled to:

   [esp + 123] += 7

on x86.

-Chris

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