[llvm-commits] [llvm][PATCH][Review request] X86 Instruction scheduler for the Intel Atom

Evan Cheng evan.cheng at apple.com
Mon Jan 16 09:00:34 PST 2012

Very nice. One question, I noticed you haven't changed the scheduling preference so x86_64 is still using ILP scheduler while i386 is using register pressure reduction scheduler. Have you tried changing the preference to latency scheduler for Atom?


On Jan 13, 2012, at 3:26 PM, Gurd, Preston wrote:

> The attached patch implements most of an instruction scheduler for the Intel Atom.
> It adds an instruction itinerary to all x86 instructions, giving each a default latency of 1, using the InstrItinClass IIC_DEFAULT.
> It sets specific latencies for Atom for the instructions in files X86InstrCMovSetCC.td, X86InstrArithmetic.td, X86InstrControl.td, and X86InstrShiftRotate.td. The Atom latencies for the remainder of the x86 instructions will be set in subsequent patches.
> It adds a test to verify that the scheduler is working.
> I realize that this patch is kind of large, but please consider that the vast majority of the changes consist only of adding an instruction itinerary class name to an instruction.
> --
> Preston Gurd <preston.gurd at intel.com>
>   Intel Waterloo
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