[llvm-dev] [RFC] Lanai backend

Hal Finkel via llvm-dev llvm-dev at lists.llvm.org
Tue Feb 9 09:58:39 PST 2016

----- Original Message ----- 
> From: "Jacques Pienaar via llvm-dev" <llvm-dev at lists.llvm.org>
> To: llvm-dev at lists.llvm.org
> Sent: Tuesday, February 9, 2016 11:40:21 AM
> Subject: [llvm-dev] [RFC] Lanai backend

> Hi all,

Hi Jacques,

> We would like to contribute a new backend for the Lanai processor

I suppose I can guess from your e-mail address who "we" are?

> (derived from the processor described in [1]).
> Lanai is a simple in-order 32-bit processor with:

Can you say a few words about what this is, in what hardware it appears, and how it can be used? Is this the Myricom processor? What version(s)? Aside from the Clang/LLVM support, what other software, drivers, etc. would be needed to make use of this support? What versions of that software?


> * 32 32-bit registers, including:
> * 2 registers with fixed values;
> * 4 used for program state tracking (PC, SP, FP, RCA);
> * 2 reserved for explicit usage by user (R10 and R11), used in
> threading library;
> * Up to 4 used for argument passing;
> * No callee-saved registers
> * No floating point support

> Backend development is focused primarily on compiling C99 code (no
> exception support). The patches implement all the parts required for
> code generation:

> * LLVM triple: http://reviews.llvm.org/D17003
> * Clang support: http://reviews.llvm.org/D17002
> * MCExpr & ELF: http://reviews.llvm.org/D17008
> * Lanai backend (lib/Target/Lanai): http://reviews.llvm.org/D17011

> We are still actively developing the backend and have many
> optimizations in mind.

> I'll be the maintainer of this backend.

> Please leave code comments on the Phab patches, while discussing
> high-level comments about the backend on this llvm-dev thread.

> Thanks,

> Jacques

> [1] David E. Culler, Anoop Gupta, and Jaswinder Pal Singh. 1997.
> Parallel Computer Architecture: A Hardware/Software Approach (1st
> ed.). Morgan Kaufmann Publishers Inc., San Francisco, CA, USA.
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Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory

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