[llvm-commits] [llvm] [PATCH] Mips JIT implementation

[Vladimir Stefanovic]

Hi Bruno,

thanks a lot for the review.
Here's the modified version, with emitInstruction relying on TSFlags.

Regards,
Vladimir


On 05/25/2011 12:41 AM, Bruno Cardoso Lopes wrote:
> Hi Vladimir,
>
> Thanks for working on this.
>
> Sorry for the delay. When I apply the patch locally, the MIPS backend
> compilation fails. You probably forgot to define stuff like
> X86_64_JIT, as you can see in the X86 backend. Please, make sure this
> patch will enable the compilation to work on a non-mips machine. Also,
> some coding standarts are not being followed.
>
> 1) Indentation problems:
>
> +  // FIXME: Move this to TargetJITInfo!
> +    setRelocationModel(Reloc::Static); //force Static relocation
>
> Align function call with the comments.
>
> +class MipsCodeEmitter : public MachineFunctionPass {
> +    MipsJITInfo *JTI;
> +    const MipsInstrInfo *II;
> +    const TargetData *TD;
>
> Use only 2 spaces here.
>
> Please read http://llvm.org/docs/CodingStandards.html for more details.
>
> 2) Regarding the way you are implementing the emitInstruction(...) method:
>
> +enum InstrType {
> +  arithm_6_5_5_5_6,
> +  arithm_6_5_5_16, // addiu
> +  load_store, // lw, sw
> +  j,
> +  jal,
> +  jalr,
> +  jr,
> +  nop,
> +  lui,
> +  ret, // fake jr $ra
> +  mul_div, // madd, maddu, msub, msubu, div, divu, mult, multu
> +  shift, // sll, sra, srl
> +  count_leading, // clo, clz
> +  branch, // beq, bgez, bgezal, bgtz, blez, bltzal, bltz, bne
> +  lea_addiu,
> +  mf,
> +  nothing,
> +  mov_fp,
> +  shift_6_5_5_5_6,
> +  fp_6_5_5_5_6,
> +  fp_6_5_5_5_3_2_2_4,
> +  branch_cp
> +};
>
> Instead of using the enums above, it would be better if you do
> something like we have today in the X86 backend. Take a look at the
> namespace X86II in lib/Target/X86/X86InstrInfo.h. MIPS also has a few
> instruction formats, you can emit instructions by matching their
> format, using annotations in similar ways that X86 does for its
> prefixes (see again the X86II), and the emitInstruction(...) would be
> a lot more clean and smaller. For instructions that aren't easy to
> directly emit only by knowing its format, you can add more enums as
> X86 does. Besides that, the instructions in MipsInstrInfo.td should
> contain as much information about the encoding as possible, so before
> fixing a instruction encoding directly in emitInstruction(...), make
> sure you can't handle that first in the instruction definition.
>
> You probably want to set MIPS as having JIT in the makefile system,
> look up for x86 and JIT there to find an example.
>
> This is a great step. Please make the requested changes and send the
> patches again, and if there are no objections from other developers, I
> would be happy to commit when it gets in shape.
>
> Thank you!
>

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