llvm dev - Sep 2015 - TableGen MCInstrDesc Instruction Size Zero

Dear all,

I am trying to write an AsmParser and a CodeEmitter for simple ADD
instruction.
Here is what I have in the TestGenInstrInfo.td:





*extern const MCInstrDesc TestInsts[] = {...{ 23, 3, 1, 0, 0, 0, 0x0ULL,
nullptr, nullptr, OperandInfo13, 0, nullptr },  // Inst #23 = ADD8_rr...}*

I parse the instruction successfully but I am not sure what I did wrong
that the Size (as you can see in the line above is Zero for this
instruction. (In EncodeInstruction, Desc.getSize() returns zero.)

Any help is appreciated....

Cheers,
ES
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Hi Sky

I think you need a ‘let Size = ‘ line in your instruction definition.

If you have fixed size instructions, then you can put a single size in the base
class for all your instructions, eg, like this from AArch64InstrFormats.td

// Real instructions (have encoding information)
class EncodedI<string cstr, list<dag> pattern> :
AArch64Inst<NormalFrm, cstr> {
  let Pattern = pattern;
  let Size = 4;
}

Or if you have variable sized instructions then you might need to set the size
on each class of instruction you define, or even each instruction.

Cheers,
Pete
> On Sep 14, 2015, at 6:44 AM, Sky Flyer via llvm-dev <llvm-dev at
lists.llvm.org> wrote:
> 
> Dear all,
> 
> I am trying to write an AsmParser and a CodeEmitter for simple ADD
instruction.
> Here is what I have in the TestGenInstrInfo.td:
> 
> extern const MCInstrDesc TestInsts[] = {
> ...
> { 23, 3, 1, 0, 0, 0, 0x0ULL, nullptr, nullptr, OperandInfo13, 0, nullptr },
// Inst #23 = ADD8_rr
> ...
> }
> 
> I parse the instruction successfully but I am not sure what I did wrong
that the Size (as you can see in the line above is Zero for this instruction.
(In EncodeInstruction, Desc.getSize() returns zero.)
> 
> Any help is appreciated....
> 
> Cheers,
> ES
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
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Thanks a lot Pete :)

On Mon, Sep 14, 2015 at 6:11 PM, Pete Cooper <peter_cooper at apple.com>
wrote:
> Hi Sky
>
> I think you need a ‘let Size = ‘ line in your instruction definition.
>
> If you have fixed size instructions, then you can put a single size in the
> base class for all your instructions, eg, like this from
> AArch64InstrFormats.td
>
> // Real instructions (have encoding information)
> class EncodedI<string cstr, list<dag> pattern> :
AArch64Inst<NormalFrm,
> cstr> {
>   let Pattern = pattern;
>   let Size = 4;
> }
>
> Or if you have variable sized instructions then you might need to set the
> size on each class of instruction you define, or even each instruction.
>
> Cheers,
> Pete
>
> On Sep 14, 2015, at 6:44 AM, Sky Flyer via llvm-dev <
> llvm-dev at lists.llvm.org> wrote:
>
> Dear all,
>
> I am trying to write an AsmParser and a CodeEmitter for simple ADD
> instruction.
> Here is what I have in the TestGenInstrInfo.td:
>
>
>
>
>
> *extern const MCInstrDesc TestInsts[] = {...{ 23, 3, 1, 0, 0, 0, 0x0ULL,
> nullptr, nullptr, OperandInfo13, 0, nullptr },  // Inst #23 = ADD8_rr...}*
>
> I parse the instruction successfully but I am not sure what I did wrong
> that the Size (as you can see in the line above is Zero for this
> instruction. (In EncodeInstruction, Desc.getSize() returns zero.)
>
> Any help is appreciated....
>
> Cheers,
> ES
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
>
>
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