[LLVMdev] adding comment

[Reed Kotler]

Nice. I suggest you submit the patch to llvm commits.

That will make more realistic make check tests for fast-isel and make it 
easy to see which code is emitted by fast-isel
and normal isel.

On 04/22/2014 03:39 AM, Daniel Sanders wrote:
> I tried out CommentFlag and it looks ideal for this purpose. The attached patch adds a FastISel flag and prints it in the AsmPrinter and the IR dump. You can then call MachineInstr::setAsmPrinterFlag(MachineInstr::FastISel) to set the flag.
>
> Some passes seem to be stripping the comment flags though. The one I noticed is the pseudo-instruction expansion pass:
> 	# *** IR Dump After Machine Copy Propagation Pass ***:
> 	# Machine code for function retfloat: Post SSA
>
> 	BB#0: derived from LLVM BB %entry
> 		RetRA; comment-flags: FastISel
>
> 	# End machine code for function retfloat.
>
> 	# *** IR Dump After Post-RA pseudo instruction expansion pass ***:
> 	# Machine code for function retfloat: Post SSA
>
> 	BB#0: derived from LLVM BB %entry
> 		RET %RA
>
> 	# End machine code for function retfloat.
>
>> -----Original Message-----
>> From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu]
>> On Behalf Of Reed Kotler
>> Sent: 17 April 2014 16:30
>> To: LLVMdev at cs.uiuc.edu
>> Subject: Re: [LLVMdev] adding comment
>>
>> Maybe adding it to CommentFlag would be slightly better.
>>
>> On 04/17/2014 02:23 AM, Daniel Sanders wrote:
>>> Would adding a flag to MachineInstr::MIFlag do the trick? I'm thinking that
>> fast isel could ensure that a flag (e.g. MIFlag::FastISel) is added to the
>> instructions it creates, then the instruction printer could optionally emit a
>> comment for instructions that have this flag.
>>>> -----Original Message-----
>>>> From: llvmdev-bounces at cs.uiuc.edu
>>>> [mailto:llvmdev-bounces at cs.uiuc.edu]
>>>> On Behalf Of Reed Kotler
>>>> Sent: 16 April 2014 22:17
>>>> To: LLVMdev at cs.uiuc.edu
>>>> Subject: Re: [LLVMdev] adding comment
>>>>
>>>> On 04/16/2014 02:06 PM, reed kotler wrote:
>>>>> Is there a simple way to add a comment in the machine instructions
>>>>> of a basic block?
>>>>>
>>>>> Ideally something that can be used with machine instruction builder.
>>>>>
>>>>> Tia.
>>>>>
>>>>> Reed
>>>> In this case, I am working on the fast instruction selector for mips.
>>>>
>>>> I want to be able to tag instructions or regions of instructions that
>>>> are emitted by the fast instruction selector as opposed to the normal
>>>> mechanism.
>>>>
>>>> In fast instruction selector can always report that it cannot emit
>>>> instructions for some construct and then that part falls on the
>>>> normal mechanism; though in some cases the actual machine instructions
>> emitted would be the same.
>>>> So I want to be able to look for some kind of tag in the make check tests.
>>>>
>>>> Tia.
>>>>
>>>> Reed
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