[llvm-dev] what is official way to determine if we are running lto 2nd stage?

[Matthias Braun via llvm-dev]

Note that it is no problem to add target specific IR passes. Just override the relevant functions in your targets TargetPassConfig (TargetPassConfig::addIRPasses() or any of the more specific functions there).

> On Sep 12, 2016, at 11:19 AM, Mehdi Amini via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> 
>> On Sep 12, 2016, at 11:07 AM, Konstantin Vladimirov <konstantin.vladimirov at gmail.com> wrote:
>> 
>> Hi,
>> 
>> This is really basic block level pass. It is no difference what is
>> level, problem is the same.
> 
> Can you clarify what you mean? If you have a MachineFunction pass, it’ll run in the backend only.
> I don’t understand why you would need to distinguish between LTO or no-LTO here.
> 
>> 
>> After fixing for asm parser, assembler syntax is no more valid for
>> backend, without processing with asm parser.
> 
> My understanding of Inline ASM is that it is supposed to be opaque to the backend till you reach MC.
> So I don’t understand this sentence "no more valid for backend, without processing with asm parser”.
> 
> Sorry if my answers don’t make sense to you, I may still be missing a key part of your problem.
> 
> — 
> Mehdi
> 
> 
>> May be it will be solution to process inline asm on insn printer level
>> to remove syntax fixes. But just switch it off without lto will make
>> compiler do less job
>> 
>> P.S. sorry for dup, maillist CC lost on first sent.
>> 
>> ---
>> WIth best regards, Konstantin
>> 
>> 
>> On Mon, Sep 12, 2016 at 8:52 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:
>>> 
>>>> On Sep 12, 2016, at 9:26 AM, Konstantin Vladimirov <konstantin.vladimirov at gmail.com> wrote:
>>>> 
>>>> Hi,
>>>> 
>>>> In LTO we have AsmParser that process inline assembler instructions to
>>>> MCInst and I want to fix some inline assembler in order to conform its
>>>> rules (do not start with non-identifier and so on) because asm syntax
>>>> of our backend allows some incompatible patterns. In order to do this
>>>> I am adding IR-level target-specific pass. But those fixes shall not
>>>> be applied when there is no AsmParser later to process them. So I want
>>>> to switch this pass off if we are not in 2nd lto stage.
>>> 
>>> This is not clear to me: how should this be different for LTO than for a non-LTO compile?
>>> 
>>> Also, if you’re only fixing the inline ASM, why doing it as an IR-level pass instead of MachineFunctionPass?
>>> 
>>> —
>>> Mehdi
>>> 
>>> 
>>>> 
>>>> I think, I can make target-specific option and make user to supply it
>>>> whenever he wants to run 2nd lto stage, but this is ugly.
>>>> 
>>>> Can I somehow ask, say, about whole string of options and then parse
>>>> it to match "lto" from here?
>>>> 
>>>> ---
>>>> With best regards, Konstantin
>>>> 
>>>> On Mon, Sep 12, 2016 at 6:17 PM, Mehdi Amini <mehdi.amini at apple.com> wrote:
>>>>> Hi,
>>>>> 
>>>>> 
>>>>>> On Sep 12, 2016, at 1:26 AM, Konstantin Vladimirov via llvm-dev <llvm-dev at lists.llvm.org> wrote:
>>>>>> 
>>>>>> Hi,
>>>>>> 
>>>>>> I want to enable some target-specific functionality only if current
>>>>>> build is 2nd LTO stage (i.e. optimizer called from plugin). What is
>>>>>> best and recommended way to do it?
>>>>> 
>>>>> There is none. We can setup a different optimizer pass pipeline for LTO, but the target specific part (i.e. the backend) isn’t supposed to behave differently.
>>>>> 
>>>>> This is an issue in general with LTO where options from the command line (like -fno-builtins, or -fveclib=xxxx) are not correctly propagated to LTO.
>>>>> 
>>>>> What kind of behavior do you want to enable exactly?
>>>>> 
>>>>> —
>>>>> Mehdi
>>>>> 
>>> 
> 
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