llvm dev - Jan 2014 - [LLVMdev] basic block missing after MachineInstr packetizing

Hi, all,

When I schedule machine instructions in a VLIW way and packetize them, a
problem is encountered, and I will show it use a simplified case as follows.

############ original instruction sequence
...
insn1
...
jump  LBB0_xx
...
LBB0_xx:
...

############ expected instruction sequence after scheduling and packetizing
insn1; jump LBB0_xx
...
LBB0_xx:
...

############ generated instruction sequence
insn1; jump LBB0_xx
...
#BB#xx:
...

BasicBlock BB#xx is commented out when insn1 and "jump LBB0_xx" is
bundled.
I guess the reference to LBB0_xx is deconstructed when insn1 and LBB0_xx
are packetized together thus BB#xx is commented out.

What should we do if the reference to LBB0_xx has to be maintained?

Thanks ahead!

--
杨勇勇 (Yang Yong-Yong)
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Yang,

 

  There is not enough info here to understand what is going wrong – what is your
target? Is dependency dag correct going into scheduling and packetization?

 

Sergei 

 

---

Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The
Linux Foundation

 

From: llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at cs.uiuc.edu] On
Behalf Of ???
Sent: Sunday, November 10, 2013 8:31 PM
To: LLVM-Dev ‎[llvmdev at cs.uiuc.edu]‎
Subject: [LLVMdev] basic block missing after MachineInstr packetizing

 

Hi, all,

 

When I schedule machine instructions in a VLIW way and packetize them, a problem
is encountered, and I will show it use a simplified case as follows.

 

############ original instruction sequence

...

insn1

...

jump  LBB0_xx

...

LBB0_xx:

...

 

############ expected instruction sequence after scheduling and packetizing

insn1; jump LBB0_xx


...

LBB0_xx:

...

 

############ generated instruction sequence

insn1; jump LBB0_xx


...

#BB#xx:

...

 

BasicBlock BB#xx is commented out when insn1 and "jump LBB0_xx" is
bundled.

I guess the reference to LBB0_xx is deconstructed when insn1 and LBB0_xx are
packetized together thus BB#xx is commented out.

 

What should we do if the reference to LBB0_xx has to be maintained?

 

Thanks ahead!


--

杨勇勇 (Yang Yong-Yong) 

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Sergei, Thank you for your attention.

My target is a custom VLIW DSP. I am not sure dependency dag is correct
when it gets scheduled and packetized. Months ago, I submitted a bug at
http://llvm.org/bugs/show_bug.cgi?id=17894 which explained more details.

I am not sure my understanding of this bug is proper, but modified my local
codes this way and it works for my target when scheduling and packetizing.

Well why this problem does not occur for Hexagon target?

Regards.


2014/1/9 Sergei Larin <slarin at codeaurora.org>
> Yang,
>
>
>
>   There is not enough info here to understand what is going wrong – what
> is your target? Is dependency dag correct going into scheduling and
> packetization?
>
>
>
> Sergei
>
>
>
> ---
>
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted
> by The Linux Foundation
>
>
>
> *From:* llvmdev-bounces at cs.uiuc.edu [mailto:llvmdev-bounces at
cs.uiuc.edu] *On
> Behalf Of *???
> *Sent:* Sunday, November 10, 2013 8:31 PM
> *To:* LLVM-Dev ‎[llvmdev at cs.uiuc.edu]‎
> *Subject:* [LLVMdev] basic block missing after MachineInstr packetizing
>
>
>
> Hi, all,
>
>
>
> When I schedule machine instructions in a VLIW way and packetize them, a
> problem is encountered, and I will show it use a simplified case as
follows.
>
>
>
> ############ original instruction sequence
>
> ...
>
> insn1
>
> ...
>
> jump  LBB0_xx
>
> ...
>
> LBB0_xx:
>
> ...
>
>
>
> ############ expected instruction sequence after scheduling and packetizing
>
> insn1; jump LBB0_xx
>
> ...
>
> LBB0_xx:
>
> ...
>
>
>
> ############ generated instruction sequence
>
> insn1; jump LBB0_xx
>
> ...
>
> #BB#xx:
>
> ...
>
>
>
> BasicBlock BB#xx is commented out when insn1 and "jump LBB0_xx"
is bundled.
>
> I guess the reference to LBB0_xx is deconstructed when insn1 and LBB0_xx
> are packetized together thus BB#xx is commented out.
>
>
>
> What should we do if the reference to LBB0_xx has to be maintained?
>
>
>
> Thanks ahead!
>
>
> --
>
> 杨勇勇 (Yang Yong-Yong)
>


-- 
杨勇勇 (Yang Yong-Yong)
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