[llvm-dev] How to interpret Selection DAG error output

Rail Shafigulin via llvm-dev llvm-dev at lists.llvm.org
Thu Feb 18 13:30:30 PST 2016

On Thu, Feb 18, 2016 at 12:20 PM, Krzysztof Parzyszek <
kparzysz at codeaurora.org> wrote:

> On 2/18/2016 2:18 PM, Rail Shafigulin wrote:
>> Thanks. I keep forgetting that I have grep at my disposal :) What I'm
>> not clear about is the first parameter in CopyFromReg node. 0x3283608:
>> i32,ch = CopyFromReg 0x3257980, 0x3283500 [ORD=1]. Based on the comments
>> for CopyFromReg, if I understand it correctly, there should be 1 input,
>> virtual or physical register, which is what is given in the pattern as a
>> second argument. So what is the first one. What does it do?
> It's a chain, it's used to maintain relative ordering between nodes. Both
> CopyToReg and CopyFromReg have the same arguments.  I agree, it's not clear
> from the comments.

Thanks for the explanation.

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

Rail Shafigulin
Software Engineer
Esencia Technologies
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