llvm dev - Nov 2018 - Convert Register Names to String

Hi.
I want to do a cutomized points-to analysis on IR. Suppose that we have:
*%91 = bitcast i8* %90 to %struct.demux_packet*, !dbg !2688*

I want to store sth similar to %91 -> target of %90, which records the
target of pointer named %91. How can I access the names (Here, %90 and %91)?
I know that I can put the whole line for an instruction into a string,
using the following code:
*string str;*
*llvm::raw_string_ostream ss(str);*
*inst->print(ss);*

But a postprocessing will be needed. I need to parse for parameters which
will not be easy in the general case. I appreciate any help.
Regards.
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Hi Ahmad,

On Sun, 11 Nov 2018 at 13:39, Ahmad Nouralizadeh Khorrami via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
> I want to do a cutomized points-to analysis on IR. Suppose that we have:
> %91 = bitcast i8* %90 to %struct.demux_packet*, !dbg !2688
>
> I want to store sth similar to %91 -> target of %90, which records the
target of pointer named %91. How can I access the names (Here, %90 and %91)?
Unfortunately it's not trivial. You can see the logic used in
AssemblyWriter::printInstruction (in lib/IR/AsmWriter.cpp).

It boils down to using Instruction::getName if it exists, otherwise
there's a special class called ModuleSlotTracker (the "Machine"
instance in that function) that gives each unnamed value a number.
You'd have to create one of those yourself; I had a quick look at the
header and it actually seems pretty easy to use, which was a pleasant
surprise.

Cheers.

Tim.

Hi Tim,
Thanks for the nice answer. The code that you mentioned, seems to generate
the IR. You mean I should reuse the code to extract and output the register
names in a file. Next, I should postprocess the file in my own pass?
Regards.

On Mon, 12 Nov 2018 at 13:09, Tim Northover <t.p.northover at gmail.com>
wrote:
> Hi Ahmad,
>
> On Sun, 11 Nov 2018 at 13:39, Ahmad Nouralizadeh Khorrami via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> > I want to do a cutomized points-to analysis on IR. Suppose that we
have:
> > %91 = bitcast i8* %90 to %struct.demux_packet*, !dbg !2688
> >
> > I want to store sth similar to %91 -> target of %90, which records
the
> target of pointer named %91. How can I access the names (Here, %90 and
%91)?
>
> Unfortunately it's not trivial. You can see the logic used in
> AssemblyWriter::printInstruction (in lib/IR/AsmWriter.cpp).
>
> It boils down to using Instruction::getName if it exists, otherwise
> there's a special class called ModuleSlotTracker (the
"Machine"
> instance in that function) that gives each unnamed value a number.
> You'd have to create one of those yourself; I had a quick look at the
> header and it actually seems pretty easy to use, which was a pleasant
> surprise.
>
> Cheers.
>
> Tim.
>
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