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From: Shubham Narlawar <gsocshubham@gmail.com>
Date: Mon, 7 Feb 2022 01:10:45 +0530
Message-ID: <CAN=hqDDKgzBoh0nqrWbQ-4Diq7dp=c76q+msas1PuN+Zr4g23A@mail.gmail.com>
Subject: Query regarding generating NOTE instruction at GIMPLE level
To: GCC Development <gcc@gcc.gnu.org>
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Hello,

Is it possible to generate a NOTE instruction at GIMPLE level?

My use case scenario is as below -
I want to create a note for __builtin_xyz(_x) such that there is a
placeholder just before function call and in RTL pass, I want to
modify/assign register number at this placeholder location.

_x = (unsigned int) _y;
__builtin_xyz(_x);    //_x is constant expression

For above builtin function call, I want to insert a note just before the
function call. I tried generating GIMPLE_NOP instruction as below -

_x = (unsigned int) _y;
GIMPLE_NOP
__builtin_xyz(_x);

But as per my understanding, a NOTE instruction behaves similar to
GIMPLE_NOP that is to create a placeholder for some computation.


1. Is there any attribute that can be added to GIMPLE instruction? If yes,
then there must be a mechanism that translates those attributes to NOTE
instructions in the RTL pass?


2. Is there any different approach on achieving above goal?

Thanks and Regards,
Shubham