llvm dev - Mar 2021 - Function call replacement

Hi all,

I am trying to replace calls to a function, say foo() with calls to
my_foo(). In the IR file, there is no call to foo(). However, foo() will be
called during execution. I can't use the conventional way to do it (i.e.
locate the call instruction, create a call site and then create a call to
my_foo(), then replace all uses with the return value of my_foo()), because
you can't locate the call instruction. So I tried to swap the name of foo()
and my_foo(). However, this only results in the original function with the
new name being called. I know I must have missed some steps, resulting in
the reference to the original function still existing after the renaming.
The question is, what is the missing step? Thank you so much for reading my
description. I hope I make my question clear.

Best,
Jason
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On Wed, Mar 3, 2021 at 11:55 AM zxhuan via llvm-dev <llvm-dev at
lists.llvm.org>
wrote:
> Hi all,
>
> I am trying to replace calls to a function, say foo() with calls to
> my_foo(). In the IR file, there is no call to foo(). However, foo() will be
> called during execution.
>
Can't say I'm following here ^ there is no call to foo() but it is
called
during execution? Is it called indirectly (eg: void (*x)() = foo; x(); )?
is the call in another module/not this IR file?

> I can't use the conventional way to do it (i.e. locate the call
> instruction, create a call site and then create a call to my_foo(), then
> replace all uses with the return value of my_foo()), because you can't
> locate the call instruction. So I tried to swap the name of foo() and
> my_foo(). However, this only results in the original function with the new
> name being called. I know I must have missed some steps, resulting in the
> reference to the original function still existing after the renaming. The
> question is, what is the missing step? Thank you so much for reading my
> description. I hope I make my question clear.
>
> Best,
> Jason
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
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