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From: Erick Ochoa <erick.ochoa@theobroma-systems.com>
Subject: Option flag with string arguments
To: GCC Development <gcc@gcc.gnu.org>
Cc: =?UTF-8?Q?Christoph_M=c3=bcllner?= <christoph.muellner@theobroma-systems.com>, "Dr. Philipp Tomsich" <philipp.tomsich@theobroma-systems.com>
Message-ID: <880c8375-41c6-eb54-7a3c-79e88c066b33@theobroma-systems.com>
Date: Thu, 19 Dec 2019 21:47:00 -0000
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Hello,

I am working on testing an optimization. I am starting to write
tests in the GCC testing suite. However, I want to develop some
fine grain testing for my own sake.

This optimization I am working on, is a variant of struct reordering.
One way I would like to test my pass is for example, making a test case
and guaranteeing that my pass is able to detect global variables of
a specific struct type.

For example, given the following C file

```
/* { dg-lto-options {{-flto -fipa-struct-reorg -fipa-struct-reorg-assert-has-structs=astruct_s}} } */

struct astruct_s { _Bool a; };
struct astruct_s astruct;

int main() { };
```

I would like to create the option flag that has a list of string arguments

-fipa-struct-reorg-assert-has-structs=<string>+

such that during the analysis time, I'd be able to have an assertion
to make sure that my pass has actually collected the types identified by the
strings.
I'm not very familiar on the DSL to specify option flags.
I've looked at gcc/common.opt for some examples and found this one:

```
frandom-seed=
Common Joined RejectNegative Var(common_deferred_options) Defer
-frandom-seed=<string>  Make compile reproducible using <string>.
```

Could anyone explain how to specify my flag? Or possibly
point to some documentation/source that explains Common, Joined, etc...?