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Date:   Tue, 5 Dec 2023 13:04:49 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     tanzirh@google.com
Cc:     Kees Cook <keescook@chromium.org>,
        Andy Shevchenko <andy@kernel.org>,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org,
        Nick DeSaulniers <nnn@google.com>, llvm@lists.linux.dev
Subject: Re: [PATCH] lib/string: shrink lib/string.i via IWYU
Message-Id: <20231205130449.8e330a26ecbed1f7b5ad5d7a@linux-foundation.org>
In-Reply-To: <20231205-libstringheader-v1-1-7f9c573053a7@gmail.com>
References: <20231205-libstringheader-v1-1-7f9c573053a7@gmail.com>
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On Tue, 05 Dec 2023 20:58:53 +0000 tanzirh@google.com wrote:

> This diff uses an open source tool include-what-you-use (IWYU) to modify
> the include list changing indirect includes to direct includes.
> IWYU is implemented using the IWYUScripts github repository which is a tool that is
> currently undergoing development. These changes seek to improve build times.
> 
> This change to lib/string.c resulted in a preprocessed size of
> lib/string.i from 26371 lines to 5232 lines (-80%).
> 
> If there are any problems with the output of the tool please raise an
> issue on the github.
> 
> Link: https://github.com/ClangBuiltLinux/IWYUScripts

Issue:

> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -16,16 +16,16 @@
>  
>  #define __NO_FORTIFY
>  #include <linux/types.h>
> +#include <asm/bitsperlong.h>

The preferred way to import bit-fiddling stuff is to include
<linux/bits.h>.  Under the hood this may include asm/bitsperlong.h.  Or
it may not, depending on Kconfig settings (particularly architecture).