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Subject: Re: [edk2-devel] [PATCH] MdePkg: DebugLib: Compilation fix for clang-13.
To: devel@edk2.groups.io, michael.d.kinney@intel.com,
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From: "Michael Brown" <mcb30@ipxe.org>
Message-ID: <8d9101ac-fbda-eecf-950e-692fa375c3f9@ipxe.org>
Date: Mon, 22 Nov 2021 23:17:21 +0000
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On 22/11/2021 16:42, Michael D Kinney wrote:
> You are also modifying the DebugLib in the paths where ASSERT() macros
> are disabled.  When they are disabled, we want all code/data associated
> with ASSERT() to be removed by the optimizing compiler/linker.  The source
> code change appears to force a reference to a variable/expression.  Does
> this have any size impact to any of the toolchains when ASSERT() is
> disabled?  Can you provide the size comparison before and after this
> change?

I would very strongly recommend having the non-debug version of the 
macro use something like:

#define ASSERT(Expression) do {   \
     if (FALSE) {                  \
       (VOID) (Expression);        \
     }                             \
   } while (FALSE)

Without the "if (FALSE)", you will find that an expression that may have 
side-effects (e.g. by calling an external function) will result in 
executable code being generated.

Michael