> On Jul 8, 2015, at 12:02 PM, Laszlo Ersek <ler...@redhat.com> wrote:
>
>>
>> It should be noted that once in a while I run into this sort of thing in
>> VxWorks as well, only it's often the other way around. We typically have
>> DEBUG()-style messages turned off by default, and sometimes there are debug
>> messages that refer to variables which no longer exist in the code. (The
>> variables were removed but the debug messages were never updated to match.)
>
> SeaBIOS employs the following trick to avoid this: all CONFIG_XXXX flags
> are checked in regular if() statements, not in #if macros. That is, any
> elmination happens during compilation / optimization / linking, not in
> preprocessing. This allows the compiler to catch such errors even when a
> CONFIG_XXXX option is predominantly false (or predominantly true).
This is how the edk2 works. Your platform has to “opt-in” to the #if. The
default is to use PCDs, and that is what happens on VC++. The MDEPKG_NDEBUG
#define was added for compilers, like gcc, that could not dead strip the code.
https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg/Include/Library/DebugLib.h
<https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg/Include/Library/DebugLib.h>
#if !defined(MDEPKG_NDEBUG)
#define ASSERT(Expression) \
do { \
if (DebugAssertEnabled ()) { \
if (!(Expression)) { \
_ASSERT (Expression); \
} \
} \
} while (FALSE)
#else
#define ASSERT(Expression)
#endif
If you are not using the optional MDEPKG_NDEBUG flag then DEBUG and ASSERT
macros just become policy for a release build based on PCD.
Also in most of the DebugLib instances what do on the ASSERT is a policy choice
(breakpoint, dead loop, no-op).
https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg/Library/BaseDebugLibSerialPort/DebugLib.c
<https://svn.code.sf.net/p/edk2/code/trunk/edk2/MdePkg/Library/BaseDebugLibSerialPort/DebugLib.c>
VOID
EFIAPI
DebugAssert (
IN CONST CHAR8 *FileName,
IN UINTN LineNumber,
IN CONST CHAR8 *Description
)
{
CHAR8 Buffer[MAX_DEBUG_MESSAGE_LENGTH];
//
// Generate the ASSERT() message in Ascii format
//
AsciiSPrint (Buffer, sizeof (Buffer), "ASSERT %a(%d): %a\n", FileName,
LineNumber, Description);
//
// Send the print string to the Console Output device
//
SerialPortWrite ((UINT8 *)Buffer, AsciiStrLen (Buffer));
//
// Generate a Breakpoint, DeadLoop, or NOP based on PCD settings
//
if ((PcdGet8(PcdDebugPropertyMask) &
DEBUG_PROPERTY_ASSERT_BREAKPOINT_ENABLED) != 0) {
CpuBreakpoint ();
} else if ((PcdGet8(PcdDebugPropertyMask) &
DEBUG_PROPERTY_ASSERT_DEADLOOP_ENABLED) != 0) {
CpuDeadLoop ();
}
}
Thanks,
Andrew Fish
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