> On Mar 18, 2016, at 3:46 PM, Michael Brown <[email protected]> wrote: > > On 18/03/16 22:30, Laszlo Ersek wrote: >> Unfortunately, I've run into a big issue: the DEBUG(()) macro. (To a >> smaller extent, the ASSERT_EFI_ERROR() macro as well.) These macros >> expand to the null replacement string when MDEPKG_NDEBUG is defined >> (which is occasionally the case for RELEASE builds). If those macro >> invocations constitute the only read accesses to some local variables, >> then the MDEPKG_NDEBUG build triggers "-Wunused-but-set-variable". >> >> For ASSERT_EFI_ERROR(), I could work it around like this: >> >> ((VOID)(TRUE ? 0 : (StatusParameter))) >> >> but I have no clue how to do the same with DEBUG(), which can receive >> any number of arguments (of any type too). > > With the caveat that I haven't looked at how DEBUG() is implemented in EDK2: > > Could this rely upon dead code elimination? At least gcc will happily accept > something which expands to > > if ( 0 ) { > do_something_with ( a_variable ); > } > > and treat that as being a "use" of a_variable (for the purposes of > -Wunused-but-set-variable). >
All the DEBUG macros work this way all ready. MDEPKG_NDEBUG was a hack-a-round for compilers that don't do link time optimization. So you don't need to redefine anything, just don't use MDEPKG_NDEBUG. That will give you the same path as VC++ and clang (assuming LTO is enabled). https://github.com/tianocore/edk2/blob/master/MdePkg/Include/Library/DebugLib.h #if !defined(MDEPKG_NDEBUG) #define DEBUG(Expression) \ do { \ if (DebugPrintEnabled ()) { \ _DEBUG (Expression); \ } \ } while (FALSE) #else #define DEBUG(Expression) #endif If you have code that only exists in DEBUG builds you can use these macros to isolate it. /** Macro that marks the beginning of debug source code. If the DEBUG_PROPERTY_DEBUG_CODE_ENABLED bit of PcdDebugProperyMask is set, then this macro marks the beginning of source code that is included in a module. Otherwise, the source lines between DEBUG_CODE_BEGIN() and DEBUG_CODE_END() are not included in a module. **/ #define DEBUG_CODE_BEGIN() do { if (DebugCodeEnabled ()) { UINT8 __DebugCodeLocal /** The macro that marks the end of debug source code. If the DEBUG_PROPERTY_DEBUG_CODE_ENABLED bit of PcdDebugProperyMask is set, then this macro marks the end of source code that is included in a module. Otherwise, the source lines between DEBUG_CODE_BEGIN() and DEBUG_CODE_END() are not included in a module. **/ #define DEBUG_CODE_END() __DebugCodeLocal = 0; __DebugCodeLocal++; } } while (FALSE) Note you only get the dead stripping if DebugPrintEnabled() or DebugCodeEnabled() resolve to a constant value at link time. The dead stripping of sets of strings is controller by PcdFixedDebugPrintErrorLevel. Thanks, Andrew Fish > Michael _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
