Re: [edk2-devel] [PATCH V2 2/2] BaseTools: Factorize GCC flags

["Laszlo Ersek" <lersek@redhat.com>]

On 07/22/20 13:03, Laszlo Ersek wrote:
> Hi Pierre,
> 
> On 07/07/20 10:35, PierreGondois wrote:
>> From: Pierre Gondois <pierre.gondois@arm.com>
>>
>> GCC48_ALL_CC_FLAGS has no dependency on GCC_ALL_CC_FLAGS.
>> By definition, there should be such dependency.
>>
>> The outcomes of this patch is that GCC48_ALL_CC_FLAGS and
>> other dependent configurations will inherit from the
>> additional "-Os" flag.
>> The "-Os" flag optimizes a build in size, not breaking any
>> build. In a gcc command line, the last optimization flag
>> has precedence. This means that this "-Os" flag will be
>> overriden by a more specific optimization configuration,
>> provided that this more specific flag is appended at the
>> end of the CC_FLAGS.
>>
>> Signed-off-by: Pierre Gondois <pierre.gondois@arm.com>
>> Suggested-by: Tomas Pilar <Tomas.Pilar@arm.com>
>> ---
>>
>> The changes can be seen at: https://github.com/PierreARM/edk2/commits/831_Add_gcc_flag_warning_v2
>>
>> Notes:
>>     v2:
>>      - Make GCC48_ALL_CC_FLAGS dependent on
>>        GCC_ALL_CC_FLAGS. [Tomas]
>>
>>  BaseTools/Conf/tools_def.template | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/BaseTools/Conf/tools_def.template b/BaseTools/Conf/tools_def.template
>> index 397b011ba38f97f81f314f8641ac8bb95d5a2197..a1fd27b1adba8769949b7d628d7fbed49fe24267 100755
>> --- a/BaseTools/Conf/tools_def.template
>> +++ b/BaseTools/Conf/tools_def.template
>> @@ -1952,7 +1952,7 @@ DEFINE GCC_RISCV64_RC_FLAGS        = -I binary -O elf64-littleriscv   -B riscv
>>  # GCC Build Flag for included header file list generation
>>  DEFINE GCC_DEPS_FLAGS              = -MMD -MF $@.deps
>>  
>> -DEFINE GCC48_ALL_CC_FLAGS            = -g -fshort-wchar -fno-builtin -fno-strict-aliasing -Wall -Werror -Wno-array-bounds -ffunction-sections -fdata-sections -include AutoGen.h -fno-common -DSTRING_ARRAY_NAME=$(BASE_NAME)Strings
>> +DEFINE GCC48_ALL_CC_FLAGS            = DEF(GCC_ALL_CC_FLAGS) -ffunction-sections -fdata-sections -DSTRING_ARRAY_NAME=$(BASE_NAME)Strings
>>  DEFINE GCC48_IA32_X64_DLINK_COMMON   = -nostdlib -Wl,-n,-q,--gc-sections -z common-page-size=0x20
>>  DEFINE GCC48_IA32_CC_FLAGS           = DEF(GCC48_ALL_CC_FLAGS) -m32 -march=i586 -malign-double -fno-stack-protector -D EFI32 -fno-asynchronous-unwind-tables -Wno-address
>>  DEFINE GCC48_X64_CC_FLAGS            = DEF(GCC48_ALL_CC_FLAGS) -m64 -fno-stack-protector "-DEFIAPI=__attribute__((ms_abi))" -maccumulate-outgoing-args -mno-red-zone -Wno-address -mcmodel=small -fpie -fno-asynchronous-unwind-tables -Wno-address
>>
> 
> As the commit message states, this change makes GCC48_ALL_CC_FLAGS inherit "-Os".
> 
> It is true that all the NOOPT_GCC flags override "-Os" with "-O0":
> 
> NOOPT_GCC48_IA32_CC_FLAGS       = DEF(GCC48_IA32_CC_FLAGS) -O0
> NOOPT_GCC48_X64_CC_FLAGS       = DEF(GCC48_X64_CC_FLAGS) -O0
> NOOPT_GCC48_ARM_CC_FLAGS       = DEF(GCC48_ARM_CC_FLAGS) -O0
> NOOPT_GCC48_AARCH64_CC_FLAGS   = DEF(GCC48_AARCH64_CC_FLAGS) -O0
> NOOPT_GCC49_IA32_CC_FLAGS       = DEF(GCC49_IA32_CC_FLAGS) -O0
> NOOPT_GCC49_X64_CC_FLAGS       = DEF(GCC49_X64_CC_FLAGS) -O0
> NOOPT_GCC49_ARM_CC_FLAGS       = DEF(GCC49_ARM_CC_FLAGS) -O0
> NOOPT_GCC49_AARCH64_CC_FLAGS     = DEF(GCC49_AARCH64_CC_FLAGS) -O0
> NOOPT_GCC5_IA32_CC_FLAGS       = DEF(GCC5_IA32_CC_FLAGS) -O0
> NOOPT_GCC5_X64_CC_FLAGS        = DEF(GCC5_X64_CC_FLAGS) -O0
> NOOPT_GCC5_ARM_CC_FLAGS        = DEF(GCC5_ARM_CC_FLAGS) -O0
> NOOPT_GCC5_AARCH64_CC_FLAGS    = DEF(GCC5_AARCH64_CC_FLAGS) -O0
> 
> However, *some* of the DEBUG and RELEASE flags now have two "-Os" flags:
> 
>   DEBUG_GCC48_IA32_CC_FLAGS       = DEF(GCC48_IA32_CC_FLAGS) -Os
> RELEASE_GCC48_IA32_CC_FLAGS       = DEF(GCC48_IA32_CC_FLAGS) -Os -Wno-unused-but-set-variable
>   DEBUG_GCC48_X64_CC_FLAGS       = DEF(GCC48_X64_CC_FLAGS) -Os
> RELEASE_GCC48_X64_CC_FLAGS       = DEF(GCC48_X64_CC_FLAGS) -Os -Wno-unused-but-set-variable
>   DEBUG_GCC49_IA32_CC_FLAGS       = DEF(GCC49_IA32_CC_FLAGS) -Os
> RELEASE_GCC49_IA32_CC_FLAGS       = DEF(GCC49_IA32_CC_FLAGS) -Os -Wno-unused-but-set-variable -Wno-unused-const-variable
>   DEBUG_GCC49_X64_CC_FLAGS       = DEF(GCC49_X64_CC_FLAGS) -Os
> RELEASE_GCC49_X64_CC_FLAGS       = DEF(GCC49_X64_CC_FLAGS) -Os -Wno-unused-but-set-variable -Wno-unused-const-variable
>   DEBUG_GCC5_IA32_CC_FLAGS       = DEF(GCC5_IA32_CC_FLAGS) -flto -Os
> RELEASE_GCC5_IA32_CC_FLAGS       = DEF(GCC5_IA32_CC_FLAGS) -flto -Os -Wno-unused-but-set-variable -Wno-unused-const-variable
>   DEBUG_GCC5_X64_CC_FLAGS        = DEF(GCC5_X64_CC_FLAGS) -flto -DUSING_LTO -Os
> RELEASE_GCC5_X64_CC_FLAGS        = DEF(GCC5_X64_CC_FLAGS) -flto -DUSING_LTO -Os -Wno-unused-but-set-variable -Wno-unused-const-variable
> 
> (The ARM and AARCH64 DEBUG/RELEASE GCC options don't seem to be affected, as they have relied on inherited -- not open-coded -- "-Os" options from much earlier. So now they do not suffer from this duplication.)
> 
> The point of this patch was a kind of "normalization", so I think the work isn't complete until the duplication is undone, i.e., the explicit "-Os" flag is removed from the last twelve defines.
> 
> Can you submit a follow-up patch please?

I have not received an answer, and I'm not aware of a follow-up patch
being on the list; so now I've filed:

https://bugzilla.tianocore.org/show_bug.cgi?id=2928

Thanks
Laszlo