[BUG] GCC assembler flags produce warnings when cmake is used.

[Hadatko]

Describe the bug Does assembler compiler needs so many flags you are providing in CmakeList.txt?

I was searching trought internet and it looks like these compiler flags are more or less C specific flags and not assembler. Actually i am not sure if any of mentioned above is usefull maybe only DNDEBUG or DDEBUG. This is related to all examples of all projects. I guess assembler should contains only application specific macros as there is none compiler specific (if i am wrong, correct me)

Why is this issue to me? For example combination of ENABLE_LANGUAGE(ASM) and -std=gnu99: https://github.com/microsoft/vscode-cmake-tools/issues/2044#issuecomment-896991481 It would be better to get rid of useless compiler macros for assembler. So many not used flags for assembler target has also another side-effect data "noise" in file (file with flags can be smaller and more transparent)

To Reproduce Look into assembler flags for armgcc

Expected behavior Smaller file with flags for compiler. More transparent

[Hadatko]

Actually i printed /arm-none-eabi-as --help So from asm flags above it looks like these are not related to asm compiler:

• -fno-common
• -ffunction-sections
• -fdata-sections
• -ffreestanding
• -fno-built
• -std=gnu99 (i have warning because this one is used)

mapcs looks like incompletly flag.

asm.txt

[mcuxsusan]

Hi @Hadatko , thanks for reporting the issue. Will try to reproduce the issue and see how shall we resolve the incorrect ASM flags. For -mapcs, I agree this is incomplete flag, will check with team. Appreciate for patience.

[Hadatko]

I found this note related to arm options 3.19.5

[mcuxsusan]

@Hadatko, thanks for clarification on why -maps now seems an incomplete flag.

[mcuxsusan]

Hi @Hadatko, I reproduced the warning "[cpptools] Unknown language: ASM" with cmake-tools in vscode. And you are correct, it's caused by the incorrect ASM flag '-std=gnu99', we will fix it in next release. For below flags you listed, currently in our implementation they are parsing to arm-none-eabi-gcc to assemble ASM files, not parse to the arm-none-eabi-as. I am not sure whether the options received via gcc will directly parse to the assembler, but per my test, these options could be removed because there's no difference in map file and elf file.

• -fno-common
• -ffunction-sections
• -fdata-sections
• -ffreestanding
• -fno-built
• -mapcs

[Hadatko]

I guess there was reason for -mapcs in past. Did you tested also -mapcs-frame? Thank you very much to solving this. I will close issue as you are going to solve it internally.

[mcuxsusan]

Yes, I tested also -mapcs-frame, for ASM flags, this should be removed because it does not have affect either map or elf, could be removed. For C flags, the generated elf and output map shows difference for debug_str location, the binary is same. But checking the documentation, the -mapcs-frame option is also deprecated.

-mapcs-frame Generate a stack frame that is compliant with the ARM Procedure Call Standard for all functions, even if this is not strictly necessary for correct execution of the code. Specifying ‘-fomit-frame-pointer’ with this option causes the stack frames not to be generated for leaf functions. The default is ‘-mno-apcs-frame’. This option is deprecated.