ARM ELF parser does not recognize EABI attributes

[llvmbot]

Bugzilla Link	15172
Resolution	FIXED
Resolved on	Feb 21, 2014 05:20
Version	trunk
OS	All
Blocks	llvm/llvm-bugzilla-archive#18926
Reporter	LLVM Bugzilla Contributor
CC	@rengolin

Extended Description

With target 'arm-linux-androideabi' or 'arm-none-linux-gnueabi', clang cannot consume the ARM assembly it generates:

$ echo "void a(){}" | clang -x c -S - -o - | clang -x assembler -c - -integrated-as

:2:2: error: unknown directive
.eabi_attribute 6, 2

[rengolin]

Example:

test.c:
void main {return;}

commandline:
arm-linux-clang -Iarm-2013.05-24-arm-none-linux/arm-none-linux-gnueabi/libc/usr/include -integrated-as -msoft-float -save-temps -O3 -mcpu=cortex-a8 -c -o test.o test.c

Errors:
ffconf.rmzKnl5U.s:2:2: error: unknown directive
.cpu cortex-a8
^
ffconf.rmzKnl5U.s:3:2: error: unknown directive
.eabi_attribute 6, 10
^

[llvmbot]

Since r193524, all LLVM-generated directives can be parsed and assembled.

However, there are still some work to do. The eabi_attribute is not fully implemented. Following list of tags are not recognized:

Tag_CPU_raw_name (NTBS)
Tag_compatibility (ULEB128, NTBS)
Tag_also_compatible_with (ULEB128, ULEB128), (ULEB128, NTBS)
Tag_conformance (STRING)

[llvmbot]

Is there any plan to support parsing named eabi_attributes in assembly to match gnu as (https://sourceware.org/binutils/docs/as/ARM-Directives.html)?

For example,
.eabi_attribute Tag_ABI_align_needed, 1

instead of
.eabi_attribute 24, 1

[rengolin]

Hi David,

Yes, the plan is to support them all, but I don't know if anyone is looking at these particular examples you shown. Certainly, adding them to this bug would be a good help.

Feel free to work on them, too, if you can. ;)

--renato

[llvmbot]

Here is the list of attribute tag names support by gnu as that I think we should also support:

Tag_CPU_raw_name, Tag_CPU_name, Tag_CPU_arch, Tag_CPU_arch_profile, Tag_ARM_ISA_use, Tag_THUMB_ISA_use, Tag_FP_arch, Tag_WMMX_arch, Tag_Advanced_SIMD_arch, Tag_PCS_config, Tag_ABI_PCS_R9_use, Tag_ABI_PCS_RW_data, Tag_ABI_PCS_RO_data, Tag_ABI_PCS_GOT_use, Tag_ABI_PCS_wchar_t, Tag_ABI_FP_rounding, Tag_ABI_FP_denormal, Tag_ABI_FP_exceptions, Tag_ABI_FP_user_exceptions, Tag_ABI_FP_number_model, Tag_ABI_align_needed, Tag_ABI_align_preserved, Tag_ABI_enum_size, Tag_ABI_HardFP_use, Tag_ABI_VFP_args, Tag_ABI_WMMX_args, Tag_ABI_optimization_goals, Tag_ABI_FP_optimization_goals, Tag_compatibility, Tag_CPU_unaligned_access, Tag_FP_HP_extension, Tag_ABI_FP_16bit_format, Tag_MPextension_use, Tag_DIV_use, Tag_nodefaults, Tag_also_compatible_with, Tag_conformance, Tag_T2EE_use, Tag_Virtualization_use

This list is taken from the document linked above. It also says,

Note - the following legacy values are also accepted by tag: Tag_VFP_arch, Tag_ABI_align8_needed, Tag_ABI_align8_preserved, Tag_VFP_HP_extension,

I'm not sure if we want to support those as well.

[rengolin]

Commit r198662 added all named tags.

[rengolin]

mentioned in issue llvm/llvm-bugzilla-archive#18926