[dejagnu] Remove default mabi and march from CFLAGS

[yaroslavsadin]

Default -mabi and -march mess with some tests' settings which results in errors.

[luismgsilva]

Out of curiosity, how are you passing the -mtune? "CFLAGS_FOR_TARGET"?

[yaroslavsadin]

Out of curiosity, how are you passing the -mtune? "CFLAGS_FOR_TARGET"?

This is done internally using ARC_MULTILIB_OPTIONS env variable and then processed here:

toolchain/dejagnu/arc-common.exp

Line 24 in 1daf90d

return $env(ARC_MULTILIB_OPTIONS)

For historical reasons the code to run DejaGNU is split between this repo and VAS.

[yaroslavsadin]

@luismgsilva Not sure if removing -march wouldn't results in issues due to missing extensions. Probably we need to test this first.

Note the nSIM flags:

toolchain/dejagnu/baseboards/arc-sim-nsimdrv.exp

Line 220 in 1daf90d

"-all.i.zicsr.zifencei.zihintpause.b.zca.zcb.zcmp.zcmt.a.m.zbb.zba.zbs"

[luismgsilva]

Isn't it possible to use a simulator wrapper? Like @kolerov did: foss-for-synopsys-dwc-arc-processors/arcv-gnu-toolchain@0008616

[yaroslavsadin]

Isn't it possible to use a simulator wrapper? Like @kolerov did: foss-for-synopsys-dwc-arc-processors/arcv-gnu-toolchain@0008616

I think we can, but the question is, are we good leaving -march and -mabi empty, as majority of the tests won't have them defined? Are there any defaults we're ok with and can deduct from the resulting ELF file?

[luismgsilva]

Isn't it possible to use a simulator wrapper? Like @kolerov did: foss-for-synopsys-dwc-arc-processors/arcv-gnu-toolchain@0008616

I think we can, but the question is, are we good leaving -march and -mabi empty, as majority of the tests won't have them defined? Are there any defaults we're ok with and can deduct from the resulting ELF file?

The configuration used to build the toolchain is used as default when invoking GCC.

[yaroslavsadin]

The configuration used to build the toolchain is used as default when invoking GCC.

Guess that's not that easy:

$ riscv64-elf-gcc -mtune=arc-v-rmx-100-series test.c 
riscv64-elf-gcc: fatal error: Cannot find suitable multilib set for '-march=rv64imafdc_zicsr_zifencei'/'-mabi=lp64d'
compilation terminated.