arm_options.txt

# -mapcs-frame  # deprecated
# -mno-apcs-frame  # deprecated

# Use AAPCS = Procedure Call Standard for the ARM Architecture
# references:
# http://kanj.github.io/elfs/book/armMusl/cross-tools/abi.html
# https://stackoverflow.com/questions/10494848/arm-whats-the-difference-between-apcs-and-aapcs-abi
-mabi=aapcs

# TODO: do i need it?
# -mapcs-stack-check
# -mno-apcs-stack-check

# No need for Position Independent Code generation usually
# -mapcs-reentrant
-mno-apcs-reentrant

# Allow reordering instructions in the function prologue
-msched-prolog
# -mno-sched-prolog 

# STM32F0xxx Cortex-M0 programming manual p. 17
-mlittle-endian
# -mbig-endian 

# Meaningless when we use little-endian images only
# -mbe8  -mbe32 

# No FPU. Use library calls for floating-point operations; update: fp disabled
# -mfloat-abi=soft
# -mfp16-format=name

# meaningless in AAPCS
# -mthumb-interwork 
# -mno-thumb-interwork 

# STM32F0 have Cortex-M0 processors
-mcpu=cortex-m0

# Cortex-M0 is ARMv6-M architecture; disable floating-point instructions
-march=armv6+nofp

# No FPU nor FP instructions (thanks to -nofp in -march)
# -mfpu=

# STM32F0 have Cortex-M0 processors; update: it's specified by -mcpu
# -mtune=cortex-m0

# Option for testing the compiler, irrelevant
# -mprint-tune-info

# Deprecated
# -mstructure-size-boundary=n

# Seems legit to abort when noreturn function tries to return
-mabort-on-noreturn

# Meaningless since the called function addr offset won't be greater than 64MB
# -mlong-calls
# -mno-long-calls

# No PIC
# -msingle-pic-base
# -mno-single-pic-base
# -mpic-register=reg

# Undocumented
-mnop-fun-dllimport

# We have debug symbol tables, don't need that one
# -mpoke-function-name

# No ARM support on ARMv6-M
-mthumb
# -marm
# -mflip-thumb

# TODO: do I need these 2?
# -mtpcs-frame
# -mtpcs-leaf-frame

# Not valid in AAPCS
# -mcaller-super-interworking 
# -mcallee-super-interworking 

# Use the best option for the given processor
-mtp=auto
# I have no idea what to put there, it doesn't seem very necessary
# -mtls-dialect=dialect

# Makes sense, but I bet it's not so necessary
-mword-relocations

# Meaningless on not-Cortex-M3
# -mfix-cortex-m3-ldrd

# No reading/writing 16-/32-bit values from addr. that aren't 16/32-bit aligned
# -munaligned-access 

# Meaningless
# -mneon-for-64bits
# -mslow-flash-data

# Use unified ASM syntax in inline assembler
-masm-syntax-unified

# The fuck? But seems like irrelevant for ARMv6-M
# -mrestrict-it

# It's for debugging the compiler, meaningless for us
# -mverbose-cost-dump

# No MOVT instruction on ARMv6-M
-mpure-code

# Meaningless on ARMv6-M
-mcmse