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[thirdparty/gcc.git] / gcc / config / avr / avr.opt

; Options for the ATMEL AVR port of the compiler.

; Copyright (C) 2005-2021 Free Software Foundation, Inc.
;
; This file is part of GCC.
;
; GCC is free software; you can redistribute it and/or modify it under
; the terms of the GNU General Public License as published by the Free
; Software Foundation; either version 3, or (at your option) any later
; version.
;
; GCC is distributed in the hope that it will be useful, but WITHOUT ANY
; WARRANTY; without even the implied warranty of MERCHANTABILITY or
; FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
; for more details.
;
; You should have received a copy of the GNU General Public License
; along with GCC; see the file COPYING3.  If not see
; <http://www.gnu.org/licenses/>.

mcall-prologues
Target Mask(CALL_PROLOGUES)
Use subroutines for function prologues and epilogues.

mmcu=
Target RejectNegative Joined Var(avr_mmcu) MissingArgError(missing device or architecture after %qs)
-mmcu=MCU	Select the target MCU.

mgas-isr-prologues
Target Var(avr_gasisr_prologues) UInteger Init(0)
Allow usage of __gcc_isr pseudo instructions in ISR prologues and epilogues.

mn-flash=
Target RejectNegative Joined Var(avr_n_flash) UInteger Init(-1)
Set the number of 64 KiB flash segments.

mskip-bug
Target Mask(SKIP_BUG)
Indicate presence of a processor erratum.

mrmw
Target Mask(RMW)
Enable Read-Modify-Write (RMW) instructions support/use.

mdeb
Target Undocumented Mask(ALL_DEBUG)

mlog=
Target RejectNegative Joined Undocumented Var(avr_log_details)

mshort-calls
Target RejectNegative Mask(SHORT_CALLS)
Use RJMP / RCALL even though CALL / JMP are available.

mint8
Target Mask(INT8)
Use an 8-bit 'int' type.

mno-interrupts
Target RejectNegative Mask(NO_INTERRUPTS)
Change the stack pointer without disabling interrupts.

mbranch-cost=
Target Joined RejectNegative UInteger Var(avr_branch_cost) Init(0)
Set the branch costs for conditional branch instructions.  Reasonable values are small, non-negative integers.  The default branch cost is 0.

mmain-is-OS_task
Target Mask(MAIN_IS_OS_TASK)
Treat main as if it had attribute OS_task.

morder1
Target Undocumented Mask(ORDER_1)

morder2
Target Undocumented Mask(ORDER_2)

mtiny-stack
Target Mask(TINY_STACK)
Change only the low 8 bits of the stack pointer.

mrelax
Target
Relax branches.

mpmem-wrap-around
Target
Make the linker relaxation machine assume that a program counter wrap-around occurs.

maccumulate-args
Target Mask(ACCUMULATE_OUTGOING_ARGS)
Accumulate outgoing function arguments and acquire/release the needed stack space for outgoing function arguments in function prologue/epilogue.  Without this option, outgoing arguments are pushed before calling a function and popped afterwards.  This option can lead to reduced code size for functions that call many functions that get their arguments on the stack like, for example printf.

mstrict-X
Target Var(avr_strict_X) Init(0)
When accessing RAM, use X as imposed by the hardware, i.e. just use pre-decrement, post-increment and indirect addressing with the X register.  Without this option, the compiler may assume that there is an addressing mode X+const similar to Y+const and Z+const and emit instructions to emulate such an addressing mode for X.

;; For rationale behind -msp8 see explanation in avr.h.
msp8
Target RejectNegative Var(avr_sp8) Init(0)
The device has no SPH special function register. This option will be overridden by the compiler driver with the correct setting if presence/absence of SPH can be deduced from -mmcu=MCU.

Waddr-space-convert
Warning C Var(avr_warn_addr_space_convert) Init(0)
Warn if the address space of an address is changed.

Wmisspelled-isr
Warning C C++ Var(avr_warn_misspelled_isr) Init(1)
Warn if the ISR is misspelled, i.e. without __vector prefix. Enabled by default.

mfract-convert-truncate
Target Mask(FRACT_CONV_TRUNC)
Allow to use truncation instead of rounding towards zero for fractional fixed-point types.

mabsdata
Target Mask(ABSDATA)
Assume that all data in static storage can be accessed by LDS / STS.  This option is only useful for reduced Tiny devices.

mdouble=
Target Joined RejectNegative Var(avr_double) Init(0) Enum(avr_bits_e)
-mdouble=<BITS>	Use <BITS> bits wide double type.

mlong-double=
Target Joined RejectNegative Var(avr_long_double) Init(0) Enum(avr_bits_e)
-mlong-double=<BITS>	Use <BITS> bits wide long double type.

nodevicelib
Driver Target RejectNegative
Do not link against the device-specific library lib<MCU>.a.

nodevicespecs
Driver Target RejectNegative
Do not use the device-specific specs file device-specs/specs-<MCU>.

Enum
Name(avr_bits_e) Type(int)
Available BITS selections:

EnumValue
Enum(avr_bits_e) String(32)  Value(32)

EnumValue
Enum(avr_bits_e) String(64) Value(64)