Commit 884b05b5 authored by Jozef Lawrynowicz's avatar Jozef Lawrynowicz Committed by Jeff Johnston

MSP430: Remove .init/.fini sections

The .init/.fini sections are not required for msp430-elf, and add unnecessary
code bloat to the CRT library. These sections are specified as "unused" by
the MSP430 EABI.

.init existed to call __crt0_run_{init,preinit}_array which run through
the functions in .{init,preinit}_array.
__crt0_run_{init,preinit}_array are already dynamically included like the
other crt0 functions, so these can be placed before the call to main,
which ensures they are still called if needed.
With these functions moved, .init has no purpose and can be removed.

.fini existed to call __crt0_run_fini_array.
However, the "__msp430_fini" symbol which marks the start of .fini has
never been used, so no termination routines have ever been run for
msp430. On returning from main(), _exit() is called which just loops
forever.
So there is no current expectation that __crt0_run_fini_array will
get called by the CRT code. Further work is to ensure functions
registered with atexit can be optionally called during program termination,
and then __crt0_run_fini_array can be registered with atexit during
program initialization.

The mechanisms for supporting the "-minrt" option have also been removed.
"-minrt" enabled a "minimum runtime environment" by removing calls to
functions which run global static initializers and constructors. Since
this behaviour is now dynamic, and these functions are only included
when needed, the minrt versions of the CRT object files are no longer
required.
parent 6b843b82
......@@ -61,7 +61,7 @@ SCRIPTS = $(srcdir)/msp430-sim.ld
SCRIPTS += $(srcdir)/msp430xl-sim.ld
SCRIPTS += $(srcdir)/intr_vectors.ld
CRT = gcrt0.o crt0.o crt0-minrt.o crtn.o crtn-minrt.o
CRT = gcrt0.o crt0.o
SIM_BSP = libsim.a
LIB_NOSYS = libnosys.a
LIB_CRT = libcrt.a
......@@ -85,7 +85,6 @@ CRT_OBJS = \
crt_movedata.o \
crt_move_highdata.o \
crt_main.o \
crt_main_minrt.o \
crt_callexit.o \
crt_run_init_array.o \
crt_run_preinit_array.o \
......@@ -102,12 +101,6 @@ all: $(CRT) $(SIM_BSP) $(LIB_NOSYS) $(LIB_CRT) copy_scripts_to_objdir
crt_%.o : crt0.S
$(CC) -DL$* -Wa,-gdwarf2 -Wa,-I$(srcdir) $(CFLAGS_FOR_TARGET) $(INCLUDES) $(CFLAGS) -c $< -o $@
crt0-minrt.o : crt0.S
$(CC) -DL0 -DMINRT -Wa,-gdwarf2 -Wa,-I$(srcdir) $(CFLAGS_FOR_TARGET) $(INCLUDES) $(CFLAGS) -c $< -o $@
crtn-minrt.o : crtn.S
$(CC) -DL0 -DMINRT -Wa,-gdwarf2 -Wa,-I$(srcdir) $(CFLAGS_FOR_TARGET) $(INCLUDES) $(CFLAGS) -c $< -o $@
# Override .S.o rule to pass assembler debugging flags
.S.o:
$(CC) -DL0 -Wa,-gdwarf2 -Wa,-I$(srcdir) $(CFLAGS_FOR_TARGET) $(INCLUDES) $(CFLAGS) -c $<
......
......@@ -52,28 +52,25 @@ __msp430_resetvec_hook:
START_CRT_FUNC 0000 start
.refsym __msp430_resetvec_hook
#ifdef MINRT
.refsym __crt0_call_just_main
#else
.refsym __crt0_call_init_then_main
#endif
.refsym __crt0_call_main
mov_ #__stack, R1
END_CRT_FUNC start
#endif
;; Some of the CRT functions below will only be present in the final linked
;; executable if the assembler decides they are needed. It will only define
;; the symbol necessary to prevent them being garbage collected by the linker
;; if the file being assembled has a specific section.
;; The CRT functions this applies to are:
;; init_bss, movedata, move_highdata, init_highbss, run_init_array,
;; run_preinit_array, run_fini_array and run_array.
;; The CRT functions below will only be present in the final linked
;; executable if the assembler decides they are needed. The assembler will
;; only define the symbol necessary to prevent them being garbage collected
;; by the linker if the file being assembled has a specific section,
;; or some other criteria is met.
;; The exception to this is __crt0_call_exit. GCC will include this function
;; if it detects that main() has an epilogue. For example, if main() has a
;; while(1) loop at the end, GCC will not generate an epilogue (since it won't
;; return) and __crt0_call_exit won't be included.
#if Lbss
;; Note - this section is only included in the startup code of the
;; application if it is needed. It is responsible for initializing
;; the contents of the .bss section.
;; This function is responsible for initializing the contents of the
;; .bss section.
START_CRT_FUNC 0100 init_bss
......@@ -91,9 +88,8 @@ END_CRT_FUNC init_bss
#ifdef __MSP430X_LARGE__
#if Lhigh_bss
;; Note - this section is only included in the startup code of the
;; application if it is needed. It is responsible for initializing
;; the contents of the .upper.bss section.
;; This function is responsible for initializing the contents of the
;; .upper.bss section.
START_CRT_FUNC 0200 init_highbss
......@@ -112,8 +108,7 @@ END_CRT_FUNC init_highbss
#if Lmovedata
;; Note - this section is only included in the startup code of the
;; application if it is needed. It is responsible for copying the
;; This function is responsible for copying the
;; contents of the .data section from its load address (in ROM) to
;; its run-time address (in RAM).
......@@ -136,8 +131,7 @@ END_CRT_FUNC movedata
#ifdef __MSP430X_LARGE__
#if Lmove_highdata
;; Note - this section is only included in the startup code of the application
;; if it is needed. It is responsible either for making sure that the
;; This function is responsible for making sure that the
;; contents of the .upper.data section have their correct startup values.
;; If a copy of the .upper.data section is stored in ROM then this means
;; copying the contents into HIFRAM. If a copy of .upper.data is stored in a
......@@ -175,44 +169,62 @@ END_CRT_FUNC move_highdata
#endif /* Lmove_highdata */
#endif /* __MSP430X_LARGE__ */
#if Lrun_preinit_array
;; This function is responsible for setting up the arguments
;; required for __crt0_run_array, to run the functions in .preinit_array.
START_CRT_FUNC 0500 run_preinit_array
mov_ #__preinit_array_start, R4
mov_ #__preinit_array_end, R5
mov_ #PTRsz, R6
call_ #__crt0_run_array
#if Lmain_minrt
;; Note - this section is only included in the startup code of the
;; application if it is needed. It is responsible for just calling
;; main. No initialization code is called first, and main is not
;; expected to return.
END_CRT_FUNC run_preinit_array
#endif /* Lrun_preinit_array */
START_CRT_FUNC 0600 call_just_main
#if Lrun_init_array
;; This function is responsible for setting up the arguments
;; required for __crt0_run_array, to run the functions in .init_array.
START_CRT_FUNC 0600 run_init_array
clr.w R12 ; Set argc == 0
call_ #main
END_CRT_FUNC call_just_main
#endif /* Lmain_minrt */
mov_ #__init_array_start, R4
mov_ #__init_array_end, R5
mov_ #PTRsz, R6
call_ #__crt0_run_array
END_CRT_FUNC run_init_array
#endif /* Lrun_init_array */
#if Lmain
;; Note - this section is only included in the startup code of the
;; application if it is needed. It is responsible for calling the
;; initialization code - constructors, etc - and then main. If main
;; returns then the following section should be present to catch it.
;; FIXME: There are currently no program termination routines executed for
;; msp430.
#if 0
#if Lrun_fini_array
;; Ensure global C++ destructors in .fini_array are called on exit
;; by registering __crt0_run_fini_array with atexit.
START_CRT_FUNC 0700 register_fini_array
mov_ #__crt0_run_fini_array, R12
call_ #atexit
END_CRT_FUNC register_fini_array
#endif /* Lrun_fini_array */
#endif /* 0 */
START_CRT_FUNC 0700 call_init_then_main
#if Lmain
;; This function is always included and calls main().
call_ #__msp430_init
START_CRT_FUNC 0800 call_main
clr.w R12 ; Set argc == 0
call_ #main
END_CRT_FUNC call_init_then_main
END_CRT_FUNC call_main
#endif /* Lmain */
#if Lcallexit
;; Note - this section is only included in the startup code of the
;; application if it is needed. It is responsible for calling exit
;; once main has finished.
;; This function is responsible for calling exit once main has finished.
START_CRT_FUNC 0800 call_exit
START_CRT_FUNC 0900 call_exit
call_ #_exit
......@@ -221,46 +233,15 @@ END_CRT_FUNC call_exit
;----------------------------------------
#ifndef MINRT
#if Lrun_preinit_array
;; Note - this section is only included in the startup code of the application
;; if it is needed. It is responsible for setting up the arguments
;; required for __crt0_run_array, to run the functions in .preinit_array.
START_CRT_FUNC 0910 run_preinit_array
mov_ #__preinit_array_start, R4
mov_ #__preinit_array_end, R5
mov_ #PTRsz, R6
br_ #__crt0_run_array
END_CRT_FUNC run_preinit_array
#endif /* Lrun_preinit_array */
#if Lrun_init_array
;; Note - this section is only included in the startup code of the application
;; if it is needed. It is responsible for setting up the arguments
;; required for __crt0_run_array, to run the functions in .init_array.
START_CRT_FUNC 0920 run_init_array
mov_ #__init_array_start, R4
mov_ #__init_array_end, R5
mov_ #PTRsz, R6
br_ #__crt0_run_array
END_CRT_FUNC run_init_array
#endif /* Lrun_init_array */
#if Lrun_fini_array
;; Note - this section is only included in the startup code of the application
;; if it is needed. It is responsible for setting up the arguments
;; This function is responsible for setting up the arguments
;; required for __crt0_run_array, to run the functions in .fini_array.
START_CRT_FUNC 0930 run_fini_array
START_CRT_FUNC 1000 run_fini_array
mov_ #__fini_array_start, R4
mov_ #__fini_array_end, R5
mov_ #-PTRsz, R6
br_ #__crt0_run_array
call_ #__crt0_run_array
END_CRT_FUNC run_fini_array
#endif /* Lrun_fini_array */
......@@ -268,7 +249,7 @@ END_CRT_FUNC run_fini_array
#if Lrun_array
;; Note - this section is only included in the startup code of the application
;; if it is needed by one of the above run_*_array functions.
START_CRT_FUNC 0980 run_array
START_CRT_FUNC 1100 run_array
cmp_ R4, R5
jeq _msp430_run_done
......@@ -282,27 +263,3 @@ END_CRT_FUNC run_array
_msp430_run_done:
ret_
#endif /* Lrun_array */
;----------------------------------------
#if L0
.section .init,"ax"
.global __msp430_init
__msp430_init:
.section .fini,"ax"
.global __msp430_fini
__msp430_fini:
call_ #__crt0_run_fini_array
;; If this function is not defined externally, we don't need it to do
;; anything.
.text
.weak __crt0_run_fini_array
__crt0_run_fini_array:
ret_
#endif
#endif /* not MINRT */
/* Copyright (c) 2013 Red Hat, Inc. All rights reserved.
This copyrighted material is made available to anyone wishing to use, modify,
copy, or redistribute it subject to the terms and conditions of the BSD
License. This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY expressed or implied, including the implied warranties
of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. A copy of this license
is available at http://www.opensource.org/licenses. Any Red Hat trademarks that
are incorporated in the source code or documentation are not subject to the BSD
License and may only be used or replicated with the express permission of
Red Hat, Inc.
*/
#include "memmodel.h"
#ifndef MINRT
.section .init,"ax"
call_ #__crt0_run_preinit_array
call_ #__crt0_run_init_array
ret_
.global __msp430_init_end
__msp430_init_end:
.section .fini,"ax"
ret_
.global __msp430_fini_end
__msp430_fini_end:
.text
;; If these functions are not defined externally, we don't need them to do
;; anything.
.balign 2
.weak __crt0_run_preinit_array
.weak __crt0_run_init_array
__crt0_run_preinit_array:
__crt0_run_init_array:
ret_
#endif
......@@ -106,8 +106,6 @@ SECTIONS
PROVIDE (_etext = .);
PROVIDE (etext = .);
. = ALIGN(2);
KEEP (*(.init))
KEEP (*(.fini))
KEEP (*(.tm_clone_table))
} > RAM
......
......@@ -387,8 +387,6 @@ SECTIONS
PROVIDE (_etext = .);
PROVIDE (etext = .);
. = ALIGN(2);
KEEP (*(.init))
KEEP (*(.fini))
KEEP (*(.tm_clone_table))
} > ROM
......
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