From 884b05b54e4595433c85f8ca9820e88b4c723e38 Mon Sep 17 00:00:00 2001 From: Jozef Lawrynowicz Date: Wed, 24 Jul 2019 10:45:49 +0100 Subject: [PATCH] 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. --- libgloss/msp430/Makefile.in | 9 +- libgloss/msp430/crt0.S | 165 ++++++++++++-------------------- libgloss/msp430/crtn.S | 41 -------- libgloss/msp430/msp430-sim.ld | 2 - libgloss/msp430/msp430xl-sim.ld | 2 - 5 files changed, 62 insertions(+), 157 deletions(-) delete mode 100644 libgloss/msp430/crtn.S diff --git a/libgloss/msp430/Makefile.in b/libgloss/msp430/Makefile.in index 77c9b8b21..59c11a9a9 100644 --- a/libgloss/msp430/Makefile.in +++ b/libgloss/msp430/Makefile.in @@ -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 $< diff --git a/libgloss/msp430/crt0.S b/libgloss/msp430/crt0.S index 42464ddbe..88876cd48 100644 --- a/libgloss/msp430/crt0.S +++ b/libgloss/msp430/crt0.S @@ -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 -#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. + mov_ #__preinit_array_start, R4 + mov_ #__preinit_array_end, R5 + mov_ #PTRsz, R6 + call_ #__crt0_run_array -START_CRT_FUNC 0600 call_just_main +END_CRT_FUNC run_preinit_array +#endif /* Lrun_preinit_array */ - clr.w R12 ; Set argc == 0 - call_ #main -END_CRT_FUNC call_just_main -#endif /* Lmain_minrt */ +#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 + 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 */ + +;; 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 */ #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. +;; This function is always included and calls main(). -START_CRT_FUNC 0700 call_init_then_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 */ diff --git a/libgloss/msp430/crtn.S b/libgloss/msp430/crtn.S deleted file mode 100644 index 110fc3090..000000000 --- a/libgloss/msp430/crtn.S +++ /dev/null @@ -1,41 +0,0 @@ -/* 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 diff --git a/libgloss/msp430/msp430-sim.ld b/libgloss/msp430/msp430-sim.ld index 283127465..fadd137e8 100644 --- a/libgloss/msp430/msp430-sim.ld +++ b/libgloss/msp430/msp430-sim.ld @@ -106,8 +106,6 @@ SECTIONS PROVIDE (_etext = .); PROVIDE (etext = .); . = ALIGN(2); - KEEP (*(.init)) - KEEP (*(.fini)) KEEP (*(.tm_clone_table)) } > RAM diff --git a/libgloss/msp430/msp430xl-sim.ld b/libgloss/msp430/msp430xl-sim.ld index cc451b853..125b7d897 100644 --- a/libgloss/msp430/msp430xl-sim.ld +++ b/libgloss/msp430/msp430xl-sim.ld @@ -387,8 +387,6 @@ SECTIONS PROVIDE (_etext = .); PROVIDE (etext = .); . = ALIGN(2); - KEEP (*(.init)) - KEEP (*(.fini)) KEEP (*(.tm_clone_table)) } > ROM