ok to me
On Mon, May 17, 2021 at 5:43 AM Sebastian Huber <sebastian.hu...@embedded-brains.de> wrote: > > The __builtin_unreachable() cannot be used with current GCC versions to > tell the compiler that a function does not return to the caller, see: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99151 > > Add a no return variant of _CPU_Context_switch() to avoid generation of > dead code in _Thread_Start_multitasking() if RTEMS was built with SMP > support enabled. > --- > bsps/powerpc/shared/cpu_asm.S | 2 ++ > cpukit/score/cpu/arm/cpu_asm.S | 3 ++ > .../score/cpu/arm/include/rtems/score/cpu.h | 5 ++++ > .../cpu/no_cpu/include/rtems/score/cpu.h | 30 +++++++++++++++++-- > .../cpu/powerpc/include/rtems/score/cpu.h | 5 ++++ > .../score/cpu/riscv/include/rtems/score/cpu.h | 5 ++++ > cpukit/score/cpu/riscv/riscv-context-switch.S | 2 ++ > cpukit/score/cpu/sparc/cpu_asm.S | 2 ++ > .../score/cpu/sparc/include/rtems/score/cpu.h | 5 ++++ > cpukit/score/src/threadstartmultitasking.c | 2 +- > 10 files changed, 57 insertions(+), 4 deletions(-) > > diff --git a/bsps/powerpc/shared/cpu_asm.S b/bsps/powerpc/shared/cpu_asm.S > index e4d627016c..63f6a3fdfe 100644 > --- a/bsps/powerpc/shared/cpu_asm.S > +++ b/bsps/powerpc/shared/cpu_asm.S > @@ -258,7 +258,9 @@ PROC (_CPU_Context_restore_fp): > > ALIGN (PPC_CACHE_ALIGNMENT, PPC_CACHE_ALIGN_POWER) > PUBLIC_PROC (_CPU_Context_switch) > + PUBLIC_PROC (_CPU_Context_switch_no_return) > PROC (_CPU_Context_switch): > +PROC (_CPU_Context_switch_no_return): > > #ifdef BSP_USE_SYNC_IN_CONTEXT_SWITCH > sync > diff --git a/cpukit/score/cpu/arm/cpu_asm.S b/cpukit/score/cpu/arm/cpu_asm.S > index 66f8ba6032..46eb46b914 100644 > --- a/cpukit/score/cpu/arm/cpu_asm.S > +++ b/cpukit/score/cpu/arm/cpu_asm.S > @@ -54,6 +54,9 @@ > */ > > DEFINE_FUNCTION_ARM(_CPU_Context_switch) > + .globl _CPU_Context_switch_no_return > + .set _CPU_Context_switch_no_return, _CPU_Context_switch > + > /* Start saving context */ > GET_SELF_CPU_CONTROL r2 > ldr r3, [r2, #PER_CPU_ISR_DISPATCH_DISABLE] > diff --git a/cpukit/score/cpu/arm/include/rtems/score/cpu.h > b/cpukit/score/cpu/arm/include/rtems/score/cpu.h > index e5b23e7100..dcda4d525c 100644 > --- a/cpukit/score/cpu/arm/include/rtems/score/cpu.h > +++ b/cpukit/score/cpu/arm/include/rtems/score/cpu.h > @@ -465,6 +465,11 @@ void _CPU_ISR_install_vector( > */ > void _CPU_Context_switch( Context_Control *run, Context_Control *heir ); > > +RTEMS_NO_RETURN void _CPU_Context_switch_no_return( > + Context_Control *executing, > + Context_Control *heir > +); > + > RTEMS_NO_RETURN void _CPU_Context_restore( Context_Control *new_context ); > > #if defined(ARM_MULTILIB_ARCH_V7M) > diff --git a/cpukit/score/cpu/no_cpu/include/rtems/score/cpu.h > b/cpukit/score/cpu/no_cpu/include/rtems/score/cpu.h > index c067501502..c437ded5fb 100644 > --- a/cpukit/score/cpu/no_cpu/include/rtems/score/cpu.h > +++ b/cpukit/score/cpu/no_cpu/include/rtems/score/cpu.h > @@ -1054,22 +1054,46 @@ void _CPU_ISR_install_vector( > void *_CPU_Thread_Idle_body( uintptr_t ignored ); > > /** > + * @brief Peforms a context switch from the executing thread to the heir > + * thread. > + * > * @addtogroup RTEMSScoreCPUExampleContext > * > * This routine switches from the run context to the heir context. > * > - * @param[in] run points to the context of the currently executing task > - * @param[in] heir points to the context of the heir task > + * @param[out] executing points to the context of the currently executing > task. > + * > + * @param[in, out] heir points to the context of the heir task. > * > * Port Specific Information: > * > * XXX document implementation including references if appropriate > */ > void _CPU_Context_switch( > - Context_Control *run, > + Context_Control *executing, > Context_Control *heir > ); > > +/** > + * @brief Peforms a context switch from the executing thread to the heir > thread > + * and does not return. > + * > + * @addtogroup RTEMSScoreCPUExampleContext > + * > + * This routine shall be a strong alias to _CPU_Context_switch(). It shall > be > + * provided for all target architectures which support an SMP build > + * configuration (RTEMS_SMP). The purpose is help to compiler to avoid > + * generation of dead code in _Thread_Start_multitasking(). > + * > + * @param[out] executing points to the context of the currently executing > task. > + * > + * @param[in, out] heir points to the context of the heir task. > + */ > +RTEMS_NO_RETURN void _CPU_Context_switch_no_return( > + Context_Control *executing, > + Context_Control *heir > +); > + > /** > * @addtogroup RTEMSScoreCPUExampleContext > * > diff --git a/cpukit/score/cpu/powerpc/include/rtems/score/cpu.h > b/cpukit/score/cpu/powerpc/include/rtems/score/cpu.h > index 996b6f8e60..f22e1cd7ec 100644 > --- a/cpukit/score/cpu/powerpc/include/rtems/score/cpu.h > +++ b/cpukit/score/cpu/powerpc/include/rtems/score/cpu.h > @@ -914,6 +914,11 @@ void _CPU_Context_switch( > Context_Control *heir > ); > > +RTEMS_NO_RETURN void _CPU_Context_switch_no_return( > + Context_Control *executing, > + Context_Control *heir > +); > + > /* > * _CPU_Context_restore > * > diff --git a/cpukit/score/cpu/riscv/include/rtems/score/cpu.h > b/cpukit/score/cpu/riscv/include/rtems/score/cpu.h > index 38eb92394d..a44b815b12 100644 > --- a/cpukit/score/cpu/riscv/include/rtems/score/cpu.h > +++ b/cpukit/score/cpu/riscv/include/rtems/score/cpu.h > @@ -383,6 +383,11 @@ void _CPU_Context_switch( > Context_Control *heir > ); > > +RTEMS_NO_RETURN void _CPU_Context_switch_no_return( > + Context_Control *executing, > + Context_Control *heir > +); > + > /* > * _CPU_Context_restore > * > diff --git a/cpukit/score/cpu/riscv/riscv-context-switch.S > b/cpukit/score/cpu/riscv/riscv-context-switch.S > index 96c117b3de..830f8629a4 100644 > --- a/cpukit/score/cpu/riscv/riscv-context-switch.S > +++ b/cpukit/score/cpu/riscv/riscv-context-switch.S > @@ -37,9 +37,11 @@ > .align 2 > > PUBLIC(_CPU_Context_switch) > +PUBLIC(_CPU_Context_switch_no_return) > PUBLIC(_CPU_Context_restore) > > SYM(_CPU_Context_switch): > +SYM(_CPU_Context_switch_no_return): > GET_SELF_CPU_CONTROL a2 > lw a3, PER_CPU_ISR_DISPATCH_DISABLE(a2) > > diff --git a/cpukit/score/cpu/sparc/cpu_asm.S > b/cpukit/score/cpu/sparc/cpu_asm.S > index e884fb2f9e..a7b87ad5f8 100644 > --- a/cpukit/score/cpu/sparc/cpu_asm.S > +++ b/cpukit/score/cpu/sparc/cpu_asm.S > @@ -57,7 +57,9 @@ > > .align 4 > PUBLIC(_CPU_Context_switch) > + PUBLIC(_CPU_Context_switch_no_return) > SYM(_CPU_Context_switch): > +SYM(_CPU_Context_switch_no_return): > st %g5, [%o0 + G5_OFFSET] ! save the global registers > > /* > diff --git a/cpukit/score/cpu/sparc/include/rtems/score/cpu.h > b/cpukit/score/cpu/sparc/include/rtems/score/cpu.h > index 8c5330b8ce..6c167e3f08 100644 > --- a/cpukit/score/cpu/sparc/include/rtems/score/cpu.h > +++ b/cpukit/score/cpu/sparc/include/rtems/score/cpu.h > @@ -971,6 +971,11 @@ void _CPU_Context_switch( > Context_Control *heir > ); > > +RTEMS_NO_RETURN void _CPU_Context_switch_no_return( > + Context_Control *executing, > + Context_Control *heir > +); > + > /** > * @brief SPARC specific context restore. > * > diff --git a/cpukit/score/src/threadstartmultitasking.c > b/cpukit/score/src/threadstartmultitasking.c > index a0b465a226..094a535394 100644 > --- a/cpukit/score/src/threadstartmultitasking.c > +++ b/cpukit/score/src/threadstartmultitasking.c > @@ -59,7 +59,7 @@ void _Thread_Start_multitasking( void ) > * executing to the currently selected heir thread. > */ > _CPU_Context_Set_is_executing( &trash, true ); > - _CPU_Context_switch( &trash, &heir->Registers ); > + _CPU_Context_switch_no_return( &trash, &heir->Registers ); > RTEMS_UNREACHABLE(); > } > #else > -- > 2.26.2 > > _______________________________________________ > devel mailing list > devel@rtems.org > http://lists.rtems.org/mailman/listinfo/devel _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
