[SUBMITTED] This patch introduces __attribute__((interrupt_handler)) support for m68k targets. Since the previous submission, it has been updated to incorporate the following suggested changes: - attribute renamed from "interrupt" to "interrupt_handler" to avoid clashing with omonimous attribute with different semantincs that has been in use for several years on Amiga's GCC port; - Decomposed complex if statement in m68k_save_reg(); - Documentation updates are not included and will follow (just need to include m68k to the list of back-ends where interrupt_handler is supported. The interrupt_handler attribute is meant to be attached to FUNCTION_DECL nodes because, unlike attributes for specifying different calling conventions such 'cdecl', its pourpose is to generate a function which isn't directly callable by C code. The only meaningful way to use such a function is by placing its address in the processor interrupt vector table. 2003-09-11 Peter Barada Bernardo Innocenti * config/m68k/m68k.c (m68k_frame): Move before protos referencing it. * config/m68k/m68k.c (m68k_save_reg): Add boolean parameter `interrupt_handler'. * config/m68k/m68k.c (m68k_interrupt_function_p): New function. * config/m68k/m68k.c (m68k_handle_fndecl_attribute): Ditto. * config/m68k/m68k.c (m68k_compute_frame_layout): Ditto. * config/m68k/m68k.c (m68k_attribute_table): Define back-end specific attributes. * config/m68k/m68k.c (m68k_output_function_epilogue): Emit rte instruction for interrupt functions. diff -Nru gcc-3.4-20030806.orig/gcc/config/m68k/m68k.c gcc-3.4-20030806/gcc/config/m68k/m68k.c --- gcc-3.4-20030806.orig/gcc/config/m68k/m68k.c 2003-08-07 19:06:25.000000000 +0200 +++ gcc-3.4-20030806/gcc/config/m68k/m68k.c 2003-08-07 19:21:01.000000000 +0200 @@ -45,6 +45,23 @@ /* Needed for use_return_insn. */ #include "flags.h" +/* Structure describing stack frame layout. */ +struct m68k_frame { + HOST_WIDE_INT offset; + HOST_WIDE_INT size; + /* data and address register */ + int reg_no; + unsigned int reg_mask; + unsigned int reg_rev_mask; + /* fpu registers */ + int fpu_no; + unsigned int fpu_mask; + unsigned int fpu_rev_mask; + /* offsets relative to ARG_POINTER. */ + HOST_WIDE_INT frame_pointer_offset; + HOST_WIDE_INT stack_pointer_offset; +}; + /* This flag is used to communicate between movhi and ASM_OUTPUT_CASE_END, if SGS_SWITCH_TABLE. */ int switch_table_difference_label_flag; @@ -59,7 +77,12 @@ #endif static void m68k_output_mi_thunk (FILE *, tree, HOST_WIDE_INT, HOST_WIDE_INT, tree); -static int m68k_save_reg (unsigned int); +static bool m68k_interrupt_function_p (tree func); +static tree m68k_handle_fndecl_attribute (tree *node, tree name, + tree args, int flags, + bool *no_add_attrs); +static void m68k_compute_frame_layout (struct m68k_frame *frame); +static bool m68k_save_reg (unsigned int regno, bool interrupt_handler); static int const_int_cost (rtx); static bool m68k_rtx_costs (rtx, int, int, int *); @@ -138,6 +161,16 @@ #undef TARGET_RTX_COSTS #define TARGET_RTX_COSTS m68k_rtx_costs +#undef TARGET_ATTRIBUTE_TABLE +#define TARGET_ATTRIBUTE_TABLE m68k_attribute_table + +static const struct attribute_spec m68k_attribute_table[] = +{ + /* { name, min_len, max_len, decl_req, type_req, fn_type_req, handler } */ + { "interrupt_handler", 0, 0, true, false, false, m68k_handle_fndecl_attribute }, + { NULL, 0, 0, false, false, false, NULL } +}; + struct gcc_target targetm = TARGET_INITIALIZER; /* Sometimes certain combinations of command options do not make @@ -216,24 +249,37 @@ real_format_for_mode[XFmode - QFmode] = &ieee_extended_motorola_format; } -/* Structure describing stack frame layout. */ -struct m68k_frame { - HOST_WIDE_INT offset; - HOST_WIDE_INT size; - /* data and address register */ - int reg_no; - unsigned int reg_mask; - unsigned int reg_rev_mask; - /* fpu registers */ - int fpu_no; - unsigned int fpu_mask; - unsigned int fpu_rev_mask; - /* fpa registers */ - int fpa_no; - /* offsets relative to ARG_POINTER. */ - HOST_WIDE_INT frame_pointer_offset; - HOST_WIDE_INT stack_pointer_offset; -}; +/* Return nonzero if FUNC is an interrupt function as specified by the + "interrupt_handler" attribute. */ +static bool +m68k_interrupt_function_p(tree func) +{ + tree a; + + if (TREE_CODE (func) != FUNCTION_DECL) + return false; + + a = lookup_attribute ("interrupt_handler", DECL_ATTRIBUTES (func)); + return (a != NULL_TREE); +} + +/* Handle an attribute requiring a FUNCTION_DECL; arguments as in + struct attribute_spec.handler. */ +static tree +m68k_handle_fndecl_attribute (tree *node, tree name, + tree args ATTRIBUTE_UNUSED, + int flags ATTRIBUTE_UNUSED, + bool *no_add_attrs) +{ + if (TREE_CODE (*node) != FUNCTION_DECL) + { + warning ("`%s' attribute only applies to functions", + IDENTIFIER_POINTER (name)); + *no_add_attrs = true; + } + + return NULL_TREE; +} static void m68k_compute_frame_layout (struct m68k_frame *frame) @@ -242,12 +290,13 @@ { int regno, saved; unsigned int mask, rmask; + bool interrupt_handler = m68k_interrupt_function_p (current_function_decl); frame->size = (get_frame_size () + 3) & -4; mask = rmask = saved = 0; for (regno = 0; regno < 16; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) { mask |= 1 << regno; rmask |= 1 << (15 - regno); @@ -311,13 +360,13 @@ abort(); } -/* Return 1 if we need to save REGNO. */ -static int -m68k_save_reg (unsigned int regno) +/* Return true if we need to save REGNO. */ +static bool +m68k_save_reg (unsigned int regno, bool interrupt_handler) { if (flag_pic && current_function_uses_pic_offset_table && regno == PIC_OFFSET_TABLE_REGNUM) - return 1; + return true; if (current_function_calls_eh_return) { @@ -329,14 +379,35 @@ if (test == INVALID_REGNUM) break; if (test == regno) - return 1; + return true; } } - return (regs_ever_live[regno] - && !call_used_regs[regno] - && !fixed_regs[regno] - && !(regno == FRAME_POINTER_REGNUM && frame_pointer_needed)); + /* Fixed regs we never touch. */ + if (fixed_regs[regno]) + return false; + + /* The frame pointer (if it is such) is handled specially. */ + if (regno == FRAME_POINTER_REGNUM && frame_pointer_needed) + return false; + + /* Interrupt handlers must also save call_used_regs + if they are live or when calling nested functions. */ + if (interrupt_handler) + { + if (regs_ever_live[regno]) + return true; + + if (!current_function_is_leaf && call_used_regs[regno]) + return true; + } + + /* Never need to save registers that aren't touched. */ + if (!regs_ever_live[regno]) + return false; + + /* Otherwise save everthing that isn't call-clobbered. */ + return !call_used_regs[regno]; } /* This function generates the assembly code for function entry. @@ -363,6 +419,7 @@ HOST_WIDE_INT fsize = (size + 3) & -4; HOST_WIDE_INT fsize_with_regs; HOST_WIDE_INT cfa_offset = INCOMING_FRAME_SP_OFFSET; + bool interrupt_handler = m68k_interrupt_function_p (current_function_decl); /* If the stack limit is a symbol, we can check it here, before actually allocating the space. */ @@ -382,7 +439,7 @@ { /* on Coldfire add register save into initial stack frame setup, if possible */ for (regno = 0; regno < 16; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) num_saved_regs++; if (num_saved_regs <= 2) @@ -534,7 +591,7 @@ if (TARGET_68881) { for (regno = 16; regno < 24; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) { mask |= 1 << (regno - 16); num_saved_regs++; @@ -567,7 +624,7 @@ num_saved_regs = 0; } for (regno = 0; regno < 16; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) { mask |= 1 << (15 - regno); num_saved_regs++; @@ -696,12 +753,15 @@ use_return_insn () { int regno; + bool interrupt_handler; if (!reload_completed || frame_pointer_needed || get_frame_size () != 0) return 0; + interrupt_handler = m68k_interrupt_function_p (current_function_decl); + for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) return 0; return 1; @@ -729,6 +787,7 @@ int big = 0; rtx insn = get_last_insn (); int restore_from_sp = 0; + bool interrupt_handler = m68k_interrupt_function_p (current_function_decl); /* If the last insn was a BARRIER, we don't have to write any code. */ if (GET_CODE (insn) == NOTE) @@ -748,7 +807,7 @@ if (TARGET_68881) { for (regno = 16; regno < 24; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) { nregs++; fmask |= 1 << (23 - regno); @@ -757,7 +816,7 @@ foffset = nregs * 12; nregs = 0; mask = 0; for (regno = 0; regno < 16; regno++) - if (m68k_save_reg (regno)) + if (m68k_save_reg (regno, interrupt_handler)) { nregs++; mask |= 1 << regno; @@ -1049,7 +1108,9 @@ asm_fprintf (stream, "\taddl %Ra0,%Rsp\n"); #endif } - if (current_function_pops_args) + if (interrupt_handler) + fprintf (stream, "\trte\n"); + else if (current_function_pops_args) asm_fprintf (stream, "\trtd %I%d\n", current_function_pops_args); else fprintf (stream, "\trts\n");