Add support for interrupt function attribute

From-SVN: r38134

gcc/ChangeLog

+2000-12-08  Nick Clifton  <nickc@redhat.com>
+
+	* extend.texi: Document ARM "interrupt" function attribute.
+	Mention that the ARM also support the "naked" function
+	attribute.
+
+	* config/arm/arm-protos.h (arm_current_func_type): Add
+	prototype.
+
+	* config/arm/arm.h (EXCEPTION_LR_REGNUM): Define.
+	(struct machine_function): Add 'func_type' field.
+	Define bit values for 'func_type' field.
+	(ARM_FUNC_TYPE): New macro.
+	(IS_INTERRUPT): New macro.
+	(IS_VOLATILE): New macro.
+	(IS_NAKED): New macro.
+	(IS_NESTED): New macro.
+	(ARM_INITIAL_ELIMINATION_OFFSET): Use IS_VOLATILE.
+
+	* config/arm/arm.c (isr_attribute_args): New Structure.  A
+	list of "interrupt" function attribute modifiers.
+	(arm_isr_value): New Function: Returns the type of the current
+	interrupt function.
+	(arm_compute_func_type): New Function: Computes the type of
+	the current function.
+	(arm_current_func_type): New Function: Returns the type of the
+	current function.
+	(use_return_insn): Use arm_current_func_type.
+	(arm_valid_type_attribute_p): Accept "interrupt" function
+	attribute.
+	(arm_comp_type_attributes): Check "interrupt" attributes.
+	(arm_valid_machine_decl): Accept "interrupt" function
+	attribute.
+	(arm_function_ok_for_sibcall): Do not allow interrupt
+	functions to use sibcalls.
+	(arm_naked_function_p): Delete.
+	(print_multi_reg): Remove redundant parameter 'hat'.
+	(arm_compute_save_reg_mask): New Function: Compute a bit mask
+	of registers saved during the current function's prologue.
+	(output_arm_return_instruction): Use arm_current_func_type.
+	Generate return instruction when LR is not poppsed off the
+	stack.
+	(arm_volatile_func): Delete.
+	(output_arm_prologue): Use arm_current_func_type and
+	arm_compute_save_reg_mask.
+	Note presernce of interrupt functions.
+	(arm_output_epilogue): Use arm_current_func_type and
+	arm_compute_save_reg_mask.
+	(arm_expand_prologue): Use arm_current_func_type and
+	arm_compute_save_reg_mask.
+	(arm_init_machine_status): Initialise func_type field, if
+	necessary.
+	(thumb_expand_prologue): Use arm_current_func_type.
+	(output_thumb_prologue): Use arm_current_func_type.
+
 2000-12-08  Brad Lucier <lucier@math.purdue.edu>
 
         * tradcpp.c (do_include): Make pointer differences 64-bit clean.

gcc/config/arm/arm-protos.h

@@ -34,6 +34,7 @@ extern void   arm_expand_prologue	PARAMS ((void));
 /* Used in arm.md, but defined in output.c.  */
 extern void   assemble_align		PARAMS ((int)); 
 extern const char * arm_strip_name_encoding	PARAMS ((const char *));
+extern unsigned long arm_current_func_type	PARAMS ((void));
 
 #ifdef TREE_CODE
 extern int    arm_return_in_memory	PARAMS ((tree));

gcc/config/arm/arm.h

@@ -903,7 +903,10 @@ extern const char * structure_size_string;
 #define LAST_ARG_REGNUM 	ARG_REGISTER (NUM_ARG_REGS)
 
 /* The number of the last "lo" register (thumb).  */
-#define LAST_LO_REGNUM  	 7
+#define LAST_LO_REGNUM  	7
+
+/* The register that holds the return address in exception handlers.  */
+#define EXCEPTION_LR_REGNUM	2
 
 /* The native (Norcroft) Pascal compiler for the ARM passes the static chain
    as an invisible last argument (possible since varargs don't exist in
@@ -1394,9 +1397,44 @@ enum reg_class
 #define CALL_LONG		0x00000001	/* Always call indirect.  */
 #define CALL_SHORT		0x00000002	/* Never call indirect.  */
 
-/* A C structure for machine-specific, per-function data.  This is added
-   to the cfun structure.  */
-struct machine_function
+/* These bits describe the different types of function supported
+   by the ARM backend.  They are exclusive.  ie a function cannot be both a
+   normal function and an interworked function, for example.  Knowing the
+   type of a function is important for determining its prologue and
+   epilogue sequences.
+   Note value 7 is currently unassigned.  Also note that the interrupt
+   function types all have bit 2 set, so that they can be tested for easily.
+   Note that 0 is deliberately chosen for ARM_FT_UNKNOWN so that when the
+   machine_function structure is initialised (to zero) func_type will
+   default to unknown.  This will force the first use of arm_current_func_type
+   to call arm_compute_func_type.  */
+#define ARM_FT_UNKNOWN		 0 /* Type has not yet been determined.  */
+#define ARM_FT_NORMAL		 1 /* Your normal, straightforward function.  */
+#define ARM_FT_INTERWORKED	 2 /* A function that supports interworking.  */
+#define ARM_FT_EXCEPTION_HANDLER 3 /* A C++ exception handler.  */
+#define ARM_FT_ISR		 4 /* An interrupt service routine.  */
+#define ARM_FT_FIQ		 5 /* A fast interrupt service routine.  */
+#define ARM_FT_EXCEPTION	 6 /* An ARM exception handler (subcase of ISR).  */
+
+#define ARM_FT_TYPE_MASK	((1 << 3) - 1)
+
+/* In addition functions can have several type modifiers,
+   outlined by these bit masks:  */
+#define ARM_FT_INTERRUPT	(1 << 2) /* Note overlap with FT_ISR and above.  */
+#define ARM_FT_NAKED		(1 << 3) /* No prologue or epilogue.  */
+#define ARM_FT_VOLATILE		(1 << 4) /* Does not return.  */
+#define ARM_FT_NESTED		(1 << 5) /* Embedded inside another func. */
+
+/* Some macros to test these flags.  */
+#define ARM_FUNC_TYPE(t)	(t & ARM_FT_TYPE_MASK)
+#define IS_INTERRUPT(t)		(t & ARM_FT_INTERRUPT)
+#define IS_VOLATILE(t)     	(t & ARM_FT_VOLATILE)
+#define IS_NAKED(t)        	(t & ARM_FT_NAKED)
+#define IS_NESTED(t)       	(t & ARM_FT_NESTED)
+
+/* A C structure for machine-specific, per-function data.
+   This is added to the cfun structure.  */
+typedef struct machine_function
 {
   /* Records __builtin_return address.  */
   struct rtx_def *ra_rtx;
@@ -1406,7 +1444,10 @@ struct machine_function
   int far_jump_used;
   /* Records if ARG_POINTER was ever live.  */
   int arg_pointer_live;
-};
+  /* Records the type of the current function.  */
+  unsigned long func_type;
+}
+machine_function;
 
 /* A C type for declaring a variable that is used as the first argument of
    `FUNCTION_ARG' and other related values.  For some target machines, the
@@ -1615,7 +1656,7 @@ typedef struct
    other its replacement, at the start of a routine.  */
 #define ARM_INITIAL_ELIMINATION_OFFSET(FROM, TO, OFFSET)		\
 {									\
-  int volatile_func = arm_volatile_func ();				\
+  int volatile_func = IS_VOLATILE (arm_current_func_type ());		\
   if ((FROM) == ARG_POINTER_REGNUM && (TO) == HARD_FRAME_POINTER_REGNUM)\
     {									\
       if (! current_function_needs_context || ! frame_pointer_needed)	\

gcc/extend.texi

@@ -1760,6 +1760,27 @@ function is an interrupt handler.  The compiler will generate function
 entry and exit sequences suitable for use in an interrupt handler when this
 attribute is present.
 
+@item interrupt
+@cindex interrupt handler functions
+Use this option on the ARM, AVR and M32R/D ports to indicate that the
+specified function is an interrupt handler.  The compiler will generate
+function entry and exit sequences suitable for use in an interrupt
+handler when this attribute is present.
+
+Note, interrupt handlers for ther H8/300 and H8/300H processors can be
+specified via the @code{interrupt_handler} attribute.
+
+Note, on the AVR interrupts will be enabled inside the function.
+
+Note, for the ARM you can specify the kind of interrupt to be handled by
+adding an optional parameter to the interrupt attribute like this:
+
+@smallexample
+void f () __attribute__ ((interrupt ("IRQ")));
+@end smallexample
+
+Permissable values for this parameter are: IRQ, FIQ, SWI, ABORT and UNDEF.
+
 @item eightbit_data
 @cindex eight bit data on the H8/300 and H8/300H
 Use this option on the H8/300 and H8/300H to indicate that the specified
@@ -1779,19 +1800,6 @@ The compiler will generate more efficient code for loads and stores
 on data in the tiny data section.  Note the tiny data area is limited to
 slightly under 32kbytes of data.
 
-@item interrupt
-@cindex interrupt handlers on the M32R/D
-Use this option on the M32R/D to indicate that the specified
-function is an interrupt handler.  The compiler will generate function
-entry and exit sequences suitable for use in an interrupt handler when this
-attribute is present.
-
-Interrupt handler functions on the AVR processors
-Use this option on the AVR to indicate that the specified
-function is an interrupt handler.  The compiler will generate function
-entry and exit sequences suitable for use in an interrupt handler when this
-attribute is present. Interrupts will be enabled inside function.
-
 @item signal
 @cindex signal handler functions on the AVR processors
 Use this option on the AVR to indicate that the specified
@@ -1800,10 +1808,10 @@ entry and exit sequences suitable for use in an signal handler when this
 attribute is present. Interrupts will be disabled inside function.
 
 @item naked
-@cindex function without a prologue/epilogue code on the AVR processors
-Use this option on the AVR to indicate that the specified
-function don't have a prologue/epilogue.  The compiler don't generate
-function entry and exit sequences.
+@cindex function without a prologue/epilogue code
+Use this option on the ARM or AVR ports to indicate that the specified
+function do not need prologue/epilogue sequences generated by the
+compiler.  It is up to the programmer to provide these sequences.
 
 @item model (@var{model-name})
 @cindex function addressability on the M32R/D