Implement x86 interrupt attribute

The interrupt and exception handlers are called by x86 processors.  X86
hardware pushes information onto stack and calls the handler.  The
requirements are

1. Both interrupt and exception handlers must use the 'IRET' instruction,
instead of the 'RET' instruction, to return from the handlers.
2. All registers are callee-saved in interrupt and exception handlers.
3. The difference between interrupt and exception handlers is the
exception handler must pop 'ERROR_CODE' off the stack before the 'IRET'
instruction.

The design goals of interrupt and exception handlers for x86 processors
are:

1. Support both 32-bit and 64-bit modes.
2. Flexible for compilers to optimize.
3. Easy to use by programmers.

To implement interrupt and exception handlers for x86 processors, a
compiler should support:

'interrupt' attribute

Use this attribute to indicate that the specified function with
mandatory arguments is an interrupt or exception handler.  The compiler
generates function entry and exit sequences suitable for use in an
interrupt handler when this attribute is present.  The 'IRET' instruction,
instead of the 'RET' instruction, is used to return from interrupt or
exception handlers.  All registers, except for the EFLAGS register which
is restored by the 'IRET' instruction, are preserved by the compiler.

Any interruptible-without-stack-switch code must be compiled with
-mno-red-zone since interrupt handlers can and will, because of the
hardware design, touch the red zone.

1. interrupt handler must be declared with a mandatory pointer argument:

struct interrupt_frame;

__attribute__ ((interrupt))
void
f (struct interrupt_frame *frame)
{
...
}

and user must properly define the structure the pointer pointing to.

2. exception handler:

The exception handler is very similar to the interrupt handler with
a different mandatory function signature:

typedef unsigned long long int uword_t;
typedef unsigned int uword_t;

struct interrupt_frame;

__attribute__ ((interrupt))
void
f (struct interrupt_frame *frame, uword_t error_code)
{
...
}

and compiler pops the error code off stack before the 'IRET' instruction.

The exception handler should only be used for exceptions which push an
error code and all other exceptions must use the interrupt handler.
The system will crash if the wrong handler is used.

	PR target/67630
	PR target/67634
	* config/i386/i386-protos.h (ix86_interrupt_return_nregs): New.
	* config/i386/i386.c (ix86_frame): Add nbndregs and nmaskregs.
	(ix86_interrupt_return_nregs): New variable.
	(ix86_nsaved_bndregs): New function.
	(ix86_nsaved_maskregs): Likewise.
	(ix86_reg_save_area_size): Likewise.
	(ix86_nsaved_sseregs): Don't return 0 in interrupt handler.
	(ix86_compute_frame_layout): Set nbndregs and nmaskregs.  Set
	save_regs_using_mov to true to save bound and mask registers.
	Call ix86_reg_save_area_size to get register save area size.
	Allocate space to save full vector registers in interrupt handler.
	(ix86_emit_save_reg_using_mov): Set alignment to word_mode
	alignment when saving full vector registers in interrupt handler.
	(ix86_emit_save_regs_using_mov): Use regno_reg_rtx to get
	register size.
	(ix86_emit_restore_regs_using_mov): Likewise.
	(ix86_emit_save_sse_regs_using_mov): Save full vector registers in
	interrupt handler.
	(ix86_emit_restore_sse_regs_using_mov): Restore full vector
	registers in interrupt handler.
	(ix86_expand_epilogue): Use move to restore bound registers.
	* config/i386/sse.md (*mov<mode>_internal): Handle misaligned
	SSE load and store in interrupt handler.

	PR target/66960
	* config/i386/i386.c (ix86_conditional_register_usage): Set
	ix86_interrupt_return_nregs/
	(ix86_set_current_function): Set is_interrupt and is_exception.
	Mark arguments in interrupt handler as used.
	(ix86_function_ok_for_sibcall): Return false if in interrupt
	handler.
	(type_natural_mode): Don't warn ABI change for MMX in interrupt
	handler.
	(ix86_function_arg_advance): Skip for callee in interrupt
	handler.
	(ix86_function_arg): Handle arguments for callee in interrupt
	handler.
	(ix86_can_use_return_insn_p): Don't use `ret' instruction in
	interrupt handler.
	(ix86_save_reg): Preserve callee-saved and caller-saved registers
	in interrupt handler if needed.
	(ix86_expand_epilogue): Generate interrupt return for
	interrupt handler and pop the 'ERROR_CODE' off the stack before
	interrupt return in exception handler.
	(ix86_expand_move): Disallow 80387 instructions in exception
	handler.
	(ix86_expand_vector_move): Disallow MMX/3Dnow instructions in
	exception handler.
	(ix86_expand_call): Set make_calls.
	(ix86_handle_interrupt_attribute): New function.
	(ix86_attribute_table): Add interrupt attribute.
	* config/i386/i386.h (machine_function): Add is_interrupt,
	is_exception, make_calls and  interrupt_data_taken.
	* config/i386/i386.md (UNSPEC_INTERRUPT_RETURN): New.
	(*interrupt_return): New pattern.
	* config/i386/predicates.md (interrupt_return_operation): New.
	* doc/extend.texi: Document x86 interrupt attribute.

gcc/testsuite/

	PR target/66960
	PR target/67630
	PR target/67634
	* gcc.target/i386/interrupt-1.c: New test.
	* gcc.target/i386/interrupt-2.c: Likewise.
	* gcc.target/i386/interrupt-3.c: Likewise.
	* gcc.target/i386/interrupt-4.c: Likewise.
	* gcc.target/i386/interrupt-5.c: Likewise.
	* gcc.target/i386/interrupt-6.c: Likewise.
	* gcc.target/i386/interrupt-7.c: Likewise.
	* gcc.target/i386/interrupt-8.c: Likewise.
	* gcc.target/i386/interrupt-9.c: Likewise.
	* gcc.target/i386/interrupt-10.c: Likewise.
	* gcc.target/i386/interrupt-11.c: Likewise.
	* gcc.target/i386/interrupt-12.c: Likewise.
	* gcc.target/i386/interrupt-13.c: Likewise.
	* gcc.target/i386/interrupt-387-err.c: Likewise.
	* gcc.target/i386/interrupt-bnd.c: Likewise.
	* gcc.target/i386/interrupt-iamcu.c: Likewise.
	* gcc.target/i386/interrupt-mmx-err.c: Likewise.
	* gcc.target/i386/interrupt-redzone-1.c: Likewise.
	* gcc.target/i386/interrupt-redzone-2.c: Likewise.
	* gcc.target/i386/interrupt-sibcall.c: Likewise.
	* gcc.target/i386/interrupt-switch-abi.c: Likewise.
	* gcc.target/i386/interrupt-xmm.c: Likewise.
	* gcc.target/i386/interrupt-ymm.c: Likewise.
	* gcc.target/i386/interrupt-zmm.c: Likewise.

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