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libjit/jit/jit-rules-x86.c  view on Meta::CPAN

	return 0;
}

void *_jit_gen_prolog(jit_gencode_t gen, jit_function_t func, void *buf)
{
	unsigned char prolog[JIT_PROLOG_SIZE];
	unsigned char *inst = prolog;
	int reg;

	/* Push ebp onto the stack */
	x86_push_reg(inst, X86_EBP);

	/* Initialize EBP for the current frame */
	x86_mov_reg_reg(inst, X86_EBP, X86_ESP, sizeof(void *));

	/* Allocate space for the local variable frame */
	if(func->builder->frame_size > 0)
	{
		x86_alu_reg_imm(inst, X86_SUB, X86_ESP,
			 			(int)(func->builder->frame_size));
	}

	/* Save registers that we need to preserve */
	for(reg = 0; reg <= 7; ++reg)
	{
		if(jit_reg_is_used(gen->touched, reg) &&
		   (_jit_reg_info[reg].flags & JIT_REG_CALL_USED) == 0)
		{
			x86_push_reg(inst, _jit_reg_info[reg].cpu_reg);
		}
	}

	/* Copy the prolog into place and return the adjusted entry position */
	reg = (int)(inst - prolog);
	jit_memcpy(((unsigned char *)buf) + JIT_PROLOG_SIZE - reg, prolog, reg);
	return (void *)(((unsigned char *)buf) + JIT_PROLOG_SIZE - reg);
}

void _jit_gen_epilog(jit_gencode_t gen, jit_function_t func)
{
	jit_nint pop_bytes = 0;
	int reg, offset;
	unsigned char *inst;
	int struct_return_offset = 0;
	void **fixup;
	void **next;

	/* Check if there is sufficient space for the epilog */
	_jit_gen_check_space(gen, 48);

#if JIT_APPLY_X86_FASTCALL == 1
	/* Determine the number of parameter bytes to pop when we return */
	{
		jit_type_t signature;
		unsigned int num_params;
		unsigned int param;
		signature = func->signature;
		if(jit_type_get_abi(signature) == jit_abi_stdcall ||
		   jit_type_get_abi(signature) == jit_abi_fastcall)
		{
			if(func->nested_parent)
			{
				pop_bytes += sizeof(void *);
			}
			if(jit_type_return_via_pointer(jit_type_get_return(signature)))
			{
				struct_return_offset = 2 * sizeof(void *) + pop_bytes;
				pop_bytes += sizeof(void *);
			}
			num_params = jit_type_num_params(signature);
			for(param = 0; param < num_params; ++param)
			{
				pop_bytes += ROUND_STACK
						(jit_type_get_size
							(jit_type_get_param(signature, param)));
			}
			if(jit_type_get_abi(signature) == jit_abi_fastcall)
			{
				/* The first two words are in fastcall registers */
				if(pop_bytes > (2 * sizeof(void *)))
				{
					pop_bytes -= 2 * sizeof(void *);
				}
				else
				{
					pop_bytes = 0;
				}
				struct_return_offset = 0;
			}
		}
		else if(!(func->nested_parent) &&
				jit_type_return_via_pointer(jit_type_get_return(signature)))
		{
#if JIT_APPLY_X86_POP_STRUCT_RETURN == 1
			pop_bytes += sizeof(void *);
#endif
			struct_return_offset = 2 * sizeof(void *);
		}
	}
#else
	{
		/* We only need to pop structure pointers in non-nested functions */
		jit_type_t signature;
		signature = func->signature;
		if(!(func->nested_parent) &&
		   jit_type_return_via_pointer(jit_type_get_return(signature)))
		{
#if JIT_APPLY_X86_POP_STRUCT_RETURN == 1
			pop_bytes += sizeof(void *);
#endif
			struct_return_offset = 2 * sizeof(void *);
		}
	}
#endif

	/* Perform fixups on any blocks that jump to the epilog */
	inst = gen->ptr;
	fixup = (void **)(gen->epilog_fixup);
	while(fixup != 0)
	{
		next = (void **)(fixup[0]);
		fixup[0] = (void *)(((jit_nint)inst) - ((jit_nint)fixup) - 4);
		fixup = next;
	}
	gen->epilog_fixup = 0;

	/* If we are returning a structure via a pointer, then copy
	   the pointer value into EAX when we return */
	if(struct_return_offset != 0)
	{
		x86_mov_reg_membase(inst, X86_EAX, X86_EBP, struct_return_offset, 4);
	}

	/* Restore the callee save registers that we used */
	if(gen->stack_changed)
	{
		offset = -(func->builder->frame_size);
		for(reg = 0; reg <= 7; ++reg)
		{
			if(jit_reg_is_used(gen->touched, reg) &&
			   (_jit_reg_info[reg].flags & JIT_REG_CALL_USED) == 0)
			{
				offset -= sizeof(void *);
				x86_mov_reg_membase(inst, _jit_reg_info[reg].cpu_reg,
									X86_EBP, offset, sizeof(void *));
			}
		}
	}
	else
	{
		for(reg = 7; reg >= 0; --reg)
		{
			if(jit_reg_is_used(gen->touched, reg) &&
			   (_jit_reg_info[reg].flags & JIT_REG_CALL_USED) == 0)
			{
				x86_pop_reg(inst, _jit_reg_info[reg].cpu_reg);
			}
		}
	}

	/* Pop the stack frame and restore the saved copy of ebp */
	if(gen->stack_changed || func->builder->frame_size > 0)
	{
		x86_mov_reg_reg(inst, X86_ESP, X86_EBP, sizeof(void *));
	}