CC78K4 Datasheet, PDF (456/523 Pages) NEC – CC78K4 Ver.2.30 or Later, C Compiler Language

CHAPTER 11 EXTENDED FUNCTIONS
(2) Location and order of storing arguments
• There are two types of arguments: arguments allocated to registers and ordinary arguments. Arguments
allocated to registers are the arguments declared with registers and the arguments when -QV is specified.
• The arguments not allocated to registers are allocated to stacks. The arguments allocated to stacks are
placed on the stack sequentially from the last argument.
(a) When the -ZO option is not specified
• Saving and restoring registers to which arguments are allocated is performed on the function definition
side.
• When -QV option is specified, the ordinary arguments are also allocated to registers regarding they are
declared with registers.
• The ordinary arguments are allocated to a stack. When the arguments are passed via stacks, the area
where the arguments are passed (stack) is used as the area to which arguments are allocated.
• On the function definition side, the arguments that are passed via a register or stack are stored in the area
to which arguments are allocated.
• Arguments with more references together with register variables are allocated to registers. When the -QF
and -ML options are specified, however, a second or subsequent argument whose size is less than 4-bytes
and number of references is two or less is not always allocated to a register.
Table 11-29. List of Storing Arguments (On Function Definition Side, When -ZO Is Not Specified)
Option
When -QF is specified
When -QF is not specified
Model
Small Model, Medium Model^Note
RP3, VP, UP
RP3, VP
Large Model
RP3, VVP, UUP
RP3, VVP
Note With the medium model, the function pointer (3 bytes) cannot be used as a register argument.
(Order of allocation)
• With small model, medium model, when -QF is specified
char, int, short, enum type: If there is long, float, double type argument, in the order of UP, RP3, VP
char, int, short, enum type: If there is no long, float, double type argument, in the order of RP3, UP,
VP
Pointer type:
In the order of UP, VP, RP3
long, float, double type: RP3 (lower), VP (higher)
• With small model, medium model, when -QF is not specified
char, int, short, enum type: In the order of RP3, VP
Pointer type:
In the order of VP, RP3
long, float, double type: RP3 (lower), VP (higher)
• With large model, when -QF is specified
char, int, short, enum type: If there is long, float, double type argument, in the order of UP, RP3, VP
char, int, short, enum type: If there is no long, float, double type argument, in the order of RP3, UP,
VP
Pointer type:
In the order of UUP, VVP
long, float, double type: RP3 (lower), VP (higher)
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