iii.3.38-ldarg-length.md

III.3.38 ldarg.<length> – load argument onto the stack

Format	Assembly Format	Description
FE 09 <unsigned int16>	ldarg num	Load argument numbered num onto the stack.
0E <unsigned int8>	ldarg.s num	Load argument numbered num onto the stack, short form.
02	ldarg.0	Load argument 0 onto the stack.
03	ldarg.1	Load argument 1 onto the stack.
04	ldarg.2	Load argument 2 onto the stack.
05	ldarg.3	Load argument 3 onto the stack.

Stack Transition:

… → …, value

Description:

The ldarg num instruction pushes onto the evaluation stack, the num'th incoming argument, where arguments are numbered 0 onwards (see Partition I). The type of the value on the stack is tracked by verification as the intermediate type (§I.8.7) of the argument type, as specified by the current method's signature.

The ldarg.0, ldarg.1, ldarg.2, and ldarg.3 instructions are efficient encodings for loading any one of the first 4 arguments. The ldarg.s instruction is an efficient encoding for loading argument numbers 4–255.

For procedures that take a variable-length argument list, the ldarg instructions can be used only for the initial fixed arguments, not those in the variable part of the signature. (See the arglist instruction.)

If required, arguments are converted to the representation of their intermediate type (§I.8.7) when loaded onto the stack (§III.1.1.1).

[Note: that is arguments that hold an integer value smaller than 4 bytes, a boolean, or a character are converted to 4 bytes by sign or zero-extension as appropriate. Floating-point values are converted to their native size (type F). end note]

Exceptions:

None.

Correctness:

Correct CIL guarantees that num is a valid argument index.

Verifiability:

Verification (§III.1.8) tracks the type of the value loaded onto the stack as the intermediate type (§I.8.7) of the method's declared argument type.