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IAR Embedded Workbench for RX 5.20

CFI directives

In this section:

The CFI directives provide C-SPY with information about the state of the calling function(s). Most important of this is the return address, and the value of the stack pointer at the entry of the function or assembler routine. Given this information, C-SPY can reconstruct the state for the calling function, and thereby unwind the stack.

A full description about the calling convention might require extensive call frame information. In many cases, a more limited approach will suffice.

When describing the call frame information, the following three components must be present:

  • A names block describing the available resources to be tracked

  • A common block corresponding to the calling convention

  • A data block describing the changes that are performed on the call frame. This typically includes information about when the stack pointer is changed, and when permanent registers are stored or restored on the stack.

This table lists all the resources defined in the names block used by the compiler:

Resource

Description

CFA_SP

The call frame of the stack

R1–R15

Normal registers

SP

The stack pointer

?RET32

The return address

Table 69. Call frame information resources defined in a names block