6.5.1 Function call parameters, return value and variables ¶

When a function is called, it have parameters, a return value and some variables.

Here is a map of how they are stored in the stack:

┌─────────────────┐
│  Caller frame   │
├─────────────────┤
│  Parameters     │  ← PUSHREL/POPREL access
├─────────────────┤
│  Return Value   │  ← PUSHREL/POPREL access
├─────────────────┤  ← SP
│  Local vars     │  ← PUSHREL/POPREL access
├─────────────────┤
│  Temporaries    │  ← Stack top
└─────────────────┘

Local variables: Accessed via SP-relative offsets - ‘PUSHREL 0’: First local - ‘PUSHREL 8’: Second local (8-byte offset) - ‘POPREL N’: Store to local at offset N

Return value and paramers: Accessed via SP-relative offsets - ‘PUSHREL -8’: Return value - ‘PUSHREL -16’: First parameter - ‘PUSHREL -24’: Second parameter