mingw/info/stabs/Parameters.html

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  12 Node:<a name="Parameters">Parameters</a>,
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  18 <h3 class="section">Parameters</h3>
  19
  20    <p>Formal parameters to a function are represented by a stab (or sometimes
  21 two; see below) for each parameter.  The stabs are in the order in which
  22 the debugger should print the parameters (i.e., the order in which the
  23 parameters are declared in the source file).  The exact form of the stab
  24 depends on how the parameter is being passed.
  25
  26    <p>Parameters passed on the stack use the symbol descriptor <code>p</code> and
  27 the <code>N_PSYM</code> symbol type (or <code>C_PSYM</code> for XCOFF).  The value
  28 of the symbol is an offset used to locate the parameter on the stack;
  29 its exact meaning is machine-dependent, but on most machines it is an
  30 offset from the frame pointer.
  31
  32    <p>As a simple example, the code:
  33
  34 <pre class="example">     main (argc, argv)
  35           int argc;
  36           char **argv;
  37      </pre>
  38
  39    <p>produces the stabs:
  40
  41 <pre class="example">     .stabs "main:F1",36,0,0,_main                 # 36 is N_FUN
  42      .stabs "argc:p1",160,0,0,68                   # 160 is N_PSYM
  43      .stabs "argv:p20=*21=*2",160,0,0,72
  44      </pre>
  45
  46    <p>The type definition of <code>argv</code> is interesting because it contains
  47 several type definitions.  Type 21 is pointer to type 2 (char) and
  48 <code>argv</code> (type 20) is pointer to type 21.
  49
  50    <p>The following symbol descriptors are also said to go with <code>N_PSYM</code>.
  51 The value of the symbol is said to be an offset from the argument
  52 pointer (I'm not sure whether this is true or not).
  53
  54 <pre class="example">     pP (&lt;&lt;??&gt;&gt;)
  55      pF Fortran function parameter
  56      X  (function result variable)
  57      </pre>
  58
  59 <ul class="menu">
  60 <li><a accesskey="1" href="Register-Parameters.html#Register%20Parameters">Register Parameters</a>:
  61 <li><a accesskey="2" href="Local-Variable-Parameters.html#Local%20Variable%20Parameters">Local Variable Parameters</a>:
  62 <li><a accesskey="3" href="Reference-Parameters.html#Reference%20Parameters">Reference Parameters</a>:
  63 <li><a accesskey="4" href="Conformant-Arrays.html#Conformant%20Arrays">Conformant Arrays</a>:
  64 </ul>
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