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| <h2 class="chapter">6 Representation of #define and #undef</h2> |
| |
| <p>This section describes the stabs support for macro define and undefine |
| information, supported on some systems. (e.g., with <samp><span class="option">-g3</span></samp> |
| <samp><span class="option">-gstabs</span></samp> when using GCC). |
| |
| <p>A <code>#define </code><var>macro-name</var> <var>macro-body</var> is represented with |
| an <code>N_MAC_DEFINE</code> stab with a string field of |
| <var>macro-name</var> <var>macro-body</var>. |
| <a name="index-N_005fMAC_005fDEFINE-51"></a> |
| An <code>#undef </code><var>macro-name</var> is represented with an |
| <code>N_MAC_UNDEF</code> stabs with a string field of simply |
| <var>macro-name</var>. |
| <a name="index-N_005fMAC_005fUNDEF-52"></a> |
| For both <code>N_MAC_DEFINE</code> and <code>N_MAC_UNDEF</code>, the desc field is |
| the line number within the file where the corresponding <code>#define</code> |
| or <code>#undef</code> occurred. |
| |
| <p>For example, the following C code: |
| |
| <pre class="example"> #define NONE 42 |
| #define TWO(a, b) (a + (a) + 2 * b) |
| #define ONE(c) (c + 19) |
| |
| main(int argc, char *argv[]) |
| { |
| func(NONE, TWO(10, 11)); |
| func(NONE, ONE(23)); |
| |
| #undef ONE |
| #define ONE(c) (c + 23) |
| |
| func(NONE, ONE(-23)); |
| |
| return (0); |
| } |
| |
| int global; |
| |
| func(int arg1, int arg2) |
| { |
| global = arg1 + arg2; |
| } |
| </pre> |
| <p class="noindent">produces the following stabs (as well as many others): |
| |
| <pre class="example"> .stabs "NONE 42",54,0,1,0 |
| .stabs "TWO(a,b) (a + (a) + 2 * b)",54,0,2,0 |
| .stabs "ONE(c) (c + 19)",54,0,3,0 |
| .stabs "ONE",58,0,10,0 |
| .stabs "ONE(c) (c + 23)",54,0,11,0 |
| </pre> |
| <p class="noindent">NOTE: In the above example, <code>54</code> is <code>N_MAC_DEFINE</code> and |
| <code>58</code> is <code>N_MAC_UNDEF</code>. |
| |
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