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| <h3 class="section">2.7 Block Structure</h3> |
| |
| <p><a name="index-N_005fLBRAC-18"></a><a name="index-N_005fRBRAC-19"></a><!-- For GCC 2.5.8 or so stabs-in-coff, these are absolute instead of --> |
| <!-- function relative (as documented below). But GDB has never been able --> |
| <!-- to deal with that (it had wanted them to be relative to the file, but --> |
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| <!-- relative just like ELF and SOM and the below documentation. --> |
| The program's block structure is represented by the <code>N_LBRAC</code> (left |
| brace) and the <code>N_RBRAC</code> (right brace) stab types. The variables |
| defined inside a block precede the <code>N_LBRAC</code> symbol for most |
| compilers, including GCC. Other compilers, such as the Convex, Acorn |
| RISC machine, and Sun <code>acc</code> compilers, put the variables after the |
| <code>N_LBRAC</code> symbol. The values of the <code>N_LBRAC</code> and |
| <code>N_RBRAC</code> symbols are the start and end addresses of the code of |
| the block, respectively. For most machines, they are relative to the |
| starting address of this source file. For the Gould NP1, they are |
| absolute. For stabs in sections (see <a href="Stab-Sections.html#Stab-Sections">Stab Sections</a>), they are |
| relative to the function in which they occur. |
| |
| <p>The <code>N_LBRAC</code> and <code>N_RBRAC</code> stabs that describe the block |
| scope of a procedure are located after the <code>N_FUN</code> stab that |
| represents the procedure itself. |
| |
| <p>Sun documents the desc field of <code>N_LBRAC</code> and |
| <code>N_RBRAC</code> symbols as containing the nesting level of the block. |
| However, dbx seems to not care, and GCC always sets desc to |
| zero. |
| |
| <p><a name="index-g_t_002ebb-20"></a><a name="index-g_t_002ebe-21"></a><a name="index-C_005fBLOCK-22"></a>For XCOFF, block scope is indicated with <code>C_BLOCK</code> symbols. If the |
| name of the symbol is ‘<samp><span class="samp">.bb</span></samp>’, then it is the beginning of the block; |
| if the name of the symbol is ‘<samp><span class="samp">.be</span></samp>’; it is the end of the block. |
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