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| <h3 class="section">4.3 Register Variables</h3> |
| |
| <p><a name="index-N_005fRSYM-29"></a><a name="index-C_005fRSYM-30"></a><!-- According to an old version of this manual, AIX uses C_RPSYM instead --> |
| <!-- of C_RSYM. I am skeptical; this should be verified. --> |
| Register variables have their own stab type, <code>N_RSYM</code> |
| (<code>C_RSYM</code> for XCOFF), and their own symbol descriptor, ‘<samp><span class="samp">r</span></samp>’. |
| The stab's value is the number of the register where the variable data |
| will be stored. |
| <!-- .stabs "name:type",N_RSYM,0,RegSize,RegNumber (Sun doc) --> |
| |
| <p>AIX defines a separate symbol descriptor ‘<samp><span class="samp">d</span></samp>’ for floating point |
| registers. This seems unnecessary; why not just just give floating |
| point registers different register numbers? I have not verified whether |
| the compiler actually uses ‘<samp><span class="samp">d</span></samp>’. |
| |
| <p>If the register is explicitly allocated to a global variable, but not |
| initialized, as in: |
| |
| <pre class="example"> register int g_bar asm ("%g5"); |
| </pre> |
| <p class="noindent">then the stab may be emitted at the end of the object file, with |
| the other bss symbols. |
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