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| <h3 class="section">17.2 Continuing at a Different Address</h3> |
| |
| <p>Ordinarily, when you continue your program, you do so at the place where |
| it stopped, with the <code>continue</code> command. You can instead continue at |
| an address of your own choosing, with the following commands: |
| |
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| <a name="index-jump-1168"></a> |
| <a name="index-j-_0040r_007b_0028_0040code_007bjump_007d_0029_007d-1169"></a> |
| <dl><dt><code>jump </code><var>location</var><dt><code>j </code><var>location</var><dd>Resume execution at <var>location</var>. Execution stops again immediately |
| if there is a breakpoint there. See <a href="Specify-Location.html#Specify-Location">Specify Location</a>, for a description |
| of the different forms of <var>location</var>. It is common |
| practice to use the <code>tbreak</code> command in conjunction with |
| <code>jump</code>. See <a href="Set-Breaks.html#Set-Breaks">Setting Breakpoints</a>. |
| |
| <p>The <code>jump</code> command does not change the current stack frame, or |
| the stack pointer, or the contents of any memory location or any |
| register other than the program counter. If <var>location</var> is in |
| a different function from the one currently executing, the results may |
| be bizarre if the two functions expect different patterns of arguments or |
| of local variables. For this reason, the <code>jump</code> command requests |
| confirmation if the specified line is not in the function currently |
| executing. However, even bizarre results are predictable if you are |
| well acquainted with the machine-language code of your program. |
| </dl> |
| |
| <p>On many systems, you can get much the same effect as the <code>jump</code> |
| command by storing a new value into the register <code>$pc</code>. The |
| difference is that this does not start your program running; it only |
| changes the address of where it <em>will</em> run when you continue. For |
| example, |
| |
| <pre class="smallexample"> set $pc = 0x485 |
| </pre> |
| <p class="noindent">makes the next <code>continue</code> command or stepping command execute at |
| address <code>0x485</code>, rather than at the address where your program stopped. |
| See <a href="Continuing-and-Stepping.html#Continuing-and-Stepping">Continuing and Stepping</a>. |
| |
| <p>The most common occasion to use the <code>jump</code> command is to back |
| up—perhaps with more breakpoints set—over a portion of a program |
| that has already executed, in order to examine its execution in more |
| detail. |
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