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| <a name="Options_002di960"></a> |
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| Next: <a href="Floating-Point_002di960.html#Floating-Point_002di960" accesskey="n" rel="next">Floating Point-i960</a>, Up: <a href="i960_002dDependent.html#i960_002dDependent" accesskey="u" rel="up">i960-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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| <hr> |
| |
| <a name="i960-Command_002dline-Options"></a> |
| <h4 class="subsection">9.17.1 i960 Command-line Options</h4> |
| |
| <a name="index-i960-options"></a> |
| <a name="index-options_002c-i960"></a> |
| <dl compact="compact"> |
| <dd> |
| <a name="index-i960-architecture-options"></a> |
| <a name="index-architecture-options_002c-i960"></a> |
| <a name="index-_002dA-options_002c-i960"></a> |
| </dd> |
| <dt><code>-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC</code></dt> |
| <dd><p>Select the 80960 architecture. Instructions or features not supported |
| by the selected architecture cause fatal errors. |
| </p> |
| <p>‘<samp>-ACA</samp>’ is equivalent to ‘<samp>-ACA_A</samp>’; ‘<samp>-AKC</samp>’ is equivalent to |
| ‘<samp>-AMC</samp>’. Synonyms are provided for compatibility with other tools. |
| </p> |
| <p>If you do not specify any of these options, <code>as</code> generates code |
| for any instruction or feature that is supported by <em>some</em> version of the |
| 960 (even if this means mixing architectures!). In principle, |
| <code>as</code> attempts to deduce the minimal sufficient processor type if |
| none is specified; depending on the object code format, the processor type may |
| be recorded in the object file. If it is critical that the <code>as</code> |
| output match a specific architecture, specify that architecture explicitly. |
| </p> |
| <a name="index-_002db-option_002c-i960"></a> |
| <a name="index-branch-recording_002c-i960"></a> |
| <a name="index-i960-branch-recording"></a> |
| </dd> |
| <dt><code>-b</code></dt> |
| <dd><p>Add code to collect information about conditional branches taken, for |
| later optimization using branch prediction bits. (The conditional branch |
| instructions have branch prediction bits in the CA, CB, and CC |
| architectures.) If <var>BR</var> represents a conditional branch instruction, |
| the following represents the code generated by the assembler when |
| ‘<samp>-b</samp>’ is specified: |
| </p> |
| <div class="smallexample"> |
| <pre class="smallexample"> call <var>increment routine</var> |
| .word 0 # pre-counter |
| Label: <var>BR</var> |
| call <var>increment routine</var> |
| .word 0 # post-counter |
| </pre></div> |
| |
| <p>The counter following a branch records the number of times that branch |
| was <em>not</em> taken; the difference between the two counters is the |
| number of times the branch <em>was</em> taken. |
| </p> |
| <a name="index-gbr960_002c-i960-postprocessor"></a> |
| <a name="index-branch-statistics-table_002c-i960"></a> |
| <p>A table of every such <code>Label</code> is also generated, so that the |
| external postprocessor <code>gbr960</code> (supplied by Intel) can locate all |
| the counters. This table is always labeled ‘<samp>__BRANCH_TABLE__</samp>’; |
| this is a local symbol to permit collecting statistics for many separate |
| object files. The table is word aligned, and begins with a two-word |
| header. The first word, initialized to 0, is used in maintaining linked |
| lists of branch tables. The second word is a count of the number of |
| entries in the table, which follow immediately: each is a word, pointing |
| to one of the labels illustrated above. |
| </p> |
| |
| <p>The first word of the header is used to locate multiple branch tables, |
| since each object file may contain one. Normally the links are |
| maintained with a call to an initialization routine, placed at the |
| beginning of each function in the file. The <small>GNU</small> C compiler |
| generates these calls automatically when you give it a ‘<samp>-b</samp>’ option. |
| For further details, see the documentation of ‘<samp>gbr960</samp>’. |
| </p> |
| <a name="index-_002dno_002drelax-option_002c-i960"></a> |
| </dd> |
| <dt><code>-no-relax</code></dt> |
| <dd><p>Normally, Compare-and-Branch instructions with targets that require |
| displacements greater than 13 bits (or that have external targets) are |
| replaced with the corresponding compare (or ‘<samp>chkbit</samp>’) and branch |
| instructions. You can use the ‘<samp>-no-relax</samp>’ option to specify that |
| <code>as</code> should generate errors instead, if the target displacement |
| is larger than 13 bits. |
| </p> |
| <p>This option does not affect the Compare-and-Jump instructions; the code |
| emitted for them is <em>always</em> adjusted when necessary (depending on |
| displacement size), regardless of whether you use ‘<samp>-no-relax</samp>’. |
| </p></dd> |
| </dl> |
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| Next: <a href="Floating-Point_002di960.html#Floating-Point_002di960" accesskey="n" rel="next">Floating Point-i960</a>, Up: <a href="i960_002dDependent.html#i960_002dDependent" accesskey="u" rel="up">i960-Dependent</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p> |
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