| <html lang="en"> |
| <head> |
| <title>Options-i960 - Using as</title> |
| <meta http-equiv="Content-Type" content="text/html"> |
| <meta name="description" content="Using as"> |
| <meta name="generator" content="makeinfo 4.13"> |
| <link title="Top" rel="start" href="index.html#Top"> |
| <link rel="up" href="i960_002dDependent.html#i960_002dDependent" title="i960-Dependent"> |
| <link rel="next" href="Floating-Point_002di960.html#Floating-Point_002di960" title="Floating Point-i960"> |
| <link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> |
| <!-- |
| This file documents the GNU Assembler "as". |
| |
| Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, |
| 2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc. |
| |
| Permission is granted to copy, distribute and/or modify this document |
| under the terms of the GNU Free Documentation License, Version 1.3 |
| or any later version published by the Free Software Foundation; |
| with no Invariant Sections, with no Front-Cover Texts, and with no |
| Back-Cover Texts. A copy of the license is included in the |
| section entitled ``GNU Free Documentation License''. |
| |
| --> |
| <meta http-equiv="Content-Style-Type" content="text/css"> |
| <style type="text/css"><!-- |
| pre.display { font-family:inherit } |
| pre.format { font-family:inherit } |
| pre.smalldisplay { font-family:inherit; font-size:smaller } |
| pre.smallformat { font-family:inherit; font-size:smaller } |
| pre.smallexample { font-size:smaller } |
| pre.smalllisp { font-size:smaller } |
| span.sc { font-variant:small-caps } |
| span.roman { font-family:serif; font-weight:normal; } |
| span.sansserif { font-family:sans-serif; font-weight:normal; } |
| --></style> |
| <link rel="stylesheet" type="text/css" href="../cs.css"> |
| </head> |
| <body> |
| <div class="node"> |
| <a name="Options-i960"></a> |
| <a name="Options_002di960"></a> |
| <p> |
| Next: <a rel="next" accesskey="n" href="Floating-Point_002di960.html#Floating-Point_002di960">Floating Point-i960</a>, |
| Up: <a rel="up" accesskey="u" href="i960_002dDependent.html#i960_002dDependent">i960-Dependent</a> |
| <hr> |
| </div> |
| |
| <h4 class="subsection">9.15.1 i960 Command-line Options</h4> |
| |
| <p><a name="index-i960-options-1008"></a><a name="index-options_002c-i960-1009"></a> |
| |
| <a name="index-i960-architecture-options-1010"></a> |
| <a name="index-architecture-options_002c-i960-1011"></a> |
| <a name="index-g_t_0040code_007b_002dA_007d-options_002c-i960-1012"></a> |
| <dl><dt><code>-ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC</code><dd>Select the 80960 architecture. Instructions or features not supported |
| by the selected architecture cause fatal errors. |
| |
| <p>‘<samp><span class="samp">-ACA</span></samp>’ is equivalent to ‘<samp><span class="samp">-ACA_A</span></samp>’; ‘<samp><span class="samp">-AKC</span></samp>’ is equivalent to |
| ‘<samp><span class="samp">-AMC</span></samp>’. Synonyms are provided for compatibility with other tools. |
| |
| <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-g_t_0040code_007b_002db_007d-option_002c-i960-1013"></a><a name="index-branch-recording_002c-i960-1014"></a><a name="index-i960-branch-recording-1015"></a><br><dt><code>-b</code><dd>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><span class="samp">-b</span></samp>’ is specified: |
| |
| <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> |
| <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-g_t_0040code_007bgbr960_007d_002c-i960-postprocessor-1016"></a><a name="index-branch-statistics-table_002c-i960-1017"></a>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><span class="samp">__BRANCH_TABLE__</span></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. |
| |
| <!-- TEXI2ROFF-KILL --> |
| <!-- END TEXI2ROFF-KILL --> |
| <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 <span class="sc">gnu</span> C compiler |
| generates these calls automatically when you give it a ‘<samp><span class="samp">-b</span></samp>’ option. |
| For further details, see the documentation of ‘<samp><span class="samp">gbr960</span></samp>’. |
| |
| <p><a name="index-g_t_0040code_007b_002dno_002drelax_007d-option_002c-i960-1018"></a><br><dt><code>-no-relax</code><dd>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><span class="samp">chkbit</span></samp>’) and branch |
| instructions. You can use the ‘<samp><span class="samp">-no-relax</span></samp>’ option to specify that |
| <code>as</code> should generate errors instead, if the target displacement |
| is larger than 13 bits. |
| |
| <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><span class="samp">-no-relax</span></samp>’. |
| </dl> |
| |
| </body></html> |
| |
