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| <h4 class="subsection">9.47.2 Syntax</h4> |
| |
| <p><a name="index-TILE_002dGx-syntax-2379"></a><a name="index-syntax_002c-TILE_002dGx-2380"></a> |
| Block comments are delimited by ‘<samp><span class="samp">/*</span></samp>’ and ‘<samp><span class="samp">*/</span></samp>’. End of line |
| comments may be introduced by ‘<samp><span class="samp">#</span></samp>’. |
| |
| <p>Instructions consist of a leading opcode or macro name followed by |
| whitespace and an optional comma-separated list of operands: |
| |
| <pre class="smallexample"> <var>opcode</var> [<var>operand</var>, ...] |
| </pre> |
| <p>Instructions must be separated by a newline or semicolon. |
| |
| <p>There are two ways to write code: either write naked instructions, |
| which the assembler is free to combine into VLIW bundles, or specify |
| the VLIW bundles explicitly. |
| |
| <p>Bundles are specified using curly braces: |
| |
| <pre class="smallexample"> { <var>add</var> r3,r4,r5 ; <var>add</var> r7,r8,r9 ; <var>lw</var> r10,r11 } |
| </pre> |
| <p>A bundle can span multiple lines. If you want to put multiple |
| instructions on a line, whether in a bundle or not, you need to |
| separate them with semicolons as in this example. |
| |
| <p>A bundle may contain one or more instructions, up to the limit |
| specified by the ISA (currently three). If fewer instructions are |
| specified than the hardware supports in a bundle, the assembler |
| inserts <code>fnop</code> instructions automatically. |
| |
| <p>The assembler will prefer to preserve the ordering of instructions |
| within the bundle, putting the first instruction in a lower-numbered |
| pipeline than the next one, etc. This fact, combined with the |
| optional use of explicit <code>fnop</code> or <code>nop</code> instructions, |
| allows precise control over which pipeline executes each instruction. |
| |
| <p>If the instructions cannot be bundled in the listed order, the |
| assembler will automatically try to find a valid pipeline |
| assignment. If there is no way to bundle the instructions together, |
| the assembler reports an error. |
| |
| <p>The assembler does not yet auto-bundle (automatically combine multiple |
| instructions into one bundle), but it reserves the right to do so in |
| the future. If you want to force an instruction to run by itself, put |
| it in a bundle explicitly with curly braces and use <code>nop</code> |
| instructions (not <code>fnop</code>) to fill the remaining pipeline slots in |
| that bundle. |
| |
| <ul class="menu"> |
| <li><a accesskey="1" href="TILE_002dGx-Opcodes.html#TILE_002dGx-Opcodes">TILE-Gx Opcodes</a>: Opcode Naming Conventions. |
| <li><a accesskey="2" href="TILE_002dGx-Registers.html#TILE_002dGx-Registers">TILE-Gx Registers</a>: Register Naming. |
| <li><a accesskey="3" href="TILE_002dGx-Modifiers.html#TILE_002dGx-Modifiers">TILE-Gx Modifiers</a>: Symbolic Operand Modifiers. |
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