rearrange some info about the instruction encoding
llvm-svn: 24204
This commit is contained in:
Chris Lattner
parent
575e828aa5
commit
db1375823d
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@ -39,8 +39,8 @@
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<li><a href="#constantpool">Global Constant Pool</a></li>
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<li><a href="#functiondefs">Function Definition</a></li>
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<li><a href="#compactiontable">Compaction Table</a></li>
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<li><a href="#instructionlist">Instruction List</a></li>
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<li><a href="#opcodes">Instruction Opcodes</a></li>
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<li><a href="#instructionlist">Instructions List</a></li>
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<li><a href="#instructions">Instructions</a></li>
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<li><a href="#symtab">Symbol Table</a></li>
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</ol>
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</li>
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@ -1363,186 +1363,23 @@ of formats. See <a href="#instruction">Instructions</a> for details.</td>
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</tbody>
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</table>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsubsection"><a name="instruction">Instructions</a></div>
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<div class="doc_subsection"><a name="instructions">Instructions</a></div>
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<div class="doc_text">
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<p>For brevity, instructions are written in one of four formats,
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depending on the number of operands to the instruction. Each
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instruction begins with a <a href="#uint32_vbr">uint32_vbr</a> that
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encodes the type of the instruction as well as other things. The tables
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that follow describe the format of this first part of each instruction.</p>
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<p><b>Instruction Format 0</b></p>
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<p>This format is used for a few instructions that can't easily be
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shortened because they have large numbers of operands (e.g. PHI Node or
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getelementptr). Each of the opcode, type, and operand fields is found in
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successive fields.</p>
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<table>
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<tbody>
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<tr>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td><a href="#uint32_vbr">uint32_vbr</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note
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that for compatibility with the other instruction formats, the opcode
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is shifted left by 2 bits. Bits 0 and 1 must have value zero for this
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format.</td>
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</tr>
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<tr>
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<td><a href="#uint24_vbr">uint24_vbr</a></td>
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<td class="td_left">Provides the type slot number of the result type of
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the instruction.</td>
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</tr>
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<tr>
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<td><a href="#uint32_vbr">uint32_vbr</a></td>
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<td class="td_left">The number of operands that follow.</td>
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</tr>
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<tr>
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<td><a href="#uint32_vbr">uint32_vbr</a>+</td>
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<td class="td_left">The slot number of the value(s) for the operand(s).
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<sup>1</sup></td>
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</tr>
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</tbody>
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</table>
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Notes:
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<ol>
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<li>Note that if the instruction is a getelementptr and the type of
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the operand is a sequential type (array or pointer) then the slot
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number is shifted up two bits and the low order bits will encode the
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type of index used, as follows: 0=uint, 1=int, 2=ulong, 3=long.</li>
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</ol>
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<p><b>Instruction Format 1</b></p>
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<p>This format encodes the opcode, type and a single operand into a
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single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
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<table>
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<tbody>
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<tr>
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<th><b>Bits</b></th>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td>0-1</td>
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<td>constant "1"</td>
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<td class="td_left">These two bits must be the value 1 which identifies
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this as an instruction of format 1.</td>
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</tr>
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<tr>
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<td>2-7</td>
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<td><a href="#opcode">opcode</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note that
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the maximum opcode value is 63.</td>
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</tr>
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<tr>
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<td>8-19</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the type for this
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instruction. Maximum slot number is 2<sup>12</sup>-1=4095.</td>
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</tr>
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<tr>
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<td>20-31</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the
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first operand. Maximum slot number is 2<sup>12</sup>-1=4095. Note that
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the value 2<sup>12</sup>-1 denotes zero operands.</td>
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</tr>
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</tbody>
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</table>
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<p><b>Instruction Format 2</b></p>
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<p>This format encodes the opcode, type and two operands into a single <a
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href="#uint32_vbr">uint32_vbr</a> as follows:</p>
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<table>
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<tbody>
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<tr>
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<th><b>Bits</b></th>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td>0-1</td>
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<td>constant "2"</td>
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<td class="td_left">These two bits must be the value 2 which identifies
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this as an instruction of format 2.</td>
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</tr>
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<tr>
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<td>2-7</td>
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<td><a href="#opcodes">opcode</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note that
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the maximum opcode value is 63.</td>
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</tr>
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<tr>
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<td>8-15</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the type for this
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instruction. Maximum slot number is 2<sup>8</sup>-1=255.</td>
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</tr>
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<tr>
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<td>16-23</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the first
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operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
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</tr>
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<tr>
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<td>24-31</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the second
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operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
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</tr>
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</tbody>
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</table>
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<p><b>Instruction Format 3</b></p>
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<p>This format encodes the opcode, type and three operands into a
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single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
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<table>
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<tbody>
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<tr>
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<th><b>Bits</b></th>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td>0-1</td>
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<td>constant "3"</td>
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<td class="td_left">These two bits must be the value 3 which identifies
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this as an instruction of format 3.</td>
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</tr>
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<tr>
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<td>2-7</td>
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<td><a href="#opcodes">opcode</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note that
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the maximum opcode value is 63.</td>
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</tr>
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<tr>
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<td>8-13</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the type for this
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instruction. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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<tr>
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<td>14-19</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the first
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operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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<tr>
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<td>20-25</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the second
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operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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<tr>
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<td>26-31</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the third
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operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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</tbody>
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</table>
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<p>Instructions are written out one at a time as distinct units. Each
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instruction
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record contains at least an <a href="#opcodes">opcode</a> and a type field,
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and may contain a list of operands (whose interpretation depends on the opcode).
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Based on the number of operands, the
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<a href="#instencode">instruction is encoded</a> in a
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dense format that tries to encoded each instruction into 32-bits if
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possible. </p>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="opcodes">Instruction Opcodes</a></div>
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<div class="doc_subsubsection"><a name="opcodes">Instruction Opcodes</a></div>
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<div class="doc_text">
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<p>Instructions encode an opcode that identifies the kind of instruction.
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Opcodes are an enumerated integer value. The specific values used depend on
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@ -1614,10 +1451,9 @@ single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
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<tr><td>Store+Volatile</td><td>63</td><td>3</td><td>1.3</td></tr>
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</tbody>
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</table>
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</div>
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<p><b><a name="pi_note">* Note: </a></b>
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These aren't really opcodes from an LLVM language prespeective. They encode
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These aren't really opcodes from an LLVM language perspective. They encode
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information into other opcodes without reserving space for that information.
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For example, opcode=63 is a Volatile Store. The opcode for this
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instruction is 25 (Store) but we encode it as 63 to indicate that is a Volatile
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@ -1639,6 +1475,188 @@ opcode (Invoke, Call, Store) plus some set of modifiers, as follows:</p>
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<dt>TailCall</dt>
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<dd>This indicates that the Call has the 'tail' modifier.</dd>
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</dl>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsubsection"><a name="instencode">Instruction
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Encoding</a></div>
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<div class="doc_text">
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<p>For brevity, instructions are written in one of four formats,
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depending on the number of operands to the instruction. Each
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instruction begins with a <a href="#uint32_vbr">uint32_vbr</a> that
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encodes the type of the instruction as well as other things. The tables
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that follow describe the format of this first part of each instruction.</p>
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<p><b>Instruction Format 0</b></p>
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<p>This format is used for a few instructions that can't easily be
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shortened because they have large numbers of operands (e.g. PHI Node or
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getelementptr). Each of the opcode, type, and operand fields is found in
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successive fields.</p>
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<table>
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<tbody>
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<tr>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td><a href="#uint32_vbr">uint32_vbr</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note
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that for compatibility with the other instruction formats, the opcode
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is shifted left by 2 bits. Bits 0 and 1 must have value zero for this
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format.</td>
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</tr>
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<tr>
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<td><a href="#uint24_vbr">uint24_vbr</a></td>
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<td class="td_left">Provides the type slot number of the result type of
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the instruction.</td>
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</tr>
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<tr>
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<td><a href="#uint32_vbr">uint32_vbr</a></td>
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<td class="td_left">The number of operands that follow.</td>
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</tr>
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<tr>
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<td><a href="#uint32_vbr">uint32_vbr</a>+</td>
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<td class="td_left">The slot number of the value(s) for the operand(s).
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<sup>1</sup></td>
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</tr>
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</tbody>
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</table>
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Notes:
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<ol>
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<li>Note that if the instruction is a getelementptr and the type of
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the operand is a sequential type (array or pointer) then the slot
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number is shifted up two bits and the low order bits will encode the
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type of index used, as follows: 0=uint, 1=int, 2=ulong, 3=long.</li>
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</ol>
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<p><b>Instruction Format 1</b></p>
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<p>This format encodes the opcode, type and a single operand into a
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single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
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<table>
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<tbody>
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<tr>
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<th><b>Bits</b></th>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td>0-1</td>
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<td>constant "1"</td>
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<td class="td_left">These two bits must be the value 1 which identifies
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this as an instruction of format 1.</td>
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</tr>
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<tr>
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<td>2-7</td>
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<td><a href="#instructions">opcode</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note that
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the maximum opcode value is 63.</td>
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</tr>
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<tr>
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<td>8-19</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the type for this
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instruction. Maximum slot number is 2<sup>12</sup>-1=4095.</td>
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</tr>
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<tr>
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<td>20-31</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the
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first operand. Maximum slot number is 2<sup>12</sup>-1=4095. Note that
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the value 2<sup>12</sup>-1 denotes zero operands.</td>
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</tr>
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</tbody>
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</table>
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<p><b>Instruction Format 2</b></p>
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<p>This format encodes the opcode, type and two operands into a single <a
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href="#uint32_vbr">uint32_vbr</a> as follows:</p>
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<table>
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<tbody>
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<tr>
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<th><b>Bits</b></th>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td>0-1</td>
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<td>constant "2"</td>
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<td class="td_left">These two bits must be the value 2 which identifies
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this as an instruction of format 2.</td>
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</tr>
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<tr>
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<td>2-7</td>
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<td><a href="#instructions">opcode</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note that
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the maximum opcode value is 63.</td>
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</tr>
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<tr>
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<td>8-15</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the type for this
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instruction. Maximum slot number is 2<sup>8</sup>-1=255.</td>
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</tr>
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<tr>
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<td>16-23</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the first
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operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
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</tr>
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<tr>
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<td>24-31</td>
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<td><a href="#unsigned">unsigned</a></td>
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<td class="td_left">Specifies the slot number of the value for the second
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operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
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</tr>
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</tbody>
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</table>
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<p><b>Instruction Format 3</b></p>
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<p>This format encodes the opcode, type and three operands into a
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single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
|
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<table>
|
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<tbody>
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<tr>
|
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<th><b>Bits</b></th>
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<th><b>Type</b></th>
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<th class="td_left"><b>Field Description</b></th>
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</tr>
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<tr>
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<td>0-1</td>
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<td>constant "3"</td>
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<td class="td_left">These two bits must be the value 3 which identifies
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this as an instruction of format 3.</td>
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</tr>
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<tr>
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<td>2-7</td>
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<td><a href="#instructions">opcode</a></td>
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<td class="td_left">Specifies the opcode of the instruction. Note that
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the maximum opcode value is 63.</td>
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</tr>
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<tr>
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<td>8-13</td>
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<td><a href="#unsigned">unsigned</a></td>
|
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<td class="td_left">Specifies the slot number of the type for this
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instruction. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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<tr>
|
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<td>14-19</td>
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<td><a href="#unsigned">unsigned</a></td>
|
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<td class="td_left">Specifies the slot number of the value for the first
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operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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<tr>
|
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<td>20-25</td>
|
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<td><a href="#unsigned">unsigned</a></td>
|
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<td class="td_left">Specifies the slot number of the value for the second
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operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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<tr>
|
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<td>26-31</td>
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<td><a href="#unsigned">unsigned</a></td>
|
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<td class="td_left">Specifies the slot number of the value for the third
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operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
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</tr>
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</tbody>
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</table>
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</div>
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<!-- _______________________________________________________________________ -->
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<div class="doc_subsection"><a name="symtab">Symbol Table</a> </div>
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Reference in New Issue