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<li><a href="#constantpool">Global Constant Pool</a></li>
<li><a href="#functiondefs">Function Definition</a></li>
<li><a href="#compactiontable">Compaction Table</a></li>
- <li><a href="#instructionlist">Instruction List</a></li>
+ <li><a href="#instructionlist">Instructions List</a></li>
+ <li><a href="#instructions">Instructions</a></li>
<li><a href="#symtab">Symbol Table</a></li>
</ol>
</li>
<li><a href="#versiondiffs">Version Differences</a>
<ol>
+ <li><a href="#vers13">Version 1.3 Differences From 1.4</a></li>
<li><a href="#vers12">Version 1.2 Differences From 1.3</a></li>
<li><a href="#vers11">Version 1.1 Differences From 1.2</a></li>
<li><a href="#vers10">Version 1.0 Differences From 1.1</a></li>
<td class="td_left">A 64-bit signed integer that occupies from one to ten
bytes using the signed variable bit rate encoding.</td>
</tr>
- <tr>
- <td><a name="opcode"><b>opcode</b></a></td>
- <td class="td_left">An enumerated integer value used in the instruction
- format that identifies the LLVM instruction opcode referenced. The
- specific values used depend on the version of LLVM you're using. See the
- <a
- href="http://llvm.org/cvsweb/cvsweb.cgi/llvm/include/llvm/Instruction.def">
- <tt>include/llvm/Instruction.def</tt></a> file for the definitive set of
- opcode values used for your release. The opcode values are the first
- argument to the various <tt>HANDLE_*_INST</tt> macros.
- </td>
<tr>
<td><a name="char"><b>char</b></a></td>
<td class="td_left">A single unsigned character encoded into one byte</td>
are written to the bytecode file in a list (sequentially). Their order in
that list determines their slot number. This means that slot #1 doesn't mean
anything unless you also specify for which type you want slot #1. Types are
-handled specially and are always written to the file first (in the <a
- href="#globaltypes">Global Type Pool</a>) and in such a way that both forward
-and backward references of the types can often be resolved with a single pass
-through the type pool. </p>
+always written to the file first (in the <a href="#globaltypes">Global Type
+Pool</a>) and in such a way that both forward and backward references of the
+types can often be resolved with a single pass through the type pool. </p>
<p>Slot numbers are also kept small by rearranging their order. Because
of the structure of LLVM, certain values are much more likely to be used
frequently in the body of a function. For this reason, a compaction table is
"{double}" but uses them thousands of time. Its worthwhile to ensure that the
slot number for these types are low so they can be encoded in a single byte
(via vbr). This is exactly what the compaction table does.</p>
+<p>In summary then, a slot number can be though of as just a vbr encoded index
+into a list of Type* or Value*. To keep slot numbers low, Value* are indexed by
+two slot numbers: the "type plane index" (type slot) and the "value index"
+(value slot).</p>
</div>
<!-- *********************************************************************** -->
<div class="doc_section"> <a name="general">General Structure</a> </div>
other blocks because there is no identifier and no block length at the start
of the block. Essentially, this block is just the "magic number" for the file.
</p>
+<p>There are two types of signatures for LLVM bytecode: uncompressed and
+compressed as shown in the table below. </p>
<table>
<tbody>
<tr>
<th><b>Type</b></th>
- <th class="td_left"><b>Field Description</b></th>
+ <th class="td_left"><b>Uncompressed</b></th>
+ <th class="td_left"><b>Compressed</b></th>
</tr>
<tr>
<td><a href="#char">char</a></td>
<td class="td_left">Constant "l" (0x6C)</td>
+ <td class="td_left">Constant "l" (0x6C)</td>
</tr>
<tr>
<td><a href="#char">char</a></td>
<td class="td_left">Constant "l" (0x6C)</td>
+ <td class="td_left">Constant "l" (0x6C)</td>
</tr>
<tr>
<td><a href="#char">char</a></td>
<td class="td_left">Constant "v" (0x76)</td>
+ <td class="td_left">Constant "v" (0x76)</td>
</tr>
<tr>
<td><a href="#char">char</a></td>
<td class="td_left">Constant "m" (0x6D)</td>
+ <td class="td_left">Constant "c" (0x63)</td>
+ </tr>
+ <tr>
+ <td><a href="#char">char</a></td>
+ <td class="td_left">N/A</td>
+ <td class="td_left">'0'=null,'1'=gzip,'2'=bzip2</td>
</tr>
</tbody>
</table>
+<p>In other words, the uncompressed signature is just the characters 'llvm'
+while the compressed signature is the characters 'llvc' followed by an ascii
+digit ('0', '1', or '2') that indicates the kind of compression used. A value of
+'0' indicates that null compression was used. This can happen when compression
+was requested on a platform that wasn't configured for gzip or bzip2. A value of
+'1' means that the rest of the file is compressed using the gzip algorithm and
+should be uncompressed before interpretation. A value of '2' means that the rest
+of the file is compressed using the bzip2 algorithm and should be uncompressed
+before interpretation. In all cases, the data resulting from uncompression
+should be interpreted as if it occurred immediately after the 'llvm'
+signature (i.e. the uncompressed data begins with the
+<a href="#module">Module Block</a></p>
+<p><b>NOTE:</b> As of LLVM 1.4, all bytecode files produced by the LLVM tools
+are compressed by default. To disable compression, pass the
+<tt>--disable-compression</tt> option to the tool, if it supports it.
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="module">Module Block</a> </div>
</table>
<p>
Of particular note, the bytecode format number is simply a 28-bit
-monotonically increase integer that identifies the version of the bytecode
+monotonically increasing integer that identifies the version of the bytecode
format (which is not directly related to the LLVM release number). The
bytecode versions defined so far are (note that this document only
describes the latest version, 1.3):</p>
<li>#0: LLVM 1.0 & 1.1</li>
<li>#1: LLVM 1.2</li>
<li>#2: LLVM 1.2.5 (not released)</li>
- <li>#3: LLVM 1.3<br>
+ <li>#3: LLVM 1.3</li>
+ <li>#4: LLVM 1.3.x (not released)</li>
+ <li>#5: LLVM 1.4 and newer</li>
</li>
</ul>
<p>Note that we plan to eventually expand the target description
capabilities
-of bytecode files to <a href="http://llvm.cs.uiuc.edu/PR263">target
+of bytecode files to <a href="http://llvm.org/PR263">target
triples</a>.
</p>
</div>
<div class="doc_subsection"><a name="globaltypes">Global Type Pool</a> </div>
<div class="doc_text">
<p>The global type pool consists of type definitions. Their order of appearance
-in the file determines their slot number (0 based). Slot numbers are
+in the file determines their type slot number (0 based). Slot numbers are
used to replace pointers in the intermediate representation. Each slot number
uniquely identifies one entry in a type plane (a collection of values of the
same type). Since all values have types and are associated with the order in
of type, as given in the following sections.</p>
<h3>Primitive Types</h3>
<p>The primitive types encompass the basic integer and floating point
-types</p>
+types. They are encoded simply as their TypeID.</p>
<table>
<tbody>
<tr>
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a></td>
- <td class="td_left">Slot number of function's return type.</td>
+ <td class="td_left">Type slot number of function's return type.</td>
</tr>
<tr>
<td><a href="#llist">llist</a>(<a href="#uint24_vbr">uint24_vbr</a>)</td>
- <td class="td_left">Slot number of each argument's type.</td>
+ <td class="td_left">Type slot number of each argument's type.</td>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a>?</td>
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a></td>
- <td class="td_left">Slot number of array's element type.</td>
+ <td class="td_left">Type slot number of array's element type.</td>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a></td>
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a></td>
- <td class="td_left">Slot number of pointer's element type.</td>
+ <td class="td_left">Type slot number of pointer's element type.</td>
</tr>
</tbody>
</table>
</tr>
</tbody>
</table>
+<h3>Packed Types</h3>
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#uint24_vbr">uint24_vbr</a></td>
+ <td class="td_left">Type ID for Packed Types (18)</td>
+ </tr>
+ <tr>
+ <td><a href="#uint24_vbr">uint24_vbr</a></td>
+ <td class="td_left">Slot number of packed vector's element type.</td>
+ </tr>
+ <tr>
+ <td><a href="#uint32_vbr">uint32_vbr</a></td>
+ <td class="td_left">The number of elements in the packed vector.</td>
+ </tr>
+ </tbody>
+</table>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="globalinfo">Module Global Info</a>
</tr>
<tr>
<td><a href="#block">block</a></td>
- <td class="td_left">Module global info identifier (0x05) + size<br>
- </td>
+ <td class="td_left">Module global info identifier (0x05) + size</td>
</tr>
<tr>
<td><a href="#zlist">zlist</a>(<a href="#globalvar">globalvar</a>)</td>
<td class="td_left">A zero terminated list of global var
-definitions occuring in the module.</td>
+definitions occurring in the module.</td>
</tr>
<tr>
- <td><a href="#zlist">zlist</a>(<a href="#uint24_vbr">uint24_vbr</a>)</td>
- <td class="td_left">A zero terminated list of function types
-occuring in the module.</td>
+ <td><a href="#zlist">zlist</a>(<a href="#funcfield">funcfield</a>)</td>
+ <td class="td_left">A zero terminated list of function definitions
+occurring in the module.</td>
</tr>
<tr>
- <td style="vertical-align: top;"><a href="#llist">llist</a>(<a
- href="#string">string</a>)<br>
- </td>
- <td style="vertical-align: top; text-align: left;">A length list
+ <td><a href="#llist">llist</a>(<a href="#string">string</a>)</td>
+ <td class="td_left">A length list
of strings that specify the names of the libraries that this module
-depends upon.<br>
- </td>
+depends upon.</td>
</tr>
<tr>
- <td style="vertical-align: top;"><a href="#string">string</a><br>
- </td>
- <td style="vertical-align: top; text-align: left;">The target
+ <td><a href="#string">string</a></td>
+ <td class="td_left">The target
triple for the module (blank means no target triple specified, i.e. a
-platform independent module).<br>
- </td>
+platform independent module).</td>
+ </tr>
+ <tr>
+ <td><a href="#llist">llist</a>(<a href="#string">string</a>)</td>
+ <td class="td_left">A length list
+of strings that defines a table of section strings for globals. A global's
+SectionID is an index into this table.</td>
+ </tr>
+ <tr>
+ <td><a href="#string">string</a></td>
+ <td class="td_left">The inline asm block for this module.</td>
</tr>
</tbody>
</table>
</div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"><a name="globalvar">Global Variable Field</a>
</div>
+
<div class="doc_text">
+
<p>Global variables are written using an <a href="#uint32_vbr">uint32_vbr</a>
-that encodes information about the global variable and a list of the
-constant initializers for the global var, if any.</p>
+that encodes information about the global variable, an optional extension vbr,
+and a an optional initializers for the global var.</p>
+
<p>The table below provides the bit layout of the first <a
href="#uint32_vbr">uint32_vbr</a> that describes the global variable.</p>
+
<table>
<tbody>
<tr>
</tr>
<tr>
<td><a href="#bit">bit(5-31)</a></td>
- <td class="td_left">Slot number of type for the global variable.</td>
+ <td class="td_left">Type slot number of type for the global variable.</td>
+ </tr>
+ </tbody>
+</table>
+
+<p>When the Linkage type is set to 3 (internal) and the initializer field is set
+to 0 (an invalid combination), an extension word follows the first <a
+href="#uint32_vbr">uint32_vbr</a> which encodes the real linkage and init flag,
+and can includes more information:</p>
+
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(0)</a></td>
+ <td class="td_left">Has initializer? Indicates the real value of the "Has
+ initializer" field for the global. </td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(2-4)</a></td>
+ <td class="td_left">Linkage type: Indicates the real value of the "linkage
+ type" field for the global.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(4-8)</a></td>
+ <td class="td_left">The log-base-2 of the alignment for the global.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(9)</a></td>
+ <td class="td_left">If this bit is set, a SectionID follows this vbr.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(10-31)</a></td>
+ <td class="td_left">Currently unassigned.</td>
+ </tr>
+ </tbody>
+</table>
+
+<p>If the SectionID bit is set above, the following field is included:</p>
+
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#uint32_vbr">uint32_vbr</a>
+ </td>
+ <td class="td_left">An optional section ID number, specifying the string
+ to use for the section of the global. This an index (+1) of an entry
+ into the SectionID llist in the <a href="#globalinfo">Module Global
+ Info</a> block. If this value is 0 or not present, the global has an
+ empty section string.</td>
+ </tr>
+ </tbody>
+</table>
+
+<p>If the "Has initializer" field is set, the following field is included:</p>
+
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#uint32_vbr">uint32_vbr</a>
+ </td>
+ <td class="td_left">An optional value slot number for the global
+ variable's constant initializer.</td>
+ </tr>
+ </tbody>
+</table>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"><a name="funcfield">Function Field</a>
+</div>
+<div class="doc_text">
+<p>Functions are written using an <a href="#uint32_vbr">uint32_vbr</a>
+that encodes information about the function and a set of flags. If needed,
+an extension word may follow this first field.</p>
+
+<p>The table below provides the bit layout of the <a
+href="#uint32_vbr">uint32_vbr</a> that describes the function.</p>
+
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(0-3)</a></td>
+ <td class="td_left">
+ Encodes the calling convention number of the function. The
+ CC number of the function is the value of this field minus one.
+ </td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(4)</a></td>
+ <td class="td_left">If this bit is set to 1, the indicated function is
+ external, and there is no <a href="#functiondefs">Function Definiton
+ Block</a> in the bytecode file for the function.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(5-30)</a></td>
+ <td class="td_left">Type slot number of type for the function.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(31)</a></td>
+ <td class="td_left">Indicates whether an extension word follows.</td>
+ </tr>
+ </tbody>
+</table>
+
+<p>If bit(31) is set, an additional <a href="#uint32_vbr">uint32_vbr</a> word
+follows with the following fields:</p>
+
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(0-4)</a></td>
+ <td class="td_left">The log-base-2 of the alignment for the function.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(5-9)</a></td>
+ <td class="td_left">The top nibble of the calling convention.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(10)</a></td>
+ <td class="td_left">If this bit is set, a SectionID follows this vbr.</td>
+ </tr>
+ <tr>
+ <td><a href="#bit">bit(11-31)</a></td>
+ <td class="td_left">Currently unassigned.</td>
</tr>
</tbody>
</table>
-<p>The table below provides the format of the constant initializers for
-the global variable field, if it has one.</p>
+
+<p>If the SectionID bit is set above, the following field is included:</p>
+
<table>
<tbody>
<tr>
<th class="td_left"><b>Description</b></th>
</tr>
<tr>
- <td>(<a href="#zlist">zlist</a>(<a href="#uint32_vbr">uint32_vbr</a>))?
+ <td><a href="#uint32_vbr">uint32_vbr</a>
</td>
- <td class="td_left">An optional zero-terminated list of slot
-numbers of the global variable's constant initializer.</td>
+ <td class="td_left">An optional section ID number, specifying the string
+ to use for the section of the function. This an index (+1) of an entry
+ into the SectionID llist in the <a href="#globalinfo">Module Global
+ Info</a> block. If this value is 0 or not present, the function has an
+ empty section string.</td>
</tr>
</tbody>
</table>
+
</div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="constantpool">Constant Pool</a> </div>
<div class="doc_text">
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a>+</td>
- <td class="td_left">Slot number of the constant string's type.
+ <td class="td_left">Type slot number of the constant string's type.
Note that the constant string's type implicitly defines the length of
the string. </td>
</tr>
</tbody>
</table>
</div>
+
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"><a name="constant">Constant Field</a></div>
+<div class="doc_subsubsection"><a name="constant">Simple Constant Pool
+Entries</a></div>
+
<div class="doc_text">
-<p>Constants come in many shapes and flavors. The sections that followe
-define the format for each of them. All constants start with a <a
+
+<p>Constant pool entries come in many shapes and flavors. The sections that
+follow define the format for each of them. All constants start with a <a
href="#uint32_vbr">uint32_vbr</a> encoded integer that provides the
number of operands for the constant. For primitive, structure, and
-array constants, this will always be zero since those types of
-constants have no operands. In this case, we have the following field
-definitions:</p>
+array constants, this will always be zero to indicate that the form of the
+constant is solely determined by its type. In this case, we have the following
+field definitions, based on type:</p>
+
<ul>
<li><b>Bool</b>. This is written as an <a href="#uint32_vbr">uint32_vbr</a>
of value 1U or 0U.</li>
<li><b>Floating Point</b>. Both the float and double types are
written literally in binary format.</li>
<li><b>Arrays</b>. Arrays are written simply as a list of <a
- href="#uint32_vbr">uint32_vbr</a> encoded slot numbers to the constant
+ href="#uint32_vbr">uint32_vbr</a> encoded value slot numbers to the constant
element values.</li>
<li><b>Structures</b>. Structures are written simply as a list of <a
- href="#uint32_vbr">uint32_vbr</a> encoded slot numbers to the constant
+ href="#uint32_vbr">uint32_vbr</a> encoded value slot numbers to the constant
field values of the structure.</li>
</ul>
-<p>When the number of operands to the constant is non-zero, we have a
-constant expression and its field format is provided in the table below.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">Undef Entries</a></div>
+
+<div class="doc_text">
+<p>When the number of operands to the constant is one, we have an 'undef' value
+of the specified type.</p>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">Inline Assembler Entries</a></div>
+
+<div class="doc_text">
+<p>Inline Assembler entries are stored in the constant pool, though they are not
+ officially LLVM constants. These entries are marked with a value of
+ "4294967295" (all ones) for the number of operands. They are encoded as
+ follows:</p>
+
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Field Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#string">string</a></td>
+ <td class="td_left">The asm string.</td>
+ </tr>
+ <tr>
+ <td><a href="#string">string</a></td>
+ <td class="td_left">The constraints string.</td>
+ </tr>
+ <tr>
+ <td><a href="#uint32_vbr">uint32_vbr</a></td>
+ <td class="td_left">Flags</sup></td>
+ </tr>
+ </tbody>
+</table>
+
+<p>Currently, the only defined flag, the low bit, indicates whether or not the
+ inline assembler has side effects.</p>
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">Constant Expression Entries</a></div>
+
+<div class="doc_text">
+
+<p>Otherwise, we have a constant expression. The format of the constant
+expression is specified in the table below, and the number is equal to the
+number of operands+1.</p>
<table>
<tbody>
<tr>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a></td>
- <td class="td_left">The slot number of the constant value for an
+ <td class="td_left">The value slot number of the constant value for an
operand.<sup>1</sup></td>
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a></td>
- <td class="td_left">The slot number for the type of the constant
+ <td class="td_left">The type slot number for the type of the constant
value for an operand.<sup>1</sup></td>
</tr>
</tbody>
<div class="doc_text">
<p>Compaction tables are part of a function definition. They are merely
a device for reducing the size of bytecode files. The size of a
-bytecode file is dependent on the <em>value</em> of the slot numbers
+bytecode file is dependent on the <em>values</em> of the slot numbers
used because larger values use more bytes in the variable bit rate
encoding scheme. Furthermore, the compressed instruction format
reserves only six bits for the type of the instruction. In large
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a>+</td>
- <td class="td_left">The slot number in the global type plane of
+ <td class="td_left">The type slot number in the global types of
the type that will be referenced in the function with the index of this
entry in the compaction table.</td>
</tr>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a>+</td>
- <td class="td_left">The slot number in the globals of the value
+ <td class="td_left">The value slot number in the global values
that will be referenced in the function with the index of this entry in
-the compaction table</td>
+the compaction table.</td>
</tr>
</tbody>
</table>
length and type, in that order.</p>
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsection"><a name="instructionlist">Instruction List</a>
-</div>
+<div class="doc_subsection"><a name="instructionlist">Instruction List</a></div>
<div class="doc_text">
<p>The instructions in a function are written as a simple list. Basic
blocks are inferred by the terminating instruction types. The format of
</tbody>
</table>
</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsection"><a name="instructions">Instructions</a></div>
+
+<div class="doc_text">
+<p>Instructions are written out one at a time as distinct units. Each
+instruction
+record contains at least an <a href="#opcodes">opcode</a> and a type field,
+and may contain a <a href="#instoperands">list of operands</a> (whose
+interpretation depends on the opcode). Based on the number of operands, the
+<a href="#instencode">instruction is encoded</a> in a
+dense format that tries to encoded each instruction into 32-bits if
+possible. </p>
+</div>
+
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"><a name="instruction">Instructions</a></div>
+<div class="doc_subsubsection"><a name="opcodes">Instruction Opcodes</a></div>
+<div class="doc_text">
+ <p>Instructions encode an opcode that identifies the kind of instruction.
+ Opcodes are an enumerated integer value. The specific values used depend on
+ the version of LLVM you're using. The opcode values are defined in the
+ <a href="http://llvm.org/cvsweb/cvsweb.cgi/llvm/include/llvm/Instruction.def">
+ <tt>include/llvm/Instruction.def</tt></a> file. You should check there for the
+ most recent definitions. The table below provides the opcodes defined as of
+ the writing of this document. The table associates each opcode mnemonic with
+ its enumeration value and the bytecode and LLVM version numbers in which the
+ opcode was introduced.</p>
+ <table>
+ <tbody>
+ <tr>
+ <th>Opcode</th>
+ <th>Number</th>
+ <th>Bytecode Version</th>
+ <th>LLVM Version</th>
+ </tr>
+ <tr><td colspan="4"><b>Terminator Instructions</b></td></tr>
+ <tr><td>Ret</td><td>1</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Br</td><td>2</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Switch</td><td>3</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Invoke</td><td>4</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Unwind</td><td>5</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Unreachable</td><td>6</td><td>1</td><td>1.4</td></tr>
+ <tr><td colspan="4"><b>Binary Operators</b></td></tr>
+ <tr><td>Add</td><td>7</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Sub</td><td>8</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Mul</td><td>9</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Div</td><td>10</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Rem</td><td>11</td><td>1</td><td>1.0</td></tr>
+ <tr><td colspan="4"><b>Logical Operators</b></td></tr>
+ <tr><td>And</td><td>12</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Or</td><td>13</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Xor</td><td>14</td><td>1</td><td>1.0</td></tr>
+ <tr><td colspan="4"><b>Binary Comparison Operators</b></td></tr>
+ <tr><td>SetEQ</td><td>15</td><td>1</td><td>1.0</td></tr>
+ <tr><td>SetNE</td><td>16</td><td>1</td><td>1.0</td></tr>
+ <tr><td>SetLE</td><td>17</td><td>1</td><td>1.0</td></tr>
+ <tr><td>SetGE</td><td>18</td><td>1</td><td>1.0</td></tr>
+ <tr><td>SetLT</td><td>19</td><td>1</td><td>1.0</td></tr>
+ <tr><td>SetGT</td><td>20</td><td>1</td><td>1.0</td></tr>
+ <tr><td colspan="4"><b>Memory Operators</b></td></tr>
+ <tr><td>Malloc</td><td>21</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Free</td><td>22</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Alloca</td><td>23</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Load</td><td>24</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Store</td><td>25</td><td>1</td><td>1.0</td></tr>
+ <tr><td>GetElementPtr</td><td>26</td><td>1</td><td>1.0</td></tr>
+ <tr><td colspan="4"><b>Other Operators</b></td></tr>
+ <tr><td>PHI</td><td>27</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Cast</td><td>28</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Call</td><td>29</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Shl</td><td>30</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Shr</td><td>31</td><td>1</td><td>1.0</td></tr>
+ <tr><td>VANext</td><td>32</td><td>1</td><td>1.0</td></tr>
+ <tr><td>VAArg</td><td>33</td><td>1</td><td>1.0</td></tr>
+ <tr><td>Select</td><td>34</td><td>2</td><td>1.2</td></tr>
+ <tr><td colspan="4">
+ <b>Pseudo Instructions<a href="#pi_note">*</a></b>
+ </td></tr>
+ <tr><td>Invoke+CC </td><td>56</td><td>5</td><td>1.5</td></tr>
+ <tr><td>Invoke+FastCC</td><td>57</td><td>5</td><td>1.5</td></tr>
+ <tr><td>Call+CC</td><td>58</td><td>5</td><td>1.5</td></tr>
+ <tr><td>Call+FastCC+TailCall</td><td>59</td><td>5</td><td>1.5</td></tr>
+ <tr><td>Call+FastCC</td><td>60</td><td>5</td><td>1.5</td></tr>
+ <tr><td>Call+CCC+TailCall</td><td>61</td><td>5</td><td>1.5</td></tr>
+ <tr><td>Load+Volatile</td><td>62</td><td>3</td><td>1.3</td></tr>
+ <tr><td>Store+Volatile</td><td>63</td><td>3</td><td>1.3</td></tr>
+ </tbody>
+ </table>
+
+<p><b><a name="pi_note">* Note: </a></b>
+These aren't really opcodes from an LLVM language perspective. They encode
+information into other opcodes without reserving space for that information.
+For example, opcode=63 is a Volatile Store. The opcode for this
+instruction is 25 (Store) but we encode it as 63 to indicate that is a Volatile
+Store. The same is done for the calling conventions and tail calls.
+In each of these entries in range 56-63, the opcode is documented as the base
+opcode (Invoke, Call, Store) plus some set of modifiers, as follows:</p>
+<dl>
+ <dt>CC</dt>
+ <dd>This means an arbitrary calling convention is specified
+ in a VBR that follows the opcode. This is used when the instruction cannot
+ be encoded with one of the more compact forms.
+ </dd>
+ <dt>FastCC</dt>
+ <dd>This indicates that the Call or Invoke is using the FastCC calling
+ convention.</dd>
+ <dt>CCC</dt>
+ <dd>This indicates that the Call or Invoke is using the native "C" calling
+ convention.</dd>
+ <dt>TailCall</dt>
+ <dd>This indicates that the Call has the 'tail' modifier.</dd>
+</dl>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"><a name="instoperands">Instruction
+Operands</a></div>
+
+<div class="doc_text">
+<p>
+Based on the instruction opcode and type, the bytecode format implicitly (to
+save space) specifies the interpretation of the operand list. For most
+instructions, the type of each operand is implicit from the type of the
+instruction itself (e.g. the type of operands of a binary operator must match
+the type of the instruction). As such, the bytecode format generally only
+encodes the value number of the operand, not the type.</p>
+
+<p>In some cases, however, this is not sufficient. This section enumerates
+those cases:</p>
+
+<ul>
+<li>getelementptr: the slot numbers for sequential type indexes are shifted up
+two bits. This allows the low order bits will encode the type of index used,
+as follows: 0=uint, 1=int, 2=ulong, 3=long.</li>
+<li>cast: the result type number is encoded as the second operand.</li>
+<li>alloca/malloc: If the allocation has an explicit alignment, the log2 of the
+ alignment is encoded as the second operand.</li>
+<li>call: If the tail marker and calling convention cannot be <a
+ href="#pi_note">encoded into the opcode</a> of the call, it is passed as an
+ additional operand. The low bit of the operand is a flag indicating whether
+ the call is a tail call. The rest of the bits contain the calling
+ convention number (shifted left by one bit).</li>
+</ul>
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"><a name="instencode">Instruction
+Encoding</a></div>
+
<div class="doc_text">
<p>For brevity, instructions are written in one of four formats,
depending on the number of operands to the instruction. Each
</tr>
<tr>
<td><a href="#uint24_vbr">uint24_vbr</a></td>
- <td class="td_left">Provides the slot number of the result type
-of the instruction</td>
+ <td class="td_left">Provides the type slot number of the result type of
+ the instruction.</td>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a></td>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a>+</td>
- <td class="td_left">The slot number of the value(s) for the
-operand(s). <sup>1</sup></td>
+ <td class="td_left">The slot number of the value(s) for the operand(s).
+ </td>
</tr>
</tbody>
</table>
-Notes:
-<ol>
- <li>Note that if the instruction is a getelementptr and the type of
-the operand is a sequential type (array or pointer) then the slot
-number is shifted up two bits and the low order bits will encode the
-type of index used, as follows: 0=uint, 1=int, 2=ulong, 3=long.</li>
-</ol>
+
<p><b>Instruction Format 1</b></p>
<p>This format encodes the opcode, type and a single operand into a
single <a href="#uint32_vbr">uint32_vbr</a> as follows:</p>
<tr>
<td>0-1</td>
<td>constant "1"</td>
- <td class="td_left">These two bits must be the value 1 which
-identifies this as an instruction of format 1.</td>
+ <td class="td_left">These two bits must be the value 1 which identifies
+ this as an instruction of format 1.</td>
</tr>
<tr>
<td>2-7</td>
- <td><a href="#opcode">opcode</a></td>
- <td class="td_left">Specifies the opcode of the instruction. Note
-that the maximum opcode value is 63.</td>
+ <td><a href="#instructions">opcode</a></td>
+ <td class="td_left">Specifies the opcode of the instruction. Note that
+ the maximum opcode value is 63.</td>
</tr>
<tr>
<td>8-19</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the type for
-this instruction. Maximum slot number is 2<sup>12</sup>-1=4095.</td>
+ <td class="td_left">Specifies the slot number of the type for this
+ instruction. Maximum slot number is 2<sup>12</sup>-1=4095.</td>
</tr>
<tr>
<td>20-31</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the value for
-the first operand. Maximum slot number is 2<sup>12</sup>-1=4095. Note
-that the value 2<sup>12</sup>-1 denotes zero operands.</td>
+ <td class="td_left">Specifies the slot number of the value for the
+ first operand. Maximum slot number is 2<sup>12</sup>-1=4095. Note that
+ the value 2<sup>12</sup>-1 denotes zero operands.</td>
</tr>
</tbody>
</table>
<tr>
<td>0-1</td>
<td>constant "2"</td>
- <td class="td_left">These two bits must be the value 2 which
-identifies this as an instruction of format 2.</td>
+ <td class="td_left">These two bits must be the value 2 which identifies
+ this as an instruction of format 2.</td>
</tr>
<tr>
<td>2-7</td>
- <td><a href="#opcodes">opcode</a></td>
- <td class="td_left">Specifies the opcode of the instruction. Note
-that the maximum opcode value is 63.</td>
+ <td><a href="#instructions">opcode</a></td>
+ <td class="td_left">Specifies the opcode of the instruction. Note that
+ the maximum opcode value is 63.</td>
</tr>
<tr>
<td>8-15</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the type for
-this instruction. Maximum slot number is 2<sup>8</sup>-1=255.</td>
+ <td class="td_left">Specifies the slot number of the type for this
+ instruction. Maximum slot number is 2<sup>8</sup>-1=255.</td>
</tr>
<tr>
<td>16-23</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the value for
-the first operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
+ <td class="td_left">Specifies the slot number of the value for the first
+ operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
</tr>
<tr>
<td>24-31</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the value for
-the second operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
+ <td class="td_left">Specifies the slot number of the value for the second
+ operand. Maximum slot number is 2<sup>8</sup>-1=255.</td>
</tr>
</tbody>
</table>
<tr>
<td>0-1</td>
<td>constant "3"</td>
- <td class="td_left">These two bits must be the value 3 which
-identifies this as an instruction of format 3.</td>
+ <td class="td_left">These two bits must be the value 3 which identifies
+ this as an instruction of format 3.</td>
</tr>
<tr>
<td>2-7</td>
- <td><a href="#opcodes">opcode</a></td>
- <td class="td_left">Specifies the opcode of the instruction. Note
-that the maximum opcode value is 63.</td>
+ <td><a href="#instructions">opcode</a></td>
+ <td class="td_left">Specifies the opcode of the instruction. Note that
+ the maximum opcode value is 63.</td>
</tr>
<tr>
<td>8-13</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the type for
-this instruction. Maximum slot number is 2<sup>6</sup>-1=63.</td>
+ <td class="td_left">Specifies the slot number of the type for this
+ instruction. Maximum slot number is 2<sup>6</sup>-1=63.</td>
</tr>
<tr>
<td>14-19</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the value for
-the first operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
+ <td class="td_left">Specifies the slot number of the value for the first
+ operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
</tr>
<tr>
<td>20-25</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the value for
-the second operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
+ <td class="td_left">Specifies the slot number of the value for the second
+ operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
</tr>
<tr>
<td>26-31</td>
<td><a href="#unsigned">unsigned</a></td>
- <td class="td_left">Specifies the slot number of the value for
-the third operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
+ <td class="td_left">Specifies the slot number of the value for the third
+ operand. Maximum slot number is 2<sup>6</sup>-1=63.</td>
</tr>
</tbody>
</table>
</div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="symtab">Symbol Table</a> </div>
<div class="doc_text">
-<p>A symbol table can be put out in conjunction with a module or a function.
-A symbol table is a list of type planes. Each type plane starts with the number
-of entries in the plane and the type plane's slot number (so the type
-can be looked up in the global type pool). For each entry in a type
-plane, the slot number of the value and the name associated with that
-value are written. The format is given in the table below. </p>
+<p>A symbol table can be put out in conjunction with a module or a function. A
+symbol table has a list of name/type associations followed by a list of
+name/value associations. The name/value associations are organized into "type
+planes" so that all values of a common type are listed together. Each type
+plane starts with the number of entries in the plane and the type slot number
+for all the values in that plane (so the type can be looked up in the global
+type pool). For each entry in a type plane, the slot number of the value and
+the name associated with that value are written. The format is given in the
+table below. </p>
<table>
<tbody>
<tr>
<td class="td_left">Symbol Table Identifier (0x04)</td>
</tr>
<tr>
- <td><a href="#llist">llist</a>(<a href="#symtab_entry">symtab_entry</a>)</td>
+ <td><a href="#llist">llist</a>(<a href="#symtab_entry">type_entry</a>)</td>
<td class="td_left">A length list of symbol table entries for
<tt>Type</tt>s
</td>
</tr>
<tr>
<td><a href="#zlist">llist</a>(<a href="#symtab_plane">symtab_plane</a>)</td>
- <td class="td_left">A length list of planes of symbol table
+ <td class="td_left">A length list of "type planes" of symbol table
entries for <tt>Value</tt>s</td>
</tr>
</tbody>
</table>
</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="type_entry">Symbol Table Type
+Entry</a>
+</div>
+<div class="doc_text">
+<p>A symbol table type entry associates a name with a type. The name is provided
+simply as an array of chars. The type is provided as a type slot number (index)
+into the global type pool. The format is given in the following table:</p>
+<table>
+ <tbody>
+ <tr>
+ <th><b>Type</b></th>
+ <th class="td_left"><b>Field Description</b></th>
+ </tr>
+ <tr>
+ <td><a href="#uint32_vbr">uint24_vbr</a></td>
+ <td class="td_left">Type slot number of the type being given a
+ name relative to the global type pool.
+ </td>
+ </tr>
+ <tr>
+ <td><a href="#uint32_vbr">uint32_vbr</a></td>
+ <td class="td_left">Length of the character array that follows.</td>
+ </tr>
+ <tr>
+ <td><a href="#char">char</a>+</td>
+ <td class="td_left">The characters of the name.</td>
+ </tr>
+ </tbody>
+</table>
+</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="symtab_plane">Symbol Table
Plane</a>
</tr>
<tr>
<td><a href="#uint32_vbr">uint32_vbr</a></td>
- <td class="td_left">Slot number of type for this plane.</td>
+ <td class="td_left">Type slot number of type for all values in this plane..</td>
</tr>
<tr>
- <td><a href="#symtab_entry">symtab_entry</a>+</td>
- <td class="td_left">The symbol table entries for this plane.</td>
+ <td><a href="#value_entry">value_entry</a>+</td>
+ <td class="td_left">The symbol table entries for to associate values with
+ names.</td>
</tr>
</tbody>
</table>
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"> <a name="symtab_entry">Symbol Table
+<div class="doc_subsubsection"><a name="value_entry">Symbol Table Value
Entry</a>
</div>
<div class="doc_text">
-<p>A symbol table entry provides the assocation between a type or
-value's slot number and the name given to that type or value. The
+<p>A symbol table value entry provides the assocation between a value and the
+name given to the value. The value is referenced by its slot number. The
format is given in the following table:</p>
<table>
<tbody>
</tr>
<tr>
<td><a href="#uint32_vbr">uint24_vbr</a></td>
- <td class="td_left">Slot number of the type or value being given a name.
+ <td class="td_left">Value slot number of the value being given a name.
</td>
</tr>
<tr>
</tbody>
</table>
</div>
+
<!-- *********************************************************************** -->
<div class="doc_section"> <a name="versiondiffs">Version Differences</a>
</div>
describes the differences between that version and the one that <i>follows</i>.
</p>
</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsection"><a name="vers13">Version 1.3 Differences From
+ 1.4</a></div>
+<!-- _______________________________________________________________________ -->
+
+<div class="doc_subsubsection">Unreachable Instruction</div>
+<div class="doc_text">
+ <p>The LLVM <a href="LangRef.html#i_unreachable">Unreachable</a> instruction
+ was added in version 1.4 of LLVM. This caused all instruction numbers after
+ it to shift down by one.</p>
+</div>
+
+<div class="doc_subsubsection">Function Flags</div>
+<div class="doc_text">
+ <p>LLVM bytecode versions prior to 1.4 did not include the 5 bit offset
+ in <a href="#funcfield">the function list</a> in the <a
+ href="#globalinfo">Module Global Info</a> block.</p>
+</div>
+
+<div class="doc_subsubsection">Function Flags</div>
+<div class="doc_text">
+ <p>LLVM bytecode versions prior to 1.4 did not include the 'undef' constant
+ value, which affects the encoding of <a href="#constant">Constant
+ Fields</a>.</p>
+</div>
+
+<!--
+<div class="doc_subsubsection">Aligned Data</div>
+<div class="doc_text">
+ <p>In version 1.3, certain data items were aligned to 32-bit boundaries. In
+ version 1.4, alignment of data was done away with completely. The need for
+ alignment has gone away and the only thing it adds is bytecode file size
+ overhead. In most cases this overhead was small. However, in functions with
+ large numbers of format 0 instructions (GEPs and PHIs with lots of parameters)
+ or regular instructions with large valued operands (e.g. because there's just
+ a lot of instructions in the function) the overhead can be extreme. In one
+ test case, the overhead was 44,000 bytes (34% of the total file size).
+ Consequently in release 1.4, the decision was made to eliminate alignment
+ altogether.</p>
+ <p>In version 1.3 format, the following bytecode constructs were aligned (i.e.
+ they were followed by one to three bytes of padding):</p>
+ <ul>
+ <li>All blocks.</li>
+ <li>Instructions using the long format (format 0).</li>
+ <li>All call instructions that called a var args function.</li>
+ <li>The target triple (a string field at the end of the module block).</li>
+ <li>The version field (immediately following the signature).</li>
+ </ul>
+ <p>None of these constructs are aligned in version 1.4</p>
+</div>
+-->
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsection"><a name="vers12">Version 1.2 Differences
From 1.3</a></div>
<!-- _______________________________________________________________________ -->
+
<div class="doc_subsubsection">Type Derives From Value</div>
<div class="doc_text">
<p>In version 1.2, the Type class in the LLVM IR derives from the Value
src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!"></a>
<a href="mailto:rspencer@x10sys.com">Reid Spencer</a> and <a
href="mailto:sabre@nondot.org">Chris Lattner</a><br>
-<a href="http://llvm.cs.uiuc.edu">The LLVM Compiler Infrastructure</a><br>
+<a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
Last modified: $Date$
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projects / oota-llvm.git / blobdiff