<li><a href="#i_shr">'<tt>shr</tt>' Instruction</a></li>
</ol>
</li>
+ <li><a href="#vectorops">Vector Operations</a>
+ <ol>
+ <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
+ <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
+ <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
+ <li><a href="#i_vsetint">'<tt>vsetint</tt>' Instruction</a></li>
+ <li><a href="#i_vsetfp">'<tt>vsetfp</tt>' Instruction</a></li>
+ <li><a href="#i_vselect">'<tt>vselect</tt>' Instruction</a></li>
+ </ol>
+ </li>
<li><a href="#memoryops">Memory Access Operations</a>
<ol>
<li><a href="#i_malloc">'<tt>malloc</tt>' Instruction</a></li>
<li><a href="#i_phi">'<tt>phi</tt>' Instruction</a></li>
<li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a></li>
<li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
- <li><a href="#i_vsetint">'<tt>vsetint</tt>' Instruction</a></li>
- <li><a href="#i_vsetfp">'<tt>vsetfp</tt>' Instruction</a></li>
- <li><a href="#i_vselect">'<tt>vselect</tt>' Instruction</a></li>
- <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
- <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
<li><a href="#i_call">'<tt>call</tt>' Instruction</a></li>
<li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a></li>
</ol>
<i>; External declaration of the puts function</i>
<a href="#functionstructure">declare</a> int %puts(sbyte*) <i>; int(sbyte*)* </i>
+<i>; Global variable / Function body section separator</i>
+implementation
+
<i>; Definition of main function</i>
int %main() { <i>; int()* </i>
<i>; Convert [13x sbyte]* to sbyte *...</i>
array of char, and a pointer to a function), and have one of the following <a
href="#linkage">linkage types</a>.</p>
+<p>Due to a limitation in the current LLVM assembly parser (it is limited by
+one-token lookahead), modules are split into two pieces by the "implementation"
+keyword. Global variable prototypes and definitions must occur before the
+keyword, and function definitions must occur after it. Function prototypes may
+occur either before or after it. In the future, the implementation keyword may
+become a noop, if the parser gets smarter.</p>
+
</div>
<!-- ======================================================================= -->
prototype and implemented declaration of the function (as does normal C).
</dd>
+ <dt><b>"<tt>csretcc</tt>" - The C struct return calling convention</b>:</dt>
+
+ <dd>This calling convention matches the target C calling conventions, except
+ that functions with this convention are required to take a pointer as their
+ first argument, and the return type of the function must be void. This is
+ used for C functions that return aggregates by-value. In this case, the
+ function has been transformed to take a pointer to the struct as the first
+ argument to the function. For targets where the ABI specifies specific
+ behavior for structure-return calls, the calling convention can be used to
+ distinguish between struct return functions and other functions that take a
+ pointer to a struct as the first argument.
+ </dd>
+
<dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>
<dd>This calling convention attempts to make calls as fast as possible
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="moduleasm">Module-Level Inline Assembly</a></li>
+ <a name="moduleasm">Module-Level Inline Assembly</a>
</div>
<div class="doc_text">
<dd>Perform the <a href="#i_insertelement">insertelement
operation</a> on constants.
+
+ <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>
+
+ <dd>Perform the <a href="#i_shufflevector">shufflevector
+ operation</a> on constants.
+
<dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>
<dd>Perform the specified operation of the LHS and RHS constants. OPCODE may
<pre>
<result> = invoke [<a href="#callingconv">cconv</a>] <ptr to function ty> %<function ptr val>(<function args>)
- to label <normal label> except label <exception label>
+ to label <normal label> unwind label <exception label>
</pre>
<h5>Overview:</h5>
<h5>Example:</h5>
<pre>
%retval = invoke int %Test(int 15) to label %Continue
- except label %TestCleanup <i>; {int}:retval set</i>
+ unwind label %TestCleanup <i>; {int}:retval set</i>
%retval = invoke <a href="#callingconv">coldcc</a> int %Test(int 15) to label %Continue
- except label %TestCleanup <i>; {int}:retval set</i>
+ unwind label %TestCleanup <i>; {int}:retval set</i>
</pre>
</div>
<!-- ======================================================================= -->
<div class="doc_subsection">
- <a name="memoryops">Memory Access Operations</a>
+ <a name="vectorops">Vector Operations</a>
</div>
<div class="doc_text">
-<p>A key design point of an SSA-based representation is how it
-represents memory. In LLVM, no memory locations are in SSA form, which
-makes things very simple. This section describes how to read, write,
-allocate, and free memory in LLVM.</p>
+<p>LLVM supports several instructions to represent vector operations in a
+target-independent manner. This instructions cover the element-access and
+vector-specific operations needed to process vectors effectively. While LLVM
+does directly support these vector operations, many sophisticated algorithms
+will want to use target-specific intrinsics to take full advantage of a specific
+target.</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
+ <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = malloc <type>[, uint <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
+ <result> = extractelement <n x <ty>> <val>, uint <idx> <i>; yields <ty></i>
</pre>
<h5>Overview:</h5>
-<p>The '<tt>malloc</tt>' instruction allocates memory from the system
-heap and returns a pointer to it.</p>
+<p>
+The '<tt>extractelement</tt>' instruction extracts a single scalar
+element from a packed vector at a specified index.
+</p>
-<h5>Arguments:</h5>
-<p>The '<tt>malloc</tt>' instruction allocates
-<tt>sizeof(<type>)*NumElements</tt>
-bytes of memory from the operating system and returns a pointer of the
-appropriate type to the program. If "NumElements" is specified, it is the
-number of elements allocated. If an alignment is specified, the value result
-of the allocation is guaranteed to be aligned to at least that boundary. If
-not specified, or if zero, the target can choose to align the allocation on any
-convenient boundary.</p>
+<h5>Arguments:</h5>
-<p>'<tt>type</tt>' must be a sized type.</p>
+<p>
+The first operand of an '<tt>extractelement</tt>' instruction is a
+value of <a href="#t_packed">packed</a> type. The second operand is
+an index indicating the position from which to extract the element.
+The index may be a variable.</p>
<h5>Semantics:</h5>
-<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
-a pointer is returned.</p>
+<p>
+The result is a scalar of the same type as the element type of
+<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
+<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
+results are undefined.
+</p>
<h5>Example:</h5>
<pre>
- %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
-
- %size = <a href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
- %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
- %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
- %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
- %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
+ %result = extractelement <4 x int> %vec, uint 0 <i>; yields int</i>
</pre>
</div>
+
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_free">'<tt>free</tt>' Instruction</a>
+ <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- free <type> <value> <i>; yields {void}</i>
+ <result> = insertelement <n x <ty>> <val>, <ty> <elt>, uint <idx> <i>; yields <n x <ty>></i>
</pre>
<h5>Overview:</h5>
-<p>The '<tt>free</tt>' instruction returns memory back to the unused
-memory heap to be reallocated in the future.</p>
+<p>
+The '<tt>insertelement</tt>' instruction inserts a scalar
+element into a packed vector at a specified index.
+</p>
+
<h5>Arguments:</h5>
-<p>'<tt>value</tt>' shall be a pointer value that points to a value
-that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
-instruction.</p>
+<p>
+The first operand of an '<tt>insertelement</tt>' instruction is a
+value of <a href="#t_packed">packed</a> type. The second operand is a
+scalar value whose type must equal the element type of the first
+operand. The third operand is an index indicating the position at
+which to insert the value. The index may be a variable.</p>
<h5>Semantics:</h5>
-<p>Access to the memory pointed to by the pointer is no longer defined
-after this instruction executes.</p>
+<p>
+The result is a packed vector of the same type as <tt>val</tt>. Its
+element values are those of <tt>val</tt> except at position
+<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
+exceeds the length of <tt>val</tt>, the results are undefined.
+</p>
<h5>Example:</h5>
<pre>
- %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
- free [4 x ubyte]* %array
+ %result = insertelement <4 x int> %vec, int 1, uint 0 <i>; yields <4 x int></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
+ <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = alloca <type>[, uint <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
+ <result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <n x uint> <mask> <i>; yields <n x <ty>></i>
</pre>
<h5>Overview:</h5>
-<p>The '<tt>alloca</tt>' instruction allocates memory on the current
-stack frame of the procedure that is live until the current function
-returns to its caller.</p>
+<p>
+The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
+from two input vectors, returning a vector of the same type.
+</p>
<h5>Arguments:</h5>
-<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(<type>)*NumElements</tt>
-bytes of memory on the runtime stack, returning a pointer of the
-appropriate type to the program. If "NumElements" is specified, it is the
-number of elements allocated. If an alignment is specified, the value result
-of the allocation is guaranteed to be aligned to at least that boundary. If
-not specified, or if zero, the target can choose to align the allocation on any
-convenient boundary.</p>
+<p>
+The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
+with types that match each other and types that match the result of the
+instruction. The third argument is a shuffle mask, which has the same number
+of elements as the other vector type, but whose element type is always 'uint'.
+</p>
-<p>'<tt>type</tt>' may be any sized type.</p>
+<p>
+The shuffle mask operand is required to be a constant vector with either
+constant integer or undef values.
+</p>
<h5>Semantics:</h5>
-<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
-memory is automatically released when the function returns. The '<tt>alloca</tt>'
-instruction is commonly used to represent automatic variables that must
-have an address available. When the function returns (either with the <tt><a
- href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
-instructions), the memory is reclaimed.</p>
+<p>
+The elements of the two input vectors are numbered from left to right across
+both of the vectors. The shuffle mask operand specifies, for each element of
+the result vector, which element of the two input registers the result element
+gets. The element selector may be undef (meaning "don't care") and the second
+operand may be undef if performing a shuffle from only one vector.
+</p>
<h5>Example:</h5>
<pre>
- %ptr = alloca int <i>; yields {int*}:ptr</i>
- %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
- %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
- %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
+ %result = shufflevector <4 x int> %v1, <4 x int> %v2,
+ <4 x uint> <uint 0, uint 4, uint 1, uint 5> <i>; yields <4 x int></i>
+ %result = shufflevector <4 x int> %v1, <4 x int> undef,
+ <4 x uint> <uint 0, uint 1, uint 2, uint 3> <i>; yields <4 x int></i> - Identity shuffle.
</pre>
</div>
+
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
+<div class="doc_subsubsection"> <a name="i_vsetint">'<tt>vsetint</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
-<pre> <result> = load <ty>* <pointer><br> <result> = volatile load <ty>* <pointer><br></pre>
-<h5>Overview:</h5>
-<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
-<h5>Arguments:</h5>
-<p>The argument to the '<tt>load</tt>' instruction specifies the memory
-address from which to load. The pointer must point to a <a
- href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
-marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
-the number or order of execution of this <tt>load</tt> with other
-volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
-instructions. </p>
-<h5>Semantics:</h5>
-<p>The location of memory pointed to is loaded.</p>
-<h5>Examples:</h5>
-<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
- <a
- href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
- %val = load int* %ptr <i>; yields {int}:val = int 3</i>
-</pre>
-</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
-Instruction</a> </div>
-<h5>Syntax:</h5>
-<pre> store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i>
- volatile store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i>
+<pre><result> = vsetint <op>, <n x <ty>> <var1>, <var2> <i>; yields <n x bool></i>
</pre>
+
<h5>Overview:</h5>
-<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
+
+<p>The '<tt>vsetint</tt>' instruction takes two integer vectors and
+returns a vector of boolean values representing, at each position, the
+result of the comparison between the values at that position in the
+two operands.</p>
+
<h5>Arguments:</h5>
-<p>There are two arguments to the '<tt>store</tt>' instruction: a value
-to store and an address in which to store it. The type of the '<tt><pointer></tt>'
-operand must be a pointer to the type of the '<tt><value></tt>'
-operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
-optimizer is not allowed to modify the number or order of execution of
-this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
- href="#i_store">store</a></tt> instructions.</p>
+
+<p>The arguments to a '<tt>vsetint</tt>' instruction are a comparison
+operation and two value arguments. The value arguments must be of <a
+href="#t_integral">integral</a> <a href="#t_packed">packed</a> type,
+and they must have identical types. The operation argument must be
+one of <tt>eq</tt>, <tt>ne</tt>, <tt>slt</tt>, <tt>sgt</tt>,
+<tt>sle</tt>, <tt>sge</tt>, <tt>ult</tt>, <tt>ugt</tt>, <tt>ule</tt>,
+<tt>uge</tt>, <tt>true</tt>, and <tt>false</tt>. The result is a
+packed <tt>bool</tt> value with the same length as each operand.</p>
+
<h5>Semantics:</h5>
-<p>The contents of memory are updated to contain '<tt><value></tt>'
-at the location specified by the '<tt><pointer></tt>' operand.</p>
+
+<p>The following table shows the semantics of '<tt>vsetint</tt>'. For
+each position of the result, the comparison is done on the
+corresponding positions of the two value arguments. Note that the
+signedness of the comparison depends on the comparison opcode and
+<i>not</i> on the signedness of the value operands. E.g., <tt>vsetint
+slt <4 x unsigned> %x, %y</tt> does an elementwise <i>signed</i>
+comparison of <tt>%x</tt> and <tt>%y</tt>.</p>
+
+<table border="1" cellspacing="0" cellpadding="4">
+ <tbody>
+ <tr><th>Operation</th><th>Result is true iff</th><th>Comparison is</th></tr>
+ <tr><td><tt>eq</tt></td><td>var1 == var2</td><td>--</td></tr>
+ <tr><td><tt>ne</tt></td><td>var1 != var2</td><td>--</td></tr>
+ <tr><td><tt>slt</tt></td><td>var1 < var2</td><td>signed</td></tr>
+ <tr><td><tt>sgt</tt></td><td>var1 > var2</td><td>signed</td></tr>
+ <tr><td><tt>sle</tt></td><td>var1 <= var2</td><td>signed</td></tr>
+ <tr><td><tt>sge</tt></td><td>var1 >= var2</td><td>signed</td></tr>
+ <tr><td><tt>ult</tt></td><td>var1 < var2</td><td>unsigned</td></tr>
+ <tr><td><tt>ugt</tt></td><td>var1 > var2</td><td>unsigned</td></tr>
+ <tr><td><tt>ule</tt></td><td>var1 <= var2</td><td>unsigned</td></tr>
+ <tr><td><tt>uge</tt></td><td>var1 >= var2</td><td>unsigned</td></tr>
+ <tr><td><tt>true</tt></td><td>always</td><td>--</td></tr>
+ <tr><td><tt>false</tt></td><td>never</td><td>--</td></tr>
+ </tbody>
+</table>
+
<h5>Example:</h5>
-<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
- <a
- href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
- %val = load int* %ptr <i>; yields {int}:val = int 3</i>
+<pre> <result> = vsetint eq <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = false, false</i>
+ <result> = vsetint ne <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = true, true</i>
+ <result> = vsetint slt <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = true, false</i>
+ <result> = vsetint sgt <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = false, true</i>
+ <result> = vsetint sle <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = true, false</i>
+ <result> = vsetint sge <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = false, true</i>
</pre>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_vsetfp">'<tt>vsetfp</tt>'
+Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
-<pre>
- <result> = getelementptr <ty>* <ptrval>{, <ty> <idx>}*
+<pre><result> = vsetfp <op>, <n x <ty>> <var1>, <var2> <i>; yields <n x bool></i>
</pre>
<h5>Overview:</h5>
-<p>
-The '<tt>getelementptr</tt>' instruction is used to get the address of a
-subelement of an aggregate data structure.</p>
+<p>The '<tt>vsetfp</tt>' instruction takes two floating point vector
+arguments and returns a vector of boolean values representing, at each
+position, the result of the comparison between the values at that
+position in the two operands.</p>
<h5>Arguments:</h5>
-<p>This instruction takes a list of integer constants that indicate what
-elements of the aggregate object to index to. The actual types of the arguments
-provided depend on the type of the first pointer argument. The
-'<tt>getelementptr</tt>' instruction is used to index down through the type
-levels of a structure or to a specific index in an array. When indexing into a
-structure, only <tt>uint</tt>
-integer constants are allowed. When indexing into an array or pointer,
-<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
-
-<p>For example, let's consider a C code fragment and how it gets
-compiled to LLVM:</p>
-
-<pre>
- struct RT {
- char A;
- int B[10][20];
- char C;
- };
- struct ST {
- int X;
- double Y;
- struct RT Z;
- };
+<p>The arguments to a '<tt>vsetfp</tt>' instruction are a comparison
+operation and two value arguments. The value arguments must be of <a
+href="t_floating">floating point</a> <a href="#t_packed">packed</a>
+type, and they must have identical types. The operation argument must
+be one of <tt>eq</tt>, <tt>ne</tt>, <tt>lt</tt>, <tt>gt</tt>,
+<tt>le</tt>, <tt>ge</tt>, <tt>oeq</tt>, <tt>one</tt>, <tt>olt</tt>,
+<tt>ogt</tt>, <tt>ole</tt>, <tt>oge</tt>, <tt>ueq</tt>, <tt>une</tt>,
+<tt>ult</tt>, <tt>ugt</tt>, <tt>ule</tt>, <tt>uge</tt>, <tt>o</tt>,
+<tt>u</tt>, <tt>true</tt>, and <tt>false</tt>. The result is a packed
+<tt>bool</tt> value with the same length as each operand.</p>
- int *foo(struct ST *s) {
- return &s[1].Z.B[5][13];
- }
+<h5>Semantics:</h5>
+
+<p>The following table shows the semantics of '<tt>vsetfp</tt>' for
+floating point types. If either operand is a floating point Not a
+Number (NaN) value, the operation is unordered, and the value in the
+first column below is produced at that position. Otherwise, the
+operation is ordered, and the value in the second column is
+produced.</p>
+
+<table border="1" cellspacing="0" cellpadding="4">
+ <tbody>
+ <tr><th>Operation</th><th>If unordered<th>Otherwise true iff</th></tr>
+ <tr><td><tt>eq</tt></td><td>undefined</td><td>var1 == var2</td></tr>
+ <tr><td><tt>ne</tt></td><td>undefined</td><td>var1 != var2</td></tr>
+ <tr><td><tt>lt</tt></td><td>undefined</td><td>var1 < var2</td></tr>
+ <tr><td><tt>gt</tt></td><td>undefined</td><td>var1 > var2</td></tr>
+ <tr><td><tt>le</tt></td><td>undefined</td><td>var1 <= var2</td></tr>
+ <tr><td><tt>ge</tt></td><td>undefined</td><td>var1 >= var2</td></tr>
+ <tr><td><tt>oeq</tt></td><td>false</td><td>var1 == var2</td></tr>
+ <tr><td><tt>one</tt></td><td>false</td><td>var1 != var2</td></tr>
+ <tr><td><tt>olt</tt></td><td>false</td><td>var1 < var2</td></tr>
+ <tr><td><tt>ogt</tt></td><td>false</td><td>var1 > var2</td></tr>
+ <tr><td><tt>ole</tt></td><td>false</td><td>var1 <= var2</td></tr>
+ <tr><td><tt>oge</tt></td><td>false</td><td>var1 >= var2</td></tr>
+ <tr><td><tt>ueq</tt></td><td>true</td><td>var1 == var2</td></tr>
+ <tr><td><tt>une</tt></td><td>true</td><td>var1 != var2</td></tr>
+ <tr><td><tt>ult</tt></td><td>true</td><td>var1 < var2</td></tr>
+ <tr><td><tt>ugt</tt></td><td>true</td><td>var1 > var2</td></tr>
+ <tr><td><tt>ule</tt></td><td>true</td><td>var1 <= var2</td></tr>
+ <tr><td><tt>uge</tt></td><td>true</td><td>var1 >= var2</td></tr>
+ <tr><td><tt>o</tt></td><td>false</td><td>always</td></tr>
+ <tr><td><tt>u</tt></td><td>true</td><td>never</td></tr>
+ <tr><td><tt>true</tt></td><td>true</td><td>always</td></tr>
+ <tr><td><tt>false</tt></td><td>false</td><td>never</td></tr>
+ </tbody>
+</table>
+
+<h5>Example:</h5>
+<pre> <result> = vsetfp eq <2 x float> <float 0.0, float 1.0>, <float 1.0, float 0.0> <i>; yields {<2 x bool>}:result = false, false</i>
+ <result> = vsetfp ne <2 x float> <float 0.0, float 1.0>, <float 1.0, float 0.0> <i>; yields {<2 x bool>}:result = true, true</i>
+ <result> = vsetfp lt <2 x float> <float 0.0, float 1.0>, <float 1.0, float 0.0> <i>; yields {<2 x bool>}:result = true, false</i>
+ <result> = vsetfp gt <2 x float> <float 0.0, float 1.0>, <float 1.0, float 0.0> <i>; yields {<2 x bool>}:result = false, true</i>
+ <result> = vsetfp le <2 x float> <float 0.0, float 1.0>, <float 1.0, float 0.0> <i>; yields {<2 x bool>}:result = true, false</i>
+ <result> = vsetfp ge <2 x float> <float 0.0, float 1.0>, <float 1.0, float 0.0> <i>; yields {<2 x bool>}:result = false, true</i>
</pre>
+</div>
-<p>The LLVM code generated by the GCC frontend is:</p>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_vselect">'<tt>vselect</tt>' Instruction</a>
+</div>
-<pre>
- %RT = type { sbyte, [10 x [20 x int]], sbyte }
- %ST = type { int, double, %RT }
+<div class="doc_text">
- implementation
+<h5>Syntax:</h5>
- int* %foo(%ST* %s) {
- entry:
- %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
- ret int* %reg
- }
+<pre>
+ <result> = vselect <n x bool> <cond>, <n x <ty>> <val1>, <n x <ty>> <val2> <i>; yields <n x <ty>></i>
</pre>
-<h5>Semantics:</h5>
+<h5>Overview:</h5>
-<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
-on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
-and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
-<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
-types require <tt>uint</tt> <b>constants</b>.</p>
+<p>
+The '<tt>vselect</tt>' instruction chooses one value at each position
+of a vector based on a condition.
+</p>
-<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
-type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
-}</tt>' type, a structure. The second index indexes into the third element of
-the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
-sbyte }</tt>' type, another structure. The third index indexes into the second
-element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
-array. The two dimensions of the array are subscripted into, yielding an
-'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
-to this element, thus computing a value of '<tt>int*</tt>' type.</p>
-<p>Note that it is perfectly legal to index partially through a
-structure, returning a pointer to an inner element. Because of this,
-the LLVM code for the given testcase is equivalent to:</p>
+<h5>Arguments:</h5>
-<pre>
- int* %foo(%ST* %s) {
- %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
- %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
- %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
- %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
- %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
- ret int* %t5
- }
-</pre>
+<p>
+The '<tt>vselect</tt>' instruction requires a <a
+href="#t_packed">packed</a> <tt>bool</tt> value indicating the
+condition at each vector position, and two values of the same packed
+type. All three operands must have the same length. The type of the
+result is the same as the type of the two value operands.</p>
-<p>Note that it is undefined to access an array out of bounds: array and
-pointer indexes must always be within the defined bounds of the array type.
-The one exception for this rules is zero length arrays. These arrays are
-defined to be accessible as variable length arrays, which requires access
-beyond the zero'th element.</p>
+<h5>Semantics:</h5>
+
+<p>
+At each position where the <tt>bool</tt> vector is true, that position
+of the result gets its value from the first value argument; otherwise,
+it gets its value from the second value argument.
+</p>
<h5>Example:</h5>
<pre>
- <i>; yields [12 x ubyte]*:aptr</i>
- %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
+ %X = vselect bool <2 x bool> <bool true, bool false>, <2 x ubyte> <ubyte 17, ubyte 17>,
+ <2 x ubyte> <ubyte 42, ubyte 42> <i>; yields <2 x ubyte>:17, 42</i>
</pre>
-
</div>
+
+
+
<!-- ======================================================================= -->
-<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
-<div class="doc_text">
-<p>The instructions in this category are the "miscellaneous"
-instructions, which defy better classification.</p>
+<div class="doc_subsection">
+ <a name="memoryops">Memory Access Operations</a>
</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
-Instruction</a> </div>
+
<div class="doc_text">
-<h5>Syntax:</h5>
-<pre> <result> = phi <ty> [ <val0>, <label0>], ...<br></pre>
-<h5>Overview:</h5>
-<p>The '<tt>phi</tt>' instruction is used to implement the φ node in
-the SSA graph representing the function.</p>
-<h5>Arguments:</h5>
-<p>The type of the incoming values are specified with the first type
-field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
-as arguments, with one pair for each predecessor basic block of the
-current block. Only values of <a href="#t_firstclass">first class</a>
-type may be used as the value arguments to the PHI node. Only labels
-may be used as the label arguments.</p>
-<p>There must be no non-phi instructions between the start of a basic
-block and the PHI instructions: i.e. PHI instructions must be first in
-a basic block.</p>
-<h5>Semantics:</h5>
-<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
-value specified by the parameter, depending on which basic block we
-came from in the last <a href="#terminators">terminator</a> instruction.</p>
-<h5>Example:</h5>
-<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre>
+
+<p>A key design point of an SSA-based representation is how it
+represents memory. In LLVM, no memory locations are in SSA form, which
+makes things very simple. This section describes how to read, write,
+allocate, and free memory in LLVM.</p>
+
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
+ <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = cast <ty> <value> to <ty2> <i>; yields ty2</i>
+ <result> = malloc <type>[, uint <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
</pre>
<h5>Overview:</h5>
-<p>
-The '<tt>cast</tt>' instruction is used as the primitive means to convert
-integers to floating point, change data type sizes, and break type safety (by
-casting pointers).
-</p>
-
+<p>The '<tt>malloc</tt>' instruction allocates memory from the system
+heap and returns a pointer to it.</p>
<h5>Arguments:</h5>
-<p>
-The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
-class value, and a type to cast it to, which must also be a <a
-href="#t_firstclass">first class</a> type.
-</p>
-
-<h5>Semantics:</h5>
+<p>The '<tt>malloc</tt>' instruction allocates
+<tt>sizeof(<type>)*NumElements</tt>
+bytes of memory from the operating system and returns a pointer of the
+appropriate type to the program. If "NumElements" is specified, it is the
+number of elements allocated. If an alignment is specified, the value result
+of the allocation is guaranteed to be aligned to at least that boundary. If
+not specified, or if zero, the target can choose to align the allocation on any
+convenient boundary.</p>
-<p>
-This instruction follows the C rules for explicit casts when determining how the
-data being cast must change to fit in its new container.
-</p>
+<p>'<tt>type</tt>' must be a sized type.</p>
-<p>
-When casting to bool, any value that would be considered true in the context of
-a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
-all else are '<tt>false</tt>'.
-</p>
+<h5>Semantics:</h5>
-<p>
-When extending an integral value from a type of one signness to another (for
-example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
-<b>source</b> value is signed, and zero-extended if the source value is
-unsigned. <tt>bool</tt> values are always zero extended into either zero or
-one.
-</p>
+<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
+a pointer is returned.</p>
<h5>Example:</h5>
<pre>
- %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
- %Y = cast int 123 to bool <i>; yields bool:true</i>
+ %array = malloc [4 x ubyte ] <i>; yields {[%4 x ubyte]*}:array</i>
+
+ %size = <a href="#i_add">add</a> uint 2, 2 <i>; yields {uint}:size = uint 4</i>
+ %array1 = malloc ubyte, uint 4 <i>; yields {ubyte*}:array1</i>
+ %array2 = malloc [12 x ubyte], uint %size <i>; yields {[12 x ubyte]*}:array2</i>
+ %array3 = malloc int, uint 4, align 1024 <i>; yields {int*}:array3</i>
+ %array4 = malloc int, align 1024 <i>; yields {int*}:array4</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_select">'<tt>select</tt>' Instruction</a>
+ <a name="i_free">'<tt>free</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = select bool <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
+ free <type> <value> <i>; yields {void}</i>
</pre>
<h5>Overview:</h5>
-<p>
-The '<tt>select</tt>' instruction is used to choose one value based on a
-condition, without branching.
-</p>
-
+<p>The '<tt>free</tt>' instruction returns memory back to the unused
+memory heap to be reallocated in the future.</p>
<h5>Arguments:</h5>
-<p>
-The '<tt>select</tt>' instruction requires a boolean value indicating the condition, and two values of the same <a href="#t_firstclass">first class</a> type.
-</p>
+<p>'<tt>value</tt>' shall be a pointer value that points to a value
+that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
+instruction.</p>
<h5>Semantics:</h5>
-<p>
-If the boolean condition evaluates to true, the instruction returns the first
-value argument; otherwise, it returns the second value argument.
-</p>
+<p>Access to the memory pointed to by the pointer is no longer defined
+after this instruction executes.</p>
<h5>Example:</h5>
<pre>
- %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
+ %array = <a href="#i_malloc">malloc</a> [4 x ubyte] <i>; yields {[4 x ubyte]*}:array</i>
+ free [4 x ubyte]* %array
</pre>
</div>
<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"> <a name="i_vsetint">'<tt>vsetint</tt>'
-Instruction</a> </div>
+<div class="doc_subsubsection">
+ <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
+</div>
+
<div class="doc_text">
+
<h5>Syntax:</h5>
-<pre><result> = vsetint <op>, <n x <ty>> <var1>, <var2> <i>; yields <n x bool></i>
+
+<pre>
+ <result> = alloca <type>[, uint <NumElements>][, align <alignment>] <i>; yields {type*}:result</i>
</pre>
<h5>Overview:</h5>
-<p>The '<tt>vsetint</tt>' instruction takes two integer vectors and
-returns a vector of boolean values representing, at each position, the
-result of the comparison between the values at that position in the
-two operands.</p>
+<p>The '<tt>alloca</tt>' instruction allocates memory on the current
+stack frame of the procedure that is live until the current function
+returns to its caller.</p>
<h5>Arguments:</h5>
-<p>The arguments to a '<tt>vsetint</tt>' instruction are a comparison
-operation and two value arguments. The value arguments must be of <a
-href="#t_integral">integral</a> <a href="#t_packed">packed</a> type,
-and they must have identical types. The operation argument must be
-one of <tt>eq</tt>, <tt>ne</tt>, <tt>slt</tt>, <tt>sgt</tt>,
-<tt>sle</tt>, <tt>sge</tt>, <tt>ult</tt>, <tt>ugt</tt>, <tt>ule</tt>,
-<tt>uge</tt>, <tt>true</tt>, and <tt>false</tt>. The result is a
-packed <tt>bool</tt> value with the same length as each operand.</p>
+<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(<type>)*NumElements</tt>
+bytes of memory on the runtime stack, returning a pointer of the
+appropriate type to the program. If "NumElements" is specified, it is the
+number of elements allocated. If an alignment is specified, the value result
+of the allocation is guaranteed to be aligned to at least that boundary. If
+not specified, or if zero, the target can choose to align the allocation on any
+convenient boundary.</p>
+
+<p>'<tt>type</tt>' may be any sized type.</p>
<h5>Semantics:</h5>
-<p>The following table shows the semantics of '<tt>vsetint</tt>'. For
-each position of the result, the comparison is done on the
-corresponding positions of the two value arguments. Note that the
-signedness of the comparison depends on the comparison opcode and
-<i>not</i> on the signedness of the value operands. E.g., <tt>vsetint
-slt <4 x unsigned> %x, %y</tt> does an elementwise <i>signed</i>
-comparison of <tt>%x</tt> and <tt>%y</tt>.</p>
+<p>Memory is allocated; a pointer is returned. '<tt>alloca</tt>'d
+memory is automatically released when the function returns. The '<tt>alloca</tt>'
+instruction is commonly used to represent automatic variables that must
+have an address available. When the function returns (either with the <tt><a
+ href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
+instructions), the memory is reclaimed.</p>
-<table border="1" cellspacing="0" cellpadding="4">
- <tbody>
- <tr><th>Operation</th><th>Result is true iff</th><th>Comparison is</th></tr>
- <tr><td><tt>eq</tt></td><td>var1 == var2</td><td>--</td></tr>
- <tr><td><tt>ne</tt></td><td>var1 != var2</td><td>--</td></tr>
- <tr><td><tt>slt</tt></td><td>var1 < var2</td><td>signed</td></tr>
- <tr><td><tt>sgt</tt></td><td>var1 > var2</td><td>signed</td></tr>
- <tr><td><tt>sle</tt></td><td>var1 <= var2</td><td>signed</td></tr>
- <tr><td><tt>sge</tt></td><td>var1 >= var2</td><td>signed</td></tr>
- <tr><td><tt>ult</tt></td><td>var1 < var2</td><td>unsigned</td></tr>
- <tr><td><tt>ugt</tt></td><td>var1 > var2</td><td>unsigned</td></tr>
- <tr><td><tt>ule</tt></td><td>var1 <= var2</td><td>unsigned</td></tr>
- <tr><td><tt>uge</tt></td><td>var1 >= var2</td><td>unsigned</td></tr>
- <tr><td><tt>true</tt></td><td>always</td><td>--</td></tr>
- <tr><td><tt>false</tt></td><td>never</td><td>--</td></tr>
- </tbody>
-</table>
+<h5>Example:</h5>
+
+<pre>
+ %ptr = alloca int <i>; yields {int*}:ptr</i>
+ %ptr = alloca int, uint 4 <i>; yields {int*}:ptr</i>
+ %ptr = alloca int, uint 4, align 1024 <i>; yields {int*}:ptr</i>
+ %ptr = alloca int, align 1024 <i>; yields {int*}:ptr</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = load <ty>* <pointer><br> <result> = volatile load <ty>* <pointer><br></pre>
+<h5>Overview:</h5>
+<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
+<h5>Arguments:</h5>
+<p>The argument to the '<tt>load</tt>' instruction specifies the memory
+address from which to load. The pointer must point to a <a
+ href="#t_firstclass">first class</a> type. If the <tt>load</tt> is
+marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
+the number or order of execution of this <tt>load</tt> with other
+volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
+instructions. </p>
+<h5>Semantics:</h5>
+<p>The location of memory pointed to is loaded.</p>
+<h5>Examples:</h5>
+<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
+ <a
+ href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
+ %val = load int* %ptr <i>; yields {int}:val = int 3</i>
+</pre>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
+Instruction</a> </div>
+<h5>Syntax:</h5>
+<pre> store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i>
+ volatile store <ty> <value>, <ty>* <pointer> <i>; yields {void}</i>
+</pre>
+<h5>Overview:</h5>
+<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
+<h5>Arguments:</h5>
+<p>There are two arguments to the '<tt>store</tt>' instruction: a value
+to store and an address in which to store it. The type of the '<tt><pointer></tt>'
+operand must be a pointer to the type of the '<tt><value></tt>'
+operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
+optimizer is not allowed to modify the number or order of execution of
+this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
+ href="#i_store">store</a></tt> instructions.</p>
+<h5>Semantics:</h5>
+<p>The contents of memory are updated to contain '<tt><value></tt>'
+at the location specified by the '<tt><pointer></tt>' operand.</p>
<h5>Example:</h5>
-<pre> <result> = vsetint eq <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = false, false</i>
- <result> = vsetint ne <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = true, true</i>
- <result> = vsetint slt <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = true, false</i>
- <result> = vsetint sgt <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = false, true</i>
- <result> = vsetint sle <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = true, false</i>
- <result> = vsetint sge <2 x int> <int 0, int 1>, <int 1, int 0> <i>; yields {<2 x bool>}:result = false, true</i>
+<pre> %ptr = <a href="#i_alloca">alloca</a> int <i>; yields {int*}:ptr</i>
+ <a
+ href="#i_store">store</a> int 3, int* %ptr <i>; yields {void}</i>
+ %val = load int* %ptr <i>; yields {int}:val = int 3</i>
</pre>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection"> <a name="i_vsetfp">'<tt>vsetfp</tt>'
-Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
-<pre><result> = vsetfp <op>, <n x <ty>> <var1>, <var2> <i>; yields <n x bool></i>
+<pre>
+ <result> = getelementptr <ty>* <ptrval>{, <ty> <idx>}*
</pre>
<h5>Overview:</h5>
-<p>The '<tt>vsetfp</tt>' instruction takes two floating point vector
-arguments and returns a vector of boolean values representing, at each
-position, the result of the comparison between the values at that
-position in the two operands.</p>
+<p>
+The '<tt>getelementptr</tt>' instruction is used to get the address of a
+subelement of an aggregate data structure.</p>
<h5>Arguments:</h5>
-<p>The arguments to a '<tt>vsetfp</tt>' instruction are a comparison
-operation and two value arguments. The value arguments must be of <a
-href="t_floating">floating point</a> <a href="#t_packed">packed</a>
-type, and they must have identical types. The operation argument must
-be one of <tt>eq</tt>, <tt>ne</tt>, <tt>lt</tt>, <tt>gt</tt>,
-<tt>le</tt>, <tt>ge</tt>, <tt>oeq</tt>, <tt>one</tt>, <tt>olt</tt>,
-<tt>ogt</tt>, <tt>ole</tt>, <tt>oge</tt>, <tt>ueq</tt>, <tt>une</tt>,
-<tt>ult</tt>, <tt>ugt</tt>, <tt>ule</tt>, <tt>uge</tt>, <tt>o</tt>,
-<tt>u</tt>, <tt>true</tt>, and <tt>false</tt>. The result is a packed
-<tt>bool</tt> value with the same length as each operand.</p>
-
-<h5>Semantics:</h5>
+<p>This instruction takes a list of integer constants that indicate what
+elements of the aggregate object to index to. The actual types of the arguments
+provided depend on the type of the first pointer argument. The
+'<tt>getelementptr</tt>' instruction is used to index down through the type
+levels of a structure or to a specific index in an array. When indexing into a
+structure, only <tt>uint</tt>
+integer constants are allowed. When indexing into an array or pointer,
+<tt>int</tt> and <tt>long</tt> indexes are allowed of any sign.</p>
-<p>The following table shows the semantics of '<tt>vsetfp</tt>' for
-floating point types. If either operand is a floating point Not a
-Number (NaN) value, the operation is unordered, and the value in the
-first column below is produced at that position. Otherwise, the
-operation is ordered, and the value in the second column is
-produced.</p>
+<p>For example, let's consider a C code fragment and how it gets
+compiled to LLVM:</p>
-<table border="1" cellspacing="0" cellpadding="4">
- <tbody>
- <tr><th>Operation</th><th>If unordered<th>Otherwise true iff</th></tr>
- <tr><td><tt>eq</tt></td><td>undefined</td><td>var1 == var2</td></tr>
- <tr><td><tt>ne</tt></td><td>undefined</td><td>var1 != var2</td></tr>
- <tr><td><tt>lt</tt></td><td>undefined</td><td>var1 < var2</td></tr>
- <tr><td><tt>gt</tt></td><td>undefined</td><td>var1 > var2</td></tr>
- <tr><td><tt>le</tt></td><td>undefined</td><td>var1 <= var2</td></tr>
- <tr><td><tt>ge</tt></td><td>undefined</td><td>var1 >= var2</td></tr>
- <tr><td><tt>oeq</tt></td><td>false</td><td>var1 == var2</td></tr>
- <tr><td><tt>one</tt></td><td>false</td><td>var1 != var2</td></tr>
- <tr><td><tt>olt</tt></td><td>false</td><td>var1 < var2</td></tr>
- <tr><td><tt>ogt</tt></td><td>false</td><td>var1 > var2</td></tr>
- <tr><td><tt>ole</tt></td><td>false</td><td>var1 <= var2</td></tr>
- <tr><td><tt>oge</tt></td><td>false</td><td>var1 >= var2</td></tr>
- <tr><td><tt>ueq</tt></td><td>true</td><td>var1 == var2</td></tr>
- <tr><td><tt>une</tt></td><td>true</td><td>var1 != var2</td></tr>
- <tr><td><tt>ult</tt></td><td>true</td><td>var1 < var2</td></tr>
- <tr><td><tt>ugt</tt></td><td>true</td><td>var1 > var2</td></tr>
- <tr><td><tt>ule</tt></td><td>true</td><td>var1 <= var2</td></tr>
- <tr><td><tt>uge</tt></td><td>true</td><td>var1 >= var2</td></tr>
- <tr><td><tt>o</tt></td><td>false</td><td>always</td></tr>
- <tr><td><tt>u</tt></td><td>true</td><td>never</td></tr>
- <tr><td><tt>true</tt></td><td>true</td><td>always</td></tr>
- <tr><td><tt>false</tt></td><td>false</td><td>never</td></tr>
- </tbody>
-</table>
+<pre>
+ struct RT {
+ char A;
+ int B[10][20];
+ char C;
+ };
+ struct ST {
+ int X;
+ double Y;
+ struct RT Z;
+ };
-<h5>Example:</h5>
-<pre> <result> = vsetfp eq <2 x float> <float 0, float 1>, <float 1, float 0> <i>; yields {<2 x bool>}:result = false, false</i>
- <result> = vsetfp ne <2 x float> <float 0, float 1>, <float 1, float 0> <i>; yields {<2 x bool>}:result = true, true</i>
- <result> = vsetfp lt <2 x float> <float 0, float 1>, <float 1, float 0> <i>; yields {<2 x bool>}:result = true, false</i>
- <result> = vsetfp gt <2 x float> <float 0, float 1>, <float 1, float 0> <i>; yields {<2 x bool>}:result = false, true</i>
- <result> = vsetfp le <2 x float> <float 0, float 1>, <float 1, float 0> <i>; yields {<2 x bool>}:result = true, false</i>
- <result> = vsetfp ge <2 x float> <float 0, float 1>, <float 1, float 0> <i>; yields {<2 x bool>}:result = false, true</i>
+ int *foo(struct ST *s) {
+ return &s[1].Z.B[5][13];
+ }
</pre>
-</div>
-<!-- _______________________________________________________________________ -->
-<div class="doc_subsubsection">
- <a name="i_vselect">'<tt>vselect</tt>' Instruction</a>
-</div>
+<p>The LLVM code generated by the GCC frontend is:</p>
-<div class="doc_text">
+<pre>
+ %RT = type { sbyte, [10 x [20 x int]], sbyte }
+ %ST = type { int, double, %RT }
-<h5>Syntax:</h5>
+ implementation
-<pre>
- <result> = vselect <n x bool> <cond>, <n x <ty>> <val1>, <n x <ty>> <val2> <i>; yields <n x <ty>></i>
+ int* %foo(%ST* %s) {
+ entry:
+ %reg = getelementptr %ST* %s, int 1, uint 2, uint 1, int 5, int 13
+ ret int* %reg
+ }
</pre>
-<h5>Overview:</h5>
-
-<p>
-The '<tt>vselect</tt>' instruction chooses one value at each position
-of a vector based on a condition.
-</p>
+<h5>Semantics:</h5>
+<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
+on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
+and <a href="#t_array">array</a> types require <tt>uint</tt>, <tt>int</tt>,
+<tt>ulong</tt>, or <tt>long</tt> values, and <a href="#t_struct">structure</a>
+types require <tt>uint</tt> <b>constants</b>.</p>
-<h5>Arguments:</h5>
+<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
+type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ int, double, %RT
+}</tt>' type, a structure. The second index indexes into the third element of
+the structure, yielding a '<tt>%RT</tt>' = '<tt>{ sbyte, [10 x [20 x int]],
+sbyte }</tt>' type, another structure. The third index indexes into the second
+element of the structure, yielding a '<tt>[10 x [20 x int]]</tt>' type, an
+array. The two dimensions of the array are subscripted into, yielding an
+'<tt>int</tt>' type. The '<tt>getelementptr</tt>' instruction returns a pointer
+to this element, thus computing a value of '<tt>int*</tt>' type.</p>
-<p>
-The '<tt>vselect</tt>' instruction requires a <a
-href="#t_packed">packed</a> <tt>bool</tt> value indicating the
-condition at each vector position, and two values of the same packed
-type. All three operands must have the same length. The type of the
-result is the same as the type of the two value operands.</p>
+<p>Note that it is perfectly legal to index partially through a
+structure, returning a pointer to an inner element. Because of this,
+the LLVM code for the given testcase is equivalent to:</p>
-<h5>Semantics:</h5>
+<pre>
+ int* %foo(%ST* %s) {
+ %t1 = getelementptr %ST* %s, int 1 <i>; yields %ST*:%t1</i>
+ %t2 = getelementptr %ST* %t1, int 0, uint 2 <i>; yields %RT*:%t2</i>
+ %t3 = getelementptr %RT* %t2, int 0, uint 1 <i>; yields [10 x [20 x int]]*:%t3</i>
+ %t4 = getelementptr [10 x [20 x int]]* %t3, int 0, int 5 <i>; yields [20 x int]*:%t4</i>
+ %t5 = getelementptr [20 x int]* %t4, int 0, int 13 <i>; yields int*:%t5</i>
+ ret int* %t5
+ }
+</pre>
-<p>
-At each position where the <tt>bool</tt> vector is true, that position
-of the result gets its value from the first value argument; otherwise,
-it gets its value from the second value argument.
-</p>
+<p>Note that it is undefined to access an array out of bounds: array and
+pointer indexes must always be within the defined bounds of the array type.
+The one exception for this rules is zero length arrays. These arrays are
+defined to be accessible as variable length arrays, which requires access
+beyond the zero'th element.</p>
<h5>Example:</h5>
<pre>
- %X = vselect bool <2 x bool> <bool true, bool false>, <2 x ubyte> <ubyte 17, ubyte 17>,
- <2 x ubyte> <ubyte 42, ubyte 42> <i>; yields <2 x ubyte>:17, 42</i>
+ <i>; yields [12 x ubyte]*:aptr</i>
+ %aptr = getelementptr {int, [12 x ubyte]}* %sptr, long 0, uint 1
</pre>
+
+</div>
+<!-- ======================================================================= -->
+<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
+<div class="doc_text">
+<p>The instructions in this category are the "miscellaneous"
+instructions, which defy better classification.</p>
+</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
+Instruction</a> </div>
+<div class="doc_text">
+<h5>Syntax:</h5>
+<pre> <result> = phi <ty> [ <val0>, <label0>], ...<br></pre>
+<h5>Overview:</h5>
+<p>The '<tt>phi</tt>' instruction is used to implement the φ node in
+the SSA graph representing the function.</p>
+<h5>Arguments:</h5>
+<p>The type of the incoming values are specified with the first type
+field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
+as arguments, with one pair for each predecessor basic block of the
+current block. Only values of <a href="#t_firstclass">first class</a>
+type may be used as the value arguments to the PHI node. Only labels
+may be used as the label arguments.</p>
+<p>There must be no non-phi instructions between the start of a basic
+block and the PHI instructions: i.e. PHI instructions must be first in
+a basic block.</p>
+<h5>Semantics:</h5>
+<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the
+value specified by the parameter, depending on which basic block we
+came from in the last <a href="#terminators">terminator</a> instruction.</p>
+<h5>Example:</h5>
+<pre>Loop: ; Infinite loop that counts from 0 on up...<br> %indvar = phi uint [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br> %nextindvar = add uint %indvar, 1<br> br label %Loop<br></pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
+ <a name="i_cast">'<tt>cast .. to</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = extractelement <n x <ty>> <val>, uint <idx> <i>; yields <ty></i>
+ <result> = cast <ty> <value> to <ty2> <i>; yields ty2</i>
</pre>
<h5>Overview:</h5>
<p>
-The '<tt>extractelement</tt>' instruction extracts a single scalar
-element from a packed vector at a specified index.
+The '<tt>cast</tt>' instruction is used as the primitive means to convert
+integers to floating point, change data type sizes, and break type safety (by
+casting pointers).
</p>
<h5>Arguments:</h5>
<p>
-The first operand of an '<tt>extractelement</tt>' instruction is a
-value of <a href="#t_packed">packed</a> type. The second operand is
-an index indicating the position from which to extract the element.
-The index may be a variable.</p>
+The '<tt>cast</tt>' instruction takes a value to cast, which must be a first
+class value, and a type to cast it to, which must also be a <a
+href="#t_firstclass">first class</a> type.
+</p>
<h5>Semantics:</h5>
<p>
-The result is a scalar of the same type as the element type of
-<tt>val</tt>. Its value is the value at position <tt>idx</tt> of
-<tt>val</tt>. If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
-results are undefined.
+This instruction follows the C rules for explicit casts when determining how the
+data being cast must change to fit in its new container.
+</p>
+
+<p>
+When casting to bool, any value that would be considered true in the context of
+a C '<tt>if</tt>' condition is converted to the boolean '<tt>true</tt>' values,
+all else are '<tt>false</tt>'.
+</p>
+
+<p>
+When extending an integral value from a type of one signness to another (for
+example '<tt>sbyte</tt>' to '<tt>ulong</tt>'), the value is sign-extended if the
+<b>source</b> value is signed, and zero-extended if the source value is
+unsigned. <tt>bool</tt> values are always zero extended into either zero or
+one.
</p>
<h5>Example:</h5>
<pre>
- %result = extractelement <4 x int> %vec, uint 0 <i>; yields int</i>
+ %X = cast int 257 to ubyte <i>; yields ubyte:1</i>
+ %Y = cast int 123 to bool <i>; yields bool:true</i>
</pre>
</div>
-
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
- <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
+ <a name="i_select">'<tt>select</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>
- <result> = insertelement <n x <ty>> <val>, <ty> <elt>, uint <idx> <i>; yields <n x <ty>></i>
+ <result> = select bool <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
</pre>
<h5>Overview:</h5>
<p>
-The '<tt>insertelement</tt>' instruction inserts a scalar
-element into a packed vector at a specified index.
+The '<tt>select</tt>' instruction is used to choose one value based on a
+condition, without branching.
</p>
<h5>Arguments:</h5>
<p>
-The first operand of an '<tt>insertelement</tt>' instruction is a
-value of <a href="#t_packed">packed</a> type. The second operand is a
-scalar value whose type must equal the element type of the first
-operand. The third operand is an index indicating the position at
-which to insert the value. The index may be a variable.</p>
+The '<tt>select</tt>' instruction requires a boolean value indicating the condition, and two values of the same <a href="#t_firstclass">first class</a> type.
+</p>
<h5>Semantics:</h5>
<p>
-The result is a packed vector of the same type as <tt>val</tt>. Its
-element values are those of <tt>val</tt> except at position
-<tt>idx</tt>, where it gets the value <tt>elt</tt>. If <tt>idx</tt>
-exceeds the length of <tt>val</tt>, the results are undefined.
+If the boolean condition evaluates to true, the instruction returns the first
+value argument; otherwise, it returns the second value argument.
</p>
<h5>Example:</h5>
<pre>
- %result = insertelement <4 x int> %vec, int 1, uint 0 <i>; yields <4 x int></i>
+ %X = select bool true, ubyte 17, ubyte 42 <i>; yields ubyte:17</i>
</pre>
</div>
transformations should be prepared to handle intrinsics with any type
used.</p>
-<p>This example shows how the <a href="#i_vanext"><tt>vanext</tt></a>
+<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
instruction and the variable argument handling intrinsic functions are
used.</p>
expected that the marker will use exported symbols to transmit the PC of the marker.
The marker makes no guarantees that it will remain with any specific instruction
after optimizations. It is possible that the presence of a marker will inhibit
-optimizations. The intended use is to be inserted after optmizations to allow
+optimizations. The intended use is to be inserted after optimizations to allow
correlations of simulation runs.
</p>
<p>
The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
in a variable. If the src == 0 then the result is the size in bits of the type
-of src. For example, <tt>llvm.cttz(int 2) = 30</tt>.
+of src. For example, <tt>llvm.ctlz(int 2) = 30</tt>.
</p>
</div>
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