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<head>
+ <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>TableGen Fundamentals</title>
<link rel="stylesheet" href="llvm.css" type="text/css">
</head>
<ol>
<li><a href="#include">File inclusion</a></li>
<li><a href="#globallet">'let' expressions</a></li>
+ <li><a href="#foreach">'foreach' blocks</a></li>
</ol></li>
</ol></li>
<li><a href="#backends">TableGen backends</a>
key feature of TableGen is that it allows the end-user to define the
abstractions they prefer to use when describing their information.</p>
+<p>Each def record has a special entry called "NAME." This is the
+name of the def ("ADD32rr" above). In the general case def names can
+be formed from various kinds of string processing expressions and NAME
+resolves to the final value obtained after resolving all of those
+expressions. The user may refer to NAME anywhere she desires to use
+the ultimate name of the def. NAME should not be defined anywhere
+else in user code to avoid conflict problems.</p>
+
</div>
<!-- ======================================================================= -->
<dt><tt>list[4-7,17,2-3]</tt></dt>
<dd>A slice of the 'list' list, including elements 4,5,6,7,17,2, and 3 from
it. Elements may be included multiple times.</dd>
+<dt><tt>foreach <var> = <list> in { <body> }</tt></dt>
+<dt><tt>foreach <var> = <list> in <def></tt></dt>
+ <dd> Replicate <body> or <def>, replacing instances of
+ <var> with each value in <list>. <var> is scoped at the
+ level of the <tt>foreach</tt> loop and must not conflict with any other object
+ introduced in <body> or <def>. Currently only <tt>def</tt>s are
+ expanded within <body>.
+ </dd>
<dt><tt>(DEF a, b)</tt></dt>
<dd>a dag value. The first element is required to be a record definition, the
remaining elements in the list may be arbitrary other values, including nested
<dt><tt>!strconcat(a, b)</tt></dt>
<dd>A string value that is the result of concatenating the 'a' and 'b'
strings.</dd>
+<dt><tt>str1#str2</tt></dt>
+ <dd>"#" (paste) is a shorthand for !strconcat. It may concatenate
+ things that are not quoted strings, in which case an implicit
+ !cast<string> is done on the operand of the paste.</dd>
<dt><tt>!cast<type>(a)</tt></dt>
<dd>A symbol of type <em>type</em> obtained by looking up the string 'a' in
the symbol table. If the type of 'a' does not match <em>type</em>, TableGen
</pre>
</div>
-<p>
-A special "multidef" may be used inside a multiclass to generate
-several defs given a list of values.
-</p>
-
-<div class="doc_code">
-<pre>
-<b>class</b> Base<int i> {
- int value = i;
-}
-
-<b>multiclass</b> Multi<list<int> values> {
- <b>def</b> ONE : Base<values[0]>;
- <b>def</b> TWO : Base<values[1]>;
-
- <b>multidef</b> COUNT<values, int v, 2> : Base<v>;
-}
-
-<b>defm</b> List : Multi<[1, 2, 3, 4, 5, 6]<;
-...
-
-<i>// Results</i>
-<b>def</b> ListCOUNT {
- int v = ?;
- int value = v;
- list<int> Multi::values = [1, 2, 3, 4, 5, 6];
-}
-<b>def</b> ListONE {
- int value = 1;
-}
-<b>def</b> ListTWO {
- int value = 2;
-}
-<b>def</b> MD2.ListCOUNT {
- int value = 3;
-}
-<b>def</b> MD3.ListCOUNT {
- int value = 4;
-}
-<b>def</b> MD4.ListCOUNT {
- int value = 5;
-}
-<b>def</b> MD5.ListCOUNT {
- int value = 6;
-}
-</pre>
-</div>
-
-<p>
-A multidef takes three "arguments" in the <> notation after the multidef
-name. The first is a list of items to process. The second is a declaration.
-This declaration creates a temporary name used as an iterator. It picks up the
-value of each processed list item as TableGen generates defs from the multidef.
-This temporary may be named and passed into the multidef body as shown in the
-example above. This provides a powerful way to generate defs with various
-values from a single multidef. The final "argument" is an integer value
-indicating where in the list to begin processing. In the above example we
-chose to begin list processing with the third item (index 2).
-</p>
</div>
</div>
</pre>
</div>
+<!-- -------------------------------------------------------------------------->
+<h4>
+ <a name="foreach">Looping</a>
+</h4>
+
+<div>
+<p>TableGen supports the '<tt>foreach</tt>' block, which textually replicates
+the loop body, substituting iterator values for iterator references in the
+body. Example:</p>
+
+<div class="doc_code">
+<pre>
+<b>foreach</b> i = [0, 1, 2, 3] in {
+ <b>def</b> R#i : Register<...>;
+ <b>def</b> F#i : Register<...>;
+}
+</pre>
+</div>
+
+<p>This will create objects <tt>R0</tt>, <tt>R1</tt>, <tt>R2</tt> and
+<tt>R3</tt>. <tt>foreach</tt> blocks may be nested. If there is only
+one item in the body the braces may be elided:</p>
+
+<div class="doc_code">
+<pre>
+<b>foreach</b> i = [0, 1, 2, 3] in
+ <b>def</b> R#i : Register<...>;
+
+</pre>
+</div>
+
+</div>
+
</div>
</div>
projects / oota-llvm.git / blobdiff