Describe the global/local naming convention.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@40890 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Spencer 2007-08-07 14:34:28 +00:00
parent f48a88054a
commit 2c45228651

View File

@ -296,25 +296,27 @@ the parser.</p>
<div class="doc_text">
<p>LLVM uses three different forms of identifiers, for different
purposes:</p>
<p>LLVM identifiers come in two basic types: global and local. Global
identifiers (functions, global variables) begin with the @ character. Local
identifiers (register names, types) begin with the % character. Additionally,
there are three different formats for identifiers, for different purposes:
<ol>
<li>Named values are represented as a string of characters with a '%' prefix.
For example, %foo, %DivisionByZero, %a.really.long.identifier. The actual
regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
<li>Named values are represented as a string of characters with their prefix.
For example, %foo, @DivisionByZero, %a.really.long.identifier. The actual
regular expression used is '<tt>[%@][a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
Identifiers which require other characters in their names can be surrounded
with quotes. In this way, anything except a <tt>&quot;</tt> character can be used
in a name.</li>
with quotes. In this way, anything except a <tt>&quot;</tt> character can
be used in a named value.</li>
<li>Unnamed values are represented as an unsigned numeric value with a '%'
prefix. For example, %12, %2, %44.</li>
<li>Unnamed values are represented as an unsigned numeric value with their
prefix. For example, %12, @2, %44.</li>
<li>Constants, which are described in a <a href="#constants">section about
constants</a>, below.</li>
</ol>
<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
<p>LLVM requires that values start with a prefix for two reasons: Compilers
don't need to worry about name clashes with reserved words, and the set of
reserved words may be expanded in the future without penalty. Additionally,
unnamed identifiers allow a compiler to quickly come up with a temporary
@ -327,7 +329,7 @@ languages. There are keywords for different opcodes
'<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
and others. These reserved words cannot conflict with variable names, because
none of them start with a '%' character.</p>
none of them start with a prefix character ('%' or '@').</p>
<p>Here is an example of LLVM code to multiply the integer variable
'<tt>%X</tt>' by 8:</p>