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Update for new varargs support

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@9218 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2003-10-18 05:51:36 +00:00
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@ -72,7 +72,8 @@
<li><a href="#i_phi" >'<tt>phi</tt>' Instruction</a>
<li><a href="#i_cast">'<tt>cast .. to</tt>' Instruction</a>
<li><a href="#i_call" >'<tt>call</tt>' Instruction</a>
<li><a href="#i_va_arg">'<tt>va_arg</tt>' Instruction</a>
<li><a href="#i_vanext">'<tt>vanext</tt>' Instruction</a>
<li><a href="#i_vaarg" >'<tt>vaarg</tt>' Instruction</a>
</ol>
</ol>
<li><a href="#intrinsics">Intrinsic Functions</a>
@ -1710,44 +1711,87 @@ case of the <a href="#i_invoke">invoke</a> instruction.<p>
</pre>
<!-- _______________________________________________________________________ -->
</ul><a name="i_va_arg"><h4><hr size=0>'<tt>va_arg</tt>' Instruction</h4><ul>
</ul><a name="i_vanext"><h4><hr size=0>'<tt>vanext</tt>' Instruction</h4><ul>
<h5>Syntax:</h5>
<pre>
&lt;result&gt; = va_arg &lt;va_list&gt;* &lt;arglist&gt;, &lt;retty&gt;
&lt;resultarglist&gt; = vanext &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
</pre>
<h5>Overview:</h5>
The '<tt>va_arg</tt>' instruction is used to access arguments passed through the
"variable argument" area of a function call. It corresponds directly to the
The '<tt>vanext</tt>' instruction is used to access arguments passed through
the "variable argument" area of a function call. It is used to implement the
<tt>va_arg</tt> macro in C.<p>
<h5>Arguments:</h5>
This instruction takes a pointer to a <tt>valist</tt> value to read a new
argument from. The return type of the instruction is defined by the second
argument, a type.<p>
This instruction takes a <tt>valist</tt> value and the type of the argument. It
returns another <tt>valist</tt>.
<h5>Semantics:</h5>
The '<tt>va_arg</tt>' instruction works just like the <tt>va_arg</tt> macro
available in C. In a target-dependent way, it reads the argument indicated by
the value the arglist points to, updates the arglist, then returns a value of
the specified type. This instruction should be used in conjunction with the
variable argument handling <a href="#int_varargs">Intrinsic Functions</a>.<p>
The '<tt>vanext</tt>' instruction advances the specified <tt>valist</tt> past
an argument of the specified type. In conjunction with the <a
href="#i_vaarg"><tt>vaarg</tt></a> instruction, it is used to implement the
<tt>va_arg</tt> macro available in C. For more information, see the variable
argument handling <a href="#int_varargs">Intrinsic Functions</a>.<p>
It is legal for this instruction to be called in a function which does not take
a variable number of arguments, for example, the <tt>vfprintf</tt> function.<p>
<tt>va_arg</tt> is an LLVM instruction instead of an <a
href="#intrinsics">intrinsic function</a> because the return type depends on an
argument.<p>
<tt>vanext</tt> is an LLVM instruction instead of an <a
href="#intrinsics">intrinsic function</a> because it takes an type as an
argument.</p>
<h5>Example:</h5>
See the <a href="#int_varargs">variable argument processing</a> section.<p>
<!-- _______________________________________________________________________ -->
</ul><a name="i_vaarg"><h4><hr size=0>'<tt>vaarg</tt>' Instruction</h4><ul>
<h5>Syntax:</h5>
<pre>
&lt;resultval&gt; = vaarg &lt;va_list&gt; &lt;arglist&gt;, &lt;argty&gt;
</pre>
<h5>Overview:</h5>
The '<tt>vaarg</tt>' instruction is used to access arguments passed through
the "variable argument" area of a function call. It is used to implement the
<tt>va_arg</tt> macro in C.<p>
<h5>Arguments:</h5>
This instruction takes a <tt>valist</tt> value and the type of the argument. It
returns a value of the specified argument type.
<h5>Semantics:</h5>
The '<tt>vaarg</tt>' instruction loads an argument of the specified type from
the specified <tt>va_list</tt>. In conjunction with the <a
href="#i_vanext"><tt>vanext</tt></a> instruction, it is used to implement the
<tt>va_arg</tt> macro available in C. For more information, see the variable
argument handling <a href="#int_varargs">Intrinsic Functions</a>.<p>
It is legal for this instruction to be called in a function which does not take
a variable number of arguments, for example, the <tt>vfprintf</tt> function.<p>
<tt>vaarg</tt> is an LLVM instruction instead of an <a
href="#intrinsics">intrinsic function</a> because it takes an type as an
argument.</p>
<h5>Example:</h5>
See the <a href="#int_varargs">variable argument processing</a> section.<p>
<!-- *********************************************************************** -->
</ul><table width="100%" bgcolor="#330077" border=0 cellpadding=4 cellspacing=0>
<tr><td align=center><font color="#EEEEFF" size=+2 face="Georgia,Palatino"><b>
@ -1781,37 +1825,35 @@ function.<p>
</b></font></td></tr></table><ul>
Variable argument support is defined in LLVM with the <a
href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three intrinsic
functions. These function correspond almost directly to the similarly named
macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.<p>
href="#i_vanext"><tt>vanext</tt></a> instruction and these three intrinsic
functions. These functions are related to the similarly named macros defined in
the <tt>&lt;stdarg.h&gt;</tt> header file.<p>
All of these functions operate on arguments that use a target-specific type
"<tt>va_list</tt>". The LLVM assembly language reference manual does not define
what this type is, so all transformations should be prepared to handle
All of these functions operate on arguments that use a target-specific value
type "<tt>va_list</tt>". The LLVM assembly language reference manual does not
define what this type is, so all transformations should be prepared to handle
intrinsics with any type used.<p>
This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a> instruction
This example shows how the <a href="#i_vanext"><tt>vanext</tt></a> instruction
and the variable argument handling intrinsic functions are used.<p>
<pre>
int %test(int %X, ...) {
; Allocate two va_list items. On this target, va_list is of type sbyte*
%ap = alloca sbyte*
%aq = alloca sbyte*
; Initialize variable argument processing
call void (sbyte**)* %<a href="#i_va_start">llvm.va_start</a>(sbyte** %ap)
%ap = call sbyte*()* %<a href="#i_va_start">llvm.va_start</a>()
; Read a single integer argument
%tmp = <a href="#i_va_arg">va_arg</a> sbyte** %ap, int
%tmp = vaarg sbyte* %ap, int
; Demonstrate usage of llvm.va_copy and llvm_va_end
%apv = load sbyte** %ap
call void %<a href="#i_va_copy">llvm.va_copy</a>(sbyte** %aq, sbyte* %apv)
call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %aq)
; Advance to the next argument
%ap2 = vanext sbyte* %ap, int
; Demonstrate usage of llvm.va_copy and llvm.va_end
%aq = call sbyte* (sbyte*)* %<a href="#i_va_copy">llvm.va_copy</a>(sbyte* %ap2)
call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %aq)
; Stop processing of arguments.
call void %<a href="#i_va_end">llvm.va_end</a>(sbyte** %ap)
call void %<a href="#i_va_end">llvm.va_end</a>(sbyte* %ap2)
ret int %tmp
}
</pre>
@ -1821,28 +1863,25 @@ int %test(int %X, ...) {
<h5>Syntax:</h5>
<pre>
call void (va_list*)* %llvm.va_start(&lt;va_list&gt;* &lt;arglist&gt;)
call va_list ()* %llvm.va_start()
</pre>
<h5>Overview:</h5>
The '<tt>llvm.va_start</tt>' intrinsic initializes <tt>*&lt;arglist&gt;</tt> for
subsequent use by <tt><a href="#i_va_arg">va_arg</a></tt> and <tt><a
href="#i_va_end">llvm.va_end</a></tt>, and must be called before either are
invoked.<p>
<h5>Arguments:</h5>
The argument is a pointer to a <tt>va_list</tt> element to initialize.<p>
The '<tt>llvm.va_start</tt>' intrinsic returns a new <tt>&lt;arglist&gt;</tt>
for subsequent use by the variable argument intrinsics.<p>
<h5>Semantics:</h5>
The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
macro available in C. In a target-dependent way, it initializes the
<tt>va_list</tt> element the argument points to, so that the next call to
<tt>va_arg</tt> will produce the first variable argument passed to the function.
Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
last argument of the function, the compiler can figure that out.<p>
macro available in C. In a target-dependent way, it initializes and returns a
<tt>va_list</tt> element, so that the next <tt>vaarg</tt> will produce the first
variable argument passed to the function. Unlike the C <tt>va_start</tt> macro,
this intrinsic does not need to know the last argument of the function, the
compiler can figure that out.<p>
Note that this intrinsic function is only legal to be called from within the
body of a variable argument function.<p>
<!-- _______________________________________________________________________ -->
@ -1850,25 +1889,25 @@ last argument of the function, the compiler can figure that out.<p>
<h5>Syntax:</h5>
<pre>
call void (va_list*)* %llvm.va_end(&lt;va_list&gt;* &lt;arglist&gt;)
call void (va_list)* %llvm.va_end(va_list &lt;arglist&gt;)
</pre>
<h5>Overview:</h5>
The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt> which
has been initialized previously with <tt><a
href="#i_va_begin">llvm.va_begin</a></tt>.<p>
The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>&lt;arglist&gt;</tt> which has
been initialized previously with <tt><a
href="#i_va_begin">llvm.va_begin</a></tt> or <tt><a
href="#i_va_copy">llvm.va_copy</a></tt>.<p>
<h5>Arguments:</h5>
The argument is a pointer to a <tt>va_list</tt> element to destroy.<p>
The argument is a <tt>va_list</tt> to destroy.<p>
<h5>Semantics:</h5>
The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt> macro
available in C. In a target-dependent way, it destroys the <tt>va_list</tt>
that the argument points to. Calls to <a
href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
available in C. In a target-dependent way, it destroys the <tt>va_list</tt>.
Calls to <a href="#i_va_start"><tt>llvm.va_start</tt></a> and <a
href="#i_va_copy"><tt>llvm.va_copy</tt></a> must be matched exactly with calls
to <tt>llvm.va_end</tt>.<p>
@ -1879,8 +1918,7 @@ to <tt>llvm.va_end</tt>.<p>
<h5>Syntax:</h5>
<pre>
call void (va_list*, va_list)* %va_copy(&lt;va_list&gt;* &lt;destarglist&gt;,
&lt;va_list&gt; &lt;srcarglist&gt;)
call va_list (va_list)* %llvm.va_copy(va_list &lt;destarglist&gt;)
</pre>
<h5>Overview:</h5>
@ -1890,15 +1928,13 @@ the source argument list to the destination argument list.<p>
<h5>Arguments:</h5>
The first argument is a pointer to a <tt>va_list</tt> element to initialize.
The second argument is a <tt>va_list</tt> element to copy from.<p>
The argument is the <tt>va_list</tt> to copy.
<h5>Semantics:</h5>
The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt> macro
available in C. In a target-dependent way, it copies the source
<tt>va_list</tt> element into the destination list. This intrinsic is necessary
<tt>va_list</tt> element into the returned list. This intrinsic is necessary
because the <tt><a href="i_va_begin">llvm.va_begin</a></tt> intrinsic may be
arbitrarily complex and require memory allocation, for example.<p>
@ -1913,7 +1949,7 @@ arbitrarily complex and require memory allocation, for example.<p>
<address><a href="mailto:sabre@nondot.org">Chris Lattner</a></address>
<!-- Created: Tue Jan 23 15:19:28 CST 2001 -->
<!-- hhmts start -->
Last modified: Thu Oct 9 23:58:41 CDT 2003
Last modified: Fri Oct 17 18:28:10 CDT 2003
<!-- hhmts end -->
</font>
</body></html>