[llvm-commits] [llvm] r48173 - /llvm/trunk/docs/LangRef.html
Devang Patel
dpatel at apple.com
Mon Mar 10 13:49:15 PDT 2008
Author: dpatel
Date: Mon Mar 10 15:49:15 2008
New Revision: 48173
URL: http://llvm.org/viewvc/llvm-project?rev=48173&view=rev
Log:
Document multiple return values.
Modified:
llvm/trunk/docs/LangRef.html
Modified: llvm/trunk/docs/LangRef.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.html?rev=48173&r1=48172&r2=48173&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.html (original)
+++ llvm/trunk/docs/LangRef.html Mon Mar 10 15:49:15 2008
@@ -144,6 +144,7 @@
<li><a href="#i_select">'<tt>select</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>
+ <li><a href="#i_getresult">'<tt>getresult</tt>' Instruction</a></li>
</ol>
</li>
</ol>
@@ -1226,16 +1227,16 @@
Function types are usually used to build virtual function tables
(which are structures of pointers to functions), for indirect function
calls, and when defining a function.</p>
-<p>
-The return type of a function type cannot be an aggregate type.
-</p>
+
<h5>Syntax:</h5>
-<pre> <returntype> (<parameter list>)<br></pre>
+<pre> <returntype list> (<parameter list>)<br></pre>
<p>...where '<tt><parameter list></tt>' is a comma-separated list of type
specifiers. Optionally, the parameter list may include a type <tt>...</tt>,
which indicates that the function takes a variable number of arguments.
Variable argument functions can access their arguments with the <a
- href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
+ href="#int_varargs">variable argument handling intrinsic</a> functions.
+'<tt><returntype list></tt>' is a comma-separated list of
+<a href="#t_firstclass">first class</a> type specifiers.</p>
<h5>Examples:</h5>
<table class="layout">
<tr class="layout">
@@ -1788,6 +1789,7 @@
<h5>Syntax:</h5>
<pre> ret <type> <value> <i>; Return a value from a non-void function</i>
ret void <i>; Return from void function</i>
+ ret <type> <value>, <type> <value> <i>; Return two values from a non-void function </i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
@@ -1796,11 +1798,11 @@
returns a value and then causes control flow, and one that just causes
control flow to occur.</p>
<h5>Arguments:</h5>
-<p>The '<tt>ret</tt>' instruction may return any '<a
- href="#t_firstclass">first class</a>' type. Notice that a function is
-not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
-instruction inside of the function that returns a value that does not
-match the return type of the function.</p>
+<p>The '<tt>ret</tt>' instruction may return one or multiple values. The
+type of each return value must be '<a href="#t_firstclass">first class</a>'
+ type. Notice that a function is not <a href="#wellformed">well formed</a>
+if there exists a '<tt>ret</tt>' instruction inside of the function that
+returns values that does not match the return type of the function.</p>
<h5>Semantics:</h5>
<p>When the '<tt>ret</tt>' instruction is executed, control flow
returns back to the calling function's context. If the caller is a "<a
@@ -1809,10 +1811,13 @@
href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
at the beginning of the "normal" destination block. If the instruction
returns a value, that value shall set the call or invoke instruction's
-return value.</p>
+return value. If the instruction returns multiple values then these
+value can only be accessed through '<a href="#i_getresult"><tt>getresult</tt>
+</a>' insctruction.</p>
<h5>Example:</h5>
<pre> ret i32 5 <i>; Return an integer value of 5</i>
ret void <i>; Return from a void function</i>
+ ret i32 4, i8 2 <i>; Return two values 4 and 2 </i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
@@ -1922,7 +1927,9 @@
"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
"normal" label. If the callee (or any indirect callees) returns with the "<a
href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
-continued at the dynamically nearest "exception" label.</p>
+continued at the dynamically nearest "exception" label. If the callee function
+returns multiple values then individual return values are accessed only through
+'<tt><a href="#i_getresult">getresult</a></tt>' instruction.</p>
<h5>Arguments:</h5>
@@ -3810,7 +3817,10 @@
the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
instruction in the called function, control flow continues with the
instruction after the function call, and the return value of the
-function is bound to the result argument. This is a simpler case of
+function is bound to the result argument. If the '<tt><a href="#i_ret">ret</a>
+</tt>' instruction returns multiple values then the return value of the
+function is only accessed through '<tt><a href="#i_getresult">getresult</a>
+</tt>' instruction. This is a simpler case of
the <a href="#i_invoke">invoke</a> instruction.</p>
<h5>Example:</h5>
@@ -3821,6 +3831,11 @@
%X = tail call i32 @foo()
%Y = tail call <a href="#callingconv">fastcc</a> i32 @foo()
%Z = call void %foo(i8 97 signext)
+
+ %struct.A = type { i32, i8 }
+ %r = call %struct.A @foo()
+ %gr = getresult %struct.A %r, 0
+ %gr1 = getresult %struct.A %r, 1
</pre>
</div>
@@ -3873,6 +3888,48 @@
</div>
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
+ <a name="i_getresult">'<tt>getresult</tt>' Instruction</a>
+</div>
+
+<div class="doc_text">
+
+<h5>Syntax:</h5>
+<pre>
+ <resultval> = getresult <type> <retval>, <index>
+</pre>
+<h5>Overview:</h5>
+
+<p> The '<tt>getresult</tt>' instruction is used to extract individual values
+from multiple values returned by '<tt><a href="#i_call">call</a></tt>'
+or '<tt><a href="#i_invoke">invoke</a></tt>' instruction.
+
+<h5>Arguments:</h5>
+
+The '<tt>getresult</tt>' instruction takes return value as first argument. The
+value must have <a href="#t_struct">structure type</a>. The second argument
+is unsigned index value.
+
+<h5>Semantics:</h5>
+
+The '<tt>getresult</tt>' instruction extracts element identified by
+'<tt>index</tt>' from the aggregate value.
+
+<h5>Example:</h5>
+
+<pre>
+ %struct.A = type { i32, i8 }
+
+ %r = call %struct.A @foo()
+ %gr = getresult %struct.A %r, 0
+ %gr1 = getresult %struct.A %r, 1
+ add i32 %gr, 42
+ add i8 %gr1, 41
+</pre>
+
+</div>
+
<!-- *********************************************************************** -->
<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
<!-- *********************************************************************** -->
More information about the llvm-commits
mailing list