From f4cde4ec8197819bf872e551455c8a2e4c4864ab Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Wed, 23 Apr 2008 04:59:35 +0000 Subject: [PATCH] fix description of 'ret' to be more correct with multiple return values. Clarify that it is impossible to 'multiply return' a struct with zero elements. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@50131 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/LangRef.html | 39 +++++++++++++++++++++++++++------------ 1 file changed, 27 insertions(+), 12 deletions(-) diff --git a/docs/LangRef.html b/docs/LangRef.html index f2fa698e09f..9679291125a 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -1223,17 +1223,21 @@ type "{ i32, [0 x float]}", for example.

Function Type
+
Overview:
+

The function type can be thought of as a function signature. It consists of a return type and a list of formal parameter types. The -return type of a function type is a scalar type or a void type or a struct type. +return type of a function type is a scalar type, a void type, or a struct type. If the return type is a struct type then all struct elements must be of first -class types. 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.

+class types, and the struct must have at least one element.

Syntax:
-
  <returntype list> (<parameter list>)
+ +
+  <returntype list> (<parameter list>)
+
+

...where '<parameter list>' is a comma-separated list of type specifiers. Optionally, the parameter list may include a type ..., which indicates that the function takes a variable number of arguments. @@ -1241,6 +1245,7 @@ Variable argument functions can access their arguments with the variable argument handling intrinsic functions. '<returntype list>' is a comma-separated list of first class type specifiers.

+
Examples:
@@ -1802,19 +1807,26 @@ Instruction ret void ; Return from void function ret <type> <value>, <type> <value> ; Return two values from a non-void function +
Overview:
+

The 'ret' instruction is used to return control flow (and a value) from a function back to the caller.

There are two forms of the 'ret' instruction: one that -returns a value and then causes control flow, and one that just causes +returns value(s) and then causes control flow, and one that just causes control flow to occur.

+
Arguments:
-

The 'ret' instruction may return one or multiple values. The -type of each return value must be a 'first class' - type. Note that a function is not well formed -if there exists a 'ret' instruction inside of the function that -returns values that do not match the return type of the function.

+ +

The 'ret' instruction may return zero, one or multiple values. +The type of each return value must be a 'first +class' type. Note that a function is not well +formed if there exists a 'ret' instruction inside of the +function that returns values that do not match the return type of the +function.

+
Semantics:
+

When the 'ret' instruction is executed, control flow returns back to the calling function's context. If the caller is a "call" instruction, execution continues at @@ -1825,8 +1837,11 @@ returns a value, that value shall set the call or invoke instruction's return value. If the instruction returns multiple values then these values can only be accessed through a 'getresult ' instruction.

+
Example:
-
  ret i32 5                       ; Return an integer value of 5
+
+
+  ret i32 5                       ; Return an integer value of 5
   ret void                        ; Return from a void function
   ret i32 4, i8 2                 ; Return two values 4 and 2