[llvm] r311459 - Emit section information for extern variables

[Erich Keane via llvm-commits]

Author: erichkeane
Date: Tue Aug 22 08:30:43 2017
New Revision: 311459

URL: http://llvm.org/viewvc/llvm-project?rev=311459&view=rev
Log:
Emit section information for extern variables

Update IR generated to retain section information for external declarations. 
This is related to https://reviews.llvm.org/D36487

Patch By: eandrews
Differential Revision: https://reviews.llvm.org/D36712

Modified:
    llvm/trunk/docs/LangRef.rst

Modified: llvm/trunk/docs/LangRef.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/LangRef.rst?rev=311459&r1=311458&r2=311459&view=diff
==============================================================================
--- llvm/trunk/docs/LangRef.rst (original)
+++ llvm/trunk/docs/LangRef.rst Tue Aug 22 08:30:43 2017
@@ -579,7 +579,9 @@ Global variables in other translation un
 case they don't have an initializer.
 
 Either global variable definitions or declarations may have an explicit section
-to be placed in and may have an optional explicit alignment specified.
+to be placed in and may have an optional explicit alignment specified. If there 
+is a mismatch between the explicit or inferred section information for the 
+variable declaration and its definition the resulting behavior is undefined. 
 
 A variable may be defined as a global ``constant``, which indicates that
 the contents of the variable will **never** be modified (enabling better
@@ -622,6 +624,12 @@ target supports it, it will emit globals
 Additionally, the global can placed in a comdat if the target has the necessary
 support.
 
+External declarations may have an explicit section specified. Section 
+information is retained in LLVM IR for targets that make use of this 
+information. Attaching section information to an external declaration is an 
+assertion that its definition is located in the specified section. If the 
+definition is located in a different section, the behavior is undefined.   
+
 By default, global initializers are optimized by assuming that global
 variables defined within the module are not modified from their
 initial values before the start of the global initializer. This is