Add support for #pragma clang section
This patch provides a means to specify section-names for global variables,
functions and static variables, using #pragma directives.
This feature is only defined to work sensibly for ELF targets.
One can specify section names as:
#pragma clang section bss="myBSS" data="myData" rodata="myRodata" text="myText"
One can "unspecify" a section name with empty string e.g.
#pragma clang section bss="" data="" text="" rodata=""
Reviewers: Roger Ferrer, Jonathan Roelofs, Reid Kleckner
Differential Revision: https://reviews.llvm.org/D33412
llvm-svn: 304705
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index f8dd1a3..dab538f 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -2521,3 +2521,45 @@
The attributes are applied to all matching declarations individually, even when
the attribute is semantically incorrect. The attributes that aren't applied to
any declaration are not verified semantically.
+
+Specifying section names for global objects (#pragma clang section)
+===================================================================
+
+The ``#pragma clang section`` directive provides a means to assign section-names
+to global variables, functions and static variables.
+
+The section names can be specified as:
+
+.. code-block:: c++
+
+ #pragma clang section bss="myBSS" data="myData" rodata="myRodata" text="myText"
+
+The section names can be reverted back to default name by supplying an empty
+string to the section kind, for example:
+
+.. code-block:: c++
+
+ #pragma clang section bss="" data="" text="" rodata=""
+
+The ``#pragma clang section`` directive obeys the following rules:
+
+* The pragma applies to all global variable, statics and function declarations
+ from the pragma to the end of the translation unit.
+
+* The pragma clang section is enabled automatically, without need of any flags.
+
+* This feature is only defined to work sensibly for ELF targets.
+
+* If section name is specified through _attribute_((section("myname"))), then
+ the attribute name gains precedence.
+
+* Global variables that are initialized to zero will be placed in the named
+ bss section, if one is present.
+
+* The ``#pragma clang section`` directive does not does try to infer section-kind
+ from the name. For example, naming a section "``.bss.mySec``" does NOT mean
+ it will be a bss section name.
+
+* The decision about which section-kind applies to each global is taken in the back-end.
+ Once the section-kind is known, appropriate section name, as specified by the user using
+ ``#pragma clang section`` directive, is applied to that global.