From bea4626f93c830e31f82cc947df28fdae583cd09 Mon Sep 17 00:00:00 2001 From: Rafael Espindola Date: Sat, 8 Jan 2011 16:42:36 +0000 Subject: First step in fixing PR8927: Add a unnamed_addr bit to global variables and functions. This will be used to indicate that the address is not significant and therefore the constant or function can be merged with others. If an optimization pass can show that an address is not used, it can set this. Examples of things that can have this set by the FE are globals created to hold string literals and C++ constructors. Adding unnamed_addr to a non-const global should have no effect unless an optimization can transform that global into a constant. Aliases are not allowed to have unnamed_addr since I couldn't figure out any use for it. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123063 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/BitCodeFormat.html | 7 +++++++ docs/LangRef.html | 13 +++++++++++-- 2 files changed, 18 insertions(+), 2 deletions(-) (limited to 'docs') diff --git a/docs/BitCodeFormat.html b/docs/BitCodeFormat.html index d8ddc2b6b2..0b8747c261 100644 --- a/docs/BitCodeFormat.html +++ b/docs/BitCodeFormat.html @@ -922,6 +922,9 @@ encoding of the visibility of this variable:
  • threadlocal: If present and non-zero, indicates that the variable is thread_local
    • +
  • unnamed_addr: If present and non-zero, indicates that the variable +has unnamed_addr
    • + @@ -975,6 +978,10 @@ entries.
  • gc: If present and nonzero, the 1-based garbage collector index in the table of MODULE_CODE_GCNAME entries.
    • + +
  • unnamed_addr: If present and non-zero, indicates that the function +has unnamed_addr
    • + diff --git a/docs/LangRef.html b/docs/LangRef.html index 21144125b0..2121fc6740 100644 --- a/docs/LangRef.html +++ b/docs/LangRef.html @@ -846,6 +846,10 @@ define i32 @main() { ; i32()*   region of memory, and all memory objects in LLVM are accessed through pointers.

    +

    Global variables can be marked with unnamed_addr which indicates + that the address is not significant, only the content. Constants marked + like this can be merged if they have the same content.

    +

    A global variable may be declared to reside in a target-specific numbered address space. For targets that support them, address spaces may affect how optimizations are performed and/or what target instructions are used to @@ -885,7 +889,8 @@ define i32 @main() { ; i32()*  

    LLVM function definitions consist of the "define" keyword, an optional linkage type, an optional visibility style, an optional - calling convention, a return type, an optional + calling convention, + an optional unnamed_addr attribute, a return type, an optional parameter attribute for the return type, a function name, a (possibly empty) argument list (each with optional parameter attributes), optional @@ -896,7 +901,8 @@ define i32 @main() { ; i32()*  

    LLVM function declarations consist of the "declare" keyword, an optional linkage type, an optional visibility style, an optional - calling convention, a return type, an optional + calling convention, + an optional unnamed_addr attribute, a return type, an optional parameter attribute for the return type, a function name, a possibly empty list of arguments, an optional alignment, and an optional garbage collector name.

    @@ -922,6 +928,9 @@ define i32 @main() { ; i32()*   specified, the function is forced to have at least that much alignment. All alignments must be a power of 2.

    +

    If the unnamed_addr attribute is given, the address is know to not + be significant and two identical functions can be merged

    . +
    Syntax:
     define [linkage] [visibility]
-- 
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