[llvm-commits] [llvm] r62986 - /llvm/trunk/docs/CodeGenerator.html

[Nate Begeman]

Author: sampo
Date: Sun Jan 25 20:54:45 2009
New Revision: 62986

URL: http://llvm.org/viewvc/llvm-project?rev=62986&view=rev
Log:
Add some documentation for address-space-based access to the segment registers.

Modified:
    llvm/trunk/docs/CodeGenerator.html

Modified: llvm/trunk/docs/CodeGenerator.html
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/CodeGenerator.html?rev=62986&r1=62985&r2=62986&view=diff

==============================================================================
--- llvm/trunk/docs/CodeGenerator.html (original)
+++ llvm/trunk/docs/CodeGenerator.html Sun Jan 25 20:54:45 2009
@@ -1718,7 +1718,7 @@
 
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
-  <a name="x86_tt">X86 Target Triples Supported</a>
+  <a name="x86_tt">X86 Target Triples supported</a>
 </div>
 
 <div class="doc_text">
@@ -1791,6 +1791,27 @@
 
 <!-- _______________________________________________________________________ -->
 <div class="doc_subsubsection">
+  <a name="x86_memory">X86 address spaces supported</a>
+</div>
+
+<div class="doc_text">
+
+<p>x86 has the ability to perform loads and stores to different address spaces 
+via the x86 segment registers.  A segment override prefix byte on an instruction
+causes the instruction's memory access to go to the specified segment.  LLVM
+address space 0 is the default address space, which includes the stack, and
+any unqualified memory accesses in a program.  Address spaces 1-255 are
+currently reserved for user-defined code.  The GS-segment is represented by
+address space 256.  Other x86 segments have yet to be allocated address space
+numbers.
+
+<p>Some operating systems use the GS-segment to implement TLS, so care should be
+taken when reading and writing to address space 256 on these platforms.
+
+</div>
+
+<!-- _______________________________________________________________________ -->
+<div class="doc_subsubsection">
   <a name="x86_names">Instruction naming</a>
 </div>