[llvm-commits] [llvm] r56596 - /llvm/trunk/lib/CodeGen/LowerSubregs.cpp

[Dan Gohman]

Author: djg
Date: Wed Sep 24 18:44:12 2008
New Revision: 56596

URL: http://llvm.org/viewvc/llvm-project?rev=56596&view=rev
Log:
Give LowerSubregs.cpp a top-level description.

Modified:
    llvm/trunk/lib/CodeGen/LowerSubregs.cpp

Modified: llvm/trunk/lib/CodeGen/LowerSubregs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LowerSubregs.cpp?rev=56596&r1=56595&r2=56596&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/LowerSubregs.cpp (original)
+++ llvm/trunk/lib/CodeGen/LowerSubregs.cpp Wed Sep 24 18:44:12 2008
@@ -6,6 +6,13 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
+//
+// This file defines a MachineFunction pass which runs after register
+// allocation that turns subreg insert/extract instructions into register
+// copies, as needed. This ensures correct codegen even if the coalescer
+// isn't able to remove all subreg instructions.
+//
+//===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "lowersubregs"
 #include "llvm/CodeGen/Passes.h"