[llvm-commits] [llvm] r162879 - /llvm/trunk/include/llvm/Target/TargetInstrInfo.h

[Jakob Stoklund Olesen]

Author: stoklund
Date: Wed Aug 29 18:52:55 2012
New Revision: 162879

URL: http://llvm.org/viewvc/llvm-project?rev=162879&view=rev
Log:
Add a bit of documentation to copyPhysReg.

Modified:
    llvm/trunk/include/llvm/Target/TargetInstrInfo.h

Modified: llvm/trunk/include/llvm/Target/TargetInstrInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetInstrInfo.h?rev=162879&r1=162878&r2=162879&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetInstrInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetInstrInfo.h Wed Aug 29 18:52:55 2012
@@ -459,6 +459,13 @@
   }
 
   /// copyPhysReg - Emit instructions to copy a pair of physical registers.
+  ///
+  /// This function should support copies within any legal register class as
+  /// well as any cross-class copies created during instruction selection.
+  ///
+  /// The source and destination registers may overlap, which may require a
+  /// careful implementation when multiple copy instructions are required for
+  /// large registers. See for example the ARM target.
   virtual void copyPhysReg(MachineBasicBlock &MBB,
                            MachineBasicBlock::iterator MI, DebugLoc DL,
                            unsigned DestReg, unsigned SrcReg,