[llvm-commits] [llvm] r113593 - /llvm/trunk/include/llvm/Target/TargetRegisterInfo.h

[Jim Grosbach]

Author: grosbach
Date: Fri Sep 10 12:51:34 2010
New Revision: 113593

URL: http://llvm.org/viewvc/llvm-project?rev=113593&view=rev
Log:
add a comment explicitly calling out that allocation orders may include
reserved regs and that register allocators need to explicitly check for
them.

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

Modified: llvm/trunk/include/llvm/Target/TargetRegisterInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetRegisterInfo.h?rev=113593&r1=113592&r2=113593&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetRegisterInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetRegisterInfo.h Fri Sep 10 12:51:34 2010
@@ -227,9 +227,12 @@
   /// cheaper to allocate caller saved registers.
   ///
   /// These methods take a MachineFunction argument, which can be used to tune
-  /// the allocatable registers based on the characteristics of the function.
-  /// One simple example is that the frame pointer register can be used if
-  /// frame-pointer-elimination is performed.
+  /// the allocatable registers based on the characteristics of the function,
+  /// subtarget, or other criteria.
+  ///
+  /// Register allocators should account for the fact that an allocation
+  /// order iterator may return a reserved register and always check
+  /// if the register is allocatable (getAllocatableSet()) before using it.
   ///
   /// By default, these methods return all registers in the class.
   ///