add a comment explicitly calling out that allocation orders may include

[oota-llvm.git] / include / llvm / Target / TargetRegisterInfo.h

diff --git a/include/llvm/Target/TargetRegisterInfo.h b/include/llvm/Target/TargetRegisterInfo.h
index 2abdae7f33724a3981ca921cb0b514b42e17ee6e..c97f172a1e715101d978d6b70983fa000e0bc18e 100644 (file)
--- a/include/llvm/Target/TargetRegisterInfo.h
+++ b/include/llvm/Target/TargetRegisterInfo.h
@@ -227,9 +227,12 @@ public:
   /// 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.
   ///
@@ -301,7 +304,7 @@ public:
     /// considered to be a 'virtual' register, which is part of the SSA
     /// namespace.  This must be the same for all targets, which means that each
     /// target is limited to this fixed number of registers.
-    FirstVirtualRegister = 1024
+    FirstVirtualRegister = 16384
   };
 
   /// isPhysicalRegister - Return true if the specified register number is in
@@ -743,14 +746,8 @@ public:
   /// specified instruction, as long as it keeps the iterator pointing at the
   /// finished product. SPAdj is the SP adjustment due to call frame setup
   /// instruction.
-  ///
-  /// When -enable-frame-index-scavenging is enabled, the virtual register
-  /// allocated for this frame index is returned and its value is stored in
-  /// *Value.
-  typedef std::pair<unsigned, int> FrameIndexValue;
-  virtual unsigned eliminateFrameIndex(MachineBasicBlock::iterator MI,
-                                       int SPAdj, FrameIndexValue *Value = NULL,
-                                       RegScavenger *RS=NULL) const = 0;
+  virtual void eliminateFrameIndex(MachineBasicBlock::iterator MI,
+                                   int SPAdj, RegScavenger *RS=NULL) const = 0;
 
   /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
   /// the function.