Added more comments

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1498 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 28 insertions, 36 deletions

diff --git a/lib/Target/SparcV9/SparcV9RegClassInfo.h b/lib/Target/SparcV9/SparcV9RegClassInfo.h
index fd76815750..0a5f5169d1 100644
--- a/lib/Target/SparcV9/SparcV9RegClassInfo.h
+++ b/lib/Target/SparcV9/SparcV9RegClassInfo.h
@@ -15,7 +15,6 @@
 // Integer Register Class
 //-----------------------------------------------------------------------------
 
-
 // Int register names in same order as enum in class SparcIntRegOrder
 
 static string const IntRegNames[] = 
@@ -38,7 +37,7 @@ class SparcIntRegOrder{
      // --- following colors are volatile across function calls
      // %g0 can't be used for coloring - always 0
                      
-     //%g1-%g5  (g6-7 are reserved for system)  
+ 
      o0, o1, o2, o3, o4, o5, o7,  // %o0-%o5, 
 
      // %o6 is sp, 
@@ -59,9 +58,12 @@ class SparcIntRegOrder{
 
      i6, i7, g0,  g1, g2, g3, g4, g5, g6, g7, o6
      
-     //*** NOTE: If we decide to use globals, some of them are volatile 
-     //**** see sparc64ABI (change isRegVloatile method below)
- 
+     //*** NOTE: If we decide to use some %g regs, they are volatile
+     // (see sparc64ABI)
+     // Move the %g regs from the end of the enumeration to just above the
+     // enumeration of %o0 (change StartOfAllRegs below)
+     // change isRegVloatile method below
+     // Also change IntRegNames above.
 
    };
 
@@ -110,6 +112,9 @@ class SparcIntRegClass : public MachineRegClassInfo
 
 };
 
+
+
+
 //-----------------------------------------------------------------------------
 // Float Register Class
 //-----------------------------------------------------------------------------
@@ -158,7 +163,6 @@ class SparcFloatRegOrder{
   }
 
 
-
 };
 
 
@@ -219,10 +223,6 @@ class SparcIntCCRegOrder{
     return IntCCRegNames[reg];
   }
 
-  // according to  Sparc 64 ABI,  %ccr is volatile
-  inline bool isRegVolatile(const int Reg) const { return true; }
-
-
 };
 
 
@@ -238,13 +238,15 @@ public:
     Node->setColor(0);    // only one int cc reg is available
   }
 
-
+  // according to  Sparc 64 ABI,  %ccr is volatile
+  //
   inline bool isRegVolatile(const int Reg) const { return true; }
 
 };
 
 
 
+
 //-----------------------------------------------------------------------------
 // Float CC Register Class
 // Only 4 Float CC registers are available
@@ -271,10 +273,6 @@ class SparcFloatCCRegOrder{
     return FloatCCRegNames[reg];
   }
 
-  // according to  Sparc 64 ABI, all %fp regs are volatile
-  inline bool isRegVolatile(const int Reg) const { return true; }
-
-
 };
 
 
@@ -293,7 +291,9 @@ public:
     Node->setColor(c);   
   }
 
-  // *** TODO: Check this
+
+  // according to  Sparc 64 ABI, all %fp CC regs are volatile
+  //
   inline bool isRegVolatile(const int Reg) const { return true; }
 
 
diff --git a/lib/Target/SparcV9/SparcV9RegInfo.cpp b/lib/Target/SparcV9/SparcV9RegInfo.cpp
index 6a0460de74..6543397957 100644
--- a/lib/Target/SparcV9/SparcV9RegInfo.cpp
+++ b/lib/Target/SparcV9/SparcV9RegInfo.cpp
@@ -1161,30 +1161,27 @@ MachineInstr * UltraSparcRegInfo::cpValue2Value(Value *Src, Value *Dest) const{
 
 //----------------------------------------------------------------------------
 // This method inserts caller saving/restoring instructons before/after
-// a call machine instruction.
+// a call machine instruction. The caller saving/restoring instructions are
+// inserted like:
+//
+//    ** caller saving instructions
+//    other instructions inserted for the call by ColorCallArg
+//    CALL instruction
+//    other instructions inserted for the call ColorCallArg
+//    ** caller restoring instructions
+//
 //----------------------------------------------------------------------------
 
 
 void UltraSparcRegInfo::insertCallerSavingCode(const MachineInstr *MInst, 
 					       const BasicBlock *BB,
 					       PhyRegAlloc &PRA) const {
-  // assert( (getInstrInfo()).isCall( MInst->getOpCode() ) );
-
-  // Clear the temp area of the stack
-  //PRA.mcInfo.popAllTempValues(target);
-  // TODO*** Don't do this since we can have a situation like
-  /*
-
-        stx     %o1     %i6     1999   <--- inserted by this code
-        stx     %o5     %i6     2007
-
-	*****
-        stx     %o1     %i6     2007 ????  <-- inserted by statck2stack call arg
 
-  */
+  // has set to record which registers were saved/restored
+  //
+  hash_set<unsigned> PushedRegSet;
 
 
-  hash_set<unsigned> PushedRegSet;
 
   // Now find the LR of the return value of the call
   // The last *implicit operand* is the return value of a call
@@ -1350,11 +1347,6 @@ void UltraSparcRegInfo::insertCallerSavingCode(const MachineInstr *MInst,
     
   } // for each value in the LV set after instruction
   
-  // Clear the temp area of the stack
-  // PRA.mcInfo.popAllTempValues(target);
-  // TODO *** see above call - optimize later
-
-
 }
 
 //---------------------------------------------------------------------------