Migrate DCB register allocation code to S390DebugCounterBumpInstruction

The code which looks for a free real register to associate with the DCB instruction can be migrated to the overloaded `assignRegisters` vritual API.
eclipse · Apr 30, 2021 · 8c45dc1 · 8c45dc1
1 parent 739caac
commit 8c45dc1
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Showing 3 changed files with 21 additions and 34 deletions.
diff --git a/compiler/z/codegen/OMRCodeGenerator.cpp b/compiler/z/codegen/OMRCodeGenerator.cpp
@@ -1707,34 +1707,6 @@ OMR::Z::CodeGenerator::doRegisterAssignment(TR_RegisterKinds kindsToAssign)
       {
       TR::Node *treeNode=instructionCursor->getNode();
 
-         /**
-         * Find a free real register for DCB to use during generate binary encoding phase
-         * @see S390DebugCounterBumpInstruction::generateBinaryEncoding()
-         */
-      if(instructionCursor->getOpCodeValue() == TR::InstOpCode::DCB)
-         {
-         TR::S390DebugCounterBumpInstruction *dcbInstr = static_cast<TR::S390DebugCounterBumpInstruction*>(instructionCursor);
-
-         int32_t first = TR::RealRegister::FirstGPR + 1;  // skip GPR0
-         int32_t last  = TR::RealRegister::LastAssignableGPR;
-
-         TR::RealRegister * realReg;
-
-         for (int32_t i=first; i<=last; i++)
-            {
-            realReg = self()->machine()->realRegister(static_cast<TR::RealRegister::RegNum>(i));
-
-            if ( realReg->getState() == TR::RealRegister::Free)
-               {
-               dcbInstr->setAssignableReg(realReg);
-               realReg->setHasBeenAssignedInMethod(true);
-               break;
-               }
-            }
-
-            self()->traceRegisterAssignment("BEST FREE REG for DCB is %R", dcbInstr->getAssignableReg());
-         }
-
       self()->tracePreRAInstruction(instructionCursor);
 
       prevInstruction = instructionCursor->getPrev();

diff --git a/compiler/z/codegen/S390Instruction.cpp b/compiler/z/codegen/S390Instruction.cpp
@@ -1028,6 +1028,25 @@ TR::S390PseudoInstruction::estimateBinaryLength(int32_t currentEstimate)
 // TR::S390DebugCounterBumpInstruction:: member functions
 ////////////////////////////////////////////////////////////////////////////////
 
+void
+TR::S390DebugCounterBumpInstruction::assignRegisters(TR_RegisterKinds kindToBeAssigned)
+   {
+   // Find a free real register for DCB to use during binary encoding to avoid spilling scratch registers
+   for (auto i = TR::RealRegister::FirstGPR + 1; i <= TR::RealRegister::LastAssignableGPR; i++)
+      {
+      TR::RealRegister *realReg = cg()->machine()->realRegister(static_cast<TR::RealRegister::RegNum>(i));
+
+      if (realReg->getState() == TR::RealRegister::Free)
+         {
+         _assignableReg = realReg;
+         realReg->setHasBeenAssignedInMethod(true);
+         break;
+         }
+      }
+
+   assignRegistersAndDependencies(kindToBeAssigned);
+   }
+
 /**
  * This instruction is bumps the value at the snippet corresponding to the address of the debug counter count.
  * The valid opcode is TR::InstOpCode::DCB

diff --git a/compiler/z/codegen/S390Instruction.hpp b/compiler/z/codegen/S390Instruction.hpp
@@ -680,12 +680,6 @@ class S390DebugCounterBumpInstruction : public S390PseudoInstruction
         _assignableReg(NULL),
         _delta(delta){}
 
-   /**
-   * A real register must only be assigned for DCB to use if it is guaranteed to be free at the cursor position where DCB is inserted
-   * @param ar Real Register to be assigned
-   */
-   void setAssignableReg(TR::RealRegister * ar){ _assignableReg = ar; }
-
    /**
    * @return Assigned Real Register
    */
@@ -701,6 +695,8 @@ class S390DebugCounterBumpInstruction : public S390PseudoInstruction
    */
    int32_t getDelta(){ return _delta; }
 
+   virtual void assignRegisters(TR_RegisterKinds kindToBeAssigned);
+
    virtual uint8_t *generateBinaryEncoding();
    };