Implement exception-less RAW conflicts

Profiling revealed that a lot of time in unit tests is spent throwing
and catching the RAWException exception across method boundaries.

Apparently, throwing the exception within the method is much cheaper,
hence the changes in this commit.

In this commit, the Instruction.ID() method returns true when a RAW
conflict is detected, false otherwise. While this is not a clean
interface, it makes the longest unit test (testSetBitSort) roughly
30% faster.

Also, while changing the instructions, some of the simplifications
suggested by IntelliJ were applied.

This should mitigate in part Issue #132.

src/main/java/org/edumips64/core/CPU.java

@@ -442,7 +442,10 @@ public void step() throws AddressErrorException, HaltException, IrregularWriteOp
       syncex = stepEX();
 
       // ID: instruction decode / register fetch stage
-      stepID();
+      boolean rawException = stepID();
+      if (rawException) {
+        throw new RAWException();
+      }
 
       // IF: instruction fetch stage.
       stepIF();
@@ -560,7 +563,9 @@ private void stepIF() throws IrregularStringOfBitsException, HaltException, Irre
     }
   }
 
-  private void stepID() throws TwosComplementSumException, WAWException, IrregularStringOfBitsException, FPInvalidOperationException, BreakException, HaltException, RAWException, IrregularWriteOperationException, JumpException, FPDividerNotAvailableException, FPFunctionalUnitNotAvailableException, EXNotAvailableException {
+  // Returns true if there is a RAW conflict, false otherwis3. See docs for Instruction.ID()
+  // for an explanation of why it is the case.
+  private boolean stepID() throws TwosComplementSumException, WAWException, IrregularStringOfBitsException, FPInvalidOperationException, BreakException, HaltException, RAWException, IrregularWriteOperationException, JumpException, FPDividerNotAvailableException, FPFunctionalUnitNotAvailableException, EXNotAvailableException {
     changeStage(PipeStage.ID);
 
     if (pipe.get(PipeStage.ID) != null) {
@@ -579,7 +584,10 @@ private void stepID() throws TwosComplementSumException, WAWException, Irregular
 
       logger.info("Executing ID() for " + pipe.get(PipeStage.ID));
       // Can change the CPU status from RUNNING to STOPPING.
-      pipe.get(PipeStage.ID).ID();
+      boolean rawException = pipe.get(PipeStage.ID).ID();
+      if (rawException) {
+        return true;
+      }
 
       if (isFP) {
         logger.info("Moving " + pipe.get(PipeStage.ID) + " to the FP pipeline.");
@@ -590,6 +598,7 @@ private void stepID() throws TwosComplementSumException, WAWException, Irregular
       }
       pipe.put(PipeStage.ID, null);
     }
+    return false;
   }
 
   private String stepEX() throws SynchronousException, HaltException, NotAlignException, TwosComplementSumException, IrregularWriteOperationException, AddressErrorException, IrregularStringOfBitsException {

src/main/java/org/edumips64/core/is/ALU_IType.java

@@ -23,6 +23,7 @@
 package org.edumips64.core.is;
 
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 //per diagnostica
 import java.util.logging.Logger;
@@ -50,12 +51,12 @@ public class ALU_IType extends ComputationalInstructions {
     this.paramCount = 3;
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     //if the source register is valid passing its own values into a temporary register
     Register rs = cpu.getRegister(params.get(RS_FIELD));
 
     if (rs.getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     TR[RS_FIELD].setBits(rs.getBinString(), 0);
@@ -64,7 +65,7 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
     rt.incrWriteSemaphore();
     //writing the immediate value of "params" on a temporary register
     TR[IMM_FIELD].writeHalf(params.get(IMM_FIELD));
-
+    return false;
   }
 
   public void EX() throws IrregularStringOfBitsException, IntegerOverflowException, TwosComplementSumException, IrregularWriteOperationException {

src/main/java/org/edumips64/core/is/ALU_RType.java

@@ -26,9 +26,9 @@
 package org.edumips64.core.is;
 
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 //per diagnostica
-import java.util.*;
 import java.util.logging.Logger;
 
 /**This is the base class for the R-Type instructions
@@ -53,7 +53,7 @@ public abstract class ALU_RType extends ComputationalInstructions {
     paramCount = 3;
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     //if source registers are valid passing their own values into temporary registers
     logger.info("Executing step ID of " + fullname);
     logger.info("RD is R" + params.get(RD_FIELD) + "; RS is R" + params.get(RS_FIELD) + "; RT is R" + params.get(RT_FIELD) + ";");
@@ -64,12 +64,12 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
     //    throw new RAWException();
     if (rs.getWriteSemaphore() > 0) {
       logger.info("RAW on RS");
-      throw new RAWException();
+      return true;
     }
 
     if (rt.getWriteSemaphore() > 0) {
       logger.info("RAW on RT");
-      throw new RAWException();
+      return true;
     }
 
     TR[RS_FIELD].setBits(rs.getBinString(), 0);
@@ -86,6 +86,7 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
     // Lock RD
     rd.incrWriteSemaphore();
     logger.info("RD = " + TR[RD_FIELD].getValue() + "; RS = " + TR[RS_FIELD].getValue() + "; RT = " + TR[RT_FIELD].getValue() + ";");
+    return false;
   }
 
   public void EX() throws IrregularStringOfBitsException, IntegerOverflowException, TwosComplementSumException, IrregularWriteOperationException, DivisionByZeroException {

src/main/java/org/edumips64/core/is/ANDI.java

@@ -24,6 +24,7 @@
  */
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 
 
@@ -46,12 +47,12 @@ class ANDI extends ALU_IType {
   }
   //since this operation is carried out with zero padding of immediate, against sign_extend(immediate) methodology
   //of all others instructions in the same category, is necessary the overriding of ID method
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     //if the source register is valid passing its own values into a temporary register
     Register rs = cpu.getRegister(params.get(RS_FIELD));
 
     if (rs.getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     TR[RS_FIELD] = rs;
@@ -69,7 +70,7 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
 
     sb.append(TR[IMM_FIELD].getBinString().substring(48, 64));
     TR[IMM_FIELD].setBits(sb.substring(0), 0);
-
+    return false;
   }
   public void EX() throws IrregularStringOfBitsException {
     //getting values from temporary registers
@@ -80,8 +81,8 @@ public void EX() throws IrregularStringOfBitsException {
 
     //performing bitwise OR between immediate and rs register
     for (int i = 0; i < 64; i++) {
-      rsbit = rs.charAt(i) == '1' ? true : false;
-      immbit = imm.charAt(i) == '1' ? true : false;
+      rsbit = rs.charAt(i) == '1';
+      immbit = imm.charAt(i) == '1';
       resbit = rsbit && immbit;
       sb.append(resbit ? '1' : '0');
     }

src/main/java/org/edumips64/core/is/B.java

@@ -24,6 +24,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /** <pre>
  *         Syntax: B offset
@@ -45,7 +46,7 @@ public class B extends FlowControl_IType {
     name = "B";
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, JumpException, TwosComplementSumException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     //getting registers rs and rt
     //converting offset into a signed binary value of 64 bits in length
     BitSet64 bs = new BitSet64();

src/main/java/org/edumips64/core/is/BC1F.java

@@ -24,6 +24,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /** <pre>
    *<pre>
@@ -45,8 +46,8 @@ public class BC1F extends FPConditionalBranchesInstructions {
     super.name = NAME;
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, JumpException {
-    boolean condition = (cpu.getFCSRConditionCode(params.get(CC_FIELD)) == 0) ? true : false;
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
+    boolean condition = cpu.getFCSRConditionCode(params.get(CC_FIELD)) == 0;
 
     //converting offset into a signed binary value of 64 bits in length
     BitSet64 bs = new BitSet64();
@@ -69,6 +70,7 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
 
       throw new JumpException();
     }
+    return false;
   }
 
 

src/main/java/org/edumips64/core/is/BC1T.java

@@ -24,6 +24,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /**
    *<pre>
@@ -46,8 +47,8 @@ public class BC1T extends FPConditionalBranchesInstructions {
     super.name = NAME;
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, JumpException {
-    boolean condition = (cpu.getFCSRConditionCode(params.get(CC_FIELD)) == 1) ? true : false;
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
+    boolean condition = cpu.getFCSRConditionCode(params.get(CC_FIELD)) == 1;
 
     //converting offset into a signed binary value of 64 bits in length
     BitSet64 bs = new BitSet64();
@@ -70,7 +71,6 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
 
       throw new JumpException();
     }
+    return false;
   }
-
-
 }

src/main/java/org/edumips64/core/is/BEQ.java

@@ -25,6 +25,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /** <pre>
  *         Syntax: BEQ rs, rt, offset
@@ -44,9 +45,9 @@ public class BEQ extends FlowControl_IType {
     name = "BEQ";
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, JumpException, TwosComplementSumException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     if (cpu.getRegister(params.get(RS_FIELD)).getWriteSemaphore() > 0 || cpu.getRegister(params.get(RT_FIELD)).getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     //getting registers rs and rt
@@ -74,7 +75,6 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
 
       throw new JumpException();
     }
+    return false;
   }
-
-
 }

src/main/java/org/edumips64/core/is/BEQZ.java

@@ -26,6 +26,7 @@
 package org.edumips64.core.is;
 
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 
 /** <pre>
@@ -46,11 +47,11 @@ public class BEQZ extends FlowControl_IType {
     name = "BEQZ";
   }
 
-  public void ID()
-  throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, JumpException, TwosComplementSumException {
+  public boolean ID()
+      throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     //getting registers rs and rt
     if (cpu.getRegister(params.get(RS_FIELD)).getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     String rs = cpu.getRegister(params.get(RS_FIELD)).getBinString();
@@ -77,6 +78,7 @@ public void ID()
 
       throw new JumpException();
     }
+    return false;
   }
   public void pack() throws IrregularStringOfBitsException {
     repr.setBits(OPCODE_VALUE, OPCODE_VALUE_INIT);

src/main/java/org/edumips64/core/is/BGEZ.java

@@ -24,6 +24,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /** <pre>
  *         Syntax: BGEZ rs, offset
@@ -45,9 +46,9 @@ public class BGEZ extends FlowControl_IType {
     name = "BGEZ";
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, JumpException, TwosComplementSumException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     if (cpu.getRegister(params.get(RS_FIELD)).getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     //getting register rs
@@ -74,6 +75,7 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
 
       throw new JumpException();
     }
+    return false;
   }
   public void pack() throws IrregularStringOfBitsException {
     repr.setBits(OPCODE_VALUE, OPCODE_VALUE_INIT);

src/main/java/org/edumips64/core/is/BNE.java

@@ -25,6 +25,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /** <pre>
  *         Syntax: BNE rt, rs, immediate
@@ -43,9 +44,9 @@ public class BNE extends FlowControl_IType {
     name = "BNE";
   }
 
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, JumpException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     if (cpu.getRegister(params.get(RS_FIELD)).getWriteSemaphore() > 0 || cpu.getRegister(params.get(RT_FIELD)).getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     //getting registers rs and rt
@@ -73,7 +74,6 @@ public void ID() throws RAWException, IrregularWriteOperationException, Irregula
 
       throw new JumpException();
     }
+    return false;
   }
-
-
 }

src/main/java/org/edumips64/core/is/BNEZ.java

@@ -26,6 +26,7 @@
 package org.edumips64.core.is;
 
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 /** <pre>
  *  Syntax:        BNEZ rs, offset
@@ -44,11 +45,11 @@ public class BNEZ extends FlowControl_IType {
     name = "BNEZ";
   }
 
-  public void ID()
-  throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, JumpException, TwosComplementSumException {
+  public boolean ID()
+      throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
     //getting registers rs and rt
     if (cpu.getRegister(params.get(RS_FIELD)).getWriteSemaphore() > 0) {
-      throw new RAWException();
+      return true;
     }
 
     String rs = cpu.getRegister(params.get(RS_FIELD)).getBinString();
@@ -75,6 +76,7 @@ public void ID()
 
       throw new JumpException();
     }
+    return false;
   }
   public void pack() throws IrregularStringOfBitsException {
 

src/main/java/org/edumips64/core/is/BREAK.java

@@ -25,6 +25,7 @@
 
 package org.edumips64.core.is;
 import org.edumips64.core.*;
+import org.edumips64.core.fpu.FPInvalidOperationException;
 import org.edumips64.utils.*;
 
 /** *Syntax:    BREAK
@@ -49,7 +50,8 @@ public void IF() throws BreakException {
 
     throw new BreakException();
   }
-  public void ID() throws RAWException, IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException {
+  public boolean ID() throws IrregularWriteOperationException, IrregularStringOfBitsException, TwosComplementSumException, HaltException, JumpException, BreakException, WAWException, FPInvalidOperationException {
+    return false;
   }
 
   public void EX() throws HaltException, IrregularStringOfBitsException, IntegerOverflowException, TwosComplementSumException {