From bf6d6aba3383de6b4d96b99db72dea2a3a73830b Mon Sep 17 00:00:00 2001
From: "rajshekar.k" <rajshekar.k@iitdh.ac.in>
Date: Sun, 8 Aug 2021 01:32:20 +0530
Subject: [PATCH] bug fixes related to implementation of FMA and LEA
 instructions

---
 .../translator/x86/instruction/FMA.java       | 20 ++++++++++++++-----
 src/simulator/generic/Instruction.java        |  4 ++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/simulator/emulatorinterface/translator/x86/instruction/FMA.java b/src/simulator/emulatorinterface/translator/x86/instruction/FMA.java
index 6b6c46a..ac137ce 100644
--- a/src/simulator/emulatorinterface/translator/x86/instruction/FMA.java
+++ b/src/simulator/emulatorinterface/translator/x86/instruction/FMA.java
@@ -25,6 +25,7 @@ package emulatorinterface.translator.x86.instruction;
 
 import emulatorinterface.translator.InvalidInstructionException;
 import emulatorinterface.translator.x86.operand.OperandTranslator;
+import emulatorinterface.translator.x86.registers.Registers;
 import emulatorinterface.translator.x86.registers.TempRegisterNum;
 import generic.Instruction;
 import generic.Operand;
@@ -66,10 +67,15 @@ public class FMA implements X86StaticInstructionHandler
 			(operand1.isFloatRegisterOperand()) &&
 			(operand2 == null || operand2.isImmediateOperand() || operand2.isFloatRegisterOperand() || operand2.isMemoryOperand()) &&
 			(operand3 == null || operand3.isImmediateOperand() || operand3.isFloatRegisterOperand() || operand3.isMemoryOperand()))
-		{
-			Operand srcOpnd1, srcOpnd2, destOpnd;
+		{	
+			/*
+			 * FMA type instructions have 3 source operands
+			 * VISA supports only 2 source operands
+			 * introducing an intALU and an intermediate result to get the approximate effect
+			 */
+			Operand srcOpnd1, srcOpnd2, srcOpnd3, destOpnd;
 			
-			srcOpnd1 = operand2;
+			srcOpnd1 = operand1;
 			
 			if(operand3.isMemoryOperand())
 			{
@@ -79,10 +85,14 @@ public class FMA implements X86StaticInstructionHandler
 			{
 				srcOpnd2 = operand3;
 			}
+			Operand intermediateResult = Registers.getTempIntReg(tempRegisterNum);
 			
+			instructionArrayList.appendInstruction(Instruction.getIntALUInstruction(srcOpnd1, srcOpnd2, intermediateResult));
+			
+			srcOpnd3 = operand2;			
 			destOpnd = operand1;
 			
-			instructionArrayList.appendInstruction(Instruction.getFMA(srcOpnd1, srcOpnd2, destOpnd));
+			instructionArrayList.appendInstruction(Instruction.getFMA(intermediateResult, srcOpnd3, destOpnd));
 		}
 		
 		else
@@ -90,4 +100,4 @@ public class FMA implements X86StaticInstructionHandler
 			misc.Error.invalidOperation("Scalar FMA ", operand1, operand2, operand3);
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/src/simulator/generic/Instruction.java b/src/simulator/generic/Instruction.java
index 06cee3b..aa08f98 100755
--- a/src/simulator/generic/Instruction.java
+++ b/src/simulator/generic/Instruction.java
@@ -358,7 +358,7 @@ public class Instruction implements Serializable
 			Operand sourceOperand2, Operand destinationOperand)
 	{
 		Instruction ins = CustomObjectPool.getInstructionPool().borrowObject();
-		ins.set(OperationType.LEA, sourceOperand1, null,
+		ins.set(OperationType.LEA, sourceOperand1, sourceOperand2,
 				destinationOperand);
 		return ins;
 	}
@@ -566,4 +566,4 @@ public class Instruction implements Serializable
 		destinationOperandMemValue = createAddressForBM(destinationOperandMemValue, bm);
 		branchTargetAddress = createAddressForBM(branchTargetAddress, bm);
 	}
-}
\ No newline at end of file
+}