From 14a5f54cebea29995a3d90eb72c35aeae78f56a8 Mon Sep 17 00:00:00 2001
From: Sanjar Ahmadov <sahmadov@ebrevia.com>
Date: Tue, 4 May 2021 13:20:13 -0400
Subject: [PATCH] Changed active frame logic - matched it with the
 implementation guide

---
 src/main/java/chocopy/pa3/CodeGenImpl.java | 54 ++++++++++++----------
 1 file changed, 30 insertions(+), 24 deletions(-)

diff --git a/src/main/java/chocopy/pa3/CodeGenImpl.java b/src/main/java/chocopy/pa3/CodeGenImpl.java
index 5844f46..6dcfd5f 100644
--- a/src/main/java/chocopy/pa3/CodeGenImpl.java
+++ b/src/main/java/chocopy/pa3/CodeGenImpl.java
@@ -116,9 +116,8 @@ public class CodeGenImpl extends CodeGenBase
         // space for return address = 1
         // space for control link = 1
         // space for static link =  1
-        // space for params = num of params 
         // space for locals = num of locals
-        int requiredStackSpace = (1 + 1 + 1 + funcInfo.getParams().size() + funcInfo.getLocals().size())*wordSize;
+        int requiredStackSpace = (1 + 1 + 1 + funcInfo.getLocals().size())*wordSize;
         
         backend.emitADDI(SP, SP, -requiredStackSpace, "Reserve space for stack frame.");
         backend.emitSW(RA, SP, requiredStackSpace-4, "return address");
@@ -129,27 +128,16 @@ public class CodeGenImpl extends CodeGenBase
         
         
         StmtAnalyzer stmtAnalyzer = new StmtAnalyzer(funcInfo);
-        int emptySlotNum = 4;
-        
-        // example usage: backend.emitLW(A0, SP, varSlotMap.get(varName)) to load the variable using its name
-        Map<String, Integer> varSlotMap = stmtAnalyzer.varSlotMap;
-        
-        for (int i = 0; i < funcInfo.getParams().size(); i++) {
-        		String param = funcInfo.getParams().get(i);
-        		backend.emitLW(A0, FP, -wordSize*i, "Load argument " + param + " from callers active frame");
-		    backend.emitSW(A0, SP, requiredStackSpace-emptySlotNum*wordSize, "Push argument " + param + " onto stack");
-		    varSlotMap.put(param, requiredStackSpace-emptySlotNum*wordSize);
-		    emptySlotNum++;
-	    }
-        
+        int emptySlotNum = 3;
         for (StackVarInfo var : funcInfo.getLocals()) {
         		Literal varLitral = var.getInitialValue();
         		varLitral.dispatch(stmtAnalyzer);
         		// All Literals should save locations for the values in A0
     			backend.emitSW(A0, SP, requiredStackSpace-emptySlotNum*wordSize, "Push local variable " + var.getVarName() + " onto stack");
-    			varSlotMap.put(var.getVarName(), requiredStackSpace-emptySlotNum*wordSize);
     			emptySlotNum++;
         }
+        
+        
         // --- Function Body ---
         // statements load all the variables that caller put on stack
         // statements use fp to load the variables
@@ -160,6 +148,8 @@ public class CodeGenImpl extends CodeGenBase
         }
         stmtAnalyzer.emitSizeLabel();
         backend.emitJ(stmtAnalyzer.epilogue, "Jump to function epilogue");
+        
+        
         // --- Epilogue ---
         backend.emitLocalLabel(stmtAnalyzer.epilogue, "Epilogue");
         backend.emitLW(RA, FP, -4, "Get return address");
@@ -209,9 +199,7 @@ public class CodeGenImpl extends CodeGenBase
         /** Label of code that exits from block. */
         protected Stack<Label> elseBlock = new Stack<Label>();
 
-        /** Variable to keep track of slots of stored variables on stack */
-        // example usage: backend.emitLW(A0, SP, varSlotMap.get(varName)) to load the variable using its name
-        private Map<String, Integer> varSlotMap = new HashMap<>();
+     
         
         private final String size_label;
         /** Variable to store offset from frame pointer to identify next 
@@ -233,6 +221,18 @@ public class CodeGenImpl extends CodeGenBase
             registerAvilMap[handle] = false;
         }
         
+        private int getParamLocationOffset(int index, int paramSize) {
+        		return (paramSize - index - 1) * wordSize;
+        }
+        
+        private int getLocalVarLocationOffset(int index, int paramSize) {
+    			return - (index - paramSize + 1) * wordSize;
+        }
+        
+        private int getStaticLinkOffset(int paramSize) {
+    			return paramSize * wordSize;
+        }
+        
         /**
          * An analyzer for the function described by FUNCINFO0, which is null for the
          * top level.
@@ -302,7 +302,7 @@ public class CodeGenImpl extends CodeGenBase
 	        		FuncInfo calleeFunctionInfo = (FuncInfo) sym.get(node.function.name);
 	        		
 	        		List<Expr> args = node.args;
-	        		int spaceRequiredForArgs = (args.size() + 1)*4;
+	        		
                     int depth = calleeFunctionInfo.getDepth();
                     int tmpHandle = getRegister();
                     Register tmp = registerPool[tmpHandle];
@@ -315,7 +315,10 @@ public class CodeGenImpl extends CodeGenBase
                         --depth;
                     }
                     freeRegister(tmpHandle);
-	        		//backend.emitSW(A0, SP, -4, "Put static link");
+                   
+                 int spaceRequiredForArgs = (args.size() + 1)*4;
+                 backend.emitMV(T0, FP, "Get static link to " + (funcInfo != null ? funcInfo.getFuncName() : "main"));
+     			backend.emitSW(T0, SP, -wordSize, "Push static link onto active frame.");
 	        		for (int i = 0; i < args.size(); i++) {
 	        			int argNum = i + 1;
 	        			int slotNum = argNum + 1; // We have extra slot for static link
@@ -467,9 +470,12 @@ public class CodeGenImpl extends CodeGenBase
         private StackVarRuntimeInfo getStackVar(StackVarInfo info){
             int curr_depth = funcInfo.getDepth();
             int d_depth = curr_depth - info.getFuncInfo().getDepth();
-            if(d_depth == 0)
-                return new StackVarRuntimeInfo(SP, varSlotMap.get(info.getVarName()));
-            else
+            if(d_depth == 0) {
+            	    int idx = funcInfo.getVarIndex(info.getVarName());
+            		int paramSize = funcInfo.getParams().size();
+            		int offset = getLocalVarLocationOffset(idx, paramSize);
+            		return new StackVarRuntimeInfo(FP, offset);
+            } else
             {
                 FuncInfo curr = funcInfo;
                 int tmpHandle = getRegister();