From ca92cffcd3d43347e244487466a7292ac3a94c62 Mon Sep 17 00:00:00 2001
From: Sanjar Ahmadov <sahmadov@ebrevia.com>
Date: Tue, 4 May 2021 19:33:47 -0400
Subject: [PATCH] added static link and accessing local variables capability

---
 src/main/java/chocopy/pa3/CodeGenImpl.java | 76 ++++++++++++----------
 1 file changed, 40 insertions(+), 36 deletions(-)

diff --git a/src/main/java/chocopy/pa3/CodeGenImpl.java b/src/main/java/chocopy/pa3/CodeGenImpl.java
index 6dcfd5f..f0483d8 100644
--- a/src/main/java/chocopy/pa3/CodeGenImpl.java
+++ b/src/main/java/chocopy/pa3/CodeGenImpl.java
@@ -300,25 +300,32 @@ public class CodeGenImpl extends CodeGenBase
 	        		// function
 	        		Identifier functionId = node.function;
 	        		FuncInfo calleeFunctionInfo = (FuncInfo) sym.get(node.function.name);
-	        		
-	        		List<Expr> args = node.args;
-	        		
-                    int depth = calleeFunctionInfo.getDepth();
+	        		boolean isInMainFunction = funcInfo == null;
+	        		if (!isInMainFunction) {
+                    System.out.println("--> caller: " + funcInfo.getFuncName() + " depth: " + funcInfo.getDepth());
+                    System.out.println("--> callee: " + calleeFunctionInfo.getFuncName() + " depth: " + calleeFunctionInfo.getDepth()); 
+                    
+                    int calleeDepth = calleeFunctionInfo.getDepth();
+                    int callerDepth = funcInfo.getDepth();
+                    int jumps = callerDepth - calleeDepth + 1;
+                    
                     int tmpHandle = getRegister();
                     Register tmp = registerPool[tmpHandle];
-                    FuncInfo currFuncInfo = calleeFunctionInfo;
+                    
                     backend.emitMV(tmp, FP, "Load FP");
-                    while (depth > 0) {
-                        final FuncInfo parentFuncInfo = currFuncInfo.getParentFuncInfo();
-                        backend.emitLW(tmp, tmp, parentFuncInfo.getParams().size()*wordSize, "Load static link to " + parentFuncInfo.getFuncName());
-                        currFuncInfo = parentFuncInfo;
-                        --depth;
+                    
+                    FuncInfo curr = funcInfo;
+                    for (int i = 0; i < jumps; i++) {
+                    		backend.emitLW(tmp, tmp, curr.getParams().size()*wordSize, "Load static link to " + curr.getFuncName());
+                    		curr = curr.getParentFuncInfo();
                     }
+                                   
+                    backend.emitSW(tmp, SP, -1 * wordSize, "Push static link onto active frame.");
                     freeRegister(tmpHandle);
-                   
-                 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.");
+	        		}
+	        		
+     			List<Expr> args = node.args;
+                int spaceRequiredForArgs = (args.size() + 1)*4;
 	        		for (int i = 0; i < args.size(); i++) {
 	        			int argNum = i + 1;
 	        			int slotNum = argNum + 1; // We have extra slot for static link
@@ -344,13 +351,14 @@ public class CodeGenImpl extends CodeGenBase
 	        			
 	        			// All expressions should save their end result in A0
 	        			// So, once expr is evaluated add value inside A0 onto stack as an actual argument
-	        			backend.emitSW(A0, SP, -wordSize*slotNum, "Push actual argument for " + formalParamName + " onto stack");
+	        			backend.emitSW(A0, SP, -slotNum * wordSize, "Push actual argument for " + formalParamName + " onto stack");
 	        		}
 	        		
 	        		backend.emitADDI(SP, SP, -spaceRequiredForArgs, "Set SP to last argument.");
 	        		backend.emitJAL(calleeFunctionInfo.getCodeLabel(), "Invoke function: " + functionId.name);
 	        		backend.emitADDI(SP, SP, spaceRequiredForArgs, "Set SP to stack frame top.");
             }
+            
             return A0;
         }
         
@@ -468,27 +476,23 @@ public class CodeGenImpl extends CodeGenBase
                 return ((GlobalVarInfo)info).getLabel();
         }
         private StackVarRuntimeInfo getStackVar(StackVarInfo info){
-            int curr_depth = funcInfo.getDepth();
-            int d_depth = curr_depth - info.getFuncInfo().getDepth();
-            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();
-                Register tmp = registerPool[tmpHandle];
-                backend.emitMV(tmp, FP, "tmp = FP");
-                while(d_depth > 0){
-                    curr = curr.getParentFuncInfo();
-                    backend.emitLW(tmp, tmp, curr.getParams().size()*wordSize, "Get static link");
-                    -- d_depth;
-                }
-                // UNSAFE!!!!! PLEASE FREE THE TMP_HANDLE MANUALLY
-                return new StackVarRuntimeInfo(tmp, -wordSize*curr.getVarIndex(info.getVarName()), tmpHandle);
-            }
+        		FuncInfo varFuncInfo = info.getFuncInfo();
+        		System.out.println("varfuncInfo name: " + varFuncInfo.getFuncName());
+        		System.out.println("var idx: " + varFuncInfo.getVarIndex(info.getVarName()));
+        		
+        		int tmpHandle = getRegister();
+            Register tmp = registerPool[tmpHandle];
+                
+        		if (funcInfo == info.getFuncInfo() || funcInfo == null) {
+        			backend.emitMV(tmp, FP, "We are referencing local variable");
+        		} else {
+        			backend.emitLW(tmp, FP, funcInfo.getParams().size()*wordSize, "We are referencing non local variable");
+        		}
+        		
+        		int idx = varFuncInfo.getVarIndex(info.getVarName());
+        		int paramSize = varFuncInfo.getParams().size();
+        		int offset = getLocalVarLocationOffset(idx, paramSize);
+        		return new StackVarRuntimeInfo(tmp, offset, tmpHandle);
         }
         
         @Override