Merge branch '16-tail-recursion-optimization' into 'master'

Resolve "Tail Recursion Optimization"

Closes #16

See merge request mkais001/klang!18

README.md

@@ -112,6 +112,9 @@ function forExample(end: int): int {
 
 ```
 
+## Tail Call Optimized
+Recursive tail calls are optimized at compile time.
+
 ## Statically typed
 KLang statically verifies the integrity of your code. These checks include:
 - Type checking
@@ -123,6 +126,7 @@ KLang statically verifies the integrity of your code. These checks include:
 ### Data Types
 - Integer "int"
 - Boolean "bool"
+- Floats  "float"
 
 ### Examples
 You can declare types for parameters, return values and variables

src/main/java/de/hsrm/compiler/Klang/ContextAnalysis.java

@@ -18,6 +18,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
   Map<String, FunctionInformation> funcs;
   Map<String, StructDefinition> structs;
   Type currentDeclaredReturnType;
+  String currentFunctionDefinitionName;
 
   private void checkNumeric(Node lhs, Node rhs, int line, int col) {
     if (!lhs.type.isNumericType() || !rhs.type.isNumericType()) {
@@ -246,6 +247,16 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
   public Node visitReturn_statement(KlangParser.Return_statementContext ctx) {
     Expression expression = (Expression) this.visit(ctx.expression());
     ReturnStatement result = new ReturnStatement(expression);
+
+    // Check if this expression is a tail recursion
+    if (expression instanceof FunctionCall) {
+      var funCall = (FunctionCall) expression;
+      if (funCall.name.equals(this.currentFunctionDefinitionName)) {
+        // Flag this function call
+        funCall.isTailRecursive = true;
+      }
+    }
+
     result.type = expression.type;
     result.line = ctx.start.getLine();
     result.col = ctx.start.getCharPositionInLine();
@@ -720,6 +731,7 @@ public class ContextAnalysis extends KlangBaseVisitor<Node> {
     int col = ctx.start.getCharPositionInLine();
     Type returnType = Type.getByName(ctx.returnType.type().getText());
     this.currentDeclaredReturnType = returnType;
+    this.currentFunctionDefinitionName = name;
 
     if (!returnType.isPrimitiveType() && this.structs.get(returnType.getName()) == null) {
       String error = "Type " + returnType.getName() + " not defined.";

src/main/java/de/hsrm/compiler/Klang/nodes/expressions/FunctionCall.java

@@ -6,6 +6,7 @@ public class FunctionCall extends Expression {
 
   public String name;
   public Expression[] arguments;
+  public boolean isTailRecursive = false;
 
   public FunctionCall(String name, Expression[] arguments) {
     this.name = name;

src/main/java/de/hsrm/compiler/Klang/visitors/GenASM.java

@@ -113,6 +113,8 @@ public class GenASM implements Visitor<Void> {
   String[] registers = { "%rdi", "%rsi", "%rdx", "%rcx", "%r8", "%r9" };
   String[] floatRegisters = { "%xmm0", "%xmm1", "%xmm2", "%xmm3", "%xmm4", "%xmm5", "%xmm6", "%xmm7" };
   private int lCount = 0; // Invariante: lCount ist benutzt
+  private int currentFunctionStartLabel = 0;
+  private Parameter[] currentFunctionParams;
 
   private void intToFloat(String src, String dst) {
     this.ex.write("    cvtsi2sd " + src + ", " + dst + "\n");
@@ -566,6 +568,11 @@ public class GenASM implements Visitor<Void> {
     if (e.expression != null) {
       e.expression.welcome(this);
       int offset = this.env.get(e.name);
+      
+      if (e.expression.type.equals(Type.getFloatType())) {
+        this.ex.write("    movq %xmm0, %rax\n");
+      }
+
       this.ex.write("    movq %rax, " + offset + "(%rbp)\n");
     }
     return null;
@@ -606,11 +613,15 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(FunctionDefinition e) {
+    int lblStart = ++lCount;
+    this.currentFunctionStartLabel = lblStart;
+    this.currentFunctionParams = e.parameters;
     this.ex.write(".globl " + e.name + "\n");
     this.ex.write(".type " + e.name + ", @function\n");
     this.ex.write(e.name + ":\n");
     this.ex.write("    pushq %rbp\n");
     this.ex.write("    movq %rsp, %rbp\n");
+    this.ex.write(".L" + lblStart + ":\n");
 
     // hole die anzahl der lokalen variablen
     this.vars = new TreeSet<String>();
@@ -682,6 +693,25 @@ public class GenASM implements Visitor<Void> {
 
   @Override
   public Void visit(FunctionCall e) {
+    if (e.isTailRecursive) {
+
+      // Visit the arguments and move them into the location of the corresponding local var
+      for(int i = 0; i < e.arguments.length; i++) {
+        e.arguments[i].welcome(this);
+        int offset = this.env.get(this.currentFunctionParams[i].name);
+
+        if (e.arguments[i].type.equals(Type.getFloatType())) {
+          this.ex.write("    movq %xmm0, %rax\n");
+        }
+
+        this.ex.write("    movq %rax, " + offset + "(%rbp)\n");
+      }
+
+      this.ex.write("    jmp .L" + this.currentFunctionStartLabel + "\n");
+      return null;
+    }
+
+
     if (e.arguments.length > 0) {
       // Mapping arguments index -> xmm registers index
       int[] xmmIdxs = new int[this.floatRegisters.length];

src/test/functionCall/functionCall.c

@@ -92,4 +92,28 @@ int runFunctionCallTests () {
   argumentTest("fgetMix8(...args)", 8, fgetMix8());
   argumentTest_f("fgetMix9(...args)", 9.0, fgetMix9());
   argumentTest("fgetMix10(...args)", 10, fgetMix10());
+
+  printf("\nTail Call Tests \n");
+  // Checks that tails calls are properly invoked
+  argumentTest("arg1Tail(...args)", 1, arg1Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg2Tail(...args)", 2, arg2Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg3Tail(...args)", 3, arg3Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg4Tail(...args)", 4, arg4Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg5Tail(...args)", 5, arg5Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg6Tail(...args)", 6, arg6Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg7Tail(...args)", 7, arg7Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg8Tail(...args)", 8, arg8Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg9Tail(...args)", 9, arg9Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  argumentTest("arg10Tail(...args)", 10, arg10Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10));
+  // Checks that parameters are correctly passed from klang to functions
+  argumentTest("get1Tail(...args)", 1, get1Tail(10));
+  argumentTest("get2Tail(...args)", 2, get2Tail(10));
+  argumentTest("get3Tail(...args)", 3, get3Tail(10));
+  argumentTest("get4Tail(...args)", 4, get4Tail(10));
+  argumentTest("get5Tail(...args)", 5, get5Tail(10));
+  argumentTest("get6Tail(...args)", 6, get6Tail(10));
+  argumentTest("get7Tail(...args)", 7, get7Tail(10));
+  argumentTest("get8Tail(...args)", 8, get8Tail(10));
+  argumentTest("get9Tail(...args)", 9, get9Tail(10));
+  argumentTest("get10Tail(...args)", 10, get10Tail(10));
 }

src/test/functionCall/functionCall.h

@@ -20,6 +20,28 @@ long get8();
 long get9();
 long get10();
 
+long arg1Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg2Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg3Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg4Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg5Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg6Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg7Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg8Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg9Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+long arg10Tail(long a, long b, long c, long d, long e, long f, long g, long h, long i, long j, long count);
+
+long get1Tail(long count);
+long get2Tail(long count);
+long get3Tail(long count);
+long get4Tail(long count);
+long get5Tail(long count);
+long get6Tail(long count);
+long get7Tail(long count);
+long get8Tail(long count);
+long get9Tail(long count);
+long get10Tail(long count);
+
 double farg1(double a, double b, double c, double d, double e, double f, double g, double h, double i, double j);
 double farg2(double a, double b, double c, double d, double e, double f, double g, double h, double i, double j);
 double farg3(double a, double b, double c, double d, double e, double f, double g, double h, double i, double j);

src/test/test.k

@@ -106,6 +106,127 @@ function get10(): int {
   return arg10(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
 }
 
+// TAIL CALL
+function arg1Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return a;
+  }
+
+  return arg1Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get1Tail(count: int): int {
+  return arg1Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg2Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return b;
+  }
+
+  return arg2Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get2Tail(count: int): int {
+  return arg2Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg3Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return c;
+  }
+
+  return arg3Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get3Tail(count: int): int {
+  return arg3Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg4Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return d;
+  }
+
+  return arg4Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get4Tail(count: int): int {
+  return arg4Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg5Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return e;
+  }
+
+  return arg5Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get5Tail(count: int): int {
+  return arg5Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg6Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return f;
+  }
+
+  return arg6Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get6Tail(count: int): int {
+  return arg6Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg7Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return g;
+  }
+
+  return arg7Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get7Tail(count: int): int {
+  return arg7Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg8Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return h;
+  }
+
+  return arg8Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get8Tail(count: int): int {
+  return arg8Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg9Tail(a: int, b: int, c: int,d: int,e: int,f: int,g: int, h: int,i: int,j: int, count: int): int {
+  if (count <= 0) {
+    return i;
+  }
+
+  return arg9Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get9Tail(count: int): int {
+  return arg9Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
+function arg10Tail(a: int, b: int, c: int, d: int, e: int, f: int, g: int, h: int, i: int, j: int, count: int): int {
+  if (count <= 0) {
+    return j;
+  }
+
+  return arg10Tail(a, b, c, d, e, f, g, h, i, j, count - 1);
+}
+
+function get10Tail(count: int): int {
+  return arg10Tail(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10);
+}
+
 // FLOATS
 
 function farg1(a: float, b: float, c: float, d: float, e: float, f: float, g: float, h: float, i: float ,j: float): float {