From c3cb22030f948bd75ebc6d9200819d38d6c7bc11 Mon Sep 17 00:00:00 2001
From: Ayke van Laethem <aykevanlaethem@gmail.com>
Date: Wed, 22 Aug 2018 00:56:11 +0200
Subject: [PATCH] Implement == and != for strings

---
 compiler.go            | 25 +++++++++++++++++++++----
 src/runtime/runtime.go | 12 ++++++++++++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/compiler.go b/compiler.go
index ce68b27f..0fbe99ba 100644
--- a/compiler.go
+++ b/compiler.go
@@ -1542,10 +1542,27 @@ func (c *Compiler) parseBinOp(frame *Frame, binop *ssa.BinOp) (llvm.Value, error
 		// Go specific. Calculate "and not" with x & (~y)
 		inv := c.builder.CreateNot(y, "") // ~y
 		return c.builder.CreateAnd(x, inv, ""), nil
-	case token.EQL: // ==
-		return c.builder.CreateICmp(llvm.IntEQ, x, y, ""), nil
-	case token.NEQ: // !=
-		return c.builder.CreateICmp(llvm.IntNE, x, y, ""), nil
+	case token.EQL, token.NEQ: // ==, !=
+		switch typ := binop.X.Type().Underlying().(type) {
+		case *types.Basic:
+			if typ.Info()&types.IsInteger != 0 || typ.Kind() == types.UnsafePointer {
+				if binop.Op == token.EQL {
+					return c.builder.CreateICmp(llvm.IntEQ, x, y, ""), nil
+				} else {
+					return c.builder.CreateICmp(llvm.IntNE, x, y, ""), nil
+				}
+			} else if typ.Kind() == types.String {
+				result := c.builder.CreateCall(c.mod.NamedFunction("runtime.stringequal"), []llvm.Value{x, y}, "")
+				if binop.Op == token.NEQ {
+					result = c.builder.CreateNot(result, "")
+				}
+				return result, nil
+			} else {
+				return llvm.Value{}, errors.New("todo: equality operator on unknown basic type: " + typ.String())
+			}
+		default:
+			return llvm.Value{}, errors.New("todo: equality operator on unknown type: " + typ.String())
+		}
 	case token.LSS: // <
 		if signed {
 			return c.builder.CreateICmp(llvm.IntSLT, x, y, ""), nil
diff --git a/src/runtime/runtime.go b/src/runtime/runtime.go
index 1e2c910a..1f85963c 100644
--- a/src/runtime/runtime.go
+++ b/src/runtime/runtime.go
@@ -17,6 +17,18 @@ func GOMAXPROCS(n int) int {
 	return 1
 }
 
+func stringequal(x, y string) bool {
+	if len(x) != len(y) {
+		return false
+	}
+	for i := 0; i < len(x); i++ {
+		if x[i] != y[i] {
+			return false
+		}
+	}
+	return true
+}
+
 func _panic(message interface{}) {
 	printstring("panic: ")
 	printitf(message)