Compile string addition into string-add instruction

6 files changed, 23 insertions, 2 deletions

diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGen.java b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGen.java
index 3062d48d..658e331e 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/LlvmCodeGen.java
@@ -235,6 +235,9 @@ public class LlvmCodeGen {
                     new LlvmReturn(LlvmCodeGenTypes.VALUE_TYPE, value)
                 );
             }
+
+            case StringAddInstruction stringAdd ->
+                throw new UnsupportedOperationException("TODO");
         };
     }
 
diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/WasmCodeGen.java b/src/main/java/org/shedlang/compiler/backends/wasm/WasmCodeGen.java
index b3a6a4ba..dbf667c2 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/WasmCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/WasmCodeGen.java
@@ -241,6 +241,9 @@ public class WasmCodeGen {
 
             case ReturnInstruction returnInstruction ->
                 context.addInstruction(new WasmReturn());
+
+            case StringAddInstruction stringAdd ->
+                throw new UnsupportedOperationException("TODO");
         };
     }
 }
diff --git a/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java b/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
index c6544550..baaf4b49 100644
--- a/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
+++ b/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
@@ -141,10 +141,14 @@ public class InstructionSerializer {
                 treeList(
                     treeIdentifier("push-unit")
                 );
+
             case ReturnInstruction returnInstruction ->
                 treeList(
                     treeIdentifier("return")
                 );
+
+            case StringAddInstruction stringAddInstruction ->
+                treeList(treeIdentifier("string-add"));
         };
     }
 
diff --git a/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java b/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
index 6bda0b6d..449360e1 100644
--- a/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
+++ b/src/main/java/org/shedlang/compiler/stackir/StackCompiler.java
@@ -25,7 +25,7 @@ public class StackCompiler {
                 case INT_SUB ->
                     new IntSubInstruction(node.source());
                 case STRING_ADD ->
-                    throw new UnsupportedOperationException("TODO");
+                    new StringAddInstruction(node.source());
             });
     }
 
diff --git a/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java b/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java
index 6d361ddb..a1ab0a39 100644
--- a/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java
+++ b/src/main/java/org/shedlang/compiler/stackir/instructions/Instruction.java
@@ -3,7 +3,7 @@ package org.shedlang.compiler.stackir.instructions;
 import org.shedlang.compiler.sources.Source;
 
 public sealed interface Instruction
-    permits CallInstruction, DefineFunctionInstruction, DiscardInstruction, FieldLoadInstruction, IntAddInstruction, IntEqualsInstruction, IntNotEqualInstruction, IntSubInstruction, LocalLoadInstruction, LocalStoreInstruction, NamespaceFieldStoreInstruction, NamespaceImportInstruction, PushBoolInstruction, PushIntInstruction, PushStringInstruction, PushUnitInstruction, ReturnInstruction {
+    permits CallInstruction, DefineFunctionInstruction, DiscardInstruction, FieldLoadInstruction, IntAddInstruction, IntEqualsInstruction, IntNotEqualInstruction, IntSubInstruction, LocalLoadInstruction, LocalStoreInstruction, NamespaceFieldStoreInstruction, NamespaceImportInstruction, PushBoolInstruction, PushIntInstruction, PushStringInstruction, PushUnitInstruction, ReturnInstruction, StringAddInstruction {
 
     Source source();
 }
diff --git a/src/main/java/org/shedlang/compiler/stackir/instructions/StringAddInstruction.java b/src/main/java/org/shedlang/compiler/stackir/instructions/StringAddInstruction.java
new file mode 100644
index 00000000..041ae30e
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/stackir/instructions/StringAddInstruction.java
@@ -0,0 +1,11 @@
+package org.shedlang.compiler.stackir.instructions;
+
+import org.shedlang.compiler.sources.Source;
+
+/**
+ * Pop the right operand from the stack, then the left operand from the stack,
+ * assume both operands are Strings, concatenate the left and right operands,
+ * then push the result onto the stack.
+ */
+public record StringAddInstruction(Source source) implements Instruction {
+}