From c8f15e5863666484de5e55a47079688d1f9d625a Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 17 Sep 2023 19:17:19 +0100
Subject: Add duplicate instruction

---
 src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java      | 3 +++
 .../org/shedlang/compiler/stackir/InstructionSerializer.java     | 5 +++++
 .../compiler/stackir/instructions/DuplicateInstruction.java      | 9 +++++++++
 .../org/shedlang/compiler/stackir/instructions/Instruction.java  | 2 +-
 4 files changed, 18 insertions(+), 1 deletion(-)
 create mode 100644 src/main/java/org/shedlang/compiler/stackir/instructions/DuplicateInstruction.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java b/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
index e6e3ba0a..4922bf14 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioCodeGen.java
@@ -225,6 +225,9 @@ public class PatioCodeGen {
             case DiscardInstruction discard ->
                 context.temporaryPop().context();
 
+            case DuplicateInstruction duplicate ->
+                throw new UnsupportedOperationException("TODO");
+
             case FieldLoadInstruction fieldLoad -> {
                 var receiverResult = context.temporaryPop();
                 var receiver = receiverResult.value();
diff --git a/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java b/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
index 875dbcec..fef6ce82 100644
--- a/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
+++ b/src/main/java/org/shedlang/compiler/stackir/InstructionSerializer.java
@@ -76,6 +76,11 @@ public class InstructionSerializer {
                     treeIdentifier("discard")
                 );
 
+            case DuplicateInstruction duplicate ->
+                treeList(
+                    treeIdentifier("duplicate")
+                );
+
             case FieldLoadInstruction fieldLoad ->
                 treeList(
                     treeIdentifier("field-load"),
diff --git a/src/main/java/org/shedlang/compiler/stackir/instructions/DuplicateInstruction.java b/src/main/java/org/shedlang/compiler/stackir/instructions/DuplicateInstruction.java
new file mode 100644
index 00000000..0d4aee1d
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/stackir/instructions/DuplicateInstruction.java
@@ -0,0 +1,9 @@
+package org.shedlang.compiler.stackir.instructions;
+
+import org.shedlang.compiler.sources.Source;
+
+/**
+ * Duplicates the value on top of the stack.
+ */
+public record DuplicateInstruction(Source source) implements Instruction {
+}
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 29703869..87466287 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, IfInstruction, IntAddInstruction, IntEqualsInstruction, IntNotEqualInstruction, IntSubInstruction, LocalLoadInstruction, LocalStoreInstruction, LoopBreakInstruction, LoopContinueInstruction, LoopInstruction, NamespaceFieldStoreInstruction, NamespaceImportInstruction, PushBoolInstruction, PushIntInstruction, PushStringInstruction, PushUnitInstruction, ReturnInstruction, StringAddInstruction, TupleCreateInstruction, TupleGetInstruction, VarLoadInstruction, VarStoreInstruction {
+    permits CallInstruction, DefineFunctionInstruction, DiscardInstruction, DuplicateInstruction, FieldLoadInstruction, IfInstruction, IntAddInstruction, IntEqualsInstruction, IntNotEqualInstruction, IntSubInstruction, LocalLoadInstruction, LocalStoreInstruction, LoopBreakInstruction, LoopContinueInstruction, LoopInstruction, NamespaceFieldStoreInstruction, NamespaceImportInstruction, PushBoolInstruction, PushIntInstruction, PushStringInstruction, PushUnitInstruction, ReturnInstruction, StringAddInstruction, TupleCreateInstruction, TupleGetInstruction, VarLoadInstruction, VarStoreInstruction {
 
     Source source();
 }
-- 
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