From b74096d96ed60c7df6bed29861f0c7f2da2a3c88 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 19 Jul 2023 20:54:48 +0100
Subject: Add memory-load instruction to Patio IR

---
 .../shedlang/compiler/patio/PatioInstructionSerializer.java   | 11 +++++++----
 .../compiler/patio/instructions/PatioInstruction.java         |  2 +-
 .../shedlang/compiler/patio/instructions/PatioMemoryLoad.java | 10 ++++++++++
 3 files changed, 18 insertions(+), 5 deletions(-)
 create mode 100644 src/main/java/org/shedlang/compiler/patio/instructions/PatioMemoryLoad.java

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java b/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java
index 382c4125..fad162dd 100644
--- a/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java
+++ b/src/main/java/org/shedlang/compiler/patio/PatioInstructionSerializer.java
@@ -1,9 +1,6 @@
 package org.shedlang.compiler.patio;
 
-import org.shedlang.compiler.patio.instructions.PatioAlloc;
-import org.shedlang.compiler.patio.instructions.PatioDiscard;
-import org.shedlang.compiler.patio.instructions.PatioInstruction;
-import org.shedlang.compiler.patio.instructions.PatioReturn;
+import org.shedlang.compiler.patio.instructions.*;
 import org.shedlang.compiler.treetext.Tree;
 
 import java.util.List;
@@ -40,6 +37,12 @@ public class PatioInstructionSerializer {
             case PatioDiscard discard ->
                 treeList(treeIdentifier("discard"));
 
+            case PatioMemoryLoad memoryLoad ->
+                treeList(
+                    treeIdentifier("memory-load"),
+                    treeNamed("offset", treeInt(memoryLoad.offset()))
+                );
+
             case PatioReturn return_ ->
                 treeList(treeIdentifier("return"));
         };
diff --git a/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java b/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java
index 6928d324..2083f0d3 100644
--- a/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java
+++ b/src/main/java/org/shedlang/compiler/patio/instructions/PatioInstruction.java
@@ -2,6 +2,6 @@ package org.shedlang.compiler.patio.instructions;
 
 import org.shedlang.compiler.sources.Source;
 
-public sealed interface PatioInstruction permits PatioAlloc, PatioDiscard, PatioReturn {
+public sealed interface PatioInstruction permits PatioAlloc, PatioDiscard, PatioMemoryLoad, PatioReturn {
     Source source();
 }
diff --git a/src/main/java/org/shedlang/compiler/patio/instructions/PatioMemoryLoad.java b/src/main/java/org/shedlang/compiler/patio/instructions/PatioMemoryLoad.java
new file mode 100644
index 00000000..7068fcbe
--- /dev/null
+++ b/src/main/java/org/shedlang/compiler/patio/instructions/PatioMemoryLoad.java
@@ -0,0 +1,10 @@
+package org.shedlang.compiler.patio.instructions;
+
+import org.shedlang.compiler.sources.Source;
+
+/**
+ * Pop a value from the stack and assume it is a pointer. Load the value at the
+ * given offset from that pointer and push it onto the stack.
+ */
+public record PatioMemoryLoad(int offset, Source source) implements PatioInstruction {
+}
-- 
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