From a4e10ae33398e1eeffae0c196379a9df1d17e34f Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 8 Apr 2026 19:12:50 +0100
Subject: Support defining Patio functions with multiple return values

---
 .../backends/llvm/codegen/PatioToLlvm.java         | 35 ++++++++++++++++++----
 1 file changed, 29 insertions(+), 6 deletions(-)

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java
index 428190aa..a49752e0 100644
--- a/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java
+++ b/src/main/java/org/shedlang/compiler/backends/llvm/codegen/PatioToLlvm.java
@@ -9,6 +9,7 @@ import org.shedlang.compiler.backends.llvm.ir.ast.*;
 import org.shedlang.compiler.backends.llvm.ir.ast.instructions.*;
 import org.shedlang.compiler.backends.llvm.ir.ast.operands.*;
 import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmType;
+import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmTypeStructure;
 import org.shedlang.compiler.backends.llvm.ir.ast.types.LlvmTypes;
 import org.shedlang.compiler.filesystem.ShedCompilerFiles;
 import org.shedlang.compiler.patio.*;
@@ -1132,13 +1133,35 @@ public class PatioToLlvm {
         if (patioReturnOperands.size() == 1) {
             return context.toResult(patioOperandToLlvmOperand(patioReturnOperands.get(0), context));
         } else {
-            return context.toResult(
-                new LlvmOperandStructure(
-                    patioReturnOperands.stream()
-                        .map(patioReturnOperand -> patioOperandToLlvmTypedOperand(patioReturnOperand, context))
-                        .toList()
-                )
+            LlvmOperand llvmOperand = new LlvmOperandPoison();
+
+            var c = context;
+            var llvmAggregateType = new LlvmTypeStructure(
+                patioReturnOperands.stream()
+                    .map(patioReturnOperand -> patioOperandToLlvmType(patioReturnOperand, c))
+                    .toList()
             );
+
+            for (var patioReturnOperandIndex = 0; patioReturnOperandIndex < patioReturnOperands.size(); patioReturnOperandIndex++) {
+                var patioReturnOperand = patioReturnOperands.get(patioReturnOperandIndex);
+
+                var llvmUpdatedAggregateResult = context.allocateLocalName(LlvmCodeGenLocalVariableSpace.TEMPORARY);
+                var llvmUpdatedAggregate = llvmUpdatedAggregateResult.value();
+                context = llvmUpdatedAggregateResult.context();
+
+                context = context.addInstruction(new LlvmInsertValue(
+                    llvmUpdatedAggregate,
+                    llvmAggregateType,
+                    llvmOperand,
+                    patioOperandToLlvmType(patioReturnOperand, context),
+                    patioOperandToLlvmOperand(patioReturnOperand, context),
+                    List.of(patioReturnOperandIndex)
+                ));
+
+                llvmOperand = llvmUpdatedAggregate;
+            }
+
+            return context.toResult(llvmOperand);
         }
     }
 
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