From aa13c97dac536bd1c4bf2f4e5c6ee505a487c634 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Sun, 26 Nov 2023 16:45:51 +0000
Subject: Support Patio exceptions in Patio Wasm backend

---
 .../compiler/backends/wasm/WasmPatioCodeGen.java   | 109 ++++++++++++++++++++-
 1 file changed, 106 insertions(+), 3 deletions(-)

(limited to 'src/main/java')

diff --git a/src/main/java/org/shedlang/compiler/backends/wasm/WasmPatioCodeGen.java b/src/main/java/org/shedlang/compiler/backends/wasm/WasmPatioCodeGen.java
index 1447ee14..585de4e6 100644
--- a/src/main/java/org/shedlang/compiler/backends/wasm/WasmPatioCodeGen.java
+++ b/src/main/java/org/shedlang/compiler/backends/wasm/WasmPatioCodeGen.java
@@ -337,18 +337,36 @@ public class WasmPatioCodeGen {
                 yield context;
             }
 
-            case PatioThrow throw_ ->
-                throw new UnsupportedOperationException("TODO");
+            case PatioThrow throw_ -> {
+                context = generateOperand(throw_.value(), context);
+
+                context = context.addInstruction(new WasmThrow(new WasmTagName(throw_.exceptionTypeName())));
+
+                yield context;
+            }
 
             case PatioTry try_ -> {
+                context = context.enterTryInstruction(
+                    new WasmBlockType(List.of(WasmValueType.I32))
+                );
+
                 context = generateBlockBody(try_.body(), context);
 
+                for (var catchClause : try_.catchClauses()) {
+                    context = context.enterCatch(new WasmTagName(catchClause.exceptionTypeName()));
+
+                    // TODO: pop into local for catch
+                    context = context.addInstruction(new WasmDrop());
+                    context = generateBlockBody(catchClause.body(), context);
+                }
+
+                context = context.exitTryInstruction();
+
                 context = popIntoPatioLocals(try_.targets(), context);
 
                 yield context;
             }
 
-
             case PatioUnreachable patioUnreachable ->
                 context.addInstruction(new WasmUnreachable());
 
@@ -732,6 +750,33 @@ public class WasmPatioCodeGen {
             return exitStructuredInstruction();
         }
 
+        public Context enterTryInstruction(WasmBlockType blockType) {
+            return new Context(
+                this.module,
+                P.vector(),
+                this.instructionsStack.plus(this.instructions),
+                this.patioLocalNameToWasmLocalIndex,
+                new WasmTryInstructionBuilder(blockType),
+                this.structuredInstructionBuilderStack.plus(this.structuredInstructionBuilder)
+            );
+        }
+
+        public Context enterCatch(WasmTagName tagName) {
+            return new Context(
+                this.module,
+                P.vector(),
+                this.instructionsStack,
+                this.patioLocalNameToWasmLocalIndex,
+                this.structuredInstructionBuilder.enterCatch(tagName, this.instructions),
+                this.structuredInstructionBuilderStack
+            );
+        }
+
+        public Context exitTryInstruction() {
+            // TODO: verify matching enter/exit?
+            return exitStructuredInstruction();
+        }
+
         public Context exitStructuredInstruction() {
             var context = new Context(
                 this.module,
@@ -775,6 +820,13 @@ public class WasmPatioCodeGen {
         default WasmStructuredInstructionBuilder enterElse(PVector<WasmInstruction> instructions) {
             throw new UnsupportedOperationException();
         }
+
+        default WasmStructuredInstructionBuilder enterCatch(
+            WasmTagName tagName,
+            PVector<WasmInstruction> instructions
+        ) {
+            throw new UnsupportedOperationException();
+        }
     }
 
     private static class NullStructuredInstructionBuilder implements WasmStructuredInstructionBuilder {
@@ -821,4 +873,55 @@ public class WasmPatioCodeGen {
             return new WasmIf(blockType, ifTrue, instructions);
         }
     }
+
+    private record WasmTryInstructionBuilder(
+        WasmBlockType blockType
+    ) implements WasmStructuredInstructionBuilder {
+        @Override
+        public WasmInstruction exit(PVector<WasmInstruction> instructions) {
+            return new WasmTry(blockType, List.of(), instructions);
+        }
+
+        @Override
+        public WasmStructuredInstructionBuilder enterCatch(
+            WasmTagName tagName,
+            PVector<WasmInstruction> instructions
+        ) {
+            return new WasmTryCatchInstructionBuilder(
+                blockType,
+                instructions,
+                tagName,
+                P.vector()
+            );
+        }
+    }
+
+    private record WasmTryCatchInstructionBuilder(
+        WasmBlockType blockType,
+        List<WasmInstruction> tryBodyInstructions,
+        WasmTagName tagName,
+        PVector<WasmCatchBlock> catchBlocks
+    ) implements WasmStructuredInstructionBuilder {
+        @Override
+        public WasmInstruction exit(PVector<WasmInstruction> instructions) {
+            return new WasmTry(
+                this.blockType,
+                this.catchBlocks.plus(new WasmCatchBlock(this.tagName, instructions)),
+                this.tryBodyInstructions
+            );
+        }
+
+        @Override
+        public WasmStructuredInstructionBuilder enterCatch(
+            WasmTagName tagName,
+            PVector<WasmInstruction> instructions
+        ) {
+            return new WasmTryCatchInstructionBuilder(
+                this.blockType,
+                this.tryBodyInstructions,
+                tagName,
+                this.catchBlocks.plus(new WasmCatchBlock(this.tagName, instructions))
+            );
+        }
+    }
 }
-- 
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