From c68eb4e8eabbb0b533604bf38e7fce76ecf08d3c Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 4 Apr 2025 17:19:06 +0200
Subject: [PATCH 1/8] Support Wasm blocks with a single result

---
 .../hosted/webimage/wasm/ast/Instruction.java | 33 +++++++++++++++---
 .../wasm/ast/visitors/WasmPrinter.java        | 34 ++++++++-----------
 .../wasm/ast/visitors/WasmValidator.java      | 22 ++++++++----
 .../wasm/ast/visitors/WasmVisitor.java        |  5 ++-
 4 files changed, 63 insertions(+), 31 deletions(-)

diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
index 45473ba4baab..5da53a578dcf 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
@@ -148,14 +148,33 @@ public abstract static class WasmBlock extends Instruction {
          * If set to null, the block has no named identifier
          */
         protected final WasmId.Label label;
+        protected final WasmValType result;
 
-        public WasmBlock(WasmId.Label label) {
+        protected WasmBlock(WasmId.Label label, WasmValType result) {
             this.label = label;
+            this.result = result;
         }
 
         public WasmId.Label getLabel() {
             return label;
         }
+
+        public WasmValType getResult() {
+            return result;
+        }
+
+        public boolean hasResult() {
+            return result != null;
+        }
+
+        @Override
+        protected String toInnerString() {
+            if (hasResult()) {
+                return "() -> " + result;
+            } else {
+                return "() -> ()";
+            }
+        }
     }
 
     /**
@@ -165,7 +184,11 @@ public static final class Block extends WasmBlock {
         public final Instructions instructions = new Instructions();
 
         public Block(WasmId.Label label) {
-            super(label);
+            this(label, null);
+        }
+
+        public Block(WasmId.Label label, WasmValType result) {
+            super(label, result);
         }
     }
 
@@ -176,7 +199,7 @@ public static final class Loop extends WasmBlock {
         public final Instructions instructions = new Instructions();
 
         public Loop(WasmId.Label label) {
-            super(label);
+            super(label, null);
         }
     }
 
@@ -190,7 +213,7 @@ public static final class If extends WasmBlock {
         public final Instruction condition;
 
         public If(WasmId.Label label, Instruction condition) {
-            super(label);
+            super(label, null);
             this.condition = condition;
         }
 
@@ -222,7 +245,7 @@ private Catch(WasmId.Tag tag) {
         public final List<Catch> catchBlocks = new ArrayList<>();
 
         public Try(WasmId.Label label) {
-            super(label);
+            super(label, null);
         }
 
         public Instructions addCatch(WasmId.Tag tag) {
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java
index d03c6604e506..43fd40e97c7f 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java
@@ -710,14 +710,22 @@ public void visitTable(Table t) {
         parenClose();
     }
 
-    @Override
-    @SuppressWarnings("try")
-    public void visitBlock(Instruction.Block block) {
-        print("block");
+    private void printBlockPrefix(String name, Instruction.WasmBlock block) {
+        print(name);
         space();
         printId(block.getLabel());
+        if (block.hasResult()) {
+            space();
+            printResult(block.getResult());
+        }
         space();
         printComment(block.getComment());
+    }
+
+    @Override
+    @SuppressWarnings("try")
+    public void visitBlock(Instruction.Block block) {
+        printBlockPrefix("block", block);
         try (var ignored = new Indenter()) {
             super.visitBlock(block);
         }
@@ -727,11 +735,7 @@ public void visitBlock(Instruction.Block block) {
     @Override
     @SuppressWarnings("try")
     public void visitLoop(Instruction.Loop loop) {
-        print("loop");
-        space();
-        printId(loop.getLabel());
-        space();
-        printComment(loop.getComment());
+        printBlockPrefix("loop", loop);
         try (var ignored = new Indenter()) {
             super.visitLoop(loop);
         }
@@ -741,11 +745,7 @@ public void visitLoop(Instruction.Loop loop) {
     @Override
     @SuppressWarnings("try")
     public void visitIf(Instruction.If ifBlock) {
-        print("if");
-        space();
-        printId(ifBlock.getLabel());
-        space();
-        printComment(ifBlock.getComment());
+        printBlockPrefix("if", ifBlock);
 
         try (var ignored = new Indenter()) {
             visitInstruction(ifBlock.condition);
@@ -774,11 +774,7 @@ public void visitIf(Instruction.If ifBlock) {
     @Override
     @SuppressWarnings("try")
     public void visitTry(Instruction.Try tryBlock) {
-        print("try");
-        space();
-        printId(tryBlock.getLabel());
-        space();
-        printComment(tryBlock.getComment());
+        printBlockPrefix("try", tryBlock);
 
         try (var ignored = new Indenter()) {
             newline();
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java
index 8341863d0d88..b0055c26b5fe 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java
@@ -64,7 +64,7 @@
  * <ul>
  * <li>Makes some simplifying assumptions (which the AST currently satisfies):
  * <ul>
- * <li>Any labeled block has no input or output types.</li>
+ * <li>Any labeled block has no input and at most one output value.</li>
  * <li>No vector or reference types exist</li>
  * <li>Functions only have a single return value</li>
  * </ul>
@@ -432,6 +432,16 @@ private void popCtrl(WasmId.Label expectedLabel) {
         ctrls.pop();
     }
 
+    private void popBlockCtrl(Instruction.WasmBlock block) {
+        if (block.hasResult()) {
+            popVals(block.getResult());
+        }
+        popCtrl(block.getLabel());
+        if (block.hasResult()) {
+            pushVal(block.getResult());
+        }
+    }
+
     private void unreachable() {
         CtrlFrame top = topFrame();
         vals.clear();
@@ -568,14 +578,14 @@ public void visitInstruction(Instruction inst) {
     public void visitBlock(Instruction.Block block) {
         pushCtrl(block.getLabel());
         super.visitBlock(block);
-        popCtrl(block.getLabel());
+        popBlockCtrl(block);
     }
 
     @Override
     public void visitLoop(Instruction.Loop loop) {
         pushCtrl(loop.getLabel());
         super.visitLoop(loop);
-        popCtrl(loop.getLabel());
+        popBlockCtrl(loop);
     }
 
     @Override
@@ -584,12 +594,12 @@ public void visitIf(Instruction.If ifBlock) {
         popVals(i32);
         pushCtrl(ifBlock.getLabel());
         visitInstructions(ifBlock.thenInstructions);
+        popBlockCtrl(ifBlock);
         if (ifBlock.hasElse()) {
-            popCtrl(ifBlock.getLabel());
             pushCtrl(ifBlock.getLabel());
             visitInstructions(ifBlock.elseInstructions);
+            popBlockCtrl(ifBlock);
         }
-        popCtrl(ifBlock.getLabel());
     }
 
     @Override
@@ -605,7 +615,7 @@ public void visitTry(Instruction.Try tryBlock) {
             popCtrl(null);
         }
 
-        popCtrl(tryBlock.getLabel());
+        popBlockCtrl(tryBlock);
     }
 
     @Override
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java
index 835794ef7885..38cb502ea4a5 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java
@@ -337,8 +337,11 @@ public void visitInstruction(Instruction inst) {
         }
     }
 
-    public void visitBlockInstr(@SuppressWarnings("unused") Instruction.WasmBlock block) {
+    public void visitBlockInstr(Instruction.WasmBlock block) {
         visitId(block.getLabel());
+        if (block.hasResult()) {
+            visitType(block.getResult());
+        }
     }
 
     public void visitBlock(Instruction.Block block) {

From c7bddd45e092ea69966e6784a67c8d67721c1f6e Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 4 Apr 2025 17:23:51 +0200
Subject: [PATCH 2/8] Add try_table instruction

---
 .../hosted/webimage/wasm/ast/Instruction.java | 42 ++++++++++++++++++-
 .../wasm/ast/visitors/WasmPrinter.java        | 20 +++++++++
 .../wasm/ast/visitors/WasmVisitor.java        | 12 ++++++
 3 files changed, 73 insertions(+), 1 deletion(-)

diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
index 5da53a578dcf..d29b9905a853 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
@@ -223,10 +223,50 @@ public boolean hasElse() {
     }
 
     /**
-     * The WASM try block from the exception handling proposal.
+     * The WASM try_table from the exception handling proposal.
      * <p>
      * Ref: https://github.com/WebAssembly/exception-handling
      */
+    public static final class TryTable extends WasmBlock {
+        /**
+         * A catch clause for a certain tag.
+         * <p>
+         * When an exception is caught, the block branches to the label of the appropriate clause.
+         */
+        public static final class Catch {
+            public final WasmId.Tag tag;
+            public final WasmId.Label label;
+
+            private Catch(WasmId.Tag tag, WasmId.Label label) {
+                this.tag = tag;
+                this.label = label;
+            }
+
+            @Override
+            public String toString() {
+                return "Catch{tag=" + tag + ", label=" + label + '}';
+            }
+        }
+
+        public final Instructions instructions = new Instructions();
+        public final List<Catch> catchBlocks = new ArrayList<>();
+
+        public TryTable(WasmId.Label label) {
+            super(label, null);
+        }
+
+        public void addCatch(WasmId.Tag tag, WasmId.Label catchLabel) {
+            var catchBlock = new Catch(tag, catchLabel);
+            catchBlocks.add(catchBlock);
+        }
+    }
+
+    /**
+     * The WASM try block from the legacy exception handling proposal.
+     * <p>
+     * Ref:
+     * https://github.com/WebAssembly/exception-handling/blob/master/proposals/exception-handling/legacy/Exceptions.md
+     */
     public static final class Try extends WasmBlock {
 
         /**
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java
index 43fd40e97c7f..e984ae8009d6 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmPrinter.java
@@ -771,6 +771,26 @@ public void visitIf(Instruction.If ifBlock) {
         newline();
     }
 
+    @Override
+    @SuppressWarnings("try")
+    public void visitTryTable(Instruction.TryTable tryBlock) {
+        printBlockPrefix("try_table", tryBlock);
+
+        try (var ignored = new Indenter()) {
+            for (Instruction.TryTable.Catch catchBlock : tryBlock.catchBlocks) {
+                newline();
+                parenOpen("catch");
+                space();
+                printId(catchBlock.tag);
+                space();
+                printId(catchBlock.label);
+                parenClose();
+            }
+            super.visitInstructions(tryBlock.instructions);
+        }
+        newline();
+    }
+
     @Override
     @SuppressWarnings("try")
     public void visitTry(Instruction.Try tryBlock) {
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java
index 38cb502ea4a5..a338a2acab6e 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmVisitor.java
@@ -278,6 +278,10 @@ public void visitInstruction(Instruction inst) {
                 visitBlockInstr(i);
                 visitIf(i);
             }
+            case Instruction.TryTable i -> {
+                visitBlockInstr(i);
+                visitTryTable(i);
+            }
             case Instruction.Try i -> {
                 visitBlockInstr(i);
                 visitTry(i);
@@ -360,6 +364,14 @@ public void visitIf(Instruction.If ifBlock) {
         }
     }
 
+    public void visitTryTable(Instruction.TryTable tryBlock) {
+        for (Instruction.TryTable.Catch catchBlock : tryBlock.catchBlocks) {
+            visitId(catchBlock.tag);
+            visitId(catchBlock.label);
+        }
+        visitInstructions(tryBlock.instructions);
+    }
+
     public void visitTry(Instruction.Try tryBlock) {
         for (Instruction.Try.Catch catchBlock : tryBlock.catchBlocks) {
             visitId(catchBlock.tag);

From af323a89218841dec6edb87e959eb90509062482 Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 24 Oct 2025 17:54:00 +0200
Subject: [PATCH 3/8] Make Validator work with TryTable and blocks with return
 types

---
 .../hosted/webimage/wasm/ast/Instruction.java |   5 +
 .../wasm/ast/visitors/WasmValidator.java      | 147 +++++++++++++++---
 .../wasm/codegen/WebImageWasmCodeGen.java     |   8 +-
 3 files changed, 135 insertions(+), 25 deletions(-)

diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
index d29b9905a853..081dcc3c7c97 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/Instruction.java
@@ -609,6 +609,11 @@ public static Const forWord(WordBase word) {
             // TODO GR-42105 Use forInt
             return forLong(word.rawValue());
         }
+
+        @Override
+        protected String toInnerString() {
+            return literal.type + ", " + literal.asText();
+        }
     }
 
     /**
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java
index b0055c26b5fe..d182f4b418e6 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/ast/visitors/WasmValidator.java
@@ -78,10 +78,24 @@
 public class WasmValidator extends WasmVisitor {
     static class CtrlFrame {
         final WasmId.Label label;
+        final WasmValType returnType;
+        /**
+         * Whether the end of this frame (block) is unreachable. There might still be reachable code
+         * in the frame, but if this is true, execution can never reach the end of the block.
+         */
         boolean unreachable = false;
+        /**
+         * Whether any instructions target this block.
+         */
+        boolean targeted = false;
 
-        CtrlFrame(WasmId.Label label) {
+        CtrlFrame(WasmId.Label label, WasmValType returnType) {
             this.label = label;
+            this.returnType = returnType;
+        }
+
+        public WasmValType getReturnType() {
+            return returnType;
         }
     }
 
@@ -343,7 +357,7 @@ private void errorIf(boolean condition, String msg) {
         }
     }
 
-    private static boolean assertIdsEqual(WasmId first, WasmId second) {
+    private static boolean idsEqual(WasmId first, WasmId second) {
         return Objects.equals(first, second);
     }
 
@@ -351,13 +365,22 @@ private CtrlFrame topFrame() {
         return Objects.requireNonNull(ctrls.peek());
     }
 
+    /**
+     * Whether the current frame is marked as unreachable.
+     *
+     * @see #markUnreachable()
+     */
+    private boolean isUnreachable() {
+        return topFrame().unreachable;
+    }
+
     private void pushVal(WasmValType t) {
+        errorIf(isUnreachable(), "Tried to push " + t + " when unreachable");
         vals.push(t);
     }
 
     private WasmValType popVal() {
-        CtrlFrame top = topFrame();
-        if (vals.isEmpty() && top.unreachable) {
+        if (isUnreachable()) {
             return null;
         }
 
@@ -383,6 +406,10 @@ private RuntimeException typeMismatch(WasmValType[] expected, Deque<WasmValType>
      * @param expected The top of the stack must match this (the last element is at the very top).
      */
     private void popVals(WasmValType... expected) {
+        if (isUnreachable()) {
+            return;
+        }
+
         int numTypes = expected.length;
         if (vals.size() < numTypes) {
             throw typeMismatch(expected);
@@ -416,12 +443,20 @@ private Global getAndAssertGlobalExists(WasmId.Global global) {
     }
 
     private void pushCtrl(WasmId.Label label) {
+        pushCtrl(label, null);
+    }
+
+    private void pushCtrl(WasmId.Label label, WasmValType resultType) {
         assertStackEmpty();
         if (label != null) {
             // No name conflicts.
             assertIdUniqueName(label, ctrls.stream().map(frame -> frame.label).filter(Objects::nonNull).collect(Collectors.toList()));
         }
-        ctrls.push(new CtrlFrame(label));
+        ctrls.push(new CtrlFrame(label, resultType));
+    }
+
+    private void pushBlockCtrl(Instruction.WasmBlock block) {
+        pushCtrl(block.getLabel(), block.getResult());
     }
 
     private void popCtrl(WasmId.Label expectedLabel) {
@@ -430,6 +465,15 @@ private void popCtrl(WasmId.Label expectedLabel) {
         assertStackEmpty();
         errorIf(frame.label != expectedLabel, "Expected control frame " + expectedLabel + " but got " + frame.label);
         ctrls.pop();
+        /*
+         * If the end of the frame was unreachable and no instruction targeted it, it means that it
+         * is impossible to reach the instruction right after it and we have to mark the outer block
+         * as unreachable as well.
+         */
+        if (!frame.targeted && frame.unreachable && !ctrls.isEmpty()) {
+            markUnreachable();
+        }
+
     }
 
     private void popBlockCtrl(Instruction.WasmBlock block) {
@@ -442,7 +486,16 @@ private void popBlockCtrl(Instruction.WasmBlock block) {
         }
     }
 
-    private void unreachable() {
+    /**
+     * Marks the top frame as unreachable.
+     * <p>
+     * An unreachable frame satisfies all requirements on the operand stack (i.e.
+     * {@link #popVals(WasmValType...) never errors.}).
+     * <p>
+     * Call this method after visiting any instruction at which execution stops and never returns
+     * (e.g. {@code br}).
+     */
+    private void markUnreachable() {
         CtrlFrame top = topFrame();
         vals.clear();
         top.unreachable = true;
@@ -461,8 +514,15 @@ private void applyTypeUse(TypeUse typeUse) {
         typeUse.results.forEach(this::pushVal);
     }
 
-    private void assertLabelExists(WasmId.Label label) {
-        errorIf(ctrls.stream().noneMatch(frame -> assertIdsEqual(label, frame.label)), "Label " + label + " does not exist.");
+    private CtrlFrame markLabelTargeted(WasmId.Label label) {
+        CtrlFrame frame = ctrls.stream().filter(f -> idsEqual(label, f.label)).findFirst().orElseThrow(() -> error("Label " + label + " does not exist."));
+        frame.targeted = true;
+        return frame;
+    }
+
+    private void markLabelTargetedWithReturnType(WasmId.Label label, WasmValType returnType) {
+        CtrlFrame frame = markLabelTargeted(label);
+        errorIf(!Objects.equals(frame.getReturnType(), returnType), "Label " + label + " has return type " + frame.getReturnType() + " but " + returnType + " was expected");
     }
 
     /**
@@ -576,14 +636,14 @@ public void visitInstruction(Instruction inst) {
 
     @Override
     public void visitBlock(Instruction.Block block) {
-        pushCtrl(block.getLabel());
+        pushBlockCtrl(block);
         super.visitBlock(block);
         popBlockCtrl(block);
     }
 
     @Override
     public void visitLoop(Instruction.Loop loop) {
-        pushCtrl(loop.getLabel());
+        pushBlockCtrl(loop);
         super.visitLoop(loop);
         popBlockCtrl(loop);
     }
@@ -592,19 +652,63 @@ public void visitLoop(Instruction.Loop loop) {
     public void visitIf(Instruction.If ifBlock) {
         visitInstruction(ifBlock.condition);
         popVals(i32);
-        pushCtrl(ifBlock.getLabel());
+        pushBlockCtrl(ifBlock);
+
+        /*
+         * Propagating the information about unreachability upward here requires some more work. We
+         * only want to mark the end of the if-block as unreachable if both the end of the then- and
+         * else-branches are unreachable.
+         */
+        boolean thenBlockUnreachable = false;
+        boolean elseBlockUnreachable = false;
+
+        // Control frame around both branches to intercept the unreachable state
+        pushCtrl(null);
+
+        // Control frame around the then-branch
+        pushCtrl(null);
         visitInstructions(ifBlock.thenInstructions);
-        popBlockCtrl(ifBlock);
+        if (topFrame().unreachable) {
+            thenBlockUnreachable = true;
+            topFrame().unreachable = false;
+        }
+        popCtrl(null);
+
         if (ifBlock.hasElse()) {
-            pushCtrl(ifBlock.getLabel());
+            pushCtrl(null);
             visitInstructions(ifBlock.elseInstructions);
-            popBlockCtrl(ifBlock);
+            if (topFrame().unreachable) {
+                elseBlockUnreachable = true;
+                topFrame().unreachable = false;
+            }
+            popCtrl(null);
+        }
+        if (thenBlockUnreachable && elseBlockUnreachable) {
+            // This will mark the parent block as unreachable once we pop this control frame.
+            markUnreachable();
         }
+        popCtrl(null);
+        popBlockCtrl(ifBlock);
+    }
+
+    @Override
+    public void visitTryTable(Instruction.TryTable tryBlock) {
+        tryBlock.catchBlocks.forEach(this::assertCatchValid);
+        pushBlockCtrl(tryBlock);
+        visitInstructions(tryBlock.instructions);
+        popBlockCtrl(tryBlock);
+    }
+
+    private void assertCatchValid(Instruction.TryTable.Catch catchClause) {
+        errorIf(!ctxt.hasTag(catchClause.tag), "No matching tag for catch clause: " + catchClause);
+        List<WasmValType> catchParams = catchClause.tag.typeUse.params;
+        errorIf(catchParams.size() != 1, "Can only support catch clause tags with a single param, got" + catchParams.size());
+        markLabelTargetedWithReturnType(catchClause.label, catchParams.getFirst());
     }
 
     @Override
     public void visitTry(Instruction.Try tryBlock) {
-        pushCtrl(tryBlock.getLabel());
+        pushBlockCtrl(tryBlock);
         visitInstructions(tryBlock.instructions);
 
         for (Instruction.Try.Catch catchBlock : tryBlock.catchBlocks) {
@@ -620,7 +724,7 @@ public void visitTry(Instruction.Try tryBlock) {
 
     @Override
     public void visitUnreachable(Instruction.Unreachable unreachable) {
-        unreachable();
+        markUnreachable();
         super.visitUnreachable(unreachable);
     }
 
@@ -642,10 +746,10 @@ public void visitBreak(Instruction.Break inst) {
 
         WasmId.Label targetLabel = inst.getTarget();
 
-        assertLabelExists(targetLabel);
+        markLabelTargeted(targetLabel);
 
         if (inst.condition == null) {
-            unreachable();
+            markUnreachable();
         } else {
             popVals(i32);
         }
@@ -658,13 +762,13 @@ public void visitBreakTable(Instruction.BreakTable inst) {
         popVals(i32);
 
         WasmId.Label defaultLabel = inst.getDefaultTarget();
-        assertLabelExists(defaultLabel);
+        markLabelTargeted(defaultLabel);
 
         for (int i = 0; i < inst.numTargets(); i++) {
-            assertLabelExists(inst.getTarget(i));
+            markLabelTargeted(inst.getTarget(i));
         }
 
-        unreachable();
+        markUnreachable();
     }
 
     @Override
@@ -753,6 +857,7 @@ public void visitThrow(Instruction.Throw inst) {
 
         errorIf(!ctxt.hasTag(inst.tag), "No matching tag for throw: " + inst);
         applyTypeUse(inst.tag.typeUse);
+        markUnreachable();
     }
 
     @Override
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WebImageWasmCodeGen.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WebImageWasmCodeGen.java
index 4d65d92f802f..cfc100d0ffa2 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WebImageWasmCodeGen.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WebImageWasmCodeGen.java
@@ -185,10 +185,6 @@ protected void emitCode() {
         module.constructActiveDataSegments();
         ((WebImageWasmHeapBreakdownProvider) HeapBreakdownProvider.singleton()).setActualTotalHeapSize((int) getFullImageHeapSize());
 
-        if (WebImageOptions.DebugOptions.VerificationPhases.getValue(options)) {
-            validateModule();
-        }
-
         emitJSCode();
 
         try (Writer writer = Files.newBufferedWriter(watFile)) {
@@ -197,6 +193,10 @@ protected void emitCode() {
             throw new RuntimeException(e);
         }
 
+        if (WebImageOptions.DebugOptions.VerificationPhases.getValue(options)) {
+            validateModule();
+        }
+
         assembleWasmFile(watFile, wasmFile);
     }
 

From 3f5580cdc4e089a5df6a64615af7d316760a1211 Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Mon, 27 Oct 2025 09:55:38 +0100
Subject: [PATCH 4/8] Add --experimental-wasm-exnref flag to node

Required for the try_table based (exnref) exception handling, for
versions before Node 25
---
 web-image/mx.web-image/mx_web_image.py                        | 4 ++--
 .../svm/hosted/webimage/test/util/WebImageTestOptions.java    | 2 +-
 .../svm/hosted/webimage/test/util/WebImageTestUtil.java       | 3 +--
 3 files changed, 4 insertions(+), 5 deletions(-)

diff --git a/web-image/mx.web-image/mx_web_image.py b/web-image/mx.web-image/mx_web_image.py
index 9dd03341c882..ba603dff6971 100644
--- a/web-image/mx.web-image/mx_web_image.py
+++ b/web-image/mx.web-image/mx_web_image.py
@@ -49,7 +49,7 @@
 
 _suite = mx.suite("web-image")
 
-_web_image_js_engine_name = os.getenv("NODE_EXE", "node")
+_web_image_js_engine_name = [os.getenv("NODE_EXE", "node"), "--experimental-wasm-exnref"]
 
 # Name of GraalVm component defining the web-image macro
 web_image_component = "web-image"
@@ -489,7 +489,7 @@ def __init__(self):
     def apply(self, config):
         vm_args, main_class, main_class_args = config
 
-        vm_args += ["-Dwebimage.test.js=" + _web_image_js_engine_name]
+        vm_args += ["-Dwebimage.test.js=" + ",".join(_web_image_js_engine_name)]
         vm_args += ["-Dwebimage.test.launcher=" + vm_web_image_path()]
         vm_args += ["-Dwebimage.test.flags=" + ",".join(get_launcher_flags(WebImageConfiguration.test_cases))]
         # If any of the arguments contains spaces and double quotes, on Windows it will add its own quotes around
diff --git a/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestOptions.java b/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestOptions.java
index 8b72fd6c6741..94a3b0165849 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestOptions.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestOptions.java
@@ -31,7 +31,7 @@
 import jdk.graal.compiler.debug.GraalError;
 
 public class WebImageTestOptions {
-    public static final String JS_CMD = System.getProperty("webimage.test.js");
+    public static final List<String> JS_CMD = Arrays.asList(System.getProperty("webimage.test.js", ",").split(","));
     private static final String LAUNCHER = System.getProperty("webimage.test.launcher");
 
     /**
diff --git a/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestUtil.java b/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestUtil.java
index b47ed66dbcba..c61c5da8222b 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestUtil.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage.test/src/com/oracle/svm/hosted/webimage/test/util/WebImageTestUtil.java
@@ -191,8 +191,7 @@ public static RunResult executeTestProgram(Class<?> c, String[] args, int expect
     }
 
     public static RunResult runJS(String cmd, String[] arguments, int expectExitCode) {
-        List<String> invokeCmd = new ArrayList<>();
-        invokeCmd.add(WebImageTestOptions.JS_CMD);
+        List<String> invokeCmd = new ArrayList<>(WebImageTestOptions.JS_CMD);
         invokeCmd.add(cmd);
 
         if (arguments != null) {

From de882ea2850e4d5fd3a035d8288bda45846bd377 Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 24 Oct 2025 17:53:41 +0200
Subject: [PATCH 5/8] Implement try_table based exception handling

This is now the default
---
 web-image/mx.web-image/mx_web_image.py        |  3 +-
 .../NativeImageWasmGeneratorRunner.java       |  6 --
 .../stackifier/StackifierData.java            |  7 ++
 .../webimage/wasm/WebImageWasmOptions.java    |  3 +
 .../webimage/wasm/codegen/BinaryenCompat.java | 24 ++++-
 .../webimage/wasm/codegen/WasmIRWalker.java   | 94 +++++++++++++++++--
 .../phases/WasmLabeledBlockGeneration.java    | 15 +++
 7 files changed, 137 insertions(+), 15 deletions(-)

diff --git a/web-image/mx.web-image/mx_web_image.py b/web-image/mx.web-image/mx_web_image.py
index ba603dff6971..1d5494faa705 100644
--- a/web-image/mx.web-image/mx_web_image.py
+++ b/web-image/mx.web-image/mx_web_image.py
@@ -63,7 +63,7 @@
     "web-image:WEBIMAGE_CLOSURE_SUPPORT",
     "web-image:WEBIMAGE_GOOGLE_CLOSURE",
 ]
-# Hosted options defined in the web-image-enterprise suite
+# Hosted options defined in the web-image suite
 # This list has to be kept in sync with the code (the 'webimageoptions' gate tag checks this)
 # See also WebImageConfiguration.hosted_options
 web_image_hosted_options = [
@@ -92,6 +92,7 @@
     "GrowthTriggerThreshold=",
     "HeapGrowthFactor=",
     "ImageHeapObjectsPerFunction=",
+    "LegacyExceptions",
     "JSComments=",
     "JSRuntime=",
     "LogFilter=",
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/NativeImageWasmGeneratorRunner.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/NativeImageWasmGeneratorRunner.java
index b95214ea3680..759d00d663c6 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/NativeImageWasmGeneratorRunner.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/NativeImageWasmGeneratorRunner.java
@@ -54,7 +54,6 @@
 import com.oracle.svm.hosted.webimage.options.WebImageOptions.CompilerBackend;
 import com.oracle.svm.hosted.webimage.util.BenchmarkLogger;
 import com.oracle.svm.hosted.webimage.wasm.WebImageWasmLMJavaMainSupport;
-import com.oracle.svm.hosted.webimage.wasm.codegen.BinaryenCompat;
 import com.oracle.svm.hosted.webimage.wasmgc.WebImageWasmGCJavaMainSupport;
 import com.oracle.svm.webimage.WebImageJSJavaMainSupport;
 import com.oracle.svm.webimage.WebImageJavaMainSupport;
@@ -169,11 +168,6 @@ public int build(ImageClassLoader classLoader) {
             // For the Wasm backends, turn off closure compiler
             optionProvider.getHostedValues().put(WebImageOptions.ClosureCompiler, false);
 
-            if (backend == CompilerBackend.WASMGC && !optionProvider.getHostedValues().containsKey(BinaryenCompat.Options.UseBinaryen)) {
-                // For WasmGC backend, use binaryen by default
-                optionProvider.getHostedValues().put(BinaryenCompat.Options.UseBinaryen, true);
-            }
-
             if (!optionProvider.getHostedValues().containsKey(WebImageOptions.NamingConvention)) {
                 // The naming convention does not affect the binary image (unless debug information
                 // is embedded) and the REDUCED mode makes the text file a lot easier to read
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/codegen/reconstruction/stackifier/StackifierData.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/codegen/reconstruction/stackifier/StackifierData.java
index a721d8653e1b..40e87474f139 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/codegen/reconstruction/stackifier/StackifierData.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/codegen/reconstruction/stackifier/StackifierData.java
@@ -58,6 +58,8 @@ public class StackifierData implements ReconstructionData {
      */
     private HIRBlock[] blocks;
 
+    private ControlFlowGraph cfg;
+
     /**
      * Mapping from a basic block to its index in {@link #blocks}.
      */
@@ -92,6 +94,10 @@ public HIRBlock[] getBlocks() {
         return blocks;
     }
 
+    public ControlFlowGraph getCfg() {
+        return cfg;
+    }
+
     public EconomicMap<HIRBlock, Scope> getEnclosingScope() {
         return enclosingScope;
     }
@@ -134,6 +140,7 @@ public void setLabeledBlockEnd(EconomicMap<HIRBlock, LabeledBlock> labeledBlockE
 
     public void setSortedBlocks(HIRBlock[] sortedBlocks, ControlFlowGraph cfg) {
         this.blocks = sortedBlocks;
+        this.cfg = cfg;
         this.blockIndexSortOrder = new BlockMap<>(cfg);
         for (int i = 0; i < sortedBlocks.length; ++i) {
             this.blockIndexSortOrder.put(sortedBlocks[i], i);
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/WebImageWasmOptions.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/WebImageWasmOptions.java
index b01b54d47575..981f84bb1d79 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/WebImageWasmOptions.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/WebImageWasmOptions.java
@@ -49,6 +49,9 @@ public class WebImageWasmOptions {
                     "Has no effect on code size, the binary format does not have comments.")//
     public static final EnumOptionKey<CommentVerbosity> WasmComments = new EnumOptionKey<>(CommentVerbosity.NORMAL);
 
+    @Option(help = "Enable the legacy exception proposal using try-catch instead of try_table") //
+    public static final HostedOptionKey<Boolean> LegacyExceptions = new HostedOptionKey<>(false);
+
     @Option(help = "Assemble the Wasm binary file with debug names.")//
     public static final HostedOptionKey<Boolean> DebugNames = new HostedOptionKey<>(false) {
 
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/BinaryenCompat.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/BinaryenCompat.java
index 34488f0fb8b6..8fbf4aa40ace 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/BinaryenCompat.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/BinaryenCompat.java
@@ -27,11 +27,17 @@
 
 import java.util.Objects;
 
+import org.graalvm.collections.UnmodifiableEconomicMap;
+
 import com.oracle.svm.core.option.HostedOptionKey;
+import com.oracle.svm.hosted.webimage.options.WebImageOptions;
+import com.oracle.svm.hosted.webimage.wasm.WebImageWasmOptions;
 import com.oracle.svm.hosted.webimage.wasm.ast.visitors.WasmPrinter;
 import com.oracle.svm.webimage.wasm.types.WasmValType;
 
 import jdk.graal.compiler.options.Option;
+import jdk.graal.compiler.options.OptionKey;
+import jdk.graal.compiler.options.OptionValues;
 import jdk.vm.ci.code.site.Reference;
 
 /**
@@ -43,7 +49,23 @@ public class BinaryenCompat {
 
     public static class Options {
         @Option(help = "Use Binaryen (wasm-as) to assemble the final Wasm binary")//
-        public static final HostedOptionKey<Boolean> UseBinaryen = new HostedOptionKey<>(false);
+        public static final HostedOptionKey<Boolean> UseBinaryen = new HostedOptionKey<>(false) {
+            @Override
+            public Boolean getValue(OptionValues values) {
+                assert checkDescriptorExists();
+                return getValueOrDefault(values.getMap());
+            }
+
+            @Override
+            public Boolean getValueOrDefault(UnmodifiableEconomicMap<OptionKey<?>, Object> values) {
+                if (values.containsKey(this)) {
+                    return (Boolean) values.get(this);
+                }
+
+                // Binaryen is the default for WasmGC or when the new exception handling is used.
+                return WebImageOptions.getBackend() == WebImageOptions.CompilerBackend.WASMGC || !WebImageWasmOptions.LegacyExceptions.getValueOrDefault(values);
+            }
+        };
     }
 
     public static boolean usesBinaryen() {
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmIRWalker.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmIRWalker.java
index 27286491f3f6..d292ccf02e18 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmIRWalker.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmIRWalker.java
@@ -35,6 +35,8 @@
 import java.util.Map;
 import java.util.stream.Stream;
 
+import com.oracle.svm.hosted.webimage.wasm.WebImageWasmOptions;
+import com.oracle.svm.hosted.webimage.wasm.ast.id.WebImageWasmIds;
 import org.graalvm.collections.Pair;
 
 import com.oracle.svm.core.graal.nodes.ReadExceptionObjectNode;
@@ -184,13 +186,16 @@ protected void predeclareVariables(StructuredGraph graph) {
      *
      * @param currentBlock block from which to jump from
      * @param successor target of the jump
+     * @return Whether a jump was generated
      */
-    private void generateForwardJump(HIRBlock currentBlock, HIRBlock successor) {
+    private boolean generateForwardJump(HIRBlock currentBlock, HIRBlock successor) {
         WasmId.Label id = getForwardJumpTarget(currentBlock, successor);
 
         if (id != null) {
             masm.genInst(new Break(id), "forward jump");
+            return true;
         }
+        return false;
     }
 
     private WasmId.Label getForwardJumpTarget(HIRBlock currentBlock, HIRBlock successor) {
@@ -278,6 +283,85 @@ protected void lowerLoopEnd(LoopEndNode loopEnd) {
     /**
      * Lower a WithExceptionNode.
      *
+     * @param currentBlock basic block that ends with {@link WithExceptionNode}
+     * @param lastNode the {@link WithExceptionNode}
+     * @see #lowerWithExceptionExnRef(HIRBlock, WithExceptionNode)
+     * @see #lowerWithExceptionLegacy(HIRBlock, WithExceptionNode)
+     */
+    @Override
+    protected void lowerWithException(HIRBlock currentBlock, WithExceptionNode lastNode) {
+        assert currentBlock.getEndNode() == lastNode : currentBlock.toString(Verbosity.Name);
+        if (WebImageWasmOptions.LegacyExceptions.getValue()) {
+            lowerWithExceptionLegacy(currentBlock, lastNode);
+        } else {
+            lowerWithExceptionExnRef(currentBlock, lastNode);
+        }
+    }
+
+    /**
+     * Lower a WithExceptionNode using the exnref exception handling proposal.
+     *
+     * <pre>
+     * {@code
+     * (block $exnBlock (result $throwable)
+     *     (try_table (catch $exc_tag $exnBlock)
+     *         WithExceptionNode();
+     *         br Successor
+     *     )
+     * )
+     * (local.set $exc_var)
+     * ExceptionEdge();
+     * }
+     * </pre>
+     *
+     * The {@link WithExceptionNode} is wrapped in a {@code try_table} block, which is surrounded by
+     * a block that's the target of the catch scope. After the block around the {@code try_table}
+     * instruction, the thrown value is already on the stack, we store it in a dedicated local
+     * variable ({@link WebImageWasmNodeLowerer#exceptionObjectVariable}) so that it can be read
+     * later by {@link ReadExceptionObjectNode}. The
+     * {@link com.oracle.svm.hosted.webimage.wasm.phases.WasmLabeledBlockGeneration} ensures that
+     * the regular successor always requires a forward jump.
+     *
+     * @see #lowerWithException(HIRBlock, WithExceptionNode)
+     */
+    protected void lowerWithExceptionExnRef(HIRBlock currentBlock, WithExceptionNode lastNode) {
+        WebImageWasmIds.InternalLabel exceptionHandlerLabel = masm.idFactory.newInternalLabel("exn" + currentBlock.getId());
+        Instruction.Block exceptionTargetBlock = new Instruction.Block(exceptionHandlerLabel, masm.getWasmProviders().util().getThrowableType());
+        masm.genInst(exceptionTargetBlock);
+
+        masm.childScope(exceptionTargetBlock.instructions, exceptionTargetBlock);
+        Instruction.TryTable tryBlock = new Instruction.TryTable(null);
+        tryBlock.addCatch(masm.getKnownIds().getJavaThrowableTag(), exceptionHandlerLabel);
+        masm.genInst(tryBlock, lastNode);
+
+        masm.childScope(tryBlock.instructions, tryBlock);
+        lowerNode(lastNode);
+        HIRBlock normSucc = cfg.blockFor(lastNode.next());
+        boolean didJump = generateForwardJump(currentBlock, normSucc);
+        GraalError.guarantee(didJump, "No jump was inserted after a WithExceptionNode");
+        masm.parentScope(tryBlock);
+
+        masm.parentScope(exceptionTargetBlock);
+
+        masm.genInst(masm.nodeLowerer().exceptionObjectVariable.setter(new Instruction.Nop()), "Store exception object");
+        masm.lowerCatchPreamble();
+
+        CatchScopeContainer scopeEntry = (CatchScopeContainer) stackifierData.getScopeEntry(lastNode);
+        Scope catchScope = scopeEntry.getCatchScope();
+        if (catchScope != null) {
+            lowerBlocks(catchScope.getSortedBlocks(stackifierData));
+            // Just a sanity check
+            masm.genInst(new Unreachable(), "End of catch block is unreachable, it must break out");
+        } else {
+            HIRBlock excpSucc = cfg.blockFor(lastNode.exceptionEdge());
+            boolean didJumpAfterCatch = generateForwardJump(currentBlock, excpSucc);
+            GraalError.guarantee(didJumpAfterCatch, "No jump was inserted in catch block");
+        }
+    }
+
+    /**
+     * Lower a WithExceptionNode using the legacy exception handling proposal.
+     *
      * <pre>
      * {@code
      * (try
@@ -301,13 +385,9 @@ protected void lowerLoopEnd(LoopEndNode loopEnd) {
      * ({@link WebImageWasmNodeLowerer#exceptionObjectVariable}) so that it can be read later by
      * {@link ReadExceptionObjectNode}.
      *
-     * @param currentBlock basic block that ends with {@link WithExceptionNode}
-     * @param lastNode the {@link WithExceptionNode}
+     * @see #lowerWithException(HIRBlock, WithExceptionNode)
      */
-    @Override
-    protected void lowerWithException(HIRBlock currentBlock, WithExceptionNode lastNode) {
-        assert currentBlock.getEndNode() == lastNode : currentBlock.toString(Verbosity.Name);
-
+    protected void lowerWithExceptionLegacy(HIRBlock currentBlock, WithExceptionNode lastNode) {
         Instruction.Try tryBlock = new Instruction.Try(null);
         masm.genInst(tryBlock, lastNode);
 
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/phases/WasmLabeledBlockGeneration.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/phases/WasmLabeledBlockGeneration.java
index 7f8893a22d02..babc3534735d 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/phases/WasmLabeledBlockGeneration.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/phases/WasmLabeledBlockGeneration.java
@@ -28,6 +28,8 @@
 import com.oracle.svm.hosted.webimage.codegen.reconstruction.stackifier.LabeledBlockGeneration;
 import com.oracle.svm.hosted.webimage.codegen.reconstruction.stackifier.StackifierData;
 
+import com.oracle.svm.hosted.webimage.wasm.WebImageWasmOptions;
+import jdk.graal.compiler.nodes.WithExceptionNode;
 import jdk.graal.compiler.nodes.cfg.ControlFlowGraph;
 import jdk.graal.compiler.nodes.cfg.HIRBlock;
 
@@ -53,6 +55,19 @@ public boolean isLabeledBlockNeeded(HIRBlock block, HIRBlock successor) {
             return true;
         }
 
+        if (!WebImageWasmOptions.LegacyExceptions.getValue() && block.getEndNode() instanceof WithExceptionNode withExceptionNode) {
+            HIRBlock normSucc = stackifierData.getCfg().blockFor(withExceptionNode.next());
+            if (normSucc.equals(successor)) {
+                /*
+                 * With the new exception handling, we need an explicit labeled block when going
+                 * from the WithExceptionNode to its regular successor because in the Wasm code, the
+                 * successor does not appear directly after, the catch block does, and we would then
+                 * fall through to that.
+                 */
+                return true;
+            }
+        }
+
         return false;
     }
 }

From 45ca113b69ffa7ee4432ebfe7ae86cb4ef146b15 Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 31 Oct 2025 12:02:25 +0100
Subject: [PATCH 6/8] Improve Web Image README

---
 web-image/README.md | 57 +++++++++++++++++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 7 deletions(-)

diff --git a/web-image/README.md b/web-image/README.md
index eb2f3f11db2c..b3f814f6019d 100644
--- a/web-image/README.md
+++ b/web-image/README.md
@@ -1,14 +1,44 @@
 # Web Image
 
+Web Image is an experimental backend for Native Image that produces a
+WebAssembly module from Java code.
+
+## Prerequisites
+
+Being part of Native Image, check out its [Quick Start Guide](../docs/reference-manual/native-image/contribute/DevelopingNativeImage.md)
+for all the prerequisites for building Native Image.
+
+In addition, Web Image also uses `wasm-as` from
+[binaryen](https://github.com/WebAssembly/binaryen) as its assembler.
+Version 119 of `wasm-as` has to be available on your `PATH`.
+
+<details>
+<summary>Installation</summary>
+
+Binaryen provides pre-built releases for all major platforms on
+[GitHub](https://github.com/WebAssembly/binaryen/releases).
+
+On MacOS, it is recommended to install through [Homebrew](https://brew.sh/), as
+the pre-built binaries are not signed and may be quarantined by MacOS.
+
+```bash
+brew install binaryen
+```
+</details>
+
 ## Building
 
+To build Web Image, run the `mx build` command in the `web-image` suite:
+
 ```bash
+cd /path/to/graal
+cd web-image
 mx build
 ```
 
 ## Usage
 
-Use this as you would regular the regular `native-image` tool, but with an
+Use this as you would use the regular `native-image` tool, but with an
 additional `--tool:svm-wasm` flag to enable the WebAssembly backend:
 
 ```bash
@@ -16,18 +46,31 @@ mx native-image --tool:svm-wasm -cp ... HelloWorld
 ```
 
 This produces `helloworld.js` and `helloworld.js.wasm` in your working
-directory. The JavaScript file is a wrapper that loads and runs the WebAssembly
-code and can be run with [Node.js](https://nodejs.org/en) 22 or later:
+directory. The `--tool:svm-wasm` flag should be the first argument if possible.
+If any experimental options specific to the Wasm backend are used, they can
+only be added after the `--tool:svm-wasm` flag.
 
-The `--tool:svm-wasm` flag should be the first argument if possible. If any
-experimental options specific to the Wasm backend are used, they can only be
-added after the `--tool:svm-wasm` flag.
+The JavaScript file is a wrapper that loads and runs the WebAssembly
+code and can be run with [Node.js](https://nodejs.org/en) 22 or later:
 
 ```bash
-$ node helloworld.js
+# --experimental-wasm-exnref is only required for Node versions before 25
+$ node --experimental-wasm-exnref helloworld.js
 Hello World
 ```
 
+## WebAssembly Features
+
+The WebAssembly code generated by Web Image makes use of various WebAssembly
+features from WebAssembly 3.0:
+
+- [Garbage Collection](https://github.com/WebAssembly/gc)
+- [Exception Handling](https://github.com/WebAssembly/exception-handling/blob/master/proposals/exception-handling/Exceptions.md)
+- [Typed Function References](https://github.com/WebAssembly/function-references/blob/main/proposals/function-references/Overview.md)
+
+Support for [WebAssembly 2.0](https://www.w3.org/TR/wasm-core-2/#release-20) is
+generally assumed.
+
 ## Contributors
 
 - Aleksandar Prokopec

From fe086b8bdc43d55883aff2b537a2f28f952ca8b3 Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 31 Oct 2025 12:04:05 +0100
Subject: [PATCH 7/8] Improve Wasm assembler error message

Now includes information about which tool is missing and where to get
it.
---
 web-image/README.md                           |  2 +-
 .../webimage/wasm/codegen/WasmAssembler.java  | 41 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/web-image/README.md b/web-image/README.md
index b3f814f6019d..d92ca706686f 100644
--- a/web-image/README.md
+++ b/web-image/README.md
@@ -5,7 +5,7 @@ WebAssembly module from Java code.
 
 ## Prerequisites
 
-Being part of Native Image, check out its [Quick Start Guide](../docs/reference-manual/native-image/contribute/DevelopingNativeImage.md)
+Being part of Native Image, see the [Quick Start Guide](../docs/reference-manual/native-image/contribute/DevelopingNativeImage.md)
 for all the prerequisites for building Native Image.
 
 In addition, Web Image also uses `wasm-as` from
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmAssembler.java b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmAssembler.java
index 97c9b5996af3..649305869f8d 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmAssembler.java
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/WasmAssembler.java
@@ -189,6 +189,16 @@ private static RunResult runCommand(Path executable, List<String> args) throws I
         }
     }
 
+    protected String getDetails() {
+        return "'%s' is part of the %s project (%s). At least version %s is required.".formatted(getExecutable(), getProjectName(), getURL(), getMinimumVersion());
+    }
+
+    protected abstract String getProjectName();
+
+    protected abstract String getURL();
+
+    protected abstract String getMinimumVersion();
+
     /**
      * The standard name of the assembler executable.
      */
@@ -243,6 +253,7 @@ private UserError.UserException rethrowWithInfo(UserError.UserException err) {
         if (!pathOption.hasBeenSet()) {
             messages.add("A custom path to the " + getExecutable() + " executable can be set with the " + SubstrateOptionsParser.commandArgument(getPathOption(), "<path>") + " command-line option");
         }
+        messages.add(getDetails());
         messages.add("To prevent native-toolchain checking provide command-line option " + SubstrateOptionsParser.commandArgument(SubstrateOptions.CheckToolchain, "-"));
         return UserError.abort(messages);
     }
@@ -394,6 +405,21 @@ protected Wat2Wasm(Path tempDirectory) {
             super(tempDirectory);
         }
 
+        @Override
+        protected String getProjectName() {
+            return "wabt";
+        }
+
+        @Override
+        protected String getURL() {
+            return "https://github.com/WebAssembly/wabt";
+        }
+
+        @Override
+        protected String getMinimumVersion() {
+            return "1.0.32";
+        }
+
         @Override
         protected String getExecutable() {
             return "wat2wasm";
@@ -439,6 +465,21 @@ protected Binaryen(Path tempDirectory) {
             super(tempDirectory);
         }
 
+        @Override
+        protected String getProjectName() {
+            return "Binaryen";
+        }
+
+        @Override
+        protected String getURL() {
+            return "https://github.com/WebAssembly/binaryen";
+        }
+
+        @Override
+        protected String getMinimumVersion() {
+            return "119";
+        }
+
         @Override
         protected String getExecutable() {
             return "wasm-as";

From 880aa247097507412783ca00eaa3952bba11a0fe Mon Sep 17 00:00:00 2001
From: Patrick Ziegler <patrick.ziegler@oracle.com>
Date: Fri, 31 Oct 2025 16:48:22 +0100
Subject: [PATCH 8/8] Update wasm verification files to use try_table

---
 .../webimage/wasm/codegen/verify-wasm-as.wast | 24 +++++++++++--------
 .../wasm/codegen/verify-wat2wasm.wast         |  2 +-
 2 files changed, 15 insertions(+), 11 deletions(-)

diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wasm-as.wast b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wasm-as.wast
index eb165423646a..5211d57c0014 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wasm-as.wast
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wasm-as.wast
@@ -23,19 +23,23 @@
 
   (start $main)
   (func $main
-    (try
-      (do (call $throwB))
-      (catch $tag0
-        (drop (call $checkException))
-      )
+    (block $catchBlock (result (ref $A))
+        (try_table
+          (catch $tag0 $catchBlock)
+          (call $throwB)
+          (unreachable)
+        )
     )
+    (drop (call $checkException))
 
-    (try
-      (do (call $throwC))
-      (catch $tag0
-        (drop (call $checkException))
-      )
+    (block $catchBlock (result (ref $A))
+        (try_table
+          (catch $tag0 $catchBlock)
+          (call $throwC)
+          (unreachable)
+        )
     )
+    (drop (call $checkException))
   )
 
   (func $checkException (param $p0 (ref $A)) (result (ref null $A))
diff --git a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wat2wasm.wast b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wat2wasm.wast
index af6d54a3ee8c..10a1a507eea0 100644
--- a/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wat2wasm.wast
+++ b/web-image/src/com.oracle.svm.hosted.webimage/src/com/oracle/svm/hosted/webimage/wasm/codegen/verify-wat2wasm.wast
@@ -1,7 +1,7 @@
 (;
   Wasm text file to verify the wat2wasm assembler works correctly.
 
-  Uses features from the exception handling proposal
+  Uses features from the legacy exception handling proposal
 ;)
 (module
   (tag $tag0 (param i32))