Translator: Fix a miscompilation for unreachable br_table

Author: kateinoigakukun

Sources/WasmKit/Translator.swift

@@ -1313,7 +1313,13 @@ struct InstructionTranslator<Context: TranslatorContext>: InstructionVisitor {
 
         let defaultFrame = try controlStack.branchTarget(relativeDepth: targets.defaultIndex)
 
-        preserveOnStack(depth: Int(defaultFrame.copyCount))
+        // If this instruction is unreachable, copyCount might be greater than the actual stack height
+        try preserveOnStack(
+            depth: min(
+                Int(defaultFrame.copyCount),
+                valueStack.height - controlStack.currentFrame().stackHeight
+            )
+        )
         let allLabelIndices = targets.labelIndices + [targets.defaultIndex]
         let tableBuffer = allocator.allocateBrTable(capacity: allLabelIndices.count)
         let operand = Instruction.BrTableOperand(

Tests/WasmKitTests/SpectestTests.swift

@@ -22,7 +22,6 @@ final class SpectestTests: XCTestCase {
             path: Self.testPaths,
             include: [],
             exclude: [
-                "br.wast",
                 "br_if.wast",
                 "call.wast",
                 "call_indirect.wast",