From 9149f4cdeee0949e5dab4b0e0e076c73b822cbfc Mon Sep 17 00:00:00 2001
From: "Alon Zakai (kripken)" <alonzakai@gmail.com>
Date: Sat, 5 Aug 2017 10:44:12 -0700
Subject: fix reading of stacky unreadable code with elements we need to drop

---
 src/wasm/wasm-binary.cpp | 32 ++++++++++++++++----------------
 1 file changed, 16 insertions(+), 16 deletions(-)

(limited to 'src/wasm/wasm-binary.cpp')

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 47bcc8ba5..018e463e0 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -2073,6 +2073,20 @@ BinaryConsts::ASTNodes WasmBinaryBuilder::readExpression(Expression*& curr) {
   return BinaryConsts::ASTNodes(code);
 }
 
+void WasmBinaryBuilder::pushBlockElements(Block* curr, size_t start, size_t end) {
+  for (size_t i = start; i < end; i++) {
+    auto* item = expressionStack[i];
+    curr->list.push_back(item);
+    if (i < end - 1) {
+      // stacky&unreachable code may introduce elements that need to be dropped in non-final positions
+      if (isConcreteWasmType(item->type)) {
+        curr->list.back() = Builder(wasm).makeDrop(curr->list.back());
+      }
+    }
+  }
+  expressionStack.resize(start);
+}
+
 void WasmBinaryBuilder::visitBlock(Block *curr) {
   if (debug) std::cerr << "zz node: Block" << std::endl;
   // special-case Block and de-recurse nested blocks in their first position, as that is
@@ -2108,18 +2122,7 @@ void WasmBinaryBuilder::visitBlock(Block *curr) {
     if (end < start) {
       throw ParseException("block cannot pop from outside");
     }
-    for (size_t i = start; i < end; i++) {
-      if (debug) std::cerr << "  " << size_t(expressionStack[i]) << "\n zz Block element " << curr->list.size() << std::endl;
-      auto* item = expressionStack[i];
-      curr->list.push_back(item);
-      if (i < end - 1) {
-        // stacky&unreachable code may introduce elements that need to be dropped in non-final positions
-        if (isConcreteWasmType(item->type)) {
-          curr->list.back() = Builder(wasm).makeDrop(curr->list.back());
-        }
-      }
-    }
-    expressionStack.resize(start);
+    pushBlockElements(curr, start, end);
     curr->finalize(curr->type);
     breakStack.pop_back();
   }
@@ -2136,11 +2139,8 @@ Expression* WasmBinaryBuilder::getMaybeBlock(WasmType type) {
     throw ParseException("block cannot pop from outside");
   }
   auto* block = allocator.alloc<Block>();
-  for (size_t i = start; i < end; i++) {
-    block->list.push_back(expressionStack[i]);
-  }
+  pushBlockElements(block, start, end);
   block->finalize(type);
-  expressionStack.resize(start);
   return block;
 }
 
-- 
cgit v1.2.3


From 5b9fff4399b959a4af28a6c82e8ab9243898f360 Mon Sep 17 00:00:00 2001
From: Alon Zakai <alonzakai@gmail.com>
Date: Thu, 3 Aug 2017 14:49:41 -0700
Subject: emit an unreachable if an unreachable block context does not end in
 an unreachable

---
 src/wasm/wasm-binary.cpp              |  5 +++++
 test/unit.wast                        | 12 ++++++++++++
 test/unit.wast.from-wast              | 12 ++++++++++++
 test/unit.wast.fromBinary             | 15 +++++++++++++++
 test/unit.wast.fromBinary.noDebugInfo | 15 +++++++++++++++
 5 files changed, 59 insertions(+)

(limited to 'src/wasm/wasm-binary.cpp')

diff --git a/src/wasm/wasm-binary.cpp b/src/wasm/wasm-binary.cpp
index 018e463e0..63dddbdd6 100644
--- a/src/wasm/wasm-binary.cpp
+++ b/src/wasm/wasm-binary.cpp
@@ -583,6 +583,11 @@ void WasmBinaryWriter::recursePossibleBlockContents(Expression* curr) {
   for (auto* child : block->list) {
     recurse(child);
   }
+  if (block->type == unreachable && block->list.back()->type != unreachable) {
+    // similar to in visitBlock, here we could skip emitting the block itself,
+    // but must still end the 'block' (the contents, really) with an unreachable
+    o << int8_t(BinaryConsts::Unreachable);
+  }
 }
 
 void WasmBinaryWriter::visitIf(If *curr) {
diff --git a/test/unit.wast b/test/unit.wast
index c1a945264..a429675de 100644
--- a/test/unit.wast
+++ b/test/unit.wast
@@ -537,4 +537,16 @@
     (if (i32.const 1) (nop) (unreachable))
     (if (i32.const 1) (unreachable) (unreachable))
   )
+  (func $unreachable-if-arm
+    (if
+      (i32.const 1)
+      (block
+        (nop)
+      )
+      (block
+        (unreachable)
+        (i32.const 1) ;; ends in a concrete, after an unreachable
+      )
+    )
+  )
 )
diff --git a/test/unit.wast.from-wast b/test/unit.wast.from-wast
index bb66845af..7fb82d69d 100644
--- a/test/unit.wast.from-wast
+++ b/test/unit.wast.from-wast
@@ -602,4 +602,16 @@
    (unreachable)
   )
  )
+ (func $unreachable-if-arm (type $FUNCSIG$v)
+  (if
+   (i32.const 1)
+   (block $block
+    (nop)
+   )
+   (block $block12
+    (unreachable)
+    (i32.const 1)
+   )
+  )
+ )
 )
diff --git a/test/unit.wast.fromBinary b/test/unit.wast.fromBinary
index 78ae640b1..8bb80bcca 100644
--- a/test/unit.wast.fromBinary
+++ b/test/unit.wast.fromBinary
@@ -646,5 +646,20 @@
   )
   (unreachable)
  )
+ (func $unreachable-if-arm (type $1)
+  (if
+   (i32.const 1)
+   (block $label$0
+    (nop)
+   )
+   (block $label$1
+    (unreachable)
+    (drop
+     (i32.const 1)
+    )
+    (unreachable)
+   )
+  )
+ )
 )
 
diff --git a/test/unit.wast.fromBinary.noDebugInfo b/test/unit.wast.fromBinary.noDebugInfo
index 3c24886f5..09da9a15b 100644
--- a/test/unit.wast.fromBinary.noDebugInfo
+++ b/test/unit.wast.fromBinary.noDebugInfo
@@ -646,5 +646,20 @@
   )
   (unreachable)
  )
+ (func $36 (type $1)
+  (if
+   (i32.const 1)
+   (block $label$0
+    (nop)
+   )
+   (block $label$1
+    (unreachable)
+    (drop
+     (i32.const 1)
+    )
+    (unreachable)
+   )
+  )
+ )
 )
 
-- 
cgit v1.2.3