Fix several wasm warnings an a use after free.

Fixing several signed/unsigned comparison warnings for wasm.
Fixing a use after free involving ostringsteam::str()

R=ahaas@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1533593004

Cr-Commit-Position: refs/heads/master@{#32946}

src/wasm/ast-decoder.cc

@@ -48,7 +48,7 @@ struct Production {
 
   WasmOpcode opcode() const { return static_cast<WasmOpcode>(*pc()); }
   const byte* pc() const { return tree->pc; }
-  bool done() const { return index >= tree->count; }
+  bool done() const { return index >= static_cast<int>(tree->count); }
   Tree* last() const { return index > 0 ? tree->children[index - 1] : nullptr; }
 };
 
@@ -611,7 +611,7 @@ class LR_WasmDecoder : public Decoder {
       return;
     }
 
-    if (trees_.size() < retcount) {
+    if (static_cast<int>(trees_.size()) < retcount) {
       error(limit_, nullptr,
             "ImplicitReturn expects %d arguments, only %d remain", retcount,
             static_cast<int>(trees_.size()));
@@ -998,7 +998,7 @@ class LR_WasmDecoder : public Decoder {
           FunctionSig* sig = FunctionSigOperand(p->pc(), &index, &len);
           USE(sig);
           buffer[0] = nullptr;  // reserved for code object.
-          for (int i = 1; i < count; i++) {
+          for (uint32_t i = 1; i < count; i++) {
             buffer[i] = p->tree->children[i - 1]->node;
           }
           p->tree->node = builder_->CallDirect(index, buffer);
@@ -1017,7 +1017,7 @@ class LR_WasmDecoder : public Decoder {
         if (p->done() && build()) {
           uint32_t count = p->tree->count;
           TFNode** buffer = builder_->Buffer(count);
-          for (int i = 0; i < count; i++) {
+          for (uint32_t i = 0; i < count; i++) {
             buffer[i] = p->tree->children[i]->node;
           }
           p->tree->node = builder_->CallIndirect(index, buffer);
@@ -1169,7 +1169,9 @@ class LR_WasmDecoder : public Decoder {
         } else if (to->effect != from->effect) {
           uint32_t count = builder_->InputCount(merge);
           TFNode** effects = builder_->Buffer(count);
-          for (int j = 0; j < count - 1; j++) effects[j] = to->effect;
+          for (uint32_t j = 0; j < count - 1; j++) {
+            effects[j] = to->effect;
+          }
           effects[count - 1] = from->effect;
           to->effect = builder_->EffectPhi(count, effects, merge);
         }
@@ -1182,7 +1184,9 @@ class LR_WasmDecoder : public Decoder {
           } else if (tnode != fnode) {
             uint32_t count = builder_->InputCount(merge);
             TFNode** vals = builder_->Buffer(count);
-            for (int j = 0; j < count - 1; j++) vals[j] = tnode;
+            for (uint32_t j = 0; j < count - 1; j++) {
+              vals[j] = tnode;
+            }
             vals[count - 1] = fnode;
             to->locals[i] = builder_->Phi(function_env_->GetLocalType(i), count,
                                           vals, merge);
@@ -1203,7 +1207,7 @@ class LR_WasmDecoder : public Decoder {
     } else if (tnode != fnode) {
       uint32_t count = builder_->InputCount(merge);
       TFNode** vals = builder_->Buffer(count);
-      for (int j = 0; j < count - 1; j++) vals[j] = tnode;
+      for (uint32_t j = 0; j < count - 1; j++) vals[j] = tnode;
       vals[count - 1] = fnode;
       return builder_->Phi(type, count, vals, merge);
     }
@@ -1430,7 +1434,7 @@ std::ostream& operator<<(std::ostream& os, const Tree& tree) {
   }
   PrintF("%s", WasmOpcodes::OpcodeName(tree.opcode()));
   if (tree.count > 0) os << "(";
-  for (int i = 0; i < tree.count; i++) {
+  for (uint32_t i = 0; i < tree.count; i++) {
     if (i > 0) os << ", ";
     os << *tree.children[i];
   }
@@ -1571,6 +1575,8 @@ int OpcodeArity(FunctionEnv* env, const byte* pc) {
       FOREACH_SIMPLE_OPCODE(DECLARE_OPCODE_CASE)
 #undef DECLARE_OPCODE_CASE
   }
+  UNREACHABLE();
+  return 0;
 }
 }  // namespace wasm
 }  // namespace internal

src/wasm/ast-decoder.h

@@ -35,8 +35,10 @@ struct FunctionEnv {
   bool IsValidLocal(uint32_t index) { return index < total_locals; }
   uint32_t GetLocalCount() { return total_locals; }
   LocalType GetLocalType(uint32_t index) {
-    if (index < sig->parameter_count()) return sig->GetParam(index);
-    index -= sig->parameter_count();
+    if (index < static_cast<uint32_t>(sig->parameter_count())) {
+      return sig->GetParam(index);
+    }
+    index -= static_cast<uint32_t>(sig->parameter_count());
     if (index < local_int32_count) return kAstI32;
     index -= local_int32_count;
     if (index < local_int64_count) return kAstI64;

src/wasm/decoder.h

@@ -198,8 +198,8 @@ class Decoder {
       error_msg_.Reset(nullptr);
     } else {
       result.error_code = kSuccess;
-      result.val = val;
     }
+    result.val = val;
     return result;
   }
 

src/wasm/encoder.cc

@@ -159,7 +159,7 @@ WasmFunctionEncoder* WasmFunctionBuilder::Build(Zone* zone,
       new (zone) WasmFunctionEncoder(zone, return_type_, exported_, external_);
   auto var_index = new uint16_t[locals_.size()];
   IndexVars(e, var_index);
-  const byte* start = body_.data();
+  const byte* start = &body_[0];
   const byte* end = start + body_.size();
   size_t local_index = 0;
   for (size_t i = 0; i < body_.size();) {
@@ -282,7 +282,7 @@ void WasmFunctionEncoder::Serialize(byte* buffer, byte** header,
   if (HasName()) {
     uint32_t name_offset = static_cast<uint32_t>(*body - buffer);
     EmitUint32(header, name_offset);
-    std::memcpy(*body, name_.data(), name_.size());
+    std::memcpy(*body, &name_[0], name_.size());
     (*body) += name_.size();
   }
 
@@ -295,7 +295,7 @@ void WasmFunctionEncoder::Serialize(byte* buffer, byte** header,
 
   if (!external_) {
     EmitUint16(header, static_cast<uint16_t>(body_.size()));
-    std::memcpy(*header, body_.data(), body_.size());
+    std::memcpy(*header, &body_[0], body_.size());
     (*header) += body_.size();
   }
 }
@@ -329,7 +329,7 @@ void WasmDataSegmentEncoder::Serialize(byte* buffer, byte** header,
   EmitUint32(header, static_cast<uint32_t>(data_.size()));
   EmitUint8(header, 1);  // init
 
-  std::memcpy(*body, data_.data(), data_.size());
+  std::memcpy(*body, &data_[0], data_.size());
   (*body) += data_.size();
 }
 
@@ -367,7 +367,7 @@ void WasmModuleBuilder::AddDataSegment(WasmDataSegmentEncoder* data) {
 
 
 int WasmModuleBuilder::CompareFunctionSigs::operator()(FunctionSig* a,
-                                                       FunctionSig* b) {
+                                                       FunctionSig* b) const {
   if (a->return_count() < b->return_count()) return -1;
   if (a->return_count() > b->return_count()) return 1;
   if (a->parameter_count() < b->parameter_count()) return -1;
@@ -493,7 +493,7 @@ WasmModuleIndex* WasmModuleWriter::WriteTo(Zone* zone) const {
   if (sizes.body_size > 0) sizes.Add(1, 0);
 
   ZoneVector<uint8_t> buffer_vector(sizes.total(), zone);
-  byte* buffer = buffer_vector.data();
+  byte* buffer = &buffer_vector[0];
   byte* header = buffer;
   byte* body = buffer + sizes.header_size;
 

src/wasm/encoder.h

@@ -135,7 +135,7 @@ class WasmModuleBuilder : public ZoneObject {
 
  private:
   struct CompareFunctionSigs {
-    int operator()(FunctionSig* a, FunctionSig* b);
+    int operator()(FunctionSig* a, FunctionSig* b) const;
   };
   typedef ZoneMap<FunctionSig*, uint16_t, CompareFunctionSigs> SignatureMap;
 

src/wasm/module-decoder.cc

@@ -371,7 +371,8 @@ class ModuleDecoder : public Decoder {
       str << "in function #" << func_num << ": ";
       // TODO(titzer): add function name for the user?
       str << result;
-      const char* raw = str.str().c_str();
+      std::string strval = str.str();
+      const char* raw = strval.c_str();
       size_t len = strlen(raw);
       char* buffer = new char[len];
       strncpy(buffer, raw, len);
@@ -387,7 +388,7 @@ class ModuleDecoder : public Decoder {
   // the offset is within bounds and advances.
   uint32_t offset(const char* name = nullptr) {
     uint32_t offset = u32(name ? name : "offset");
-    if (offset > (limit_ - start_)) {
+    if (offset > static_cast<uint32_t>(limit_ - start_)) {
       error(pc_ - sizeof(uint32_t), "offset out of bounds of module");
     }
     return offset;