MIPS: Fix unaligned read/write operations in wasm.

src/wasm/ast-decoder.cc

Index: src/wasm/ast-decoder.cc
diff --git a/src/wasm/ast-decoder.cc b/src/wasm/ast-decoder.cc
index ffb815771a7c5061a94e15b5925d2c3a9810d4e6..ccce0213054e15d91fb3678526b3cc9e5da45d4b 100644
--- a/src/wasm/ast-decoder.cc
+++ b/src/wasm/ast-decoder.cc
@@ -394,8 +394,8 @@ class LR_WasmDecoder : public Decoder {
             error("expected #tableswitch <cases> <table>, fell off end");
             break;
           }
-          uint16_t case_count = *reinterpret_cast<const uint16_t*>(pc_ + 1);
-          uint16_t table_count = *reinterpret_cast<const uint16_t*>(pc_ + 3);
+          uint16_t case_count = ReadUnalignedUInt16(pc_ + 1);
+          uint16_t table_count = ReadUnalignedUInt16(pc_ + 3);
           len = 5 + table_count * 2;
 
           if (table_count == 0) {
@@ -412,8 +412,8 @@ class LR_WasmDecoder : public Decoder {
 
           // Verify table.
           for (int i = 0; i < table_count; i++) {
-            uint16_t target =
-                *reinterpret_cast<const uint16_t*>(pc_ + 5 + i * 2);
+            uint16_t target = ReadUnalignedUInt16(pc_ + 5 + i * 2);
+
             if (target >= 0x8000) {
               size_t depth = target - 0x8000;
               if (depth > blocks_.size()) {
@@ -805,7 +805,7 @@ class LR_WasmDecoder : public Decoder {
         break;
       }
       case kExprTableSwitch: {
-        uint16_t table_count = *reinterpret_cast<const uint16_t*>(p->pc() + 3);
+        uint16_t table_count = ReadUnalignedUInt16(p->pc() + 3);
         if (table_count == 1) {
           // Degenerate switch with only a default target.
           if (p->index == 1) {
@@ -830,7 +830,7 @@ class LR_WasmDecoder : public Decoder {
           TFNode* sw = BUILD(Switch, table_count, p->last()->node);
 
           // Allocate environments for each case.
-          uint16_t case_count = *reinterpret_cast<const uint16_t*>(p->pc() + 1);
+          uint16_t case_count = ReadUnalignedUInt16(p->pc() + 1);
           SsaEnv** case_envs = zone_->NewArray<SsaEnv*>(case_count);
           for (int i = 0; i < case_count; i++) {
             case_envs[i] = UnreachableEnv();
@@ -846,7 +846,7 @@ class LR_WasmDecoder : public Decoder {
           const uint16_t* table =
               reinterpret_cast<const uint16_t*>(p->pc() + 5);
           for (int i = 0; i < table_count; i++) {
-            uint16_t target = table[i];
+            uint16_t target = ReadUnalignedUInt16(table + i);
             SsaEnv* env = Split(copy);
             env->control = (i == table_count - 1) ? BUILD(IfDefault, sw)
                                                   : BUILD(IfValue, i, sw);
@@ -1307,7 +1307,7 @@ class LR_WasmDecoder : public Decoder {
       error(pc, msg);
       return -1;
     }
-    return *reinterpret_cast<const V*>(pc + 1);
+    return ReadUnalignedValue<V>(pc + 1);
   }
 
   int EnvironmentCount() {
@@ -1502,7 +1502,7 @@ int OpcodeLength(const byte* pc) {
       return 1 + length;
     }
     case kExprTableSwitch: {
-      uint16_t table_count = *reinterpret_cast<const uint16_t*>(pc + 3);
+      uint16_t table_count = ReadUnalignedUInt16(pc + 3);
       return 5 + table_count * 2;
     }