Bug 1256956 - Silence some GCC warnings. r=luke.

--HG--
extra : commitid : DSvLpEoSinI
extra : rebase_source : 2a801a7f74212d9cec100deb23de899f0c3d50e3

js/src/asmjs/AsmJS.cpp

@@ -1630,6 +1630,7 @@ class MOZ_STACK_CLASS ModuleValidator
         return standardLibrarySimdOpNames_.putNew(atom->asPropertyName(), op);
     }
     bool newSig(Sig&& sig, uint32_t* sigIndex) {
+        *sigIndex = 0;
         if (mg_.numSigs() >= MaxSigs)
             return failCurrentOffset("too many signatures");
 
@@ -2907,6 +2908,7 @@ CheckFunctionHead(ModuleValidator& m, ParseNode* fn)
 static bool
 CheckArgument(ModuleValidator& m, ParseNode* arg, PropertyName** name)
 {
+    *name = nullptr;
     if (!IsDefinition(arg))
         return m.fail(arg, "duplicate argument name not allowed");
 
@@ -3621,6 +3623,8 @@ static bool
 CheckArrayAccess(FunctionValidator& f, ParseNode* viewName, ParseNode* indexExpr,
                  bool isSimd, Scalar::Type* viewType, int32_t* mask)
 {
+    *mask = 0;
+
     if (!viewName->isKind(PNK_NAME))
         return f.fail(viewName, "base of array access must be a typed array view name");
 

js/src/asmjs/Wasm.cpp

@@ -1086,7 +1086,7 @@ typedef Vector<ImportName, 0, SystemAllocPolicy> ImportNameVector;
 static bool
 DecodeImport(JSContext* cx, Decoder& d, ModuleGeneratorData* init, ImportNameVector* importNames)
 {
-    const DeclaredSig* sig;
+    const DeclaredSig* sig = nullptr;
     if (!DecodeSignatureIndex(cx, d, *init, &sig))
         return false;
 

js/src/asmjs/WasmTextToBinary.cpp

@@ -2301,6 +2301,8 @@ template <typename Float>
 static bool
 ParseFloatLiteral(WasmParseContext& c, WasmToken token, Float* result)
 {
+    *result = 0;
+
     switch (token.kind()) {
       case WasmToken::Index:
         *result = token.index();

js/src/jit/MIR.cpp

@@ -3207,6 +3207,7 @@ MustBeUInt32(MDefinition* def, MDefinition** pwrapped)
         return defConst->type() == MIRType_Int32 && defConst->toInt32() >= 0;
     }
 
+    *pwrapped = nullptr;  // silence GCC warning
     return false;
 }