[wasm] Remove the module environment and signature as arguments to OpcodeArity.

src/wasm/ast-decoder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/signature.h"
 
 #include "src/bit-vector.h"
 #include "src/flags.h"
 #include "src/handles.h"
 #include "src/zone-containers.h"
@@ skipping 269 matching lines @@
         return 1 + operand.arity;
       }
 
       case kExprIf:
         return 1;
       case kExprSelect:
         return 3;
 
       case kExprCallFunction: {
         CallFunctionOperand operand(this, pc);
-        return static_cast<int>(
-            module_->GetFunctionSignature(operand.index)->parameter_count());
+        return operand.arity;

[ahaas, 2016/05/02 14:48:28]

Could the arity be calculated in a static function?

[titzer, 2016/05/02 14:57:31]

Not sure what value that would add, since this function already handles all
bytecodes. Or do you mean to suggest that this functionality should be instead
moved to the top-level functions OpcodeArity and OpcodeLength?

       }
       case kExprCallIndirect: {
         CallIndirectOperand operand(this, pc);
-        return 1 + static_cast<int>(
-                       module_->GetSignature(operand.index)->parameter_count());
+        return 1 + operand.arity;
       }
       case kExprCallImport: {
         CallImportOperand operand(this, pc);
-        return static_cast<int>(
-            module_->GetImportSignature(operand.index)->parameter_count());
+        return operand.arity;
       }
       case kExprReturn: {
-        return static_cast<int>(sig_->return_count());
+        ReturnArityOperand operand(this, pc);
+        return operand.arity;
       }
 
 #define DECLARE_OPCODE_CASE(name, opcode, sig) \
   case kExpr##name:                            \
     return kArity_##sig;
 
         FOREACH_LOAD_MEM_OPCODE(DECLARE_OPCODE_CASE)
         FOREACH_STORE_MEM_OPCODE(DECLARE_OPCODE_CASE)
         FOREACH_MISC_MEM_OPCODE(DECLARE_OPCODE_CASE)
         FOREACH_SIMPLE_OPCODE(DECLARE_OPCODE_CASE)
@@ skipping 1201 matching lines @@
   }
   if (tree.count > 0) os << ")";
   return os;
 }
 
 int OpcodeLength(const byte* pc, const byte* end) {
   WasmDecoder decoder(nullptr, nullptr, pc, end);
   return decoder.OpcodeLength(pc);
 }
 
-int OpcodeArity(ModuleEnv* module, FunctionSig* sig, const byte* pc,
-                const byte* end) {
-  WasmDecoder decoder(module, sig, pc, end);
+int OpcodeArity(const byte* pc, const byte* end) {
+  WasmDecoder decoder(nullptr, nullptr, pc, end);

[ahaas, 2016/05/02 14:48:28]

Could you make OpcodeArity a static function?

[titzer, 2016/05/02 14:57:31]

The decoder classes are not exposed through the header file, but instead a
top-level function, so that would require adding a wrapper class.

[ahaas, 2016/05/02 15:12:41]

What I mean is, I don't see a point why you have to make a WasmDecoder object to
call decoder.OpcodeArity. Could also just be a personal preference. 

   return decoder.OpcodeArity(pc);
 }
 
 void PrintAst(base::AccountingAllocator* allocator, FunctionBody& body) {
   Zone zone(allocator);
   SR_WasmDecoder decoder(&zone, nullptr, body);
 
   OFStream os(stdout);
 
   // Print the function signature.
@@ skipping 81 matching lines @@
 BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone, size_t num_locals,
                                            const byte* start, const byte* end) {
   FunctionBody body = {nullptr, nullptr, nullptr, start, end};
   SR_WasmDecoder decoder(zone, nullptr, body);
   return decoder.AnalyzeLoopAssignmentForTesting(start, num_locals);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8