[wasm] Cleanup AST decoder. Remove Tree and TreeResult.

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 13 matching lines @@
 
 #if DEBUG
 #define TRACE(...)                                    \
   do {                                                \
     if (FLAG_trace_wasm_decoder) PrintF(__VA_ARGS__); \
   } while (false)
 #else
 #define TRACE(...)
 #endif
 
-// The root of a decoded tree.
-struct Tree {
-  LocalType type;     // tree type.
-  uint32_t count;     // number of children.
-  const byte* pc;     // start of the syntax tree.
-  TFNode* node;       // node in the TurboFan graph.
-  Tree* children[1];  // pointers to children.
-
-  WasmOpcode opcode() const { return static_cast<WasmOpcode>(*pc); }
-};
-
 // An SsaEnv environment carries the current local variable renaming
 // as well as the current effect and control dependency in the TF graph.
 // It maintains a control state that tracks whether the environment
 // is reachable, has reached a control end, or has been merged.
 struct SsaEnv {
   enum State { kControlEnd, kUnreachable, kReached, kMerged };
 
   State state;
   TFNode* control;
   TFNode* effect;
@@ skipping 347 matching lines @@
         ReturnArityOperand operand(this, pc);
         return 1 + operand.length;
       }
 
       default:
         return 1;
     }
   }
 };
 
-// A shift-reduce-parser strategy for decoding Wasm code that uses an explicit
-// shift-reduce strategy with multiple internal stacks.
-class SR_WasmDecoder : public WasmDecoder {
+// The full WASM decoder for bytecode. Both verifies bytecode and generates
+// a TurboFan IR graph.
+class WasmFullDecoder : public WasmDecoder {
  public:
-  SR_WasmDecoder(Zone* zone, TFBuilder* builder, const FunctionBody& body)
+  WasmFullDecoder(Zone* zone, TFBuilder* builder, const FunctionBody& body)
       : WasmDecoder(body.module, body.sig, body.start, body.end),
         zone_(zone),
         builder_(builder),
         base_(body.base),
         local_type_vec_(zone),
         stack_(zone),
         control_(zone) {
     local_types_ = &local_type_vec_;
   }
 
@@ skipping 1061 matching lines @@
     DCHECK_EQ(pc_ - start_, offset);  // overflows cannot happen
     return offset;
   }
 };
 
 bool DecodeLocalDecls(AstLocalDecls& decls, const byte* start,
                       const byte* end) {
   base::AccountingAllocator allocator;
   Zone tmp(&allocator);
   FunctionBody body = {nullptr, nullptr, nullptr, start, end};
-  SR_WasmDecoder decoder(&tmp, nullptr, body);
+  WasmFullDecoder decoder(&tmp, nullptr, body);
   return decoder.DecodeLocalDecls(decls);
 }
 
-TreeResult VerifyWasmCode(base::AccountingAllocator* allocator,
-                          FunctionBody& body) {
+DecodeResult VerifyWasmCode(base::AccountingAllocator* allocator,
+                            FunctionBody& body) {
   Zone zone(allocator);
-  SR_WasmDecoder decoder(&zone, nullptr, body);
+  WasmFullDecoder decoder(&zone, nullptr, body);
   decoder.Decode();
-  return decoder.toResult<Tree*>(nullptr);
+  return decoder.toResult<DecodeStruct*>(nullptr);
 }
 
-TreeResult BuildTFGraph(base::AccountingAllocator* allocator,
-                        TFBuilder* builder, FunctionBody& body) {
+DecodeResult BuildTFGraph(base::AccountingAllocator* allocator,
+                          TFBuilder* builder, FunctionBody& body) {
   Zone zone(allocator);
-  SR_WasmDecoder decoder(&zone, builder, body);
+  WasmFullDecoder decoder(&zone, builder, body);
   decoder.Decode();
-  return decoder.toResult<Tree*>(nullptr);
-}
-
-std::ostream& operator<<(std::ostream& os, const Tree& tree) {
-  if (tree.pc == nullptr) {
-    os << "null";
-    return os;
-  }
-  PrintF("%s", WasmOpcodes::OpcodeName(tree.opcode()));
-  if (tree.count > 0) os << "(";
-  for (uint32_t i = 0; i < tree.count; ++i) {
-    if (i > 0) os << ", ";
-    os << *tree.children[i];
-  }
-  if (tree.count > 0) os << ")";
-  return os;
+  return decoder.toResult<DecodeStruct*>(nullptr);
 }
 
 unsigned OpcodeLength(const byte* pc, const byte* end) {
   WasmDecoder decoder(nullptr, nullptr, pc, end);
   return decoder.OpcodeLength(pc);
 }
 
 unsigned OpcodeArity(const byte* pc, const byte* end) {
   WasmDecoder decoder(nullptr, nullptr, pc, end);
   return decoder.OpcodeArity(pc);
 }
 
 void PrintAstForDebugging(const byte* start, const byte* end) {
   base::AccountingAllocator allocator;
   OFStream os(stdout);
   PrintAst(&allocator, FunctionBodyForTesting(start, end), os, nullptr);
 }
 
 bool PrintAst(base::AccountingAllocator* allocator, const FunctionBody& body,
               std::ostream& os,
               std::vector<std::tuple<uint32_t, int, int>>* offset_table) {
   Zone zone(allocator);
-  SR_WasmDecoder decoder(&zone, nullptr, body);
+  WasmFullDecoder decoder(&zone, nullptr, body);
   int line_nr = 0;
 
   // Print the function signature.
   if (body.sig) {
     os << "// signature: " << *body.sig << std::endl;
     ++line_nr;
   }
 
   // Print the local declarations.
   AstLocalDecls decls(&zone);
@@ skipping 108 matching lines @@
     os << std::endl;
     ++line_nr;
   }
 
   return decoder.ok();
 }
 
 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);
+  WasmFullDecoder decoder(zone, nullptr, body);
   return decoder.AnalyzeLoopAssignmentForTesting(start, num_locals);
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8