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

R=ahaas@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2110053002
Cr-Commit-Position: refs/heads/master@{#37387}

src/compiler/wasm-compiler.h

@@ -29,7 +29,7 @@ namespace wasm {
 struct ModuleEnv;
 struct WasmFunction;
 class ErrorThrower;
-struct Tree;
+struct DecodeStruct;
 
 // Expose {Node} and {Graph} opaquely as {wasm::TFNode} and {wasm::TFGraph}.
 typedef compiler::Node TFNode;
@@ -72,7 +72,7 @@ class WasmCompilationUnit final {
   CompilationInfo info_;
   base::SmartPointer<CompilationJob> job_;
   uint32_t index_;
-  wasm::Result<wasm::Tree*> graph_construction_result_;
+  wasm::Result<wasm::DecodeStruct*> graph_construction_result_;
   bool ok_;
 };
 

src/wasm/ast-decoder.cc

@@ -31,17 +31,6 @@ namespace wasm {
 #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
@@ -385,11 +374,11 @@ class WasmDecoder : public Decoder {
   }
 };
 
-// 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),
@@ -1471,39 +1460,24 @@ bool DecodeLocalDecls(AstLocalDecls& decls, const byte* start,
   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) {
@@ -1526,7 +1500,7 @@ 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.
@@ -1655,7 +1629,7 @@ bool PrintAst(base::AccountingAllocator* allocator, const FunctionBody& body,
 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);
 }
 

src/wasm/ast-decoder.h

@@ -222,15 +222,18 @@ static inline FunctionBody FunctionBodyForTesting(const byte* start,
   return {nullptr, nullptr, start, start, end};
 }
 
-struct Tree;
-typedef Result<Tree*> TreeResult;
-
-std::ostream& operator<<(std::ostream& os, const Tree& tree);
+struct DecodeStruct {
+  int unused;
+};
+typedef Result<DecodeStruct*> DecodeResult;
+inline std::ostream& operator<<(std::ostream& os, const DecodeStruct& tree) {
+  return os;
+}
 
-TreeResult VerifyWasmCode(base::AccountingAllocator* allocator,
-                          FunctionBody& body);
-TreeResult BuildTFGraph(base::AccountingAllocator* allocator,
-                        TFBuilder* builder, FunctionBody& body);
+DecodeResult VerifyWasmCode(base::AccountingAllocator* allocator,
+                            FunctionBody& body);
+DecodeResult BuildTFGraph(base::AccountingAllocator* allocator,
+                          TFBuilder* builder, FunctionBody& body);
 bool PrintAst(base::AccountingAllocator* allocator, const FunctionBody& body,
               std::ostream& os,
               std::vector<std::tuple<uint32_t, int, int>>* offset_table);
@@ -238,17 +241,17 @@ bool PrintAst(base::AccountingAllocator* allocator, const FunctionBody& body,
 // A simplified form of AST printing, e.g. from a debugger.
 void PrintAstForDebugging(const byte* start, const byte* end);
 
-inline TreeResult VerifyWasmCode(base::AccountingAllocator* allocator,
-                                 ModuleEnv* module, FunctionSig* sig,
-                                 const byte* start, const byte* end) {
+inline DecodeResult VerifyWasmCode(base::AccountingAllocator* allocator,
+                                   ModuleEnv* module, FunctionSig* sig,
+                                   const byte* start, const byte* end) {
   FunctionBody body = {module, sig, nullptr, start, end};
   return VerifyWasmCode(allocator, body);
 }
 
-inline TreeResult BuildTFGraph(base::AccountingAllocator* allocator,
-                               TFBuilder* builder, ModuleEnv* module,
-                               FunctionSig* sig, const byte* start,
-                               const byte* end) {
+inline DecodeResult BuildTFGraph(base::AccountingAllocator* allocator,
+                                 TFBuilder* builder, ModuleEnv* module,
+                                 FunctionSig* sig, const byte* start,
+                                 const byte* end) {
   FunctionBody body = {module, sig, nullptr, start, end};
   return BuildTFGraph(allocator, builder, body);
 }

src/wasm/module-decoder.cc

@@ -546,7 +546,7 @@ class ModuleDecoder : public Decoder {
     FunctionBody body = {menv, function->sig, start_,
                          start_ + function->code_start_offset,
                          start_ + function->code_end_offset};
-    TreeResult result = VerifyWasmCode(module_zone->allocator(), body);
+    DecodeResult result = VerifyWasmCode(module_zone->allocator(), body);
     if (result.failed()) {
       // Wrap the error message from the function decoder.
       std::ostringstream str;

test/cctest/wasm/wasm-run-utils.h

@@ -269,7 +269,7 @@ inline void TestBuildingGraph(Zone* zone, JSGraph* jsgraph, ModuleEnv* module,
                               SourcePositionTable* source_position_table,
                               const byte* start, const byte* end) {
   compiler::WasmGraphBuilder builder(zone, jsgraph, sig, source_position_table);
-  TreeResult result =
+  DecodeResult result =
       BuildTFGraph(zone->allocator(), &builder, module, sig, start, end);
   if (result.failed()) {
     ptrdiff_t pc = result.error_pc - result.start;

test/unittests/wasm/ast-decoder-unittest.cc

@@ -84,7 +84,7 @@ class AstDecoderTest : public TestWithZone {
               const byte* end) {
     local_decls.Prepend(zone(), &start, &end);
     // Verify the code.
-    TreeResult result =
+    DecodeResult result =
         VerifyWasmCode(zone()->allocator(), module, sig, start, end);
 
     if (result.error_code != expected) {