[wasm] Implement AST printing into an ostream

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 390a67300a34a22640952dc5bc92339d341217f7..9d1debcbcaab68bb0b955cf2ec1dac923cdbc2aa 100644
--- a/src/wasm/ast-decoder.cc
+++ b/src/wasm/ast-decoder.cc
@@ -148,7 +148,8 @@ class WasmDecoder : public Decoder {
 
   inline bool Validate(const byte* pc, GlobalIndexOperand& operand) {
     ModuleEnv* m = module_;
-    if (m && m->module && operand.index < m->module->globals.size()) {
+    if (!m || !m->module) return false;

[titzer, 2016/06/10 10:57:40]

This change means that there will not be an error recorded for when there isn't
a module environment supplied. That will probably break downstream assumptions.

[Clemens Hammacher, 2016/06/13 09:45:17]

I changed it to have a Complete() and a Validate() function, s.t. Validate()
calls Complete(), and only Validate() will report any errors.

+    if (operand.index < m->module->globals.size()) {
       operand.machine_type = m->module->globals[operand.index].type;
       operand.type = WasmOpcodes::LocalTypeFor(operand.machine_type);
       return true;
@@ -159,7 +160,8 @@ class WasmDecoder : public Decoder {
 
   inline bool Validate(const byte* pc, CallFunctionOperand& operand) {
     ModuleEnv* m = module_;
-    if (m && m->module && operand.index < m->module->functions.size()) {
+    if (!m || !m->module) return false;
+    if (operand.index < m->module->functions.size()) {
       operand.sig = m->module->functions[operand.index].sig;
       uint32_t expected = static_cast<uint32_t>(operand.sig->parameter_count());
       if (operand.arity != expected) {
@@ -176,7 +178,8 @@ class WasmDecoder : public Decoder {
 
   inline bool Validate(const byte* pc, CallIndirectOperand& operand) {
     ModuleEnv* m = module_;
-    if (m && m->module && operand.index < m->module->signatures.size()) {
+    if (!m || !m->module) return false;
+    if (operand.index < m->module->signatures.size()) {
       operand.sig = m->module->signatures[operand.index];
       uint32_t expected = static_cast<uint32_t>(operand.sig->parameter_count());
       if (operand.arity != expected) {
@@ -193,7 +196,8 @@ class WasmDecoder : public Decoder {
 
   inline bool Validate(const byte* pc, CallImportOperand& operand) {
     ModuleEnv* m = module_;
-    if (m && m->module && operand.index < m->module->import_table.size()) {
+    if (!m || !m->module) return false;
+    if (operand.index < m->module->import_table.size()) {
       operand.sig = m->module->import_table[operand.index].sig;
       uint32_t expected = static_cast<uint32_t>(operand.sig->parameter_count());
       if (operand.arity != expected) {
@@ -391,7 +395,7 @@ class WasmDecoder : public Decoder {
 // shift-reduce strategy with multiple internal stacks.
 class SR_WasmDecoder : public WasmDecoder {
  public:
-  SR_WasmDecoder(Zone* zone, TFBuilder* builder, FunctionBody& body)
+  SR_WasmDecoder(Zone* zone, TFBuilder* builder, const FunctionBody& body)
       : WasmDecoder(body.module, body.sig, body.start, body.end),
         zone_(zone),
         builder_(builder),
@@ -1526,17 +1530,17 @@ int OpcodeArity(const byte* pc, const byte* end) {
 }
 
 void PrintAstForDebugging(const byte* start, const byte* end) {
-  FunctionBody body = {nullptr, nullptr, start, start, end};
   base::AccountingAllocator allocator;
-  PrintAst(&allocator, body);
+  OFStream os(stdout);
+  PrintAst(&allocator, FunctionBody::ForTesting(start, end), os);
 }
 
-void PrintAst(base::AccountingAllocator* allocator, FunctionBody& body) {
+bool PrintAst(base::AccountingAllocator* allocator, const FunctionBody& body,
+              std::ostream& os,
+              std::function<void(uint32_t)> instruction_callback) {
   Zone zone(allocator);
   SR_WasmDecoder decoder(&zone, nullptr, body);
 
-  OFStream os(stdout);
-
   // Print the function signature.
   if (body.sig) {
     os << "// signature: " << *body.sig << std::endl;
@@ -1556,24 +1560,29 @@ void PrintAst(base::AccountingAllocator* allocator, FunctionBody& body) {
     os << std::endl;
 
     for (const byte* locals = body.start; locals < pc; locals++) {
-      printf(" 0x%02x,", *locals);
+      os << (locals == body.start ? "0x" : " 0x") << AsHex(*locals, 2) << ",";
     }
     os << std::endl;
   }
 
   os << "// body: \n";
-  int control_depth = 0;
+  unsigned control_depth = 0;
   while (pc < body.end) {
     size_t length = decoder.OpcodeLength(pc);
 
     WasmOpcode opcode = static_cast<WasmOpcode>(*pc);
     if (opcode == kExprElse) control_depth--;
 
-    for (int i = 0; i < control_depth && i < 32; i++) printf("  ");
-    printf("k%s,", WasmOpcodes::OpcodeName(opcode));
+    // 32 whitespaces
+    const char* padding = "                                ";
+    os.write(padding, control_depth < 32 ? control_depth : 32);
+    if (instruction_callback) {
+      instruction_callback(static_cast<int>(pc - body.start));
+    }
+    os << "k" << WasmOpcodes::OpcodeName(opcode) << ",";
 
     for (size_t i = 1; i < length; i++) {
-      printf(" 0x%02x,", pc[i]);
+      os << " " << AsHex(pc[i], 2) << ",";
     }
 
     switch (opcode) {
@@ -1643,6 +1652,8 @@ void PrintAst(base::AccountingAllocator* allocator, FunctionBody& body) {
     pc += length;
     os << std::endl;
   }
+
+  return decoder.ok();
 }
 
 BitVector* AnalyzeLoopAssignmentForTesting(Zone* zone, size_t num_locals,