[wasm] Identify wasm functions with index into the function tables.

Currently, the default name for wasm functions in generated code is 'wasm', tag wasm functions with the index into the function table to identify functions. Snippets of sample output with --print-code below.

Before:
--- Code ---
kind = WASM_FUNCTION
name = wasm
compiler = turbofan

After:
--- Code ---
kind = WASM_FUNCTION
name = wasm#200
compiler = turbofan

R=mtrofin@chromium.org

Review-Url: https://codereview.chromium.org/2690113012
Cr-Commit-Position: refs/heads/master@{#43296}

src/compiler/wasm-compiler.cc

@@ -4011,6 +4011,13 @@ SourcePositionTable* WasmCompilationUnit::BuildGraphForWasmFunction(
   return source_position_table;
 }
 
+char* WasmCompilationUnit::GetTaggedFunctionName(
+    const wasm::WasmFunction* function) {
+  snprintf(function_name_, sizeof(function_name_), "wasm#%d",
+           function->func_index);
+  return function_name_;
+}
+
 WasmCompilationUnit::WasmCompilationUnit(wasm::ErrorThrower* thrower,
                                          Isolate* isolate,
                                          wasm::ModuleBytesEnv* module_env,
@@ -4031,7 +4038,7 @@ WasmCompilationUnit::WasmCompilationUnit(wasm::ErrorThrower* thrower,
       compilation_zone_(isolate->allocator(), ZONE_NAME),
       info_(function->name_length != 0
                 ? module_env->wire_bytes.GetNameOrNull(function)
-                : ArrayVector("wasm"),
+                : CStrVector(GetTaggedFunctionName(function)),
             isolate, &compilation_zone_,
             Code::ComputeFlags(Code::WASM_FUNCTION)),
       job_(),

src/compiler/wasm-compiler.h

@@ -68,11 +68,14 @@ class WasmCompilationUnit final {
 
  private:
   SourcePositionTable* BuildGraphForWasmFunction(double* decode_ms);
+  char* GetTaggedFunctionName(const wasm::WasmFunction* function);
 
   wasm::ErrorThrower* thrower_;
   Isolate* isolate_;
   wasm::ModuleBytesEnv* module_env_;
   const wasm::WasmFunction* function_;
+  // Function name is tagged with uint32 func_index - wasm#<func_index>
+  char function_name_[16];
   // The graph zone is deallocated at the end of ExecuteCompilation.
   std::unique_ptr<Zone> graph_zone_;
   JSGraph* jsgraph_;