[wasm] Write fuzzers for single wasm sections.

src/flag-definitions.h

 // Copyright 2012 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.
 
 // This file defines all of the flags.  It is separated into different section,
 // for Debug, Release, Logging and Profiling, etc.  To add a new flag, find the
 // correct section, and use one of the DEFINE_ macros, without a trailing ';'.
 //
 // This include does not have a guard, because it is a template-style include,
 // which can be included multiple times in different modes.  It expects to have
@@ skipping 1075 matching lines @@
 
 DEFINE_BOOL(redirect_code_traces, false,
             "output deopt information and disassembly into file "
             "code-<pid>-<isolate id>.asm")
 DEFINE_STRING(redirect_code_traces_to, NULL,
               "output deopt information and disassembly into the given file")
 
 DEFINE_BOOL(hydrogen_track_positions, false,
             "track source code positions when building IR")
 
+// Parameters for the wasm-section-fuzzer, not used by V8.

[Michael Starzinger, 2016/09/13 09:27:08]

We already employ a similar solution for some "d8-only" flags, that are not
respected for other embedders besides the "d8" binary. The section is currently
called "Dev shell flags" in this file.

nit: Can we move this section close to the other, and also clean up the section
headers somehow so that both specifically mention the name of the binary for
which they are used? Something along the lines of ...

//
// Specific flags for {d8}, not used within V8 proper.
//

[...]

//
// Specific flags for {v8_simple_wasm_fuzzer}, not used within V8 proper.
//

[...]

[ahaas, 2016/09/13 09:50:22]

Done.

+DEFINE_BOOL(wasm_fuzz_types, false, "fuzz the types section of a wasm module")
+DEFINE_BOOL(wasm_fuzz_names, false, "fuzz the names section of a wasm module")
+DEFINE_BOOL(wasm_fuzz_globals, false,
+            "fuzz the globals section of a wasm module")
+DEFINE_BOOL(wasm_fuzz_imports, false,
+            "fuzz the imports section of a wasm module")
+DEFINE_BOOL(wasm_fuzz_function_sigs, false,
+            "fuzz the function signatures section of a wasm module")
+DEFINE_BOOL(wasm_fuzz_memory, false, "fuzz the memory section of a wasm module")
+DEFINE_BOOL(wasm_fuzz_data, false, "fuzz the data section of a wasm module")
+
 //
 // Disassembler only flags
 //
 #undef FLAG
 #ifdef ENABLE_DISASSEMBLER
 #define FLAG FLAG_FULL
 #else
 #define FLAG FLAG_READONLY
 #endif
 
@@ skipping 100 matching lines @@
 #undef DEFINE_ALIAS_FLOAT
 #undef DEFINE_ALIAS_ARGS
 
 #undef FLAG_MODE_DECLARE
 #undef FLAG_MODE_DEFINE
 #undef FLAG_MODE_DEFINE_DEFAULTS
 #undef FLAG_MODE_META
 #undef FLAG_MODE_DEFINE_IMPLICATIONS
 
 #undef COMMA