Add --print-wasm-code-function-index

This flag allows you to filter printing Wasm code to one particular
function index.

Bug: v8:10791
Change-Id: I400ccaadb8330e5e31e2faefdeddb169cdc85f71
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2459259
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#70457}

src/flags/flag-definitions.h

@@ -874,8 +874,10 @@ DEFINE_BOOL(wasm_trap_handler, true,
 DEFINE_BOOL(wasm_fuzzer_gen_test, false,
             "generate a test case when running a wasm fuzzer")
 DEFINE_IMPLICATION(wasm_fuzzer_gen_test, single_threaded)
-DEFINE_BOOL(print_wasm_code, false, "Print WebAssembly code")
-DEFINE_BOOL(print_wasm_stub_code, false, "Print WebAssembly stub code")
+DEFINE_BOOL(print_wasm_code, false, "print WebAssembly code")
+DEFINE_INT(print_wasm_code_function_index, -1,
+           "print WebAssembly code for function at index")
+DEFINE_BOOL(print_wasm_stub_code, false, "print WebAssembly stub code")
 DEFINE_BOOL(asm_wasm_lazy_compilation, false,
             "enable lazy compilation for asm-wasm modules")
 DEFINE_IMPLICATION(validate_asm, asm_wasm_lazy_compilation)

src/wasm/wasm-code-manager.cc

@@ -323,8 +323,12 @@ void WasmCode::Validate() const {
 
 void WasmCode::MaybePrint(const char* name) const {
   // Determines whether flags want this code to be printed.
-  if ((FLAG_print_wasm_code && kind() == kFunction) ||
-      (FLAG_print_wasm_stub_code && kind() != kFunction) || FLAG_print_code) {
+  bool function_index_matches =
+      (!IsAnonymous() &&
+       FLAG_print_wasm_code_function_index == static_cast<int>(index()));
+  if (FLAG_print_code ||
+      (kind() == kFunction ? (FLAG_print_wasm_code || function_index_matches)
+                           : FLAG_print_wasm_stub_code)) {
     Print(name);
   }
 }