[wasm] Allow specifying larger code space limits

Even though we provide a --wasm-max-code-space flag (defaulting to
{kMaxWasmCodeMB}, we still had checks in place that the actual committed
code space is not bigger than that constant.
This CL fixes that by always comparing against the value of the flag.
This will allow us to specify a code space limit which is larger than
the default. This is useful when debugging larger Wasm apps which exceed
the limit, but are not meant to be shipped that way.

Drive-by: Remove a dead use of the {kMaxWasmCodeMemory} constant.

R=ecmziegler@chromium.org

Bug: chromium:1117033, chromium:1114093, chromium:1107649, chromium:1111266
Change-Id: I2684446230a8a6f0a27ad963dd6f36e5764b25e0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2376810Reviewed-by: Emanuel Ziegler <ecmziegler@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69611}

src/wasm/wasm-code-manager.cc

@@ -671,7 +671,7 @@ Vector<byte> WasmCodeAllocator::AllocateForCodeInRegion(
   if (commit_start < commit_end) {
     committed_code_space_.fetch_add(commit_end - commit_start);
     // Committed code cannot grow bigger than maximum code space size.
-    DCHECK_LE(committed_code_space_.load(), kMaxWasmCodeMemory);
+    DCHECK_LE(committed_code_space_.load(), FLAG_wasm_max_code_space * MB);
     for (base::AddressRegion split_range : SplitRangeByReservationsIfNeeded(
              {commit_start, commit_end - commit_start}, owned_code_space_)) {
       code_manager_->Commit(split_range);
@@ -1538,7 +1538,7 @@ NativeModule::~NativeModule() {
 WasmCodeManager::WasmCodeManager(size_t max_committed)
     : max_committed_code_space_(max_committed),
       critical_committed_code_space_(max_committed / 2) {
-  DCHECK_LE(max_committed, kMaxWasmCodeMemory);
+  DCHECK_LE(max_committed, FLAG_wasm_max_code_space * MB);
 }
 
 #if defined(V8_OS_WIN64)

test/cctest/wasm/test-wasm-shared-engine.cc

@@ -26,8 +26,6 @@ namespace test_wasm_shared_engine {
 // shared between multiple Isolates, sharing the underlying generated code.
 class SharedEngine {
  public:
-  explicit SharedEngine(size_t max_committed = kMaxWasmCodeMemory)
-      : wasm_engine_(std::make_unique<WasmEngine>()) {}
   ~SharedEngine() {
     // Ensure no remaining uses exist.
     CHECK(wasm_engine_.unique());
@@ -44,7 +42,7 @@ class SharedEngine {
   std::shared_ptr<WasmEngine> ExportEngineForSharing() { return wasm_engine_; }
 
  private:
-  std::shared_ptr<WasmEngine> wasm_engine_;
+  std::shared_ptr<WasmEngine> wasm_engine_ = std::make_unique<WasmEngine>();
 };
 
 // Helper type definition representing a WebAssembly module shared between