Disable variable initialization in function-body-decoder-impl.h users

It's probably possible to limit this to a few variables.
However, at the moment I am able to create a patch with tens of
V8_STACK_UNINITIALIZED. It seems tiny changes in functions sizes causes
significant changes in optimizer behavior.

For now I'd like just to restore the perf.

Bug: chromium:1055312, chromium:977230

Change-Id: I48efc3c872a4039b253011b70baf40763e181a20
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2087452
Commit-Queue: Vitaly Buka <vitalybuka@chromium.org>
Reviewed-by: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66589}

BUILD.gn

@@ -2983,13 +2983,11 @@ v8_source_set("v8_base_without_compiler") {
     "src/wasm/baseline/liftoff-assembler-defs.h",
     "src/wasm/baseline/liftoff-assembler.cc",
     "src/wasm/baseline/liftoff-assembler.h",
-    "src/wasm/baseline/liftoff-compiler.cc",
     "src/wasm/baseline/liftoff-compiler.h",
     "src/wasm/baseline/liftoff-register.h",
     "src/wasm/compilation-environment.h",
     "src/wasm/decoder.h",
     "src/wasm/function-body-decoder-impl.h",
-    "src/wasm/function-body-decoder.cc",
     "src/wasm/function-body-decoder.h",
     "src/wasm/function-compiler.cc",
     "src/wasm/function-compiler.h",
@@ -3405,6 +3403,7 @@ v8_source_set("v8_base_without_compiler") {
     ":v8_libbase",
     ":v8_libsampler",
     ":v8_shared_internal_headers",
+    ":v8_uninitialized",
     ":v8_version",
     "src/inspector:inspector",
   ]
@@ -3498,6 +3497,25 @@ v8_source_set("v8_base_without_compiler") {
   }
 }
 
+# Disable -ftrivial-auto-var-init=pattern for this sources. Initialization
+# can increase v8/Wasm validation time. See crbug.com/1055312.
+v8_source_set("v8_uninitialized") {
+  visibility = [ ":*" ]
+
+  sources = [
+    "src/wasm/baseline/liftoff-compiler.cc",
+    "src/wasm/function-body-decoder.cc",
+  ]
+
+  public_deps = [
+    ":run_torque",
+    ":v8_maybe_icu",
+  ]
+
+  remove_configs = [ "//build/config/compiler:default_init_stack_vars" ]
+  configs = [ ":internal_config" ]
+}
+
 group("v8_base") {
   public_deps = [
     ":v8_base_without_compiler",