Reland "[maglev] Enable by default on desktop"

This is a reland of commit cea93e2

Original change's description:
> [maglev] Enable by default on desktop
>
> Bug: v8:7700
> Change-Id: I45cfea506ef54fb0703cbda486f593a48b373f2c
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4686061
> Auto-Submit: Victor Gomes <victorgomes@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#88956}

Bug: v8:7700
Change-Id: I2f4a85e451da61a6c4abbd5fb4a6754c10081810
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4701653
Auto-Submit: Victor Gomes <victorgomes@chromium.org>
Commit-Queue: Victor Gomes <victorgomes@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/main@{#89063}

src/flags/flag-definitions.h

@@ -130,6 +130,13 @@
 #define ENABLE_SPARKPLUG_BY_DEFAULT false
 #endif
 
+#if V8_ENABLE_MAGLEV && !defined(ANDROID)
+// Enable Maglev by default on desktop-only.
+#define ENABLE_MAGLEV_BY_DEFAULT true
+#else
+#define ENABLE_MAGLEV_BY_DEFAULT false
+#endif
+
 // Supported ARM configurations are:
 //  "armv6":       ARMv6 + VFPv2
 //  "armv7":       ARMv7 + VFPv3-D32 + NEON
@@ -480,8 +487,8 @@ DEFINE_BOOL(force_emit_interrupt_budget_checks, false,
             "force emit tier-up logic from all non-turbofan code, even if it "
             "is the top enabled tier")
 #ifdef V8_ENABLE_MAGLEV
-#define V8_ENABLE_MAGLEV_BOOL true
-DEFINE_BOOL(maglev, false, "enable the maglev optimizing compiler")
+DEFINE_BOOL(maglev, ENABLE_MAGLEV_BY_DEFAULT,
+            "enable the maglev optimizing compiler")
 DEFINE_WEAK_IMPLICATION(future, maglev)
 DEFINE_EXPERIMENTAL_FEATURE(
     maglev_future,
@@ -538,7 +545,6 @@ DEFINE_BOOL(stress_maglev, false, "trigger maglev compilation earlier")
 DEFINE_IMPLICATION(stress_maglev, maglev)
 DEFINE_WEAK_VALUE_IMPLICATION(stress_maglev, invocation_count_for_maglev, 4)
 #else
-#define V8_ENABLE_MAGLEV_BOOL false
 DEFINE_BOOL_READONLY(maglev, false, "enable the maglev optimizing compiler")
 DEFINE_BOOL_READONLY(
     maglev_future, false,

tools/testrunner/local/variants.py

@@ -58,7 +58,7 @@
     # compilation. "Liftoff-only" and eager compilation is not a problem,
     # because test functions do typically not get optimized to TurboFan anyways.
     "nooptimization": [[
-        "--no-turbofan", "--liftoff", "--no-wasm-tier-up",
+        "--no-turbofan", "--no-maglev", "--liftoff", "--no-wasm-tier-up",
         "--no-wasm-lazy-compilation"
     ]],
     "slow_path": [["--force-slow-path"]],