cppgc: Adjust assert ensuring Oilpan generally satisfies alignof(std::max_align_t)

GCC on x86 wants alignof(std::max_align_t) == 16 which is not
supported by Oilpan. Stricter checks in
MakeGarbageCollectedTraitBase::Allocate() cover problems per type.

Bug: v8:12295
Change-Id: Icdd6517a2828280ed19279ca45004e26c99505a4
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3229372
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Cr-Commit-Position: refs/heads/main@{#77432}

include/cppgc/internal/api-constants.h

@@ -43,9 +43,6 @@ static constexpr size_t kDefaultAlignment = sizeof(void*);
 
 // Maximum support alignment for a type as in `alignof(T)`.
 static constexpr size_t kMaxSupportedAlignment = 2 * kDefaultAlignment;
-static_assert(kMaxSupportedAlignment >= alignof(std::max_align_t),
-              "Maximum support alignment must at least cover "
-              "alignof(std::max_align_t).");
 
 }  // namespace api_constants
 

src/heap/cppgc/allocation.cc

@@ -21,6 +21,15 @@ namespace internal {
 STATIC_ASSERT(api_constants::kLargeObjectSizeThreshold ==
               kLargeObjectSizeThreshold);
 
+#if !(defined(V8_TARGET_ARCH_32_BIT) && defined(V8_CC_GNU))
+// GCC on x86 has alignof(std::max_alignt) == 16 (quad word) which is not
+// satisfied by Oilpan.
+static_assert(api_constants::kMaxSupportedAlignment >=
+                  alignof(std::max_align_t),
+              "Maximum support alignment must at least cover "
+              "alignof(std::max_align_t).");
+#endif  // !(defined(V8_TARGET_ARCH_32_BIT) && defined(V8_CC_GNU))
+
 // Using CPPGC_FORCE_ALWAYS_INLINE to guide LTO for inlining the allocation
 // fast path.
 // static