[compiler] Fix endianness issue when reading HeapNumber

The value needs to be assembled in correct order depending
on the machine endianness.

Bug: v8:7790
Change-Id: I247ce97486721b846ea77de1f075f32c089537ed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2878296Reviewed-by: Junliang Yan <junyan@redhat.com>
Reviewed-by: Michael Stanton <mvstanton@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/master@{#74467}

src/objects/heap-number-inl.h

@@ -26,10 +26,17 @@ uint64_t HeapNumber::value_as_bits() const {
 }
 
 uint64_t HeapNumber::value_as_bits_relaxed() const {
+#if defined(V8_TARGET_BIG_ENDIAN)
+  return (static_cast<uint64_t>(RELAXED_READ_UINT32_FIELD(*this, kValueOffset))
+          << 32) |
+         static_cast<uint64_t>(
+             RELAXED_READ_UINT32_FIELD(*this, kValueOffset + kUInt32Size));
+#else
   return static_cast<uint64_t>(RELAXED_READ_UINT32_FIELD(*this, kValueOffset)) |
          (static_cast<uint64_t>(
               RELAXED_READ_UINT32_FIELD(*this, kValueOffset + kUInt32Size))
           << 32);
+#endif
 }
 
 void HeapNumber::set_value_as_bits(uint64_t bits) {