[PATCH] Avoid default-initializing auto_vec storage

[Richard Biener via Gcc-patches]

The following avoids default-initializing auto_vec storage for
non-POD T since that's not what the allocated storage fallback
will do and it's also not expected for existing cases like

  auto_vec<std::pair<unsigned, unsigned>, 64> elts;

which exist to optimize the allocation.

Bootstrapped and tested on x86_64-unknown-linux-gnu.

It saves around 1kB of text size for cc1.

OK for trunk?

Thanks,
Richard.

        * vec.h (auto_vec<T, N>): Turn m_data storage into
        uninitialized unsigned char.
---
 gcc/vec.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gcc/vec.h b/gcc/vec.h
index a536b68732d..cee96254a31 100644
--- a/gcc/vec.h
+++ b/gcc/vec.h
@@ -1584,7 +1584,7 @@ public:
 
 private:
   vec<T, va_heap, vl_embed> m_auto;
-  T m_data[MAX (N - 1, 1)];
+  alignas(T) unsigned char m_data[sizeof (T) * MAX (N - 1, 1)];
 };
 
 /* auto_vec is a sub class of vec whose storage is released when it is
-- 
2.35.3