[PATCH 05/13] allow constructing a auto_vec with a preallocation, and a possibly larger actual allocation size

[tbsaunde+gcc]

From: Trevor Saunders <tbsaunde+...@tbsaunde.org>

This allows us to set the capacity of the vector when we construct it,
and still use a stack buffer when the size is small enough.

gcc/ChangeLog:

2017-05-09  Trevor Saunders  <tbsaunde+...@tbsaunde.org>

        * genrecog.c (int_set::int_set): Explicitly construct our
auto_vec base class.
        * vec.h (auto_vec::auto_vec): New constructor.
---
 gcc/genrecog.c |  8 +++++---
 gcc/vec.h      | 12 ++++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/gcc/genrecog.c b/gcc/genrecog.c
index 6a9e610e7a0..b69043f0d02 100644
--- a/gcc/genrecog.c
+++ b/gcc/genrecog.c
@@ -1407,14 +1407,16 @@ struct int_set : public auto_vec <uint64_t, 1>
   iterator end ();
 };
 
-int_set::int_set () {}
+int_set::int_set () : auto_vec<uint64_t, 1> () {}
 
-int_set::int_set (uint64_t label)
+int_set::int_set (uint64_t label) :
+  auto_vec<uint64_t, 1> ()
 {
   safe_push (label);
 }
 
-int_set::int_set (const int_set &other)
+int_set::int_set (const int_set &other) :
+  auto_vec<uint64_t, 1> ()
 {
   safe_splice (other);
 }
diff --git a/gcc/vec.h b/gcc/vec.h
index fee46164b01..914f89c350c 100644
--- a/gcc/vec.h
+++ b/gcc/vec.h
@@ -1272,6 +1272,18 @@ public:
     this->m_vec = &m_auto;
   }
 
+  auto_vec (size_t s)
+  {
+    if (s > N)
+      {
+       this->create (s);
+       return;
+      }
+
+    m_auto.embedded_init (MAX (N, 2), 0, 1);
+    this->m_vec = &m_auto;
+  }
+
   ~auto_vec ()
   {
     this->release ();
-- 
2.11.0