QMetaType: don't record trivial construction function pointers

We can implement the trivial {default,copy,move} construction outselves
inside qmetatype.cpp and qvariant.cpp, simplifying the QMetaType
interface object, removing up to three relocations per QMTI.

This adds the testing for QMetaType::isXxxConstructible and
isDestructible that couldn't be added before.

Change-Id: Ic44396b31ba04712aab3fffd16ff0a28f541d507
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 35 insertions, 4 deletions

diff --git a/src/corelib/kernel/qmetatype_p.h b/src/corelib/kernel/qmetatype_p.h
index 89f1854bf6..08c1aeaa1d 100644
--- a/src/corelib/kernel/qmetatype_p.h
+++ b/src/corelib/kernel/qmetatype_p.h
@@ -141,21 +141,52 @@ inline bool isDefaultConstructible(const QtPrivate::QMetaTypeInterface *iface) n
 
 inline bool isCopyConstructible(const QtPrivate::QMetaTypeInterface *iface) noexcept
 {
-    // ### broken
-    return checkMetaTypeFlagOrPointer(iface, iface->copyCtr, QMetaType::NeedsConstruction);
+    return checkMetaTypeFlagOrPointer(iface, iface->copyCtr, QMetaType::NeedsCopyConstruction);
 }
 
 inline bool isMoveConstructible(const QtPrivate::QMetaTypeInterface *iface) noexcept
 {
-    return iface->moveCtr;
+    return checkMetaTypeFlagOrPointer(iface, iface->moveCtr, QMetaType::NeedsMoveConstruction);
 }
 
 inline bool isDestructible(const QtPrivate::QMetaTypeInterface *iface) noexcept
 {
-    // ### broken
     return checkMetaTypeFlagOrPointer(iface, iface->dtor, QMetaType::NeedsDestruction);
 }
 
+inline void defaultConstruct(const QtPrivate::QMetaTypeInterface *iface, void *where)
+{
+    Q_ASSERT(isDefaultConstructible(iface));
+    if (iface->defaultCtr)
+        iface->defaultCtr(iface, where);
+    else
+        memset(where, 0, iface->size);
+}
+
+inline void copyConstruct(const QtPrivate::QMetaTypeInterface *iface, void *where, const void *copy)
+{
+    Q_ASSERT(isCopyConstructible(iface));
+    if (iface->copyCtr)
+        iface->copyCtr(iface, where, copy);
+    else
+        memcpy(where, copy, iface->size);
+}
+
+inline void construct(const QtPrivate::QMetaTypeInterface *iface, void *where, const void *copy)
+{
+    if (copy)
+        copyConstruct(iface, where, copy);
+    else
+        defaultConstruct(iface, where);
+}
+
+inline void destruct(const QtPrivate::QMetaTypeInterface *iface, void *where)
+{
+    Q_ASSERT(isDestructible(iface));
+    if (iface->dtor)
+        iface->dtor(iface, where);
+}
+
 const char *typedefNameForType(const QtPrivate::QMetaTypeInterface *type_d);
 
 template<typename T>