qom: allow turning cast debugging off

Cast debugging can have a substantial cost (20% or more).  Instead of adding
special-cased "fast casts" in the hot paths, we can just disable it in
releases.  The tracing facilities we just added make it easier to analyze
those problems that cast debugging would reveal.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1368188203-3407-7-git-send-email-pbonzini@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/configure b/configure
index 9439f1c727..cab6332991 100755
--- a/configure
+++ b/configure
@@ -220,6 +220,7 @@ blobs="yes"
 pkgversion=""
 pie=""
 zero_malloc=""
+qom_cast_debug="yes"
 trace_backend="nop"
 trace_file="trace"
 spice=""
@@ -688,6 +689,10 @@ for opt do
   ;;
   --enable-sdl) sdl="yes"
   ;;
+  --disable-qom-cast-debug) qom_cast_debug="no"
+  ;;
+  --enable-qom-cast-debug) qom_cast_debug="yes"
+  ;;
   --disable-virtfs) virtfs="no"
   ;;
   --enable-virtfs) virtfs="yes"
@@ -3575,6 +3580,7 @@ echo "gcov enabled      $gcov"
 echo "TPM support       $tpm"
 echo "libssh2 support   $libssh2"
 echo "TPM passthrough   $tpm_passthrough"
+echo "QOM debugging     $qom_cast_debug"
 
 if test "$sdl_too_old" = "yes"; then
 echo "-> Your SDL version is too old - please upgrade to have SDL support"
@@ -3909,6 +3915,9 @@ echo "CONFIG_UNAME_RELEASE=\"$uname_release\"" >> $config_host_mak
 if test "$zero_malloc" = "yes" ; then
   echo "CONFIG_ZERO_MALLOC=y" >> $config_host_mak
 fi
+if test "$qom_cast_debug" = "yes" ; then
+  echo "CONFIG_QOM_CAST_DEBUG=y" >> $config_host_mak
+fi
 if test "$rbd" = "yes" ; then
   echo "CONFIG_RBD=y" >> $config_host_mak
 fi