configure: fix performance regression due to PIC objects

Because most files in QEMU are grouped into static libraries, Meson conservatively
compiles them with -fPIC.  This is overkill and produces slowdowns up to 20% on
some TCG tests.

As a stopgap measure, use the b_staticpic option to limit the slowdown to
--enable-pie.  mesonbuild/meson#7760 will allow
us to use b_staticpic=false and let Meson do the right thing.

Reported-by: Ahmed Karaman <ahmedkrmn@outlook.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20200919155639.1045857-1-pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

MAINTAINERS

@@ -2462,6 +2462,7 @@ F: include/monitor/qdev.h
 F: include/qom/
 F: qapi/qom.json
 F: qapi/qdev.json
+F: scripts/coccinelle/qom-parent-type.cocci
 F: softmmu/qdev-monitor.c
 F: qom/
 F: tests/check-qom-interface.c

configure

@@ -7209,6 +7209,7 @@ NINJA=${ninja:-$PWD/ninjatool} $meson setup \
         -Dwerror=$(if test "$werror" = yes; then echo true; else echo false; fi) \
         -Dstrip=$(if test "$strip_opt" = yes; then echo true; else echo false; fi) \
         -Db_pie=$(if test "$pie" = yes; then echo true; else echo false; fi) \
+        -Db_staticpic=$(if test "$pie" = yes; then echo true; else echo false; fi) \
         -Db_coverage=$(if test "$gcov" = yes; then echo true; else echo false; fi) \
 	-Dmalloc=$malloc -Dmalloc_trim=$malloc_trim -Dsparse=$sparse \
 	-Dkvm=$kvm -Dhax=$hax -Dwhpx=$whpx -Dhvf=$hvf \

include/hw/acpi/vmgenid.h

@@ -19,7 +19,7 @@
 OBJECT_DECLARE_SIMPLE_TYPE(VmGenIdState, VMGENID)
 
 struct VmGenIdState {
-    DeviceClass parent_obj;
+    DeviceState parent_obj;
     QemuUUID guid;                /* The 128-bit GUID seen by the guest */
     uint8_t vmgenid_addr_le[8];   /* Address of the GUID (little-endian) */
 };

include/hw/misc/vmcoreinfo.h

@@ -24,7 +24,7 @@ DECLARE_INSTANCE_CHECKER(VMCoreInfoState, VMCOREINFO,
 typedef struct fw_cfg_vmcoreinfo FWCfgVMCoreInfo;
 
 struct VMCoreInfoState {
-    DeviceClass parent_obj;
+    DeviceState parent_obj;
 
     bool has_vmcoreinfo;
     FWCfgVMCoreInfo vmcoreinfo;

include/net/can_host.h

@@ -35,7 +35,7 @@
 OBJECT_DECLARE_TYPE(CanHostState, CanHostClass, CAN_HOST)
 
 struct CanHostState {
-    ObjectClass oc;
+    Object oc;
 
     CanBusState *bus;
     CanBusClientState bus_client;

scripts/coccinelle/qom-parent-type.cocci

@@ -0,0 +1,26 @@
+// Highlight object declarations that don't look like object class but
+// accidentally inherit from it.
+
+@match@
+identifier obj_t, fld;
+type parent_t =~ ".*Class$";
+@@
+struct obj_t {
+    parent_t fld;
+    ...
+};
+
+@script:python filter depends on match@
+obj_t << match.obj_t;
+@@
+is_class_obj = obj_t.endswith('Class')
+cocci.include_match(not is_class_obj)
+
+@replacement depends on filter@
+identifier match.obj_t, match.fld;
+type match.parent_t;
+@@
+struct obj_t {
+*   parent_t fld;
+    ...
+};