[RFC,for-10.0] include/hw/boards: Optimize the booleans in MachineClass

Commit Message

Thomas Huth Nov. 22, 2024, 8:49 a.m. UTC

While looking at the QEMU binary with "pahole", I noticed that we
could optimize the size of MachineClass a little bit: So far we
are using a mixture of a bitfield and single "bool" members here
for the boolean flags. Declaring all flags as part of the bitfield
helps to shrink the size of the struct a little bit.

Signed-off-by: Thomas Huth <[e-mail]>
---
 It's just a micro-optimization (the size of the struct decreases by
 eight bytes), so I'm not sure whether it's worth the effort...?

 include/hw/boards.h | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

Patch

diff --git a/include/hw/boards.h b/include/hw/boards.h
index 36fbb9b59d..c6946bd319 100644
--- a/include/hw/boards.h
+++ b/include/hw/boards.h
@@ -285,8 +285,16 @@  struct MachineClass {
         no_cdrom:1,
         no_sdcard:1,
         pci_allow_0_address:1,
-        legacy_fw_cfg_order:1;
-    bool is_default;
+        legacy_fw_cfg_order:1,
+        is_default:1,
+        auto_enable_numa_with_memhp:1,
+        auto_enable_numa_with_memdev:1,
+        ignore_boot_device_suffixes:1,
+        smbus_no_migration_support:1,
+        nvdimm_supported:1,
+        numa_mem_supported:1,
+        auto_enable_numa:1,
+        cpu_cluster_has_numa_boundary:1;
     const char *default_machine_opts;
     const char *default_boot_order;
     const char *default_display;
@@ -304,14 +312,6 @@  struct MachineClass {
     int numa_mem_align_shift;
     const char * const *valid_cpu_types;
     strList *allowed_dynamic_sysbus_devices;
-    bool auto_enable_numa_with_memhp;
-    bool auto_enable_numa_with_memdev;
-    bool ignore_boot_device_suffixes;
-    bool smbus_no_migration_support;
-    bool nvdimm_supported;
-    bool numa_mem_supported;
-    bool auto_enable_numa;
-    bool cpu_cluster_has_numa_boundary;
     SMPCompatProps smp_props;
     const char *default_ram_id;