[PATCH 3/3] drm/i915: Allow optimized platform checks

Tvrtko Ursulin
2017-09-20T09:27:12Z

From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

If we store the platform as a bitmask, and convert the
IS_PLATFORM macro to use it, we allow the compiler to
merge the IS_PLATFORM(a) || IS_PLATFORM(b) || ... checks
into a single conditional.

Even with the added BUG_ON this saves almost 1k of text:

text data bss dec hex filename
-1460254 60014 3656 1523924 1740d4 drivers/gpu/drm/i915/i915.ko
+1459260 60026 3656 1522942 173cfe drivers/gpu/drm/i915/i915.ko

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
---
drivers/gpu/drm/i915/i915_drv.c | 6 ++++++
drivers/gpu/drm/i915/i915_drv.h | 3 ++-
2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index b1f96eb1be16..c3bd4b7cb19b 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -869,6 +869,12 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
memcpy(device_info, match_info, sizeof(*device_info));
device_info->device_id = dev_priv->drm.pdev->device;

+ BUILD_BUG_ON(sizeof(device_info->platform_mask) * BITS_PER_BYTE <
+ (INTEL_MAX_PLATFORMS - 1));
+ BUG_ON(device_info->platform == 0 ||
+ device_info->platform >= INTEL_MAX_PLATFORMS);
+ device_info->platform_mask = BIT(device_info->platform - 1);
+
BUG_ON(device_info->gen > sizeof(device_info->gen_mask) * BITS_PER_BYTE);
device_info->gen_mask = BIT(device_info->gen - 1);

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 950aa109f8cb..81211f23326a 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -861,6 +861,7 @@ struct intel_device_info {
u8 ring_mask; /* Rings supported by the HW */

enum intel_platform platform;
+ u32 platform_mask;

u32 display_mmio_offset;

@@ -2984,7 +2985,7 @@ intel_info(const struct drm_i915_private *dev_priv)
#define IS_REVID(p, since, until) \
(INTEL_REVID(p) >= (since) && INTEL_REVID(p) <= (until))

-#define IS_PLATFORM(dev_priv, p) ((dev_priv)->info.platform == (p))
+#define IS_PLATFORM(dev_priv, p) ((dev_priv)->info.platform_mask & BIT((p) - 1))

#define IS_I830(dev_priv) IS_PLATFORM(dev_priv, INTEL_I830)
#define IS_I845G(dev_priv) IS_PLATFORM(dev_priv, INTEL_I845G)
--
2.9.5