From 991bfc64db096cb924d5d216a9cb469590f00428 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 17 May 2017 13:09:58 +0100 Subject: [PATCH] drm/i915: Make ptr_unpack_bits() more function-like ptr_unpack_bits() is a function-like macro, as such it is meant to be replaceable by a function. In this case, we should be passing in the out-param as a pointer. Bizarrely this does affect code generation: function old new delta i915_gem_object_pin_map 409 389 -20 An improvement(?) in this case, but one can't help wonder what strict-aliasing optimisations we are preventing. The generated code looks identical in using ptr_unpack_bits (no extra motions to stack, the pointer and bits appear to be kept in registers), the difference appears to be code ordering and with a reorder it is able to use smaller forward jumps. Signed-off-by: Chris Wilson Reviewed-by: Joonas Lahtinen Link: http://patchwork.freedesktop.org/patch/msgid/20170517121007.27224-3-chris@chris-wilson.co.uk --- drivers/gpu/drm/i915/i915_gem.c | 2 +- drivers/gpu/drm/i915/i915_utils.h | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem.c b/drivers/gpu/drm/i915/i915_gem.c index f9c6b9b..5d68bec 100644 --- a/drivers/gpu/drm/i915/i915_gem.c +++ b/drivers/gpu/drm/i915/i915_gem.c @@ -2612,7 +2612,7 @@ void *i915_gem_object_pin_map(struct drm_i915_gem_object *obj, } GEM_BUG_ON(!obj->mm.pages); - ptr = ptr_unpack_bits(obj->mm.mapping, has_type); + ptr = ptr_unpack_bits(obj->mm.mapping, &has_type); if (ptr && has_type != type) { if (pinned) { ret = -EBUSY; diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h index f9d6607..18630d8 100644 --- a/drivers/gpu/drm/i915/i915_utils.h +++ b/drivers/gpu/drm/i915/i915_utils.h @@ -77,7 +77,7 @@ #define ptr_unpack_bits(ptr, bits) ({ \ unsigned long __v = (unsigned long)(ptr); \ - (bits) = __v & ~PAGE_MASK; \ + *(bits) = __v & ~PAGE_MASK; \ (typeof(ptr))(__v & PAGE_MASK); \ }) -- 2.7.4