From 991bfc64db096cb924d5d216a9cb469590f00428 Mon Sep 17 00:00:00 2001 From: Chris Wilson Date: Wed, 17 May 2017 13:09:58 +0100 Subject: 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_utils.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/gpu/drm/i915/i915_utils.h') diff --git a/drivers/gpu/drm/i915/i915_utils.h b/drivers/gpu/drm/i915/i915_utils.h index f9d6607ef52f..18630d8f4be8 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); \ }) -- cgit v1.2.3