From 2db9dd5aeb9566c8480651989981cb1169957748 Mon Sep 17 00:00:00 2001 From: Francisco Jerez Date: Mon, 23 May 2016 19:32:51 -0700 Subject: [PATCH] i965/fs: Fix off-by-one region overlap comparison in copy propagation. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit This was introduced in cf375a3333e54a01462f192202d609436e5fbec8 but the blame is mine because the pseudocode I sent in my review comment for the original patch suggesting to do things this way already had the off-by-one error. This may have caused copy propagation to be unnecessarily strict while checking whether VGRF writes interfere with any ACP entries and possibly miss valid optimization opportunities in cases where multiple copy instructions write sequential locations of the same VGRF. Cc: Iago Toral Quiroga Reviewed-by: Samuel Iglesias Gonsálvez --- src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp index 9b92986fdf0..ceaaf5f411f 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_copy_propagation.cpp @@ -719,8 +719,8 @@ inline bool regions_overlap(const fs_reg &r, unsigned n, const fs_reg &s, unsigned m) { return r.file == s.file && r.nr == s.nr && - !(r.reg_offset + n < s.reg_offset || - s.reg_offset + m < r.reg_offset); + !(r.reg_offset + n <= s.reg_offset || + s.reg_offset + m <= r.reg_offset); } /* Walks a basic block and does copy propagation on it using the acp -- 2.30.2