From: Matt Turner <mattst88@gmail.com>
Date: Thu, 18 Aug 2016 22:54:47 +0000 (-0700)
Subject: i965/vec4: Ignore swizzle of VGRF for use by var_range_end().
X-Git-Tag: android-x86-6.0-r1^2~55
X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=bf61f2e5c3daf257fcfb0d484df05bad59265887;hp=d2f0a2925f2f1cd3d95e36f0cc8540371257641b;p=android-x86%2Fexternal-mesa.git

i965/vec4: Ignore swizzle of VGRF for use by var_range_end().

var_range_end(v, n) loops over the n components of variable number v and
finds the maximum value, giving the last use of any component of v.
Therefore it expects v to correspond to the variable associated with the
.x channel of the VGRF.

var_from_reg() however returns the variable for the first channel of the
VGRF, post-swizzle.

So, if the last register had a swizzle with y, z, or w in the swizzle
component, we would read out of bounds. For any other register, we would
read liveness information from the next register.

The fix is to convert the src_reg to a dst_reg in order to call the
dst_reg version of var_from_reg() that doesn't consider the swizzle.

Cc: mesa-stable@lists.freedesktop.org
Reviewed-by: Francisco Jerez <currojerez@riseup.net>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
(cherry picked from commit e7c376adfdecd4c1333997c8be8bb066a87c67b4)
---

diff --git a/src/mesa/drivers/dri/i965/brw_vec4.cpp b/src/mesa/drivers/dri/i965/brw_vec4.cpp
index 2cf0e1759e4..a7398a797bb 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4.cpp
@@ -1111,7 +1111,7 @@ vec4_visitor::opt_register_coalesce()
       /* Can't coalesce this GRF if someone else was going to
        * read it later.
        */
-      if (var_range_end(var_from_reg(alloc, inst->src[0]), 4) > ip)
+      if (var_range_end(var_from_reg(alloc, dst_reg(inst->src[0])), 4) > ip)
 	 continue;
 
       /* We need to check interference with the final destination between this
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
index 0c1f0c31b0d..10898a5917d 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_cse.cpp
@@ -246,7 +246,7 @@ vec4_visitor::opt_cse_local(bblock_t *block)
              * more -- a sure sign they'll fail operands_match().
              */
             if (src->file == VGRF) {
-               if (var_range_end(var_from_reg(alloc, *src), 4) < ip) {
+               if (var_range_end(var_from_reg(alloc, dst_reg(*src)), 4) < ip) {
                   entry->remove();
                   ralloc_free(entry);
                   break;