intel/fs: Use the original destination region for int MUL lowering

Some hardware (CHV, BXT) have special restrictions on register regions
when doing integer multiplication.  We want to respect those when we
lower to DxW multiplication.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Cc: mesa-stable@lists.freedesktop.org

diff --git a/src/intel/compiler/brw_fs.cpp b/src/intel/compiler/brw_fs.cpp
index fea5a145a8e4fa568d94029bc1afb4e39c4eafcf..fdbc6dbd0eaaae449f66070d925e7622a7d32917 100644 (file)
--- a/src/intel/compiler/brw_fs.cpp
+++ b/src/intel/compiler/brw_fs.cpp
@@ -3489,18 +3489,20 @@ fs_visitor::lower_integer_multiplication()
 
             bool needs_mov = false;
             fs_reg orig_dst = inst->dst;
+            fs_reg low = inst->dst;
             if (orig_dst.is_null() || orig_dst.file == MRF ||
                 regions_overlap(inst->dst, inst->size_written,
                                 inst->src[0], inst->size_read(0)) ||
                 regions_overlap(inst->dst, inst->size_written,
                                 inst->src[1], inst->size_read(1))) {
                needs_mov = true;
-               inst->dst = fs_reg(VGRF, alloc.allocate(dispatch_width / 8),
-                                  inst->dst.type);
+               low.nr = alloc.allocate(regs_written(inst));
+               low.offset = low.offset % REG_SIZE;
             }
-            fs_reg low = inst->dst;
-            fs_reg high(VGRF, alloc.allocate(dispatch_width / 8),
-                        inst->dst.type);
+
+            fs_reg high = inst->dst;
+            high.nr = alloc.allocate(regs_written(inst));
+            high.offset = high.offset % REG_SIZE;
 
             if (devinfo->gen >= 7) {
                if (inst->src[1].file == IMM) {
@@ -3521,13 +3523,13 @@ fs_visitor::lower_integer_multiplication()
                         inst->src[1]);
             }
 
-            ibld.ADD(subscript(inst->dst, BRW_REGISTER_TYPE_UW, 1),
+            ibld.ADD(subscript(low, BRW_REGISTER_TYPE_UW, 1),
                      subscript(low, BRW_REGISTER_TYPE_UW, 1),
                      subscript(high, BRW_REGISTER_TYPE_UW, 0));
 
             if (needs_mov || inst->conditional_mod) {
                set_condmod(inst->conditional_mod,
-                           ibld.MOV(orig_dst, inst->dst));
+                           ibld.MOV(orig_dst, low));
             }
          }