Mesa (vulkan): Revert "i965/fs: Feel free to spill partial reads/writes"

[Jason Ekstrand]

Module: Mesa
Branch: vulkan
Commit: d31d9fa199a5fd4c717a263affe0738c9fc7c674
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=d31d9fa199a5fd4c717a263affe0738c9fc7c674

Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Fri Apr 15 09:53:42 2016 -0700

Revert "i965/fs: Feel free to spill partial reads/writes"

This reverts commit 2434ceabf41e66f2a3627ea8591e5ca427a78cce.

---

 src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp b/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp
index 8396854..791da0e 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_reg_allocate.cpp
@@ -808,13 +808,30 @@ fs_visitor::choose_spill_reg(struct ra_graph *g)
     */
    foreach_block_and_inst(block, fs_inst, inst, cfg) {
       for (unsigned int i = 0; i < inst->sources; i++) {
-	 if (inst->src[i].file == VGRF)
+	 if (inst->src[i].file == VGRF) {
             spill_costs[inst->src[i].nr] += loop_scale;
+
+            /* Register spilling logic assumes full-width registers; smeared
+             * registers have a width of 1 so if we try to spill them we'll
+             * generate invalid assembly.  This shouldn't be a problem because
+             * smeared registers are only used as short-term temporaries when
+             * loading pull constants, so spilling them is unlikely to reduce
+             * register pressure anyhow.
+             */
+            if (!inst->src[i].is_contiguous()) {
+               no_spill[inst->src[i].nr] = true;
+            }
+	 }
       }
 
-      if (inst->dst.file == VGRF)
+      if (inst->dst.file == VGRF) {
          spill_costs[inst->dst.nr] += inst->regs_written * loop_scale;
 
+         if (!inst->dst.is_contiguous()) {
+            no_spill[inst->dst.nr] = true;
+         }
+      }
+
       switch (inst->opcode) {
 
       case BRW_OPCODE_DO: