Mesa (master): i965/vec4: skip copy-propate for logical instructions with negated src entries

[Matt Turner]

Module: Mesa
Branch: master
Commit: c17db7537fe112841bb76b91865a30d97aae3594
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=c17db7537fe112841bb76b91865a30d97aae3594

Author: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>
Date:   Thu Jun  5 11:05:31 2014 -0700

i965/vec4: skip copy-propate for logical instructions with negated src entries

The negation source modifier on src registers has changed meaning in Broadwell when
used with logical operations. Don't copy propagate when negate src modifier is set
and when the destination instruction is a logical op.

Reviewed-by: Matt Turner <mattst88 at gmail.com>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue at linux.intel.com>

---

 .../drivers/dri/i965/brw_vec4_copy_propagation.cpp    |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
index 83cf191..3242c3a 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_copy_propagation.cpp
@@ -195,6 +195,15 @@ try_constant_propagation(vec4_instruction *inst, int arg, src_reg *values[4])
    return false;
 }
 
+static bool
+is_logic_op(enum opcode opcode)
+{
+   return (opcode == BRW_OPCODE_AND ||
+           opcode == BRW_OPCODE_OR  ||
+           opcode == BRW_OPCODE_XOR ||
+           opcode == BRW_OPCODE_NOT);
+}
+
 bool
 vec4_visitor::try_copy_propagation(vec4_instruction *inst, int arg,
                                    src_reg *values[4])
@@ -233,6 +242,14 @@ vec4_visitor::try_copy_propagation(vec4_instruction *inst, int arg,
        value.file != ATTR)
       return false;
 
+   if (brw->gen >= 8) {
+      if (value.negate) {
+         if (is_logic_op(inst->opcode)) {
+            return false;
+         }
+      }
+   }
+
    if (inst->src[arg].abs) {
       value.negate = false;
       value.abs = true;