[Mesa-dev] [RFC 9/9] i965/fs: Emit MAD instructions when possible.

[Matt Turner]

Previously we didn't emit MAD instructions since they cannot take
immediate arguments, but with the opt_combine_constants() pass we can
handle this properly.
---
 src/mesa/drivers/dri/i965/brw_fs_fp.cpp      | 11 ++++++++---
 src/mesa/drivers/dri/i965/brw_fs_visitor.cpp |  5 -----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_fp.cpp b/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
index 6348bc1..62cea7a 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_fp.cpp
@@ -318,9 +318,14 @@ fs_visitor::emit_fragment_program_code()
       case OPCODE_MAD:
          for (int i = 0; i < 4; i++) {
             if (fpi->DstReg.WriteMask & (1 << i)) {
-               fs_reg temp = fs_reg(this, glsl_type::float_type);
-               emit(MUL(temp, offset(src[0], i), offset(src[1], i)));
-               emit(ADD(offset(dst, i), temp, offset(src[2], i)));
+               if (brw->gen >= 6) {
+                  emit(MAD(offset(dst, i), offset(src[2], i),
+                           offset(src[1], i), offset(src[0], i)));
+               } else {
+                  fs_reg temp = fs_reg(this, glsl_type::float_type);
+                  emit(MUL(temp, offset(src[0], i), offset(src[1], i)));
+                  emit(ADD(offset(dst, i), temp, offset(src[2], i)));
+               }
             }
          }
          break;
diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 3fc9e39..c610a9e 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -319,11 +319,6 @@ fs_visitor::try_emit_mad(ir_expression *ir)
          return false;
    }
 
-   if (nonmul->as_constant() ||
-       mul->operands[0]->as_constant() ||
-       mul->operands[1]->as_constant())
-      return false;
-
    nonmul->accept(this);
    fs_reg src0 = this->result;
 
-- 
2.0.4