i965/fs: in MAD optimizations, switch last argument to be immediate

Commit bb33a31 introduced optimizations that transform cases of MAD
in to simpler forms but it did not take in to account that src[0]
can not be immediate and did not report progress. Patch switches
src[0] and src[1] if src[0] is immediate and adds progress
reporting. If both sources are immediates, this is taken care of by
the same opt_algebraic pass on later run.

v2: Fix for all cases, use temporary fs_reg (Matt, Kenneth)

Signed-off-by: Tapani Pälli <tapani.palli@intel.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=89569
Reviewed-by: Francisco Jerez <currojerez@riseup.net> (v1)
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Cc: "10.5" <mesa-stable@lists.freedesktop.org>

1 files changed, 10 insertions, 1 deletions

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 8702ea8..53ceb29 100644
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -2491,6 +2491,7 @@ fs_visitor::opt_algebraic()
             inst->opcode = BRW_OPCODE_MUL;
             inst->src[0] = inst->src[2];
             inst->src[2] = reg_undef;
+            progress = true;
          } else if (inst->src[1].is_one()) {
             inst->opcode = BRW_OPCODE_ADD;
             inst->src[1] = inst->src[2];
@@ -2521,8 +2522,16 @@ fs_visitor::opt_algebraic()
       default:
 	 break;
       }
-   }
 
+      /* Swap if src[0] is immediate. */
+      if (progress && inst->is_commutative()) {
+         if (inst->src[0].file == IMM) {
+            fs_reg tmp = inst->src[1];
+            inst->src[1] = inst->src[0];
+            inst->src[0] = tmp;
+         }
+      }
+   }
    return progress;
 }