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>

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 8702ea8a21f6dbd82af7a6e734b9c0726cfbedee..53ceb29e919d4393bcb40759c8563187117ac63f 100644 (file)
--- 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;
 }