Just use the negation source modifier on one of the multiplicand arguments.
total instructions in shared programs: 5889529 -> 5880016 (-0.16%) instructions in affected programs: 600846 -> 591333 (-1.58%) --- src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp index bd9345e..dd4beff 100644 --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp @@ -426,10 +426,21 @@ fs_visitor::try_emit_mad(ir_expression *ir) ir_rvalue *nonmul = ir->operands[1]; ir_expression *mul = ir->operands[0]->as_expression(); + bool mul_negate = false; + if (mul && mul->operation == ir_unop_neg) { + mul = mul->operands[0]->as_expression(); + mul_negate = true; + } + if (!mul || mul->operation != ir_binop_mul) { nonmul = ir->operands[0]; mul = ir->operands[1]->as_expression(); + if (mul && mul->operation == ir_unop_neg) { + mul = mul->operands[0]->as_expression(); + mul_negate = true; + } + if (!mul || mul->operation != ir_binop_mul) return false; } @@ -444,6 +455,7 @@ fs_visitor::try_emit_mad(ir_expression *ir) mul->operands[0]->accept(this); fs_reg src1 = this->result; + src1.negate ^= mul_negate; mul->operands[1]->accept(this); fs_reg src2 = this->result; -- 2.0.4 _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev