From b44648c9186d403abaeeeb3190d6759f951a49e4 Mon Sep 17 00:00:00 2001 From: Bryan Cain Date: Fri, 5 Aug 2011 14:09:37 -0500 Subject: [PATCH] glsl_to_tgsi: try to avoid emitting a MOV_SAT to saturate an expression tree This is a port of commit 62722d9 to glsl_to_tgsi, with minor aesthetic changes (moved the declaration and assignment of new_inst inside the if block). --- src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 32 ++++++++++++++++++++++++------ 1 file changed, 26 insertions(+), 6 deletions(-) diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp index 460bafb..e10243a 100644 --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp @@ -1232,12 +1232,32 @@ glsl_to_tgsi_visitor::try_emit_sat(ir_expression *ir) sat_src->accept(this); st_src_reg src = this->result; - this->result = get_temp(ir->type); - st_dst_reg result_dst = st_dst_reg(this->result); - result_dst.writemask = (1 << ir->type->vector_elements) - 1; - glsl_to_tgsi_instruction *inst; - inst = emit(ir, TGSI_OPCODE_MOV, result_dst, src); - inst->saturate = true; + /* If we generated an expression instruction into a temporary in + * processing the saturate's operand, apply the saturate to that + * instruction. Otherwise, generate a MOV to do the saturate. + * + * Note that we have to be careful to only do this optimization if + * the instruction in question was what generated src->result. For + * example, ir_dereference_array might generate a MUL instruction + * to create the reladdr, and return us a src reg using that + * reladdr. That MUL result is not the value we're trying to + * saturate. + */ + ir_expression *sat_src_expr = sat_src->as_expression(); + if (sat_src_expr && (sat_src_expr->operation == ir_binop_mul || + sat_src_expr->operation == ir_binop_add || + sat_src_expr->operation == ir_binop_dot)) { + glsl_to_tgsi_instruction *new_inst; + new_inst = (glsl_to_tgsi_instruction *)this->instructions.get_tail(); + new_inst->saturate = true; + } else { + this->result = get_temp(ir->type); + st_dst_reg result_dst = st_dst_reg(this->result); + result_dst.writemask = (1 << ir->type->vector_elements) - 1; + glsl_to_tgsi_instruction *inst; + inst = emit(ir, TGSI_OPCODE_MOV, result_dst, src); + inst->saturate = true; + } return true; } -- 2.7.4