diff options
| -rw-r--r-- | src/mesa/program/ir_to_mesa.cpp | 111 |
1 files changed, 99 insertions, 12 deletions
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp index 0458625ab0..870fd6f25e 100644 --- a/src/mesa/program/ir_to_mesa.cpp +++ b/src/mesa/program/ir_to_mesa.cpp @@ -285,6 +285,8 @@ public: GLboolean try_emit_mad(ir_expression *ir, int mul_operand); + bool process_move_condition(ir_rvalue *ir); + void *mem_ctx; }; @@ -1326,6 +1328,93 @@ get_assignment_lhs(ir_dereference *ir, ir_to_mesa_visitor *v) return ir_to_mesa_dst_reg_from_src(v->result); } +/** + * Process the condition of a conditional assignment + * + * Examines the condition of a conditional assignment to generate the optimal + * first operand of a \c CMP instruction. If the condition is a relational + * operator with 0 (e.g., \c ir_binop_less), the value being compared will be + * used as the source for the \c CMP instruction. Otherwise the comparison + * is processed to a boolean result, and the boolean result is used as the + * operand to the CMP instruction. + */ +bool +ir_to_mesa_visitor::process_move_condition(ir_rvalue *ir) +{ + ir_rvalue *src_ir = ir; + bool negate = true; + bool switch_order = false; + + ir_expression *const expr = ir->as_expression(); + if ((expr != NULL) && (expr->get_num_operands() == 2)) { + bool zero_on_left = false; + + if (expr->operands[0]->is_zero()) { + src_ir = expr->operands[1]; + zero_on_left = true; + } else if (expr->operands[1]->is_zero()) { + src_ir = expr->operands[0]; + zero_on_left = false; + } + + /* a is - 0 + - 0 + + * (a < 0) T F F ( a < 0) T F F + * (0 < a) F F T (-a < 0) F F T + * (a <= 0) T T F (-a < 0) F F T (swap order of other operands) + * (0 <= a) F T T ( a < 0) T F F (swap order of other operands) + * (a > 0) F F T (-a < 0) F F T + * (0 > a) T F F ( a < 0) T F F + * (a >= 0) F T T ( a < 0) T F F (swap order of other operands) + * (0 >= a) T T F (-a < 0) F F T (swap order of other operands) + * + * Note that exchanging the order of 0 and 'a' in the comparison simply + * means that the value of 'a' should be negated. + */ + if (src_ir != ir) { + switch (expr->operation) { + case ir_binop_less: + switch_order = false; + negate = zero_on_left; + break; + + case ir_binop_greater: + switch_order = false; + negate = !zero_on_left; + break; + + case ir_binop_lequal: + switch_order = true; + negate = !zero_on_left; + break; + + case ir_binop_gequal: + switch_order = true; + negate = zero_on_left; + break; + + default: + /* This isn't the right kind of comparison afterall, so make sure + * the whole condition is visited. + */ + src_ir = ir; + break; + } + } + } + + src_ir->accept(this); + + /* We use the OPCODE_CMP (a < 0 ? b : c) for conditional moves, and the + * condition we produced is 0.0 or 1.0. By flipping the sign, we can + * choose which value OPCODE_CMP produces without an extra instruction + * computing the condition. + */ + if (negate) + this->result.negate = ~this->result.negate; + + return switch_order; +} + void ir_to_mesa_visitor::visit(ir_assignment *ir) { @@ -1385,20 +1474,18 @@ ir_to_mesa_visitor::visit(ir_assignment *ir) assert(r.file != PROGRAM_UNDEFINED); if (ir->condition) { - ir_to_mesa_src_reg condition; - - ir->condition->accept(this); - condition = this->result; + const bool switch_order = this->process_move_condition(ir->condition); + ir_to_mesa_src_reg condition = this->result; - /* We use the OPCODE_CMP (a < 0 ? b : c) for conditional moves, - * and the condition we produced is 0.0 or 1.0. By flipping the - * sign, we can choose which value OPCODE_CMP produces without - * an extra computing the condition. - */ - condition.negate = ~condition.negate; for (i = 0; i < type_size(ir->lhs->type); i++) { - ir_to_mesa_emit_op3(ir, OPCODE_CMP, l, - condition, r, ir_to_mesa_src_reg_from_dst(l)); + if (switch_order) { + ir_to_mesa_emit_op3(ir, OPCODE_CMP, l, + condition, ir_to_mesa_src_reg_from_dst(l), r); + } else { + ir_to_mesa_emit_op3(ir, OPCODE_CMP, l, + condition, r, ir_to_mesa_src_reg_from_dst(l)); + } + l.index++; r.index++; } |