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-rw-r--r--src/mesa/program/ir_to_mesa.cpp52
1 files changed, 52 insertions, 0 deletions
diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp
index 4c8b097de6b..b1211c1145c 100644
--- a/src/mesa/program/ir_to_mesa.cpp
+++ b/src/mesa/program/ir_to_mesa.cpp
@@ -314,6 +314,8 @@ public:
GLboolean try_emit_mad(ir_expression *ir,
int mul_operand);
+ bool try_emit_mad_for_and_not(ir_expression *ir,
+ int mul_operand);
GLboolean try_emit_sat(ir_expression *ir);
void emit_swz(ir_expression *ir);
@@ -892,6 +894,46 @@ ir_to_mesa_visitor::try_emit_mad(ir_expression *ir, int mul_operand)
return true;
}
+/**
+ * Emit OPCODE_MAD(a, -b, a) instead of AND(a, NOT(b))
+ *
+ * The logic values are 1.0 for true and 0.0 for false. Logical-and is
+ * implemented using multiplication, and logical-or is implemented using
+ * addition. Logical-not can be implemented as (true - x), or (1.0 - x).
+ * As result, the logical expression (a & !b) can be rewritten as:
+ *
+ * - a * !b
+ * - a * (1 - b)
+ * - (a * 1) - (a * b)
+ * - a + -(a * b)
+ * - a + (a * -b)
+ *
+ * This final expression can be implemented as a single MAD(a, -b, a)
+ * instruction.
+ */
+bool
+ir_to_mesa_visitor::try_emit_mad_for_and_not(ir_expression *ir, int try_operand)
+{
+ const int other_operand = 1 - try_operand;
+ src_reg a, b;
+
+ ir_expression *expr = ir->operands[try_operand]->as_expression();
+ if (!expr || expr->operation != ir_unop_logic_not)
+ return false;
+
+ ir->operands[other_operand]->accept(this);
+ a = this->result;
+ expr->operands[0]->accept(this);
+ b = this->result;
+
+ b.negate = ~b.negate;
+
+ this->result = get_temp(ir->type);
+ emit(ir, OPCODE_MAD, dst_reg(this->result), a, b, a);
+
+ return true;
+}
+
GLboolean
ir_to_mesa_visitor::try_emit_sat(ir_expression *ir)
{
@@ -1088,6 +1130,16 @@ ir_to_mesa_visitor::visit(ir_expression *ir)
if (try_emit_mad(ir, 0))
return;
}
+
+ /* Quick peephole: Emit OPCODE_MAD(-a, -b, a) instead of AND(a, NOT(b))
+ */
+ if (ir->operation == ir_binop_logic_and) {
+ if (try_emit_mad_for_and_not(ir, 1))
+ return;
+ if (try_emit_mad_for_and_not(ir, 0))
+ return;
+ }
+
if (try_emit_sat(ir))
return;