From 92ca560d68e8a6b532998707afcf4f60c0ce2806 Mon Sep 17 00:00:00 2001 From: Ian Romanick Date: Wed, 3 Aug 2011 15:27:43 -0700 Subject: ir_to_mesa: Implement ir_unop_any using DP4 w/saturate or DP4 w/SLT This is just like the ir_binop_logic_or case. The operation ir_unop_any is (a.x || a.y || a.z || a.w). Logical-or is implemented using addition (followed by clampling to [0,1]) on values of 0.0 and 1.0. Replacing the logical-or operators with addition gives (a.x + a.y + a.z + a.w). This can be implemented using a dot-product with a vector of all 1.0. Previously a SNE instruction was used to clamp the resulting logic value to [0,1]. In a fragment shader, using a saturate on the dot-product has the same effect. Adding the saturate to the dot-product is free, so (at least) one instruction is saved. In a vertex shader, using an SLT on the negation of the dot-product result has the same effect. Many older shader architectures do not support the SNE instruction. It must be emulated using two SLT instructions and an ADD. On these architectures, the single SLT saves two instructions. Reviewed-by: Eric Anholt --- src/mesa/program/ir_to_mesa.cpp | 27 +++++++++++++++++++++++---- 1 file changed, 23 insertions(+), 4 deletions(-) (limited to 'src/mesa/program/ir_to_mesa.cpp') diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp index 60d498bd9e3..1bd9a2eee1b 100644 --- a/src/mesa/program/ir_to_mesa.cpp +++ b/src/mesa/program/ir_to_mesa.cpp @@ -1256,12 +1256,31 @@ ir_to_mesa_visitor::visit(ir_expression *ir) } break; - case ir_unop_any: + case ir_unop_any: { assert(ir->operands[0]->type->is_vector()); - emit_dp(ir, result_dst, op[0], op[0], - ir->operands[0]->type->vector_elements); - emit(ir, OPCODE_SNE, result_dst, result_src, src_reg_for_float(0.0)); + + /* After the dot-product, the value will be an integer on the + * range [0,4]. Zero stays zero, and positive values become 1.0. + */ + ir_to_mesa_instruction *const dp = + emit_dp(ir, result_dst, op[0], op[0], + ir->operands[0]->type->vector_elements); + if (this->prog->Target == GL_FRAGMENT_PROGRAM_ARB) { + /* The clamping to [0,1] can be done for free in the fragment + * shader with a saturate. + */ + dp->saturate = true; + } else { + /* Negating the result of the dot-product gives values on the range + * [-4, 0]. Zero stays zero, and negative values become 1.0. This + * is achieved using SLT. + */ + src_reg slt_src = result_src; + slt_src.negate = ~slt_src.negate; + emit(ir, OPCODE_SLT, result_dst, slt_src, src_reg_for_float(0.0)); + } break; + } case ir_binop_logic_xor: emit(ir, OPCODE_SNE, result_dst, op[0], op[1]); -- cgit v1.2.3