From 478034f34a59969103237eb78bc82f9e70fe81c2 Mon Sep 17 00:00:00 2001 From: Bryan Cain Date: Sat, 27 Aug 2011 18:32:58 -0500 Subject: [PATCH] glsl: Use a separate div_to_mul_rcp lowering flag for integers. Using multiply and reciprocal for integer division involves potentially lossy floating point conversions. This is okay for older GPUs that represent integers as floating point, but undesirable for GPUs with native integer division instructions. TGSI, for example, has UDIV/IDIV instructions for integer division, so it makes sense to handle this directly. Likewise for i965. Reviewed-by: Ian Romanick Signed-off-by: Bryan Cain Signed-off-by: Kenneth Graunke --- src/glsl/ir_optimization.h | 13 ++- src/glsl/lower_instructions.cpp | 125 ++++++++++++--------- src/mesa/drivers/dri/i965/brw_shader.cpp | 1 + src/mesa/program/ir_to_mesa.cpp | 2 +- src/mesa/state_tracker/st_glsl_to_tgsi.cpp | 2 +- 5 files changed, 80 insertions(+), 63 deletions(-) diff --git a/src/glsl/ir_optimization.h b/src/glsl/ir_optimization.h index f7808bdda9a..48448d4a16a 100644 --- a/src/glsl/ir_optimization.h +++ b/src/glsl/ir_optimization.h @@ -29,12 +29,13 @@ */ /* Operations for lower_instructions() */ -#define SUB_TO_ADD_NEG 0x01 -#define DIV_TO_MUL_RCP 0x02 -#define EXP_TO_EXP2 0x04 -#define POW_TO_EXP2 0x08 -#define LOG_TO_LOG2 0x10 -#define MOD_TO_FRACT 0x20 +#define SUB_TO_ADD_NEG 0x01 +#define DIV_TO_MUL_RCP 0x02 +#define EXP_TO_EXP2 0x04 +#define POW_TO_EXP2 0x08 +#define LOG_TO_LOG2 0x10 +#define MOD_TO_FRACT 0x20 +#define INT_DIV_TO_MUL_RCP 0x40 bool do_common_optimization(exec_list *ir, bool linked, unsigned max_unroll_iterations); diff --git a/src/glsl/lower_instructions.cpp b/src/glsl/lower_instructions.cpp index 23aa19bde6f..d79eb0a7ffb 100644 --- a/src/glsl/lower_instructions.cpp +++ b/src/glsl/lower_instructions.cpp @@ -32,6 +32,7 @@ * Currently supported transformations: * - SUB_TO_ADD_NEG * - DIV_TO_MUL_RCP + * - INT_DIV_TO_MUL_RCP * - EXP_TO_EXP2 * - POW_TO_EXP2 * - LOG_TO_LOG2 @@ -47,8 +48,8 @@ * want to recognize add(op0, neg(op1)) or the other way around to * produce a subtract anyway. * - * DIV_TO_MUL_RCP: - * --------------- + * DIV_TO_MUL_RCP and INT_DIV_TO_MUL_RCP: + * -------------------------------------- * Breaks an ir_unop_div expression down to op0 * (rcp(op1)). * * Many GPUs don't have a divide instruction (945 and 965 included), @@ -56,6 +57,10 @@ * reciprocal. By breaking the operation down, constant reciprocals * can get constant folded. * + * DIV_TO_MUL_RCP only lowers floating point division; INT_DIV_TO_MUL_RCP + * handles the integer case, converting to and from floating point so that + * RCP is possible. + * * EXP_TO_EXP2 and LOG_TO_LOG2: * ---------------------------- * Many GPUs don't have a base e log or exponent instruction, but they @@ -95,6 +100,7 @@ private: void sub_to_add_neg(ir_expression *); void div_to_mul_rcp(ir_expression *); + void int_div_to_mul_rcp(ir_expression *); void mod_to_fract(ir_expression *); void exp_to_exp2(ir_expression *); void pow_to_exp2(ir_expression *); @@ -127,60 +133,67 @@ lower_instructions_visitor::sub_to_add_neg(ir_expression *ir) void lower_instructions_visitor::div_to_mul_rcp(ir_expression *ir) { - if (!ir->operands[1]->type->is_integer()) { - /* New expression for the 1.0 / op1 */ - ir_rvalue *expr; - expr = new(ir) ir_expression(ir_unop_rcp, - ir->operands[1]->type, - ir->operands[1], - NULL); - - /* op0 / op1 -> op0 * (1.0 / op1) */ - ir->operation = ir_binop_mul; - ir->operands[1] = expr; + assert(ir->operands[1]->type->is_float()); + + /* New expression for the 1.0 / op1 */ + ir_rvalue *expr; + expr = new(ir) ir_expression(ir_unop_rcp, + ir->operands[1]->type, + ir->operands[1]); + + /* op0 / op1 -> op0 * (1.0 / op1) */ + ir->operation = ir_binop_mul; + ir->operands[1] = expr; + + this->progress = true; +} + +void +lower_instructions_visitor::int_div_to_mul_rcp(ir_expression *ir) +{ + assert(ir->operands[1]->type->is_integer()); + + /* Be careful with integer division -- we need to do it as a + * float and re-truncate, since rcp(n > 1) of an integer would + * just be 0. + */ + ir_rvalue *op0, *op1; + const struct glsl_type *vec_type; + + vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT, + ir->operands[1]->type->vector_elements, + ir->operands[1]->type->matrix_columns); + + if (ir->operands[1]->type->base_type == GLSL_TYPE_INT) + op1 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[1], NULL); + else + op1 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[1], NULL); + + op1 = new(ir) ir_expression(ir_unop_rcp, op1->type, op1, NULL); + + vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT, + ir->operands[0]->type->vector_elements, + ir->operands[0]->type->matrix_columns); + + if (ir->operands[0]->type->base_type == GLSL_TYPE_INT) + op0 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[0], NULL); + else + op0 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[0], NULL); + + vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT, + ir->type->vector_elements, + ir->type->matrix_columns); + + op0 = new(ir) ir_expression(ir_binop_mul, vec_type, op0, op1); + + if (ir->operands[1]->type->base_type == GLSL_TYPE_INT) { + ir->operation = ir_unop_f2i; + ir->operands[0] = op0; } else { - /* Be careful with integer division -- we need to do it as a - * float and re-truncate, since rcp(n > 1) of an integer would - * just be 0. - */ - ir_rvalue *op0, *op1; - const struct glsl_type *vec_type; - - vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT, - ir->operands[1]->type->vector_elements, - ir->operands[1]->type->matrix_columns); - - if (ir->operands[1]->type->base_type == GLSL_TYPE_INT) - op1 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[1], NULL); - else - op1 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[1], NULL); - - op1 = new(ir) ir_expression(ir_unop_rcp, op1->type, op1, NULL); - - vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT, - ir->operands[0]->type->vector_elements, - ir->operands[0]->type->matrix_columns); - - if (ir->operands[0]->type->base_type == GLSL_TYPE_INT) - op0 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[0], NULL); - else - op0 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[0], NULL); - - vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT, - ir->type->vector_elements, - ir->type->matrix_columns); - - op0 = new(ir) ir_expression(ir_binop_mul, vec_type, op0, op1); - - if (ir->operands[1]->type->base_type == GLSL_TYPE_INT) { - ir->operation = ir_unop_f2i; - ir->operands[0] = op0; - } else { - ir->operation = ir_unop_i2u; - ir->operands[0] = new(ir) ir_expression(ir_unop_f2i, op0); - } - ir->operands[1] = NULL; + ir->operation = ir_unop_i2u; + ir->operands[0] = new(ir) ir_expression(ir_unop_f2i, op0); } + ir->operands[1] = NULL; this->progress = true; } @@ -265,7 +278,9 @@ lower_instructions_visitor::visit_leave(ir_expression *ir) break; case ir_binop_div: - if (lowering(DIV_TO_MUL_RCP)) + if (ir->operands[1]->type->is_integer() && lowering(INT_DIV_TO_MUL_RCP)) + int_div_to_mul_rcp(ir); + else if (ir->operands[1]->type->is_float() && lowering(DIV_TO_MUL_RCP)) div_to_mul_rcp(ir); break; diff --git a/src/mesa/drivers/dri/i965/brw_shader.cpp b/src/mesa/drivers/dri/i965/brw_shader.cpp index 0a21094708b..a6ed810a16e 100644 --- a/src/mesa/drivers/dri/i965/brw_shader.cpp +++ b/src/mesa/drivers/dri/i965/brw_shader.cpp @@ -100,6 +100,7 @@ brw_link_shader(struct gl_context *ctx, struct gl_shader_program *prog) lower_instructions(shader->ir, MOD_TO_FRACT | DIV_TO_MUL_RCP | + INT_DIV_TO_MUL_RCP | SUB_TO_ADD_NEG | EXP_TO_EXP2 | LOG_TO_LOG2); diff --git a/src/mesa/program/ir_to_mesa.cpp b/src/mesa/program/ir_to_mesa.cpp index 6820e4c6ba7..dd154db8b03 100644 --- a/src/mesa/program/ir_to_mesa.cpp +++ b/src/mesa/program/ir_to_mesa.cpp @@ -3232,7 +3232,7 @@ _mesa_ir_link_shader(struct gl_context *ctx, struct gl_shader_program *prog) /* Lowering */ do_mat_op_to_vec(ir); lower_instructions(ir, (MOD_TO_FRACT | DIV_TO_MUL_RCP | EXP_TO_EXP2 - | LOG_TO_LOG2 + | LOG_TO_LOG2 | INT_DIV_TO_MUL_RCP | ((options->EmitNoPow) ? POW_TO_EXP2 : 0))); progress = do_lower_jumps(ir, true, true, options->EmitNoMainReturn, options->EmitNoCont, options->EmitNoLoops) || progress; diff --git a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp index 3fbb0cdd248..98bea69b959 100644 --- a/src/mesa/state_tracker/st_glsl_to_tgsi.cpp +++ b/src/mesa/state_tracker/st_glsl_to_tgsi.cpp @@ -4982,7 +4982,7 @@ st_link_shader(struct gl_context *ctx, struct gl_shader_program *prog) /* Lowering */ do_mat_op_to_vec(ir); lower_instructions(ir, (MOD_TO_FRACT | DIV_TO_MUL_RCP | EXP_TO_EXP2 - | LOG_TO_LOG2 + | LOG_TO_LOG2 | INT_DIV_TO_MUL_RCP | ((options->EmitNoPow) ? POW_TO_EXP2 : 0))); progress = do_lower_jumps(ir, true, true, options->EmitNoMainReturn, options->EmitNoCont, options->EmitNoLoops) || progress; -- 2.30.2