lower_instructions.cpp revision 01e04c3f
1/*
2 * Copyright © 2010 Intel Corporation
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
10 *
11 * The above copyright notice and this permission notice (including the next
12 * paragraph) shall be included in all copies or substantial portions of the
13 * Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
21 * DEALINGS IN THE SOFTWARE.
22 */
23
24/**
25 * \file lower_instructions.cpp
26 *
27 * Many GPUs lack native instructions for certain expression operations, and
28 * must replace them with some other expression tree.  This pass lowers some
29 * of the most common cases, allowing the lowering code to be implemented once
30 * rather than in each driver backend.
31 *
32 * Currently supported transformations:
33 * - SUB_TO_ADD_NEG
34 * - DIV_TO_MUL_RCP
35 * - INT_DIV_TO_MUL_RCP
36 * - EXP_TO_EXP2
37 * - POW_TO_EXP2
38 * - LOG_TO_LOG2
39 * - MOD_TO_FLOOR
40 * - LDEXP_TO_ARITH
41 * - DFREXP_TO_ARITH
42 * - CARRY_TO_ARITH
43 * - BORROW_TO_ARITH
44 * - SAT_TO_CLAMP
45 * - DOPS_TO_DFRAC
46 *
47 * SUB_TO_ADD_NEG:
48 * ---------------
49 * Breaks an ir_binop_sub expression down to add(op0, neg(op1))
50 *
51 * This simplifies expression reassociation, and for many backends
52 * there is no subtract operation separate from adding the negation.
53 * For backends with native subtract operations, they will probably
54 * want to recognize add(op0, neg(op1)) or the other way around to
55 * produce a subtract anyway.
56 *
57 * FDIV_TO_MUL_RCP, DDIV_TO_MUL_RCP, and INT_DIV_TO_MUL_RCP:
58 * ---------------------------------------------------------
59 * Breaks an ir_binop_div expression down to op0 * (rcp(op1)).
60 *
61 * Many GPUs don't have a divide instruction (945 and 965 included),
62 * but they do have an RCP instruction to compute an approximate
63 * reciprocal.  By breaking the operation down, constant reciprocals
64 * can get constant folded.
65 *
66 * FDIV_TO_MUL_RCP only lowers single-precision floating point division;
67 * DDIV_TO_MUL_RCP only lowers double-precision floating point division.
68 * DIV_TO_MUL_RCP is a convenience macro that sets both flags.
69 * INT_DIV_TO_MUL_RCP handles the integer case, converting to and from floating
70 * point so that RCP is possible.
71 *
72 * EXP_TO_EXP2 and LOG_TO_LOG2:
73 * ----------------------------
74 * Many GPUs don't have a base e log or exponent instruction, but they
75 * do have base 2 versions, so this pass converts exp and log to exp2
76 * and log2 operations.
77 *
78 * POW_TO_EXP2:
79 * -----------
80 * Many older GPUs don't have an x**y instruction.  For these GPUs, convert
81 * x**y to 2**(y * log2(x)).
82 *
83 * MOD_TO_FLOOR:
84 * -------------
85 * Breaks an ir_binop_mod expression down to (op0 - op1 * floor(op0 / op1))
86 *
87 * Many GPUs don't have a MOD instruction (945 and 965 included), and
88 * if we have to break it down like this anyway, it gives an
89 * opportunity to do things like constant fold the (1.0 / op1) easily.
90 *
91 * Note: before we used to implement this as op1 * fract(op / op1) but this
92 * implementation had significant precision errors.
93 *
94 * LDEXP_TO_ARITH:
95 * -------------
96 * Converts ir_binop_ldexp to arithmetic and bit operations for float sources.
97 *
98 * DFREXP_DLDEXP_TO_ARITH:
99 * ---------------
100 * Converts ir_binop_ldexp, ir_unop_frexp_sig, and ir_unop_frexp_exp to
101 * arithmetic and bit ops for double arguments.
102 *
103 * CARRY_TO_ARITH:
104 * ---------------
105 * Converts ir_carry into (x + y) < x.
106 *
107 * BORROW_TO_ARITH:
108 * ----------------
109 * Converts ir_borrow into (x < y).
110 *
111 * SAT_TO_CLAMP:
112 * -------------
113 * Converts ir_unop_saturate into min(max(x, 0.0), 1.0)
114 *
115 * DOPS_TO_DFRAC:
116 * --------------
117 * Converts double trunc, ceil, floor, round to fract
118 */
119
120#include "c99_math.h"
121#include "program/prog_instruction.h" /* for swizzle */
122#include "compiler/glsl_types.h"
123#include "ir.h"
124#include "ir_builder.h"
125#include "ir_optimization.h"
126
127using namespace ir_builder;
128
129namespace {
130
131class lower_instructions_visitor : public ir_hierarchical_visitor {
132public:
133   lower_instructions_visitor(unsigned lower)
134      : progress(false), lower(lower) { }
135
136   ir_visitor_status visit_leave(ir_expression *);
137
138   bool progress;
139
140private:
141   unsigned lower; /** Bitfield of which operations to lower */
142
143   void sub_to_add_neg(ir_expression *);
144   void div_to_mul_rcp(ir_expression *);
145   void int_div_to_mul_rcp(ir_expression *);
146   void mod_to_floor(ir_expression *);
147   void exp_to_exp2(ir_expression *);
148   void pow_to_exp2(ir_expression *);
149   void log_to_log2(ir_expression *);
150   void ldexp_to_arith(ir_expression *);
151   void dldexp_to_arith(ir_expression *);
152   void dfrexp_sig_to_arith(ir_expression *);
153   void dfrexp_exp_to_arith(ir_expression *);
154   void carry_to_arith(ir_expression *);
155   void borrow_to_arith(ir_expression *);
156   void sat_to_clamp(ir_expression *);
157   void double_dot_to_fma(ir_expression *);
158   void double_lrp(ir_expression *);
159   void dceil_to_dfrac(ir_expression *);
160   void dfloor_to_dfrac(ir_expression *);
161   void dround_even_to_dfrac(ir_expression *);
162   void dtrunc_to_dfrac(ir_expression *);
163   void dsign_to_csel(ir_expression *);
164   void bit_count_to_math(ir_expression *);
165   void extract_to_shifts(ir_expression *);
166   void insert_to_shifts(ir_expression *);
167   void reverse_to_shifts(ir_expression *ir);
168   void find_lsb_to_float_cast(ir_expression *ir);
169   void find_msb_to_float_cast(ir_expression *ir);
170   void imul_high_to_mul(ir_expression *ir);
171   void sqrt_to_abs_sqrt(ir_expression *ir);
172
173   ir_expression *_carry(operand a, operand b);
174};
175
176} /* anonymous namespace */
177
178/**
179 * Determine if a particular type of lowering should occur
180 */
181#define lowering(x) (this->lower & x)
182
183bool
184lower_instructions(exec_list *instructions, unsigned what_to_lower)
185{
186   lower_instructions_visitor v(what_to_lower);
187
188   visit_list_elements(&v, instructions);
189   return v.progress;
190}
191
192void
193lower_instructions_visitor::sub_to_add_neg(ir_expression *ir)
194{
195   ir->operation = ir_binop_add;
196   ir->init_num_operands();
197   ir->operands[1] = new(ir) ir_expression(ir_unop_neg, ir->operands[1]->type,
198					   ir->operands[1], NULL);
199   this->progress = true;
200}
201
202void
203lower_instructions_visitor::div_to_mul_rcp(ir_expression *ir)
204{
205   assert(ir->operands[1]->type->is_float() || ir->operands[1]->type->is_double());
206
207   /* New expression for the 1.0 / op1 */
208   ir_rvalue *expr;
209   expr = new(ir) ir_expression(ir_unop_rcp,
210				ir->operands[1]->type,
211				ir->operands[1]);
212
213   /* op0 / op1 -> op0 * (1.0 / op1) */
214   ir->operation = ir_binop_mul;
215   ir->init_num_operands();
216   ir->operands[1] = expr;
217
218   this->progress = true;
219}
220
221void
222lower_instructions_visitor::int_div_to_mul_rcp(ir_expression *ir)
223{
224   assert(ir->operands[1]->type->is_integer());
225
226   /* Be careful with integer division -- we need to do it as a
227    * float and re-truncate, since rcp(n > 1) of an integer would
228    * just be 0.
229    */
230   ir_rvalue *op0, *op1;
231   const struct glsl_type *vec_type;
232
233   vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
234				      ir->operands[1]->type->vector_elements,
235				      ir->operands[1]->type->matrix_columns);
236
237   if (ir->operands[1]->type->base_type == GLSL_TYPE_INT)
238      op1 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[1], NULL);
239   else
240      op1 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[1], NULL);
241
242   op1 = new(ir) ir_expression(ir_unop_rcp, op1->type, op1, NULL);
243
244   vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
245				      ir->operands[0]->type->vector_elements,
246				      ir->operands[0]->type->matrix_columns);
247
248   if (ir->operands[0]->type->base_type == GLSL_TYPE_INT)
249      op0 = new(ir) ir_expression(ir_unop_i2f, vec_type, ir->operands[0], NULL);
250   else
251      op0 = new(ir) ir_expression(ir_unop_u2f, vec_type, ir->operands[0], NULL);
252
253   vec_type = glsl_type::get_instance(GLSL_TYPE_FLOAT,
254				      ir->type->vector_elements,
255				      ir->type->matrix_columns);
256
257   op0 = new(ir) ir_expression(ir_binop_mul, vec_type, op0, op1);
258
259   if (ir->operands[1]->type->base_type == GLSL_TYPE_INT) {
260      ir->operation = ir_unop_f2i;
261      ir->operands[0] = op0;
262   } else {
263      ir->operation = ir_unop_i2u;
264      ir->operands[0] = new(ir) ir_expression(ir_unop_f2i, op0);
265   }
266   ir->init_num_operands();
267   ir->operands[1] = NULL;
268
269   this->progress = true;
270}
271
272void
273lower_instructions_visitor::exp_to_exp2(ir_expression *ir)
274{
275   ir_constant *log2_e = new(ir) ir_constant(float(M_LOG2E));
276
277   ir->operation = ir_unop_exp2;
278   ir->init_num_operands();
279   ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[0]->type,
280					   ir->operands[0], log2_e);
281   this->progress = true;
282}
283
284void
285lower_instructions_visitor::pow_to_exp2(ir_expression *ir)
286{
287   ir_expression *const log2_x =
288      new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,
289			    ir->operands[0]);
290
291   ir->operation = ir_unop_exp2;
292   ir->init_num_operands();
293   ir->operands[0] = new(ir) ir_expression(ir_binop_mul, ir->operands[1]->type,
294					   ir->operands[1], log2_x);
295   ir->operands[1] = NULL;
296   this->progress = true;
297}
298
299void
300lower_instructions_visitor::log_to_log2(ir_expression *ir)
301{
302   ir->operation = ir_binop_mul;
303   ir->init_num_operands();
304   ir->operands[0] = new(ir) ir_expression(ir_unop_log2, ir->operands[0]->type,
305					   ir->operands[0], NULL);
306   ir->operands[1] = new(ir) ir_constant(float(1.0 / M_LOG2E));
307   this->progress = true;
308}
309
310void
311lower_instructions_visitor::mod_to_floor(ir_expression *ir)
312{
313   ir_variable *x = new(ir) ir_variable(ir->operands[0]->type, "mod_x",
314                                         ir_var_temporary);
315   ir_variable *y = new(ir) ir_variable(ir->operands[1]->type, "mod_y",
316                                         ir_var_temporary);
317   this->base_ir->insert_before(x);
318   this->base_ir->insert_before(y);
319
320   ir_assignment *const assign_x =
321      new(ir) ir_assignment(new(ir) ir_dereference_variable(x),
322                            ir->operands[0]);
323   ir_assignment *const assign_y =
324      new(ir) ir_assignment(new(ir) ir_dereference_variable(y),
325                            ir->operands[1]);
326
327   this->base_ir->insert_before(assign_x);
328   this->base_ir->insert_before(assign_y);
329
330   ir_expression *const div_expr =
331      new(ir) ir_expression(ir_binop_div, x->type,
332                            new(ir) ir_dereference_variable(x),
333                            new(ir) ir_dereference_variable(y));
334
335   /* Don't generate new IR that would need to be lowered in an additional
336    * pass.
337    */
338   if ((lowering(FDIV_TO_MUL_RCP) && ir->type->is_float()) ||
339       (lowering(DDIV_TO_MUL_RCP) && ir->type->is_double()))
340      div_to_mul_rcp(div_expr);
341
342   ir_expression *const floor_expr =
343      new(ir) ir_expression(ir_unop_floor, x->type, div_expr);
344
345   if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
346      dfloor_to_dfrac(floor_expr);
347
348   ir_expression *const mul_expr =
349      new(ir) ir_expression(ir_binop_mul,
350                            new(ir) ir_dereference_variable(y),
351                            floor_expr);
352
353   ir->operation = ir_binop_sub;
354   ir->init_num_operands();
355   ir->operands[0] = new(ir) ir_dereference_variable(x);
356   ir->operands[1] = mul_expr;
357   this->progress = true;
358}
359
360void
361lower_instructions_visitor::ldexp_to_arith(ir_expression *ir)
362{
363   /* Translates
364    *    ir_binop_ldexp x exp
365    * into
366    *
367    *    extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift);
368    *    resulting_biased_exp = min(extracted_biased_exp + exp, 255);
369    *
370    *    if (extracted_biased_exp >= 255)
371    *       return x; // +/-inf, NaN
372    *
373    *    sign_mantissa = bitcast_f2u(x) & sign_mantissa_mask;
374    *
375    *    if (min(resulting_biased_exp, extracted_biased_exp) < 1)
376    *       resulting_biased_exp = 0;
377    *    if (resulting_biased_exp >= 255 ||
378    *        min(resulting_biased_exp, extracted_biased_exp) < 1) {
379    *       sign_mantissa &= sign_mask;
380    *    }
381    *
382    *    return bitcast_u2f(sign_mantissa |
383    *                       lshift(i2u(resulting_biased_exp), exp_shift));
384    *
385    * which we can't actually implement as such, since the GLSL IR doesn't
386    * have vectorized if-statements. We actually implement it without branches
387    * using conditional-select:
388    *
389    *    extracted_biased_exp = rshift(bitcast_f2i(abs(x)), exp_shift);
390    *    resulting_biased_exp = min(extracted_biased_exp + exp, 255);
391    *
392    *    sign_mantissa = bitcast_f2u(x) & sign_mantissa_mask;
393    *
394    *    flush_to_zero = lequal(min(resulting_biased_exp, extracted_biased_exp), 0);
395    *    resulting_biased_exp = csel(flush_to_zero, 0, resulting_biased_exp)
396    *    zero_mantissa = logic_or(flush_to_zero,
397    *                             gequal(resulting_biased_exp, 255));
398    *    sign_mantissa = csel(zero_mantissa, sign_mantissa & sign_mask, sign_mantissa);
399    *
400    *    result = sign_mantissa |
401    *             lshift(i2u(resulting_biased_exp), exp_shift));
402    *
403    *    return csel(extracted_biased_exp >= 255, x, bitcast_u2f(result));
404    *
405    * The definition of ldexp in the GLSL spec says:
406    *
407    *    "If this product is too large to be represented in the
408    *     floating-point type, the result is undefined."
409    *
410    * However, the definition of ldexp in the GLSL ES spec does not contain
411    * this sentence, so we do need to handle overflow correctly.
412    *
413    * There is additional language limiting the defined range of exp, but this
414    * is merely to allow implementations that store 2^exp in a temporary
415    * variable.
416    */
417
418   const unsigned vec_elem = ir->type->vector_elements;
419
420   /* Types */
421   const glsl_type *ivec = glsl_type::get_instance(GLSL_TYPE_INT, vec_elem, 1);
422   const glsl_type *uvec = glsl_type::get_instance(GLSL_TYPE_UINT, vec_elem, 1);
423   const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
424
425   /* Temporary variables */
426   ir_variable *x = new(ir) ir_variable(ir->type, "x", ir_var_temporary);
427   ir_variable *exp = new(ir) ir_variable(ivec, "exp", ir_var_temporary);
428   ir_variable *result = new(ir) ir_variable(uvec, "result", ir_var_temporary);
429
430   ir_variable *extracted_biased_exp =
431      new(ir) ir_variable(ivec, "extracted_biased_exp", ir_var_temporary);
432   ir_variable *resulting_biased_exp =
433      new(ir) ir_variable(ivec, "resulting_biased_exp", ir_var_temporary);
434
435   ir_variable *sign_mantissa =
436      new(ir) ir_variable(uvec, "sign_mantissa", ir_var_temporary);
437
438   ir_variable *flush_to_zero =
439      new(ir) ir_variable(bvec, "flush_to_zero", ir_var_temporary);
440   ir_variable *zero_mantissa =
441      new(ir) ir_variable(bvec, "zero_mantissa", ir_var_temporary);
442
443   ir_instruction &i = *base_ir;
444
445   /* Copy <x> and <exp> arguments. */
446   i.insert_before(x);
447   i.insert_before(assign(x, ir->operands[0]));
448   i.insert_before(exp);
449   i.insert_before(assign(exp, ir->operands[1]));
450
451   /* Extract the biased exponent from <x>. */
452   i.insert_before(extracted_biased_exp);
453   i.insert_before(assign(extracted_biased_exp,
454                          rshift(bitcast_f2i(abs(x)),
455                                 new(ir) ir_constant(23, vec_elem))));
456
457   /* The definition of ldexp in the GLSL 4.60 spec says:
458    *
459    *    "If exp is greater than +128 (single-precision) or +1024
460    *     (double-precision), the value returned is undefined. If exp is less
461    *     than -126 (single-precision) or -1022 (double-precision), the value
462    *     returned may be flushed to zero."
463    *
464    * So we do not have to guard against the possibility of addition overflow,
465    * which could happen when exp is close to INT_MAX. Addition underflow
466    * cannot happen (the worst case is 0 + (-INT_MAX)).
467    */
468   i.insert_before(resulting_biased_exp);
469   i.insert_before(assign(resulting_biased_exp,
470                          min2(add(extracted_biased_exp, exp),
471                               new(ir) ir_constant(255, vec_elem))));
472
473   i.insert_before(sign_mantissa);
474   i.insert_before(assign(sign_mantissa,
475                          bit_and(bitcast_f2u(x),
476                                  new(ir) ir_constant(0x807fffffu, vec_elem))));
477
478   /* We flush to zero if the original or resulting biased exponent is 0,
479    * indicating a +/-0.0 or subnormal input or output.
480    *
481    * The mantissa is set to 0 if the resulting biased exponent is 255, since
482    * an overflow should produce a +/-inf result.
483    *
484    * Note that NaN inputs are handled separately.
485    */
486   i.insert_before(flush_to_zero);
487   i.insert_before(assign(flush_to_zero,
488                          lequal(min2(resulting_biased_exp,
489                                      extracted_biased_exp),
490                                 ir_constant::zero(ir, ivec))));
491   i.insert_before(assign(resulting_biased_exp,
492                          csel(flush_to_zero,
493                               ir_constant::zero(ir, ivec),
494                               resulting_biased_exp)));
495
496   i.insert_before(zero_mantissa);
497   i.insert_before(assign(zero_mantissa,
498                          logic_or(flush_to_zero,
499                                   equal(resulting_biased_exp,
500                                         new(ir) ir_constant(255, vec_elem)))));
501   i.insert_before(assign(sign_mantissa,
502                          csel(zero_mantissa,
503                               bit_and(sign_mantissa,
504                                       new(ir) ir_constant(0x80000000u, vec_elem)),
505                               sign_mantissa)));
506
507   /* Don't generate new IR that would need to be lowered in an additional
508    * pass.
509    */
510   i.insert_before(result);
511   if (!lowering(INSERT_TO_SHIFTS)) {
512      i.insert_before(assign(result,
513                             bitfield_insert(sign_mantissa,
514                                             i2u(resulting_biased_exp),
515                                             new(ir) ir_constant(23u, vec_elem),
516                                             new(ir) ir_constant(8u, vec_elem))));
517   } else {
518      i.insert_before(assign(result,
519                             bit_or(sign_mantissa,
520                                    lshift(i2u(resulting_biased_exp),
521                                           new(ir) ir_constant(23, vec_elem)))));
522   }
523
524   ir->operation = ir_triop_csel;
525   ir->init_num_operands();
526   ir->operands[0] = gequal(extracted_biased_exp,
527                            new(ir) ir_constant(255, vec_elem));
528   ir->operands[1] = new(ir) ir_dereference_variable(x);
529   ir->operands[2] = bitcast_u2f(result);
530
531   this->progress = true;
532}
533
534void
535lower_instructions_visitor::dldexp_to_arith(ir_expression *ir)
536{
537   /* See ldexp_to_arith for structure. Uses frexp_exp to extract the exponent
538    * from the significand.
539    */
540
541   const unsigned vec_elem = ir->type->vector_elements;
542
543   /* Types */
544   const glsl_type *ivec = glsl_type::get_instance(GLSL_TYPE_INT, vec_elem, 1);
545   const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
546
547   /* Constants */
548   ir_constant *zeroi = ir_constant::zero(ir, ivec);
549
550   ir_constant *sign_mask = new(ir) ir_constant(0x80000000u);
551
552   ir_constant *exp_shift = new(ir) ir_constant(20u);
553   ir_constant *exp_width = new(ir) ir_constant(11u);
554   ir_constant *exp_bias = new(ir) ir_constant(1022, vec_elem);
555
556   /* Temporary variables */
557   ir_variable *x = new(ir) ir_variable(ir->type, "x", ir_var_temporary);
558   ir_variable *exp = new(ir) ir_variable(ivec, "exp", ir_var_temporary);
559
560   ir_variable *zero_sign_x = new(ir) ir_variable(ir->type, "zero_sign_x",
561                                                  ir_var_temporary);
562
563   ir_variable *extracted_biased_exp =
564      new(ir) ir_variable(ivec, "extracted_biased_exp", ir_var_temporary);
565   ir_variable *resulting_biased_exp =
566      new(ir) ir_variable(ivec, "resulting_biased_exp", ir_var_temporary);
567
568   ir_variable *is_not_zero_or_underflow =
569      new(ir) ir_variable(bvec, "is_not_zero_or_underflow", ir_var_temporary);
570
571   ir_instruction &i = *base_ir;
572
573   /* Copy <x> and <exp> arguments. */
574   i.insert_before(x);
575   i.insert_before(assign(x, ir->operands[0]));
576   i.insert_before(exp);
577   i.insert_before(assign(exp, ir->operands[1]));
578
579   ir_expression *frexp_exp = expr(ir_unop_frexp_exp, x);
580   if (lowering(DFREXP_DLDEXP_TO_ARITH))
581      dfrexp_exp_to_arith(frexp_exp);
582
583   /* Extract the biased exponent from <x>. */
584   i.insert_before(extracted_biased_exp);
585   i.insert_before(assign(extracted_biased_exp, add(frexp_exp, exp_bias)));
586
587   i.insert_before(resulting_biased_exp);
588   i.insert_before(assign(resulting_biased_exp,
589                          add(extracted_biased_exp, exp)));
590
591   /* Test if result is ±0.0, subnormal, or underflow by checking if the
592    * resulting biased exponent would be less than 0x1. If so, the result is
593    * 0.0 with the sign of x. (Actually, invert the conditions so that
594    * immediate values are the second arguments, which is better for i965)
595    * TODO: Implement in a vector fashion.
596    */
597   i.insert_before(zero_sign_x);
598   for (unsigned elem = 0; elem < vec_elem; elem++) {
599      ir_variable *unpacked =
600         new(ir) ir_variable(glsl_type::uvec2_type, "unpacked", ir_var_temporary);
601      i.insert_before(unpacked);
602      i.insert_before(
603            assign(unpacked,
604                   expr(ir_unop_unpack_double_2x32, swizzle(x, elem, 1))));
605      i.insert_before(assign(unpacked, bit_and(swizzle_y(unpacked), sign_mask->clone(ir, NULL)),
606                             WRITEMASK_Y));
607      i.insert_before(assign(unpacked, ir_constant::zero(ir, glsl_type::uint_type), WRITEMASK_X));
608      i.insert_before(assign(zero_sign_x,
609                             expr(ir_unop_pack_double_2x32, unpacked),
610                             1 << elem));
611   }
612   i.insert_before(is_not_zero_or_underflow);
613   i.insert_before(assign(is_not_zero_or_underflow,
614                          gequal(resulting_biased_exp,
615                                  new(ir) ir_constant(0x1, vec_elem))));
616   i.insert_before(assign(x, csel(is_not_zero_or_underflow,
617                                  x, zero_sign_x)));
618   i.insert_before(assign(resulting_biased_exp,
619                          csel(is_not_zero_or_underflow,
620                               resulting_biased_exp, zeroi)));
621
622   /* We could test for overflows by checking if the resulting biased exponent
623    * would be greater than 0xFE. Turns out we don't need to because the GLSL
624    * spec says:
625    *
626    *    "If this product is too large to be represented in the
627    *     floating-point type, the result is undefined."
628    */
629
630   ir_rvalue *results[4] = {NULL};
631   for (unsigned elem = 0; elem < vec_elem; elem++) {
632      ir_variable *unpacked =
633         new(ir) ir_variable(glsl_type::uvec2_type, "unpacked", ir_var_temporary);
634      i.insert_before(unpacked);
635      i.insert_before(
636            assign(unpacked,
637                   expr(ir_unop_unpack_double_2x32, swizzle(x, elem, 1))));
638
639      ir_expression *bfi = bitfield_insert(
640            swizzle_y(unpacked),
641            i2u(swizzle(resulting_biased_exp, elem, 1)),
642            exp_shift->clone(ir, NULL),
643            exp_width->clone(ir, NULL));
644
645      i.insert_before(assign(unpacked, bfi, WRITEMASK_Y));
646
647      results[elem] = expr(ir_unop_pack_double_2x32, unpacked);
648   }
649
650   ir->operation = ir_quadop_vector;
651   ir->init_num_operands();
652   ir->operands[0] = results[0];
653   ir->operands[1] = results[1];
654   ir->operands[2] = results[2];
655   ir->operands[3] = results[3];
656
657   /* Don't generate new IR that would need to be lowered in an additional
658    * pass.
659    */
660
661   this->progress = true;
662}
663
664void
665lower_instructions_visitor::dfrexp_sig_to_arith(ir_expression *ir)
666{
667   const unsigned vec_elem = ir->type->vector_elements;
668   const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
669
670   /* Double-precision floating-point values are stored as
671    *   1 sign bit;
672    *   11 exponent bits;
673    *   52 mantissa bits.
674    *
675    * We're just extracting the significand here, so we only need to modify
676    * the upper 32-bit uint. Unfortunately we must extract each double
677    * independently as there is no vector version of unpackDouble.
678    */
679
680   ir_instruction &i = *base_ir;
681
682   ir_variable *is_not_zero =
683      new(ir) ir_variable(bvec, "is_not_zero", ir_var_temporary);
684   ir_rvalue *results[4] = {NULL};
685
686   ir_constant *dzero = new(ir) ir_constant(0.0, vec_elem);
687   i.insert_before(is_not_zero);
688   i.insert_before(
689         assign(is_not_zero,
690                nequal(abs(ir->operands[0]->clone(ir, NULL)), dzero)));
691
692   /* TODO: Remake this as more vector-friendly when int64 support is
693    * available.
694    */
695   for (unsigned elem = 0; elem < vec_elem; elem++) {
696      ir_constant *zero = new(ir) ir_constant(0u, 1);
697      ir_constant *sign_mantissa_mask = new(ir) ir_constant(0x800fffffu, 1);
698
699      /* Exponent of double floating-point values in the range [0.5, 1.0). */
700      ir_constant *exponent_value = new(ir) ir_constant(0x3fe00000u, 1);
701
702      ir_variable *bits =
703         new(ir) ir_variable(glsl_type::uint_type, "bits", ir_var_temporary);
704      ir_variable *unpacked =
705         new(ir) ir_variable(glsl_type::uvec2_type, "unpacked", ir_var_temporary);
706
707      ir_rvalue *x = swizzle(ir->operands[0]->clone(ir, NULL), elem, 1);
708
709      i.insert_before(bits);
710      i.insert_before(unpacked);
711      i.insert_before(assign(unpacked, expr(ir_unop_unpack_double_2x32, x)));
712
713      /* Manipulate the high uint to remove the exponent and replace it with
714       * either the default exponent or zero.
715       */
716      i.insert_before(assign(bits, swizzle_y(unpacked)));
717      i.insert_before(assign(bits, bit_and(bits, sign_mantissa_mask)));
718      i.insert_before(assign(bits, bit_or(bits,
719                                          csel(swizzle(is_not_zero, elem, 1),
720                                               exponent_value,
721                                               zero))));
722      i.insert_before(assign(unpacked, bits, WRITEMASK_Y));
723      results[elem] = expr(ir_unop_pack_double_2x32, unpacked);
724   }
725
726   /* Put the dvec back together */
727   ir->operation = ir_quadop_vector;
728   ir->init_num_operands();
729   ir->operands[0] = results[0];
730   ir->operands[1] = results[1];
731   ir->operands[2] = results[2];
732   ir->operands[3] = results[3];
733
734   this->progress = true;
735}
736
737void
738lower_instructions_visitor::dfrexp_exp_to_arith(ir_expression *ir)
739{
740   const unsigned vec_elem = ir->type->vector_elements;
741   const glsl_type *bvec = glsl_type::get_instance(GLSL_TYPE_BOOL, vec_elem, 1);
742   const glsl_type *uvec = glsl_type::get_instance(GLSL_TYPE_UINT, vec_elem, 1);
743
744   /* Double-precision floating-point values are stored as
745    *   1 sign bit;
746    *   11 exponent bits;
747    *   52 mantissa bits.
748    *
749    * We're just extracting the exponent here, so we only care about the upper
750    * 32-bit uint.
751    */
752
753   ir_instruction &i = *base_ir;
754
755   ir_variable *is_not_zero =
756      new(ir) ir_variable(bvec, "is_not_zero", ir_var_temporary);
757   ir_variable *high_words =
758      new(ir) ir_variable(uvec, "high_words", ir_var_temporary);
759   ir_constant *dzero = new(ir) ir_constant(0.0, vec_elem);
760   ir_constant *izero = new(ir) ir_constant(0, vec_elem);
761
762   ir_rvalue *absval = abs(ir->operands[0]);
763
764   i.insert_before(is_not_zero);
765   i.insert_before(high_words);
766   i.insert_before(assign(is_not_zero, nequal(absval->clone(ir, NULL), dzero)));
767
768   /* Extract all of the upper uints. */
769   for (unsigned elem = 0; elem < vec_elem; elem++) {
770      ir_rvalue *x = swizzle(absval->clone(ir, NULL), elem, 1);
771
772      i.insert_before(assign(high_words,
773                             swizzle_y(expr(ir_unop_unpack_double_2x32, x)),
774                             1 << elem));
775
776   }
777   ir_constant *exponent_shift = new(ir) ir_constant(20, vec_elem);
778   ir_constant *exponent_bias = new(ir) ir_constant(-1022, vec_elem);
779
780   /* For non-zero inputs, shift the exponent down and apply bias. */
781   ir->operation = ir_triop_csel;
782   ir->init_num_operands();
783   ir->operands[0] = new(ir) ir_dereference_variable(is_not_zero);
784   ir->operands[1] = add(exponent_bias, u2i(rshift(high_words, exponent_shift)));
785   ir->operands[2] = izero;
786
787   this->progress = true;
788}
789
790void
791lower_instructions_visitor::carry_to_arith(ir_expression *ir)
792{
793   /* Translates
794    *   ir_binop_carry x y
795    * into
796    *   sum = ir_binop_add x y
797    *   bcarry = ir_binop_less sum x
798    *   carry = ir_unop_b2i bcarry
799    */
800
801   ir_rvalue *x_clone = ir->operands[0]->clone(ir, NULL);
802   ir->operation = ir_unop_i2u;
803   ir->init_num_operands();
804   ir->operands[0] = b2i(less(add(ir->operands[0], ir->operands[1]), x_clone));
805   ir->operands[1] = NULL;
806
807   this->progress = true;
808}
809
810void
811lower_instructions_visitor::borrow_to_arith(ir_expression *ir)
812{
813   /* Translates
814    *   ir_binop_borrow x y
815    * into
816    *   bcarry = ir_binop_less x y
817    *   carry = ir_unop_b2i bcarry
818    */
819
820   ir->operation = ir_unop_i2u;
821   ir->init_num_operands();
822   ir->operands[0] = b2i(less(ir->operands[0], ir->operands[1]));
823   ir->operands[1] = NULL;
824
825   this->progress = true;
826}
827
828void
829lower_instructions_visitor::sat_to_clamp(ir_expression *ir)
830{
831   /* Translates
832    *   ir_unop_saturate x
833    * into
834    *   ir_binop_min (ir_binop_max(x, 0.0), 1.0)
835    */
836
837   ir->operation = ir_binop_min;
838   ir->init_num_operands();
839   ir->operands[0] = new(ir) ir_expression(ir_binop_max, ir->operands[0]->type,
840                                           ir->operands[0],
841                                           new(ir) ir_constant(0.0f));
842   ir->operands[1] = new(ir) ir_constant(1.0f);
843
844   this->progress = true;
845}
846
847void
848lower_instructions_visitor::double_dot_to_fma(ir_expression *ir)
849{
850   ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type->get_base_type(), "dot_res",
851					   ir_var_temporary);
852   this->base_ir->insert_before(temp);
853
854   int nc = ir->operands[0]->type->components();
855   for (int i = nc - 1; i >= 1; i--) {
856      ir_assignment *assig;
857      if (i == (nc - 1)) {
858         assig = assign(temp, mul(swizzle(ir->operands[0]->clone(ir, NULL), i, 1),
859                                  swizzle(ir->operands[1]->clone(ir, NULL), i, 1)));
860      } else {
861         assig = assign(temp, fma(swizzle(ir->operands[0]->clone(ir, NULL), i, 1),
862                                  swizzle(ir->operands[1]->clone(ir, NULL), i, 1),
863                                  temp));
864      }
865      this->base_ir->insert_before(assig);
866   }
867
868   ir->operation = ir_triop_fma;
869   ir->init_num_operands();
870   ir->operands[0] = swizzle(ir->operands[0], 0, 1);
871   ir->operands[1] = swizzle(ir->operands[1], 0, 1);
872   ir->operands[2] = new(ir) ir_dereference_variable(temp);
873
874   this->progress = true;
875
876}
877
878void
879lower_instructions_visitor::double_lrp(ir_expression *ir)
880{
881   int swizval;
882   ir_rvalue *op0 = ir->operands[0], *op2 = ir->operands[2];
883   ir_constant *one = new(ir) ir_constant(1.0, op2->type->vector_elements);
884
885   switch (op2->type->vector_elements) {
886   case 1:
887      swizval = SWIZZLE_XXXX;
888      break;
889   default:
890      assert(op0->type->vector_elements == op2->type->vector_elements);
891      swizval = SWIZZLE_XYZW;
892      break;
893   }
894
895   ir->operation = ir_triop_fma;
896   ir->init_num_operands();
897   ir->operands[0] = swizzle(op2, swizval, op0->type->vector_elements);
898   ir->operands[2] = mul(sub(one, op2->clone(ir, NULL)), op0);
899
900   this->progress = true;
901}
902
903void
904lower_instructions_visitor::dceil_to_dfrac(ir_expression *ir)
905{
906   /*
907    * frtemp = frac(x);
908    * temp = sub(x, frtemp);
909    * result = temp + ((frtemp != 0.0) ? 1.0 : 0.0);
910    */
911   ir_instruction &i = *base_ir;
912   ir_constant *zero = new(ir) ir_constant(0.0, ir->operands[0]->type->vector_elements);
913   ir_constant *one = new(ir) ir_constant(1.0, ir->operands[0]->type->vector_elements);
914   ir_variable *frtemp = new(ir) ir_variable(ir->operands[0]->type, "frtemp",
915                                             ir_var_temporary);
916
917   i.insert_before(frtemp);
918   i.insert_before(assign(frtemp, fract(ir->operands[0])));
919
920   ir->operation = ir_binop_add;
921   ir->init_num_operands();
922   ir->operands[0] = sub(ir->operands[0]->clone(ir, NULL), frtemp);
923   ir->operands[1] = csel(nequal(frtemp, zero), one, zero->clone(ir, NULL));
924
925   this->progress = true;
926}
927
928void
929lower_instructions_visitor::dfloor_to_dfrac(ir_expression *ir)
930{
931   /*
932    * frtemp = frac(x);
933    * result = sub(x, frtemp);
934    */
935   ir->operation = ir_binop_sub;
936   ir->init_num_operands();
937   ir->operands[1] = fract(ir->operands[0]->clone(ir, NULL));
938
939   this->progress = true;
940}
941void
942lower_instructions_visitor::dround_even_to_dfrac(ir_expression *ir)
943{
944   /*
945    * insane but works
946    * temp = x + 0.5;
947    * frtemp = frac(temp);
948    * t2 = sub(temp, frtemp);
949    * if (frac(x) == 0.5)
950    *     result = frac(t2 * 0.5) == 0 ? t2 : t2 - 1;
951    *  else
952    *     result = t2;
953
954    */
955   ir_instruction &i = *base_ir;
956   ir_variable *frtemp = new(ir) ir_variable(ir->operands[0]->type, "frtemp",
957                                             ir_var_temporary);
958   ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type, "temp",
959                                           ir_var_temporary);
960   ir_variable *t2 = new(ir) ir_variable(ir->operands[0]->type, "t2",
961                                           ir_var_temporary);
962   ir_constant *p5 = new(ir) ir_constant(0.5, ir->operands[0]->type->vector_elements);
963   ir_constant *one = new(ir) ir_constant(1.0, ir->operands[0]->type->vector_elements);
964   ir_constant *zero = new(ir) ir_constant(0.0, ir->operands[0]->type->vector_elements);
965
966   i.insert_before(temp);
967   i.insert_before(assign(temp, add(ir->operands[0], p5)));
968
969   i.insert_before(frtemp);
970   i.insert_before(assign(frtemp, fract(temp)));
971
972   i.insert_before(t2);
973   i.insert_before(assign(t2, sub(temp, frtemp)));
974
975   ir->operation = ir_triop_csel;
976   ir->init_num_operands();
977   ir->operands[0] = equal(fract(ir->operands[0]->clone(ir, NULL)),
978                           p5->clone(ir, NULL));
979   ir->operands[1] = csel(equal(fract(mul(t2, p5->clone(ir, NULL))),
980                                zero),
981                          t2,
982                          sub(t2, one));
983   ir->operands[2] = new(ir) ir_dereference_variable(t2);
984
985   this->progress = true;
986}
987
988void
989lower_instructions_visitor::dtrunc_to_dfrac(ir_expression *ir)
990{
991   /*
992    * frtemp = frac(x);
993    * temp = sub(x, frtemp);
994    * result = x >= 0 ? temp : temp + (frtemp == 0.0) ? 0 : 1;
995    */
996   ir_rvalue *arg = ir->operands[0];
997   ir_instruction &i = *base_ir;
998
999   ir_constant *zero = new(ir) ir_constant(0.0, arg->type->vector_elements);
1000   ir_constant *one = new(ir) ir_constant(1.0, arg->type->vector_elements);
1001   ir_variable *frtemp = new(ir) ir_variable(arg->type, "frtemp",
1002                                             ir_var_temporary);
1003   ir_variable *temp = new(ir) ir_variable(ir->operands[0]->type, "temp",
1004                                           ir_var_temporary);
1005
1006   i.insert_before(frtemp);
1007   i.insert_before(assign(frtemp, fract(arg)));
1008   i.insert_before(temp);
1009   i.insert_before(assign(temp, sub(arg->clone(ir, NULL), frtemp)));
1010
1011   ir->operation = ir_triop_csel;
1012   ir->init_num_operands();
1013   ir->operands[0] = gequal(arg->clone(ir, NULL), zero);
1014   ir->operands[1] = new (ir) ir_dereference_variable(temp);
1015   ir->operands[2] = add(temp,
1016                         csel(equal(frtemp, zero->clone(ir, NULL)),
1017                              zero->clone(ir, NULL),
1018                              one));
1019
1020   this->progress = true;
1021}
1022
1023void
1024lower_instructions_visitor::dsign_to_csel(ir_expression *ir)
1025{
1026   /*
1027    * temp = x > 0.0 ? 1.0 : 0.0;
1028    * result = x < 0.0 ? -1.0 : temp;
1029    */
1030   ir_rvalue *arg = ir->operands[0];
1031   ir_constant *zero = new(ir) ir_constant(0.0, arg->type->vector_elements);
1032   ir_constant *one = new(ir) ir_constant(1.0, arg->type->vector_elements);
1033   ir_constant *neg_one = new(ir) ir_constant(-1.0, arg->type->vector_elements);
1034
1035   ir->operation = ir_triop_csel;
1036   ir->init_num_operands();
1037   ir->operands[0] = less(arg->clone(ir, NULL),
1038                          zero->clone(ir, NULL));
1039   ir->operands[1] = neg_one;
1040   ir->operands[2] = csel(greater(arg, zero),
1041                          one,
1042                          zero->clone(ir, NULL));
1043
1044   this->progress = true;
1045}
1046
1047void
1048lower_instructions_visitor::bit_count_to_math(ir_expression *ir)
1049{
1050   /* For more details, see:
1051    *
1052    * http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetPaallel
1053    */
1054   const unsigned elements = ir->operands[0]->type->vector_elements;
1055   ir_variable *temp = new(ir) ir_variable(glsl_type::uvec(elements), "temp",
1056                                           ir_var_temporary);
1057   ir_constant *c55555555 = new(ir) ir_constant(0x55555555u);
1058   ir_constant *c33333333 = new(ir) ir_constant(0x33333333u);
1059   ir_constant *c0F0F0F0F = new(ir) ir_constant(0x0F0F0F0Fu);
1060   ir_constant *c01010101 = new(ir) ir_constant(0x01010101u);
1061   ir_constant *c1 = new(ir) ir_constant(1u);
1062   ir_constant *c2 = new(ir) ir_constant(2u);
1063   ir_constant *c4 = new(ir) ir_constant(4u);
1064   ir_constant *c24 = new(ir) ir_constant(24u);
1065
1066   base_ir->insert_before(temp);
1067
1068   if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
1069      base_ir->insert_before(assign(temp, ir->operands[0]));
1070   } else {
1071      assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
1072      base_ir->insert_before(assign(temp, i2u(ir->operands[0])));
1073   }
1074
1075   /* temp = temp - ((temp >> 1) & 0x55555555u); */
1076   base_ir->insert_before(assign(temp, sub(temp, bit_and(rshift(temp, c1),
1077                                                         c55555555))));
1078
1079   /* temp = (temp & 0x33333333u) + ((temp >> 2) & 0x33333333u); */
1080   base_ir->insert_before(assign(temp, add(bit_and(temp, c33333333),
1081                                           bit_and(rshift(temp, c2),
1082                                                   c33333333->clone(ir, NULL)))));
1083
1084   /* int(((temp + (temp >> 4) & 0xF0F0F0Fu) * 0x1010101u) >> 24); */
1085   ir->operation = ir_unop_u2i;
1086   ir->init_num_operands();
1087   ir->operands[0] = rshift(mul(bit_and(add(temp, rshift(temp, c4)), c0F0F0F0F),
1088                                c01010101),
1089                            c24);
1090
1091   this->progress = true;
1092}
1093
1094void
1095lower_instructions_visitor::extract_to_shifts(ir_expression *ir)
1096{
1097   ir_variable *bits =
1098      new(ir) ir_variable(ir->operands[0]->type, "bits", ir_var_temporary);
1099
1100   base_ir->insert_before(bits);
1101   base_ir->insert_before(assign(bits, ir->operands[2]));
1102
1103   if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
1104      ir_constant *c1 =
1105         new(ir) ir_constant(1u, ir->operands[0]->type->vector_elements);
1106      ir_constant *c32 =
1107         new(ir) ir_constant(32u, ir->operands[0]->type->vector_elements);
1108      ir_constant *cFFFFFFFF =
1109         new(ir) ir_constant(0xFFFFFFFFu, ir->operands[0]->type->vector_elements);
1110
1111      /* At least some hardware treats (x << y) as (x << (y%32)).  This means
1112       * we'd get a mask of 0 when bits is 32.  Special case it.
1113       *
1114       * mask = bits == 32 ? 0xffffffff : (1u << bits) - 1u;
1115       */
1116      ir_expression *mask = csel(equal(bits, c32),
1117                                 cFFFFFFFF,
1118                                 sub(lshift(c1, bits), c1->clone(ir, NULL)));
1119
1120      /* Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
1121       *
1122       *    If bits is zero, the result will be zero.
1123       *
1124       * Since (1 << 0) - 1 == 0, we don't need to bother with the conditional
1125       * select as in the signed integer case.
1126       *
1127       * (value >> offset) & mask;
1128       */
1129      ir->operation = ir_binop_bit_and;
1130      ir->init_num_operands();
1131      ir->operands[0] = rshift(ir->operands[0], ir->operands[1]);
1132      ir->operands[1] = mask;
1133      ir->operands[2] = NULL;
1134   } else {
1135      ir_constant *c0 =
1136         new(ir) ir_constant(int(0), ir->operands[0]->type->vector_elements);
1137      ir_constant *c32 =
1138         new(ir) ir_constant(int(32), ir->operands[0]->type->vector_elements);
1139      ir_variable *temp =
1140         new(ir) ir_variable(ir->operands[0]->type, "temp", ir_var_temporary);
1141
1142      /* temp = 32 - bits; */
1143      base_ir->insert_before(temp);
1144      base_ir->insert_before(assign(temp, sub(c32, bits)));
1145
1146      /* expr = value << (temp - offset)) >> temp; */
1147      ir_expression *expr =
1148         rshift(lshift(ir->operands[0], sub(temp, ir->operands[1])), temp);
1149
1150      /* Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
1151       *
1152       *    If bits is zero, the result will be zero.
1153       *
1154       * Due to the (x << (y%32)) behavior mentioned before, the (value <<
1155       * (32-0)) doesn't "erase" all of the data as we would like, so finish
1156       * up with:
1157       *
1158       * (bits == 0) ? 0 : e;
1159       */
1160      ir->operation = ir_triop_csel;
1161      ir->init_num_operands();
1162      ir->operands[0] = equal(c0, bits);
1163      ir->operands[1] = c0->clone(ir, NULL);
1164      ir->operands[2] = expr;
1165   }
1166
1167   this->progress = true;
1168}
1169
1170void
1171lower_instructions_visitor::insert_to_shifts(ir_expression *ir)
1172{
1173   ir_constant *c1;
1174   ir_constant *c32;
1175   ir_constant *cFFFFFFFF;
1176   ir_variable *offset =
1177      new(ir) ir_variable(ir->operands[0]->type, "offset", ir_var_temporary);
1178   ir_variable *bits =
1179      new(ir) ir_variable(ir->operands[0]->type, "bits", ir_var_temporary);
1180   ir_variable *mask =
1181      new(ir) ir_variable(ir->operands[0]->type, "mask", ir_var_temporary);
1182
1183   if (ir->operands[0]->type->base_type == GLSL_TYPE_INT) {
1184      c1 = new(ir) ir_constant(int(1), ir->operands[0]->type->vector_elements);
1185      c32 = new(ir) ir_constant(int(32), ir->operands[0]->type->vector_elements);
1186      cFFFFFFFF = new(ir) ir_constant(int(0xFFFFFFFF), ir->operands[0]->type->vector_elements);
1187   } else {
1188      assert(ir->operands[0]->type->base_type == GLSL_TYPE_UINT);
1189
1190      c1 = new(ir) ir_constant(1u, ir->operands[0]->type->vector_elements);
1191      c32 = new(ir) ir_constant(32u, ir->operands[0]->type->vector_elements);
1192      cFFFFFFFF = new(ir) ir_constant(0xFFFFFFFFu, ir->operands[0]->type->vector_elements);
1193   }
1194
1195   base_ir->insert_before(offset);
1196   base_ir->insert_before(assign(offset, ir->operands[2]));
1197
1198   base_ir->insert_before(bits);
1199   base_ir->insert_before(assign(bits, ir->operands[3]));
1200
1201   /* At least some hardware treats (x << y) as (x << (y%32)).  This means
1202    * we'd get a mask of 0 when bits is 32.  Special case it.
1203    *
1204    * mask = (bits == 32 ? 0xffffffff : (1u << bits) - 1u) << offset;
1205    *
1206    * Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
1207    *
1208    *    The result will be undefined if offset or bits is negative, or if the
1209    *    sum of offset and bits is greater than the number of bits used to
1210    *    store the operand.
1211    *
1212    * Since it's undefined, there are a couple other ways this could be
1213    * implemented.  The other way that was considered was to put the csel
1214    * around the whole thing:
1215    *
1216    *    final_result = bits == 32 ? insert : ... ;
1217    */
1218   base_ir->insert_before(mask);
1219
1220   base_ir->insert_before(assign(mask, csel(equal(bits, c32),
1221                                            cFFFFFFFF,
1222                                            lshift(sub(lshift(c1, bits),
1223                                                       c1->clone(ir, NULL)),
1224                                                   offset))));
1225
1226   /* (base & ~mask) | ((insert << offset) & mask) */
1227   ir->operation = ir_binop_bit_or;
1228   ir->init_num_operands();
1229   ir->operands[0] = bit_and(ir->operands[0], bit_not(mask));
1230   ir->operands[1] = bit_and(lshift(ir->operands[1], offset), mask);
1231   ir->operands[2] = NULL;
1232   ir->operands[3] = NULL;
1233
1234   this->progress = true;
1235}
1236
1237void
1238lower_instructions_visitor::reverse_to_shifts(ir_expression *ir)
1239{
1240   /* For more details, see:
1241    *
1242    * http://graphics.stanford.edu/~seander/bithacks.html#ReverseParallel
1243    */
1244   ir_constant *c1 =
1245      new(ir) ir_constant(1u, ir->operands[0]->type->vector_elements);
1246   ir_constant *c2 =
1247      new(ir) ir_constant(2u, ir->operands[0]->type->vector_elements);
1248   ir_constant *c4 =
1249      new(ir) ir_constant(4u, ir->operands[0]->type->vector_elements);
1250   ir_constant *c8 =
1251      new(ir) ir_constant(8u, ir->operands[0]->type->vector_elements);
1252   ir_constant *c16 =
1253      new(ir) ir_constant(16u, ir->operands[0]->type->vector_elements);
1254   ir_constant *c33333333 =
1255      new(ir) ir_constant(0x33333333u, ir->operands[0]->type->vector_elements);
1256   ir_constant *c55555555 =
1257      new(ir) ir_constant(0x55555555u, ir->operands[0]->type->vector_elements);
1258   ir_constant *c0F0F0F0F =
1259      new(ir) ir_constant(0x0F0F0F0Fu, ir->operands[0]->type->vector_elements);
1260   ir_constant *c00FF00FF =
1261      new(ir) ir_constant(0x00FF00FFu, ir->operands[0]->type->vector_elements);
1262   ir_variable *temp =
1263      new(ir) ir_variable(glsl_type::uvec(ir->operands[0]->type->vector_elements),
1264                          "temp", ir_var_temporary);
1265   ir_instruction &i = *base_ir;
1266
1267   i.insert_before(temp);
1268
1269   if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
1270      i.insert_before(assign(temp, ir->operands[0]));
1271   } else {
1272      assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
1273      i.insert_before(assign(temp, i2u(ir->operands[0])));
1274   }
1275
1276   /* Swap odd and even bits.
1277    *
1278    * temp = ((temp >> 1) & 0x55555555u) | ((temp & 0x55555555u) << 1);
1279    */
1280   i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c1), c55555555),
1281                                       lshift(bit_and(temp, c55555555->clone(ir, NULL)),
1282                                              c1->clone(ir, NULL)))));
1283   /* Swap consecutive pairs.
1284    *
1285    * temp = ((temp >> 2) & 0x33333333u) | ((temp & 0x33333333u) << 2);
1286    */
1287   i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c2), c33333333),
1288                                       lshift(bit_and(temp, c33333333->clone(ir, NULL)),
1289                                              c2->clone(ir, NULL)))));
1290
1291   /* Swap nibbles.
1292    *
1293    * temp = ((temp >> 4) & 0x0F0F0F0Fu) | ((temp & 0x0F0F0F0Fu) << 4);
1294    */
1295   i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c4), c0F0F0F0F),
1296                                       lshift(bit_and(temp, c0F0F0F0F->clone(ir, NULL)),
1297                                              c4->clone(ir, NULL)))));
1298
1299   /* The last step is, basically, bswap.  Swap the bytes, then swap the
1300    * words.  When this code is run through GCC on x86, it does generate a
1301    * bswap instruction.
1302    *
1303    * temp = ((temp >> 8) & 0x00FF00FFu) | ((temp & 0x00FF00FFu) << 8);
1304    * temp = ( temp >> 16              ) | ( temp                << 16);
1305    */
1306   i.insert_before(assign(temp, bit_or(bit_and(rshift(temp, c8), c00FF00FF),
1307                                       lshift(bit_and(temp, c00FF00FF->clone(ir, NULL)),
1308                                              c8->clone(ir, NULL)))));
1309
1310   if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
1311      ir->operation = ir_binop_bit_or;
1312      ir->init_num_operands();
1313      ir->operands[0] = rshift(temp, c16);
1314      ir->operands[1] = lshift(temp, c16->clone(ir, NULL));
1315   } else {
1316      ir->operation = ir_unop_u2i;
1317      ir->init_num_operands();
1318      ir->operands[0] = bit_or(rshift(temp, c16),
1319                               lshift(temp, c16->clone(ir, NULL)));
1320   }
1321
1322   this->progress = true;
1323}
1324
1325void
1326lower_instructions_visitor::find_lsb_to_float_cast(ir_expression *ir)
1327{
1328   /* For more details, see:
1329    *
1330    * http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightFloatCast
1331    */
1332   const unsigned elements = ir->operands[0]->type->vector_elements;
1333   ir_constant *c0 = new(ir) ir_constant(unsigned(0), elements);
1334   ir_constant *cminus1 = new(ir) ir_constant(int(-1), elements);
1335   ir_constant *c23 = new(ir) ir_constant(int(23), elements);
1336   ir_constant *c7F = new(ir) ir_constant(int(0x7F), elements);
1337   ir_variable *temp =
1338      new(ir) ir_variable(glsl_type::ivec(elements), "temp", ir_var_temporary);
1339   ir_variable *lsb_only =
1340      new(ir) ir_variable(glsl_type::uvec(elements), "lsb_only", ir_var_temporary);
1341   ir_variable *as_float =
1342      new(ir) ir_variable(glsl_type::vec(elements), "as_float", ir_var_temporary);
1343   ir_variable *lsb =
1344      new(ir) ir_variable(glsl_type::ivec(elements), "lsb", ir_var_temporary);
1345
1346   ir_instruction &i = *base_ir;
1347
1348   i.insert_before(temp);
1349
1350   if (ir->operands[0]->type->base_type == GLSL_TYPE_INT) {
1351      i.insert_before(assign(temp, ir->operands[0]));
1352   } else {
1353      assert(ir->operands[0]->type->base_type == GLSL_TYPE_UINT);
1354      i.insert_before(assign(temp, u2i(ir->operands[0])));
1355   }
1356
1357   /* The int-to-float conversion is lossless because (value & -value) is
1358    * either a power of two or zero.  We don't use the result in the zero
1359    * case.  The uint() cast is necessary so that 0x80000000 does not
1360    * generate a negative value.
1361    *
1362    * uint lsb_only = uint(value & -value);
1363    * float as_float = float(lsb_only);
1364    */
1365   i.insert_before(lsb_only);
1366   i.insert_before(assign(lsb_only, i2u(bit_and(temp, neg(temp)))));
1367
1368   i.insert_before(as_float);
1369   i.insert_before(assign(as_float, u2f(lsb_only)));
1370
1371   /* This is basically an open-coded frexp.  Implementations that have a
1372    * native frexp instruction would be better served by that.  This is
1373    * optimized versus a full-featured open-coded implementation in two ways:
1374    *
1375    * - We don't care about a correct result from subnormal numbers (including
1376    *   0.0), so the raw exponent can always be safely unbiased.
1377    *
1378    * - The value cannot be negative, so it does not need to be masked off to
1379    *   extract the exponent.
1380    *
1381    * int lsb = (floatBitsToInt(as_float) >> 23) - 0x7f;
1382    */
1383   i.insert_before(lsb);
1384   i.insert_before(assign(lsb, sub(rshift(bitcast_f2i(as_float), c23), c7F)));
1385
1386   /* Use lsb_only in the comparison instead of temp so that the & (far above)
1387    * can possibly generate the result without an explicit comparison.
1388    *
1389    * (lsb_only == 0) ? -1 : lsb;
1390    *
1391    * Since our input values are all integers, the unbiased exponent must not
1392    * be negative.  It will only be negative (-0x7f, in fact) if lsb_only is
1393    * 0.  Instead of using (lsb_only == 0), we could use (lsb >= 0).  Which is
1394    * better is likely GPU dependent.  Either way, the difference should be
1395    * small.
1396    */
1397   ir->operation = ir_triop_csel;
1398   ir->init_num_operands();
1399   ir->operands[0] = equal(lsb_only, c0);
1400   ir->operands[1] = cminus1;
1401   ir->operands[2] = new(ir) ir_dereference_variable(lsb);
1402
1403   this->progress = true;
1404}
1405
1406void
1407lower_instructions_visitor::find_msb_to_float_cast(ir_expression *ir)
1408{
1409   /* For more details, see:
1410    *
1411    * http://graphics.stanford.edu/~seander/bithacks.html#ZerosOnRightFloatCast
1412    */
1413   const unsigned elements = ir->operands[0]->type->vector_elements;
1414   ir_constant *c0 = new(ir) ir_constant(int(0), elements);
1415   ir_constant *cminus1 = new(ir) ir_constant(int(-1), elements);
1416   ir_constant *c23 = new(ir) ir_constant(int(23), elements);
1417   ir_constant *c7F = new(ir) ir_constant(int(0x7F), elements);
1418   ir_constant *c000000FF = new(ir) ir_constant(0x000000FFu, elements);
1419   ir_constant *cFFFFFF00 = new(ir) ir_constant(0xFFFFFF00u, elements);
1420   ir_variable *temp =
1421      new(ir) ir_variable(glsl_type::uvec(elements), "temp", ir_var_temporary);
1422   ir_variable *as_float =
1423      new(ir) ir_variable(glsl_type::vec(elements), "as_float", ir_var_temporary);
1424   ir_variable *msb =
1425      new(ir) ir_variable(glsl_type::ivec(elements), "msb", ir_var_temporary);
1426
1427   ir_instruction &i = *base_ir;
1428
1429   i.insert_before(temp);
1430
1431   if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
1432      i.insert_before(assign(temp, ir->operands[0]));
1433   } else {
1434      assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
1435
1436      /* findMSB(uint(abs(some_int))) almost always does the right thing.
1437       * There are two problem values:
1438       *
1439       * * 0x80000000.  Since abs(0x80000000) == 0x80000000, findMSB returns
1440       *   31.  However, findMSB(int(0x80000000)) == 30.
1441       *
1442       * * 0xffffffff.  Since abs(0xffffffff) == 1, findMSB returns
1443       *   31.  Section 8.8 (Integer Functions) of the GLSL 4.50 spec says:
1444       *
1445       *    For a value of zero or negative one, -1 will be returned.
1446       *
1447       * For all negative number cases, including 0x80000000 and 0xffffffff,
1448       * the correct value is obtained from findMSB if instead of negating the
1449       * (already negative) value the logical-not is used.  A conditonal
1450       * logical-not can be achieved in two instructions.
1451       */
1452      ir_variable *as_int =
1453         new(ir) ir_variable(glsl_type::ivec(elements), "as_int", ir_var_temporary);
1454      ir_constant *c31 = new(ir) ir_constant(int(31), elements);
1455
1456      i.insert_before(as_int);
1457      i.insert_before(assign(as_int, ir->operands[0]));
1458      i.insert_before(assign(temp, i2u(expr(ir_binop_bit_xor,
1459                                            as_int,
1460                                            rshift(as_int, c31)))));
1461   }
1462
1463   /* The int-to-float conversion is lossless because bits are conditionally
1464    * masked off the bottom of temp to ensure the value has at most 24 bits of
1465    * data or is zero.  We don't use the result in the zero case.  The uint()
1466    * cast is necessary so that 0x80000000 does not generate a negative value.
1467    *
1468    * float as_float = float(temp > 255 ? temp & ~255 : temp);
1469    */
1470   i.insert_before(as_float);
1471   i.insert_before(assign(as_float, u2f(csel(greater(temp, c000000FF),
1472                                             bit_and(temp, cFFFFFF00),
1473                                             temp))));
1474
1475   /* This is basically an open-coded frexp.  Implementations that have a
1476    * native frexp instruction would be better served by that.  This is
1477    * optimized versus a full-featured open-coded implementation in two ways:
1478    *
1479    * - We don't care about a correct result from subnormal numbers (including
1480    *   0.0), so the raw exponent can always be safely unbiased.
1481    *
1482    * - The value cannot be negative, so it does not need to be masked off to
1483    *   extract the exponent.
1484    *
1485    * int msb = (floatBitsToInt(as_float) >> 23) - 0x7f;
1486    */
1487   i.insert_before(msb);
1488   i.insert_before(assign(msb, sub(rshift(bitcast_f2i(as_float), c23), c7F)));
1489
1490   /* Use msb in the comparison instead of temp so that the subtract can
1491    * possibly generate the result without an explicit comparison.
1492    *
1493    * (msb < 0) ? -1 : msb;
1494    *
1495    * Since our input values are all integers, the unbiased exponent must not
1496    * be negative.  It will only be negative (-0x7f, in fact) if temp is 0.
1497    */
1498   ir->operation = ir_triop_csel;
1499   ir->init_num_operands();
1500   ir->operands[0] = less(msb, c0);
1501   ir->operands[1] = cminus1;
1502   ir->operands[2] = new(ir) ir_dereference_variable(msb);
1503
1504   this->progress = true;
1505}
1506
1507ir_expression *
1508lower_instructions_visitor::_carry(operand a, operand b)
1509{
1510   if (lowering(CARRY_TO_ARITH))
1511      return i2u(b2i(less(add(a, b),
1512                          a.val->clone(ralloc_parent(a.val), NULL))));
1513   else
1514      return carry(a, b);
1515}
1516
1517void
1518lower_instructions_visitor::imul_high_to_mul(ir_expression *ir)
1519{
1520   /*   ABCD
1521    * * EFGH
1522    * ======
1523    * (GH * CD) + (GH * AB) << 16 + (EF * CD) << 16 + (EF * AB) << 32
1524    *
1525    * In GLSL, (a * b) becomes
1526    *
1527    * uint m1 = (a & 0x0000ffffu) * (b & 0x0000ffffu);
1528    * uint m2 = (a & 0x0000ffffu) * (b >> 16);
1529    * uint m3 = (a >> 16)         * (b & 0x0000ffffu);
1530    * uint m4 = (a >> 16)         * (b >> 16);
1531    *
1532    * uint c1;
1533    * uint c2;
1534    * uint lo_result;
1535    * uint hi_result;
1536    *
1537    * lo_result = uaddCarry(m1, m2 << 16, c1);
1538    * hi_result = m4 + c1;
1539    * lo_result = uaddCarry(lo_result, m3 << 16, c2);
1540    * hi_result = hi_result + c2;
1541    * hi_result = hi_result + (m2 >> 16) + (m3 >> 16);
1542    */
1543   const unsigned elements = ir->operands[0]->type->vector_elements;
1544   ir_variable *src1 =
1545      new(ir) ir_variable(glsl_type::uvec(elements), "src1", ir_var_temporary);
1546   ir_variable *src1h =
1547      new(ir) ir_variable(glsl_type::uvec(elements), "src1h", ir_var_temporary);
1548   ir_variable *src1l =
1549      new(ir) ir_variable(glsl_type::uvec(elements), "src1l", ir_var_temporary);
1550   ir_variable *src2 =
1551      new(ir) ir_variable(glsl_type::uvec(elements), "src2", ir_var_temporary);
1552   ir_variable *src2h =
1553      new(ir) ir_variable(glsl_type::uvec(elements), "src2h", ir_var_temporary);
1554   ir_variable *src2l =
1555      new(ir) ir_variable(glsl_type::uvec(elements), "src2l", ir_var_temporary);
1556   ir_variable *t1 =
1557      new(ir) ir_variable(glsl_type::uvec(elements), "t1", ir_var_temporary);
1558   ir_variable *t2 =
1559      new(ir) ir_variable(glsl_type::uvec(elements), "t2", ir_var_temporary);
1560   ir_variable *lo =
1561      new(ir) ir_variable(glsl_type::uvec(elements), "lo", ir_var_temporary);
1562   ir_variable *hi =
1563      new(ir) ir_variable(glsl_type::uvec(elements), "hi", ir_var_temporary);
1564   ir_variable *different_signs = NULL;
1565   ir_constant *c0000FFFF = new(ir) ir_constant(0x0000FFFFu, elements);
1566   ir_constant *c16 = new(ir) ir_constant(16u, elements);
1567
1568   ir_instruction &i = *base_ir;
1569
1570   i.insert_before(src1);
1571   i.insert_before(src2);
1572   i.insert_before(src1h);
1573   i.insert_before(src2h);
1574   i.insert_before(src1l);
1575   i.insert_before(src2l);
1576
1577   if (ir->operands[0]->type->base_type == GLSL_TYPE_UINT) {
1578      i.insert_before(assign(src1, ir->operands[0]));
1579      i.insert_before(assign(src2, ir->operands[1]));
1580   } else {
1581      assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
1582
1583      ir_variable *itmp1 =
1584         new(ir) ir_variable(glsl_type::ivec(elements), "itmp1", ir_var_temporary);
1585      ir_variable *itmp2 =
1586         new(ir) ir_variable(glsl_type::ivec(elements), "itmp2", ir_var_temporary);
1587      ir_constant *c0 = new(ir) ir_constant(int(0), elements);
1588
1589      i.insert_before(itmp1);
1590      i.insert_before(itmp2);
1591      i.insert_before(assign(itmp1, ir->operands[0]));
1592      i.insert_before(assign(itmp2, ir->operands[1]));
1593
1594      different_signs =
1595         new(ir) ir_variable(glsl_type::bvec(elements), "different_signs",
1596                             ir_var_temporary);
1597
1598      i.insert_before(different_signs);
1599      i.insert_before(assign(different_signs, expr(ir_binop_logic_xor,
1600                                                   less(itmp1, c0),
1601                                                   less(itmp2, c0->clone(ir, NULL)))));
1602
1603      i.insert_before(assign(src1, i2u(abs(itmp1))));
1604      i.insert_before(assign(src2, i2u(abs(itmp2))));
1605   }
1606
1607   i.insert_before(assign(src1l, bit_and(src1, c0000FFFF)));
1608   i.insert_before(assign(src2l, bit_and(src2, c0000FFFF->clone(ir, NULL))));
1609   i.insert_before(assign(src1h, rshift(src1, c16)));
1610   i.insert_before(assign(src2h, rshift(src2, c16->clone(ir, NULL))));
1611
1612   i.insert_before(lo);
1613   i.insert_before(hi);
1614   i.insert_before(t1);
1615   i.insert_before(t2);
1616
1617   i.insert_before(assign(lo, mul(src1l, src2l)));
1618   i.insert_before(assign(t1, mul(src1l, src2h)));
1619   i.insert_before(assign(t2, mul(src1h, src2l)));
1620   i.insert_before(assign(hi, mul(src1h, src2h)));
1621
1622   i.insert_before(assign(hi, add(hi, _carry(lo, lshift(t1, c16->clone(ir, NULL))))));
1623   i.insert_before(assign(lo,            add(lo, lshift(t1, c16->clone(ir, NULL)))));
1624
1625   i.insert_before(assign(hi, add(hi, _carry(lo, lshift(t2, c16->clone(ir, NULL))))));
1626   i.insert_before(assign(lo,            add(lo, lshift(t2, c16->clone(ir, NULL)))));
1627
1628   if (different_signs == NULL) {
1629      assert(ir->operands[0]->type->base_type == GLSL_TYPE_UINT);
1630
1631      ir->operation = ir_binop_add;
1632      ir->init_num_operands();
1633      ir->operands[0] = add(hi, rshift(t1, c16->clone(ir, NULL)));
1634      ir->operands[1] = rshift(t2, c16->clone(ir, NULL));
1635   } else {
1636      assert(ir->operands[0]->type->base_type == GLSL_TYPE_INT);
1637
1638      i.insert_before(assign(hi, add(add(hi, rshift(t1, c16->clone(ir, NULL))),
1639                                     rshift(t2, c16->clone(ir, NULL)))));
1640
1641      /* For channels where different_signs is set we have to perform a 64-bit
1642       * negation.  This is *not* the same as just negating the high 32-bits.
1643       * Consider -3 * 2.  The high 32-bits is 0, but the desired result is
1644       * -1, not -0!  Recall -x == ~x + 1.
1645       */
1646      ir_variable *neg_hi =
1647         new(ir) ir_variable(glsl_type::ivec(elements), "neg_hi", ir_var_temporary);
1648      ir_constant *c1 = new(ir) ir_constant(1u, elements);
1649
1650      i.insert_before(neg_hi);
1651      i.insert_before(assign(neg_hi, add(bit_not(u2i(hi)),
1652                                         u2i(_carry(bit_not(lo), c1)))));
1653
1654      ir->operation = ir_triop_csel;
1655      ir->init_num_operands();
1656      ir->operands[0] = new(ir) ir_dereference_variable(different_signs);
1657      ir->operands[1] = new(ir) ir_dereference_variable(neg_hi);
1658      ir->operands[2] = u2i(hi);
1659   }
1660}
1661
1662void
1663lower_instructions_visitor::sqrt_to_abs_sqrt(ir_expression *ir)
1664{
1665   ir->operands[0] = new(ir) ir_expression(ir_unop_abs, ir->operands[0]);
1666   this->progress = true;
1667}
1668
1669ir_visitor_status
1670lower_instructions_visitor::visit_leave(ir_expression *ir)
1671{
1672   switch (ir->operation) {
1673   case ir_binop_dot:
1674      if (ir->operands[0]->type->is_double())
1675         double_dot_to_fma(ir);
1676      break;
1677   case ir_triop_lrp:
1678      if (ir->operands[0]->type->is_double())
1679         double_lrp(ir);
1680      break;
1681   case ir_binop_sub:
1682      if (lowering(SUB_TO_ADD_NEG))
1683	 sub_to_add_neg(ir);
1684      break;
1685
1686   case ir_binop_div:
1687      if (ir->operands[1]->type->is_integer() && lowering(INT_DIV_TO_MUL_RCP))
1688	 int_div_to_mul_rcp(ir);
1689      else if ((ir->operands[1]->type->is_float() && lowering(FDIV_TO_MUL_RCP)) ||
1690               (ir->operands[1]->type->is_double() && lowering(DDIV_TO_MUL_RCP)))
1691	 div_to_mul_rcp(ir);
1692      break;
1693
1694   case ir_unop_exp:
1695      if (lowering(EXP_TO_EXP2))
1696	 exp_to_exp2(ir);
1697      break;
1698
1699   case ir_unop_log:
1700      if (lowering(LOG_TO_LOG2))
1701	 log_to_log2(ir);
1702      break;
1703
1704   case ir_binop_mod:
1705      if (lowering(MOD_TO_FLOOR) && (ir->type->is_float() || ir->type->is_double()))
1706	 mod_to_floor(ir);
1707      break;
1708
1709   case ir_binop_pow:
1710      if (lowering(POW_TO_EXP2))
1711	 pow_to_exp2(ir);
1712      break;
1713
1714   case ir_binop_ldexp:
1715      if (lowering(LDEXP_TO_ARITH) && ir->type->is_float())
1716         ldexp_to_arith(ir);
1717      if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->type->is_double())
1718         dldexp_to_arith(ir);
1719      break;
1720
1721   case ir_unop_frexp_exp:
1722      if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->operands[0]->type->is_double())
1723         dfrexp_exp_to_arith(ir);
1724      break;
1725
1726   case ir_unop_frexp_sig:
1727      if (lowering(DFREXP_DLDEXP_TO_ARITH) && ir->operands[0]->type->is_double())
1728         dfrexp_sig_to_arith(ir);
1729      break;
1730
1731   case ir_binop_carry:
1732      if (lowering(CARRY_TO_ARITH))
1733         carry_to_arith(ir);
1734      break;
1735
1736   case ir_binop_borrow:
1737      if (lowering(BORROW_TO_ARITH))
1738         borrow_to_arith(ir);
1739      break;
1740
1741   case ir_unop_saturate:
1742      if (lowering(SAT_TO_CLAMP))
1743         sat_to_clamp(ir);
1744      break;
1745
1746   case ir_unop_trunc:
1747      if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
1748         dtrunc_to_dfrac(ir);
1749      break;
1750
1751   case ir_unop_ceil:
1752      if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
1753         dceil_to_dfrac(ir);
1754      break;
1755
1756   case ir_unop_floor:
1757      if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
1758         dfloor_to_dfrac(ir);
1759      break;
1760
1761   case ir_unop_round_even:
1762      if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
1763         dround_even_to_dfrac(ir);
1764      break;
1765
1766   case ir_unop_sign:
1767      if (lowering(DOPS_TO_DFRAC) && ir->type->is_double())
1768         dsign_to_csel(ir);
1769      break;
1770
1771   case ir_unop_bit_count:
1772      if (lowering(BIT_COUNT_TO_MATH))
1773         bit_count_to_math(ir);
1774      break;
1775
1776   case ir_triop_bitfield_extract:
1777      if (lowering(EXTRACT_TO_SHIFTS))
1778         extract_to_shifts(ir);
1779      break;
1780
1781   case ir_quadop_bitfield_insert:
1782      if (lowering(INSERT_TO_SHIFTS))
1783         insert_to_shifts(ir);
1784      break;
1785
1786   case ir_unop_bitfield_reverse:
1787      if (lowering(REVERSE_TO_SHIFTS))
1788         reverse_to_shifts(ir);
1789      break;
1790
1791   case ir_unop_find_lsb:
1792      if (lowering(FIND_LSB_TO_FLOAT_CAST))
1793         find_lsb_to_float_cast(ir);
1794      break;
1795
1796   case ir_unop_find_msb:
1797      if (lowering(FIND_MSB_TO_FLOAT_CAST))
1798         find_msb_to_float_cast(ir);
1799      break;
1800
1801   case ir_binop_imul_high:
1802      if (lowering(IMUL_HIGH_TO_MUL))
1803         imul_high_to_mul(ir);
1804      break;
1805
1806   case ir_unop_rsq:
1807   case ir_unop_sqrt:
1808      if (lowering(SQRT_TO_ABS_SQRT))
1809         sqrt_to_abs_sqrt(ir);
1810      break;
1811
1812   default:
1813      return visit_continue;
1814   }
1815
1816   return visit_continue;
1817}
1818