1//===-- lib/Evaluate/real.cpp ---------------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "flang/Evaluate/real.h"
10#include "int-power.h"
11#include "flang/Common/idioms.h"
12#include "flang/Decimal/decimal.h"
13#include "flang/Parser/characters.h"
14#include "llvm/Support/raw_ostream.h"
15#include <limits>
16
17namespace Fortran::evaluate::value {
18
19template <typename W, int P> Relation Real<W, P>::Compare(const Real &y) const {
20 if (IsNotANumber() || y.IsNotANumber()) { // NaN vs x, x vs NaN
21 return Relation::Unordered;
22 } else if (IsInfinite()) {
23 if (y.IsInfinite()) {
24 if (IsNegative()) { // -Inf vs +/-Inf
25 return y.IsNegative() ? Relation::Equal : Relation::Less;
26 } else { // +Inf vs +/-Inf
27 return y.IsNegative() ? Relation::Greater : Relation::Equal;
28 }
29 } else { // +/-Inf vs finite
30 return IsNegative() ? Relation::Less : Relation::Greater;
31 }
32 } else if (y.IsInfinite()) { // finite vs +/-Inf
33 return y.IsNegative() ? Relation::Greater : Relation::Less;
34 } else { // two finite numbers
35 bool isNegative{IsNegative()};
36 if (isNegative != y.IsNegative()) {
37 if (word_.IOR(y.word_).IBCLR(bits - 1).IsZero()) {
38 return Relation::Equal; // +/-0.0 == -/+0.0
39 } else {
40 return isNegative ? Relation::Less : Relation::Greater;
41 }
42 } else {
43 // same sign
44 Ordering order{evaluate::Compare(Exponent(), y.Exponent())};
45 if (order == Ordering::Equal) {
46 order = GetSignificand().CompareUnsigned(y.GetSignificand());
47 }
48 if (isNegative) {
49 order = Reverse(order);
50 }
51 return RelationFromOrdering(order);
52 }
53 }
54}
55
56template <typename W, int P>
57ValueWithRealFlags<Real<W, P>> Real<W, P>::Add(
58 const Real &y, Rounding rounding) const {
59 ValueWithRealFlags<Real> result;
60 if (IsNotANumber() || y.IsNotANumber()) {
61 result.value = NotANumber(); // NaN + x -> NaN
62 if (IsSignalingNaN() || y.IsSignalingNaN()) {
63 result.flags.set(RealFlag::InvalidArgument);
64 }
65 return result;
66 }
67 bool isNegative{IsNegative()};
68 bool yIsNegative{y.IsNegative()};
69 if (IsInfinite()) {
70 if (y.IsInfinite()) {
71 if (isNegative == yIsNegative) {
72 result.value = *this; // +/-Inf + +/-Inf -> +/-Inf
73 } else {
74 result.value = NotANumber(); // +/-Inf + -/+Inf -> NaN
75 result.flags.set(RealFlag::InvalidArgument);
76 }
77 } else {
78 result.value = *this; // +/-Inf + x -> +/-Inf
79 }
80 return result;
81 }
82 if (y.IsInfinite()) {
83 result.value = y; // x + +/-Inf -> +/-Inf
84 return result;
85 }
86 int exponent{Exponent()};
87 int yExponent{y.Exponent()};
88 if (exponent < yExponent) {
89 // y is larger in magnitude; simplify by reversing operands
90 return y.Add(*this, rounding);
91 }
92 if (exponent == yExponent && isNegative != yIsNegative) {
93 Ordering order{GetSignificand().CompareUnsigned(y.GetSignificand())};
94 if (order == Ordering::Less) {
95 // Same exponent, opposite signs, and y is larger in magnitude
96 return y.Add(*this, rounding);
97 }
98 if (order == Ordering::Equal) {
99 // x + (-x) -> +0.0 unless rounding is directed downwards
100 if (rounding.mode == common::RoundingMode::Down) {
101 result.value = NegativeZero();
102 }
103 return result;
104 }
105 }
106 // Our exponent is greater than y's, or the exponents match and y is not
107 // of the opposite sign and greater magnitude. So (x+y) will have the
108 // same sign as x.
109 Fraction fraction{GetFraction()};
110 Fraction yFraction{y.GetFraction()};
111 int rshift = exponent - yExponent;
112 if (exponent > 0 && yExponent == 0) {
113 --rshift; // correct overshift when only y is subnormal
114 }
115 RoundingBits roundingBits{yFraction, rshift};
116 yFraction = yFraction.SHIFTR(rshift);
117 bool carry{false};
118 if (isNegative != yIsNegative) {
119 // Opposite signs: subtract via addition of two's complement of y and
120 // the rounding bits.
121 yFraction = yFraction.NOT();
122 carry = roundingBits.Negate();
123 }
124 auto sum{fraction.AddUnsigned(yFraction, carry)};
125 fraction = sum.value;
126 if (isNegative == yIsNegative && sum.carry) {
127 roundingBits.ShiftRight(sum.value.BTEST(0));
128 fraction = fraction.SHIFTR(1).IBSET(fraction.bits - 1);
129 ++exponent;
130 }
131 NormalizeAndRound(
132 result, isNegative, exponent, fraction, rounding, roundingBits);
133 return result;
134}
135
136template <typename W, int P>
137ValueWithRealFlags<Real<W, P>> Real<W, P>::Multiply(
138 const Real &y, Rounding rounding) const {
139 ValueWithRealFlags<Real> result;
140 if (IsNotANumber() || y.IsNotANumber()) {
141 result.value = NotANumber(); // NaN * x -> NaN
142 if (IsSignalingNaN() || y.IsSignalingNaN()) {
143 result.flags.set(RealFlag::InvalidArgument);
144 }
145 } else {
146 bool isNegative{IsNegative() != y.IsNegative()};
147 if (IsInfinite() || y.IsInfinite()) {
148 if (IsZero() || y.IsZero()) {
149 result.value = NotANumber(); // 0 * Inf -> NaN
150 result.flags.set(RealFlag::InvalidArgument);
151 } else {
152 result.value = Infinity(isNegative);
153 }
154 } else {
155 auto product{GetFraction().MultiplyUnsigned(y.GetFraction())};
156 std::int64_t exponent{CombineExponents(y, false)};
157 if (exponent < 1) {
158 int rshift = 1 - exponent;
159 exponent = 1;
160 bool sticky{false};
161 if (rshift >= product.upper.bits + product.lower.bits) {
162 sticky = !product.lower.IsZero() || !product.upper.IsZero();
163 } else if (rshift >= product.lower.bits) {
164 sticky = !product.lower.IsZero() ||
165 !product.upper
166 .IAND(product.upper.MASKR(rshift - product.lower.bits))
167 .IsZero();
168 } else {
169 sticky = !product.lower.IAND(product.lower.MASKR(rshift)).IsZero();
170 }
171 product.lower = product.lower.SHIFTRWithFill(product.upper, rshift);
172 product.upper = product.upper.SHIFTR(rshift);
173 if (sticky) {
174 product.lower = product.lower.IBSET(0);
175 }
176 }
177 int leadz{product.upper.LEADZ()};
178 if (leadz >= product.upper.bits) {
179 leadz += product.lower.LEADZ();
180 }
181 int lshift{leadz};
182 if (lshift > exponent - 1) {
183 lshift = exponent - 1;
184 }
185 exponent -= lshift;
186 product.upper = product.upper.SHIFTLWithFill(product.lower, lshift);
187 product.lower = product.lower.SHIFTL(lshift);
188 RoundingBits roundingBits{product.lower, product.lower.bits};
189 NormalizeAndRound(result, isNegative, exponent, product.upper, rounding,
190 roundingBits, true /*multiply*/);
191 }
192 }
193 return result;
194}
195
196template <typename W, int P>
197ValueWithRealFlags<Real<W, P>> Real<W, P>::Divide(
198 const Real &y, Rounding rounding) const {
199 ValueWithRealFlags<Real> result;
200 if (IsNotANumber() || y.IsNotANumber()) {
201 result.value = NotANumber(); // NaN / x -> NaN, x / NaN -> NaN
202 if (IsSignalingNaN() || y.IsSignalingNaN()) {
203 result.flags.set(RealFlag::InvalidArgument);
204 }
205 } else {
206 bool isNegative{IsNegative() != y.IsNegative()};
207 if (IsInfinite()) {
208 if (y.IsInfinite()) {
209 result.value = NotANumber(); // Inf/Inf -> NaN
210 result.flags.set(RealFlag::InvalidArgument);
211 } else { // Inf/x -> Inf, Inf/0 -> Inf
212 result.value = Infinity(isNegative);
213 }
214 } else if (y.IsZero()) {
215 if (IsZero()) { // 0/0 -> NaN
216 result.value = NotANumber();
217 result.flags.set(RealFlag::InvalidArgument);
218 } else { // x/0 -> Inf, Inf/0 -> Inf
219 result.value = Infinity(isNegative);
220 result.flags.set(RealFlag::DivideByZero);
221 }
222 } else if (IsZero() || y.IsInfinite()) { // 0/x, x/Inf -> 0
223 if (isNegative) {
224 result.value = NegativeZero();
225 }
226 } else {
227 // dividend and divisor are both finite and nonzero numbers
228 Fraction top{GetFraction()}, divisor{y.GetFraction()};
229 std::int64_t exponent{CombineExponents(y, true)};
230 Fraction quotient;
231 bool msb{false};
232 if (!top.BTEST(top.bits - 1) || !divisor.BTEST(divisor.bits - 1)) {
233 // One or two subnormals
234 int topLshift{top.LEADZ()};
235 top = top.SHIFTL(topLshift);
236 int divisorLshift{divisor.LEADZ()};
237 divisor = divisor.SHIFTL(divisorLshift);
238 exponent += divisorLshift - topLshift;
239 }
240 for (int j{1}; j <= quotient.bits; ++j) {
241 if (NextQuotientBit(top, msb, divisor)) {
242 quotient = quotient.IBSET(quotient.bits - j);
243 }
244 }
245 bool guard{NextQuotientBit(top, msb, divisor)};
246 bool round{NextQuotientBit(top, msb, divisor)};
247 bool sticky{msb || !top.IsZero()};
248 RoundingBits roundingBits{guard, round, sticky};
249 if (exponent < 1) {
250 std::int64_t rshift{1 - exponent};
251 for (; rshift > 0; --rshift) {
252 roundingBits.ShiftRight(quotient.BTEST(0));
253 quotient = quotient.SHIFTR(1);
254 }
255 exponent = 1;
256 }
257 NormalizeAndRound(
258 result, isNegative, exponent, quotient, rounding, roundingBits);
259 }
260 }
261 return result;
262}
263
264template <typename W, int P>
265ValueWithRealFlags<Real<W, P>> Real<W, P>::SQRT(Rounding rounding) const {
266 ValueWithRealFlags<Real> result;
267 if (IsNotANumber()) {
268 result.value = NotANumber();
269 if (IsSignalingNaN()) {
270 result.flags.set(RealFlag::InvalidArgument);
271 }
272 } else if (IsNegative()) {
273 if (IsZero()) {
274 // SQRT(-0) == -0 in IEEE-754.
275 result.value = NegativeZero();
276 } else {
277 result.flags.set(RealFlag::InvalidArgument);
278 result.value = NotANumber();
279 }
280 } else if (IsInfinite()) {
281 // SQRT(+Inf) == +Inf
282 result.value = Infinity(false);
283 } else if (IsZero()) {
284 result.value = PositiveZero();
285 } else {
286 int expo{UnbiasedExponent()};
287 if (expo < -1 || expo > 1) {
288 // Reduce the range to [0.5 .. 4.0) by dividing by an integral power
289 // of four to avoid trouble with very large and very small values
290 // (esp. truncation of subnormals).
291 // SQRT(2**(2a) * x) = SQRT(2**(2a)) * SQRT(x) = 2**a * SQRT(x)
292 Real scaled;
293 int adjust{expo / 2};
294 scaled.Normalize(false, expo - 2 * adjust + exponentBias, GetFraction());
295 result = scaled.SQRT(rounding);
296 result.value.Normalize(false,
297 result.value.UnbiasedExponent() + adjust + exponentBias,
298 result.value.GetFraction());
299 return result;
300 }
301 // (-1) <= expo <= 1; use it as a shift to set the desired square.
302 using Extended = typename value::Integer<(binaryPrecision + 2)>;
303 Extended goal{
304 Extended::ConvertUnsigned(GetFraction()).value.SHIFTL(expo + 1)};
305 // Calculate the exact square root by maximizing a value whose square
306 // does not exceed the goal. Use two extra bits of precision for
307 // rounding.
308 bool sticky{true};
309 Extended extFrac{};
310 for (int bit{Extended::bits - 1}; bit >= 0; --bit) {
311 Extended next{extFrac.IBSET(bit)};
312 auto squared{next.MultiplyUnsigned(next)};
313 auto cmp{squared.upper.CompareUnsigned(goal)};
314 if (cmp == Ordering::Less) {
315 extFrac = next;
316 } else if (cmp == Ordering::Equal && squared.lower.IsZero()) {
317 extFrac = next;
318 sticky = false;
319 break; // exact result
320 }
321 }
322 RoundingBits roundingBits{extFrac.BTEST(1), extFrac.BTEST(0), sticky};
323 NormalizeAndRound(result, false, exponentBias,
324 Fraction::ConvertUnsigned(extFrac.SHIFTR(2)).value, rounding,
325 roundingBits);
326 }
327 return result;
328}
329
330template <typename W, int P>
331ValueWithRealFlags<Real<W, P>> Real<W, P>::NEAREST(bool upward) const {
332 ValueWithRealFlags<Real> result;
333 if (IsFinite()) {
334 Fraction fraction{GetFraction()};
335 int expo{Exponent()};
336 Fraction one{1};
337 Fraction nearest;
338 bool isNegative{IsNegative()};
339 if (upward != isNegative) { // upward in magnitude
340 auto next{fraction.AddUnsigned(one)};
341 if (next.carry) {
342 ++expo;
343 nearest = Fraction::Least(); // MSB only
344 } else {
345 nearest = next.value;
346 }
347 } else { // downward in magnitude
348 if (IsZero()) {
349 nearest = 1; // smallest magnitude negative subnormal
350 isNegative = !isNegative;
351 } else {
352 auto sub1{fraction.SubtractSigned(one)};
353 if (sub1.overflow && expo > 1) {
354 nearest = Fraction{0}.NOT();
355 --expo;
356 } else {
357 nearest = sub1.value;
358 }
359 }
360 }
361 result.flags = result.value.Normalize(isNegative, expo, nearest);
362 } else {
363 result.flags.set(RealFlag::InvalidArgument);
364 result.value = *this;
365 }
366 return result;
367}
368
369// HYPOT(x,y) = SQRT(x**2 + y**2) by definition, but those squared intermediate
370// values are susceptible to over/underflow when computed naively.
371// Assuming that x>=y, calculate instead:
372// HYPOT(x,y) = SQRT(x**2 * (1+(y/x)**2))
373// = ABS(x) * SQRT(1+(y/x)**2)
374template <typename W, int P>
375ValueWithRealFlags<Real<W, P>> Real<W, P>::HYPOT(
376 const Real &y, Rounding rounding) const {
377 ValueWithRealFlags<Real> result;
378 if (IsNotANumber() || y.IsNotANumber()) {
379 result.flags.set(RealFlag::InvalidArgument);
380 result.value = NotANumber();
381 } else if (ABS().Compare(y.ABS()) == Relation::Less) {
382 return y.HYPOT(*this);
383 } else if (IsZero()) {
384 return result; // x==y==0
385 } else {
386 auto yOverX{y.Divide(*this, rounding)}; // y/x
387 bool inexact{yOverX.flags.test(RealFlag::Inexact)};
388 auto squared{yOverX.value.Multiply(yOverX.value, rounding)}; // (y/x)**2
389 inexact |= squared.flags.test(RealFlag::Inexact);
390 Real one;
391 one.Normalize(false, exponentBias, Fraction::MASKL(1)); // 1.0
392 auto sum{squared.value.Add(one, rounding)}; // 1.0 + (y/x)**2
393 inexact |= sum.flags.test(RealFlag::Inexact);
394 auto sqrt{sum.value.SQRT()};
395 inexact |= sqrt.flags.test(RealFlag::Inexact);
396 result = sqrt.value.Multiply(ABS(), rounding);
397 if (inexact) {
398 result.flags.set(RealFlag::Inexact);
399 }
400 }
401 return result;
402}
403
404// MOD(x,y) = x - AINT(x/y)*y in the standard; unfortunately, this definition
405// can be pretty inaccurate when x is much larger than y in magnitude due to
406// cancellation. Implement instead with (essentially) arbitrary precision
407// long division, discarding the quotient and returning the remainder.
408// See runtime/numeric.cpp for more details.
409template <typename W, int P>
410ValueWithRealFlags<Real<W, P>> Real<W, P>::MOD(
411 const Real &p, Rounding rounding) const {
412 ValueWithRealFlags<Real> result;
413 if (IsNotANumber() || p.IsNotANumber() || IsInfinite()) {
414 result.flags.set(RealFlag::InvalidArgument);
415 result.value = NotANumber();
416 } else if (p.IsZero()) {
417 result.flags.set(RealFlag::DivideByZero);
418 result.value = NotANumber();
419 } else if (p.IsInfinite()) {
420 result.value = *this;
421 } else {
422 result.value = ABS();
423 auto pAbs{p.ABS()};
424 Real half, adj;
425 half.Normalize(false, exponentBias - 1, Fraction::MASKL(1)); // 0.5
426 for (adj.Normalize(false, Exponent(), pAbs.GetFraction());
427 result.value.Compare(pAbs) != Relation::Less;
428 adj = adj.Multiply(half).value) {
429 if (result.value.Compare(adj) != Relation::Less) {
430 result.value =
431 result.value.Subtract(adj, rounding).AccumulateFlags(result.flags);
432 if (result.value.IsZero()) {
433 break;
434 }
435 }
436 }
437 if (IsNegative()) {
438 result.value = result.value.Negate();
439 }
440 }
441 return result;
442}
443
444// MODULO(x,y) = x - FLOOR(x/y)*y in the standard; here, it is defined
445// in terms of MOD() with adjustment of the result.
446template <typename W, int P>
447ValueWithRealFlags<Real<W, P>> Real<W, P>::MODULO(
448 const Real &p, Rounding rounding) const {
449 ValueWithRealFlags<Real> result{MOD(p, rounding)};
450 if (IsNegative() != p.IsNegative()) {
451 if (result.value.IsZero()) {
452 result.value = result.value.Negate();
453 } else {
454 result.value =
455 result.value.Add(p, rounding).AccumulateFlags(result.flags);
456 }
457 }
458 return result;
459}
460
461template <typename W, int P>
462ValueWithRealFlags<Real<W, P>> Real<W, P>::DIM(
463 const Real &y, Rounding rounding) const {
464 ValueWithRealFlags<Real> result;
465 if (IsNotANumber() || y.IsNotANumber()) {
466 result.flags.set(RealFlag::InvalidArgument);
467 result.value = NotANumber();
468 } else if (Compare(y) == Relation::Greater) {
469 result = Subtract(y, rounding);
470 } else {
471 // result is already zero
472 }
473 return result;
474}
475
476template <typename W, int P>
477ValueWithRealFlags<Real<W, P>> Real<W, P>::ToWholeNumber(
478 common::RoundingMode mode) const {
479 ValueWithRealFlags<Real> result{*this};
480 if (IsNotANumber()) {
481 result.flags.set(RealFlag::InvalidArgument);
482 result.value = NotANumber();
483 } else if (IsInfinite()) {
484 result.flags.set(RealFlag::Overflow);
485 } else {
486 constexpr int noClipExponent{exponentBias + binaryPrecision - 1};
487 if (Exponent() < noClipExponent) {
488 Real adjust; // ABS(EPSILON(adjust)) == 0.5
489 adjust.Normalize(IsSignBitSet(), noClipExponent, Fraction::MASKL(1));
490 // Compute ival=(*this + adjust), losing any fractional bits; keep flags
491 result = Add(adjust, Rounding{mode});
492 result.flags.reset(RealFlag::Inexact); // result *is* exact
493 // Return (ival-adjust) with original sign in case we've generated a zero.
494 result.value =
495 result.value.Subtract(adjust, Rounding{common::RoundingMode::ToZero})
496 .value.SIGN(*this);
497 }
498 }
499 return result;
500}
501
502template <typename W, int P>
503RealFlags Real<W, P>::Normalize(bool negative, int exponent,
504 const Fraction &fraction, Rounding rounding, RoundingBits *roundingBits) {
505 int lshift{fraction.LEADZ()};
506 if (lshift == fraction.bits /* fraction is zero */ &&
507 (!roundingBits || roundingBits->empty())) {
508 // No fraction, no rounding bits -> +/-0.0
509 exponent = lshift = 0;
510 } else if (lshift < exponent) {
511 exponent -= lshift;
512 } else if (exponent > 0) {
513 lshift = exponent - 1;
514 exponent = 0;
515 } else if (lshift == 0) {
516 exponent = 1;
517 } else {
518 lshift = 0;
519 }
520 if (exponent >= maxExponent) {
521 // Infinity or overflow
522 if (rounding.mode == common::RoundingMode::TiesToEven ||
523 rounding.mode == common::RoundingMode::TiesAwayFromZero ||
524 (rounding.mode == common::RoundingMode::Up && !negative) ||
525 (rounding.mode == common::RoundingMode::Down && negative)) {
526 word_ = Word{maxExponent}.SHIFTL(significandBits); // Inf
527 } else {
528 // directed rounding: round to largest finite value rather than infinity
529 // (x86 does this, not sure whether it's standard behavior)
530 word_ = Word{word_.MASKR(word_.bits - 1)}.IBCLR(significandBits);
531 }
532 if (negative) {
533 word_ = word_.IBSET(bits - 1);
534 }
535 RealFlags flags{RealFlag::Overflow};
536 if (!fraction.IsZero()) {
537 flags.set(RealFlag::Inexact);
538 }
539 return flags;
540 }
541 word_ = Word::ConvertUnsigned(fraction).value;
542 if (lshift > 0) {
543 word_ = word_.SHIFTL(lshift);
544 if (roundingBits) {
545 for (; lshift > 0; --lshift) {
546 if (roundingBits->ShiftLeft()) {
547 word_ = word_.IBSET(lshift - 1);
548 }
549 }
550 }
551 }
552 if constexpr (isImplicitMSB) {
553 word_ = word_.IBCLR(significandBits);
554 }
555 word_ = word_.IOR(Word{exponent}.SHIFTL(significandBits));
556 if (negative) {
557 word_ = word_.IBSET(bits - 1);
558 }
559 return {};
560}
561
562template <typename W, int P>
563RealFlags Real<W, P>::Round(
564 Rounding rounding, const RoundingBits &bits, bool multiply) {
565 int origExponent{Exponent()};
566 RealFlags flags;
567 bool inexact{!bits.empty()};
568 if (inexact) {
569 flags.set(RealFlag::Inexact);
570 }
571 if (origExponent < maxExponent &&
572 bits.MustRound(rounding, IsNegative(), word_.BTEST(0) /* is odd */)) {
573 typename Fraction::ValueWithCarry sum{
574 GetFraction().AddUnsigned(Fraction{}, true)};
575 int newExponent{origExponent};
576 if (sum.carry) {
577 // The fraction was all ones before rounding; sum.value is now zero
578 sum.value = sum.value.IBSET(binaryPrecision - 1);
579 if (++newExponent >= maxExponent) {
580 flags.set(RealFlag::Overflow); // rounded away to an infinity
581 }
582 }
583 flags |= Normalize(IsNegative(), newExponent, sum.value);
584 }
585 if (inexact && origExponent == 0) {
586 // inexact subnormal input: signal Underflow unless in an x86-specific
587 // edge case
588 if (rounding.x86CompatibleBehavior && Exponent() != 0 && multiply &&
589 bits.sticky() &&
590 (bits.guard() ||
591 (rounding.mode != common::RoundingMode::Up &&
592 rounding.mode != common::RoundingMode::Down))) {
593 // x86 edge case in which Underflow fails to signal when a subnormal
594 // inexact multiplication product rounds to a normal result when
595 // the guard bit is set or we're not using directed rounding
596 } else {
597 flags.set(RealFlag::Underflow);
598 }
599 }
600 return flags;
601}
602
603template <typename W, int P>
604void Real<W, P>::NormalizeAndRound(ValueWithRealFlags<Real> &result,
605 bool isNegative, int exponent, const Fraction &fraction, Rounding rounding,
606 RoundingBits roundingBits, bool multiply) {
607 result.flags |= result.value.Normalize(
608 isNegative, exponent, fraction, rounding, &roundingBits);
609 result.flags |= result.value.Round(rounding, roundingBits, multiply);
610}
611
612inline enum decimal::FortranRounding MapRoundingMode(
613 common::RoundingMode rounding) {
614 switch (rounding) {
615 case common::RoundingMode::TiesToEven:
616 break;
617 case common::RoundingMode::ToZero:
618 return decimal::RoundToZero;
619 case common::RoundingMode::Down:
620 return decimal::RoundDown;
621 case common::RoundingMode::Up:
622 return decimal::RoundUp;
623 case common::RoundingMode::TiesAwayFromZero:
624 return decimal::RoundCompatible;
625 }
626 return decimal::RoundNearest; // dodge gcc warning about lack of result
627}
628
629inline RealFlags MapFlags(decimal::ConversionResultFlags flags) {
630 RealFlags result;
631 if (flags & decimal::Overflow) {
632 result.set(RealFlag::Overflow);
633 }
634 if (flags & decimal::Inexact) {
635 result.set(RealFlag::Inexact);
636 }
637 if (flags & decimal::Invalid) {
638 result.set(RealFlag::InvalidArgument);
639 }
640 return result;
641}
642
643template <typename W, int P>
644ValueWithRealFlags<Real<W, P>> Real<W, P>::Read(
645 const char *&p, Rounding rounding) {
646 auto converted{
647 decimal::ConvertToBinary<P>(p, MapRoundingMode(rounding.mode))};
648 const auto *value{reinterpret_cast<Real<W, P> *>(&converted.binary)};
649 return {*value, MapFlags(converted.flags)};
650}
651
652template <typename W, int P> std::string Real<W, P>::DumpHexadecimal() const {
653 if (IsNotANumber()) {
654 return "NaN0x"s + word_.Hexadecimal();
655 } else if (IsNegative()) {
656 return "-"s + Negate().DumpHexadecimal();
657 } else if (IsInfinite()) {
658 return "Inf"s;
659 } else if (IsZero()) {
660 return "0.0"s;
661 } else {
662 Fraction frac{GetFraction()};
663 std::string result{"0x"};
664 char intPart = '0' + frac.BTEST(frac.bits - 1);
665 result += intPart;
666 result += '.';
667 int trailz{frac.TRAILZ()};
668 if (trailz >= frac.bits - 1) {
669 result += '0';
670 } else {
671 int remainingBits{frac.bits - 1 - trailz};
672 int wholeNybbles{remainingBits / 4};
673 int lostBits{remainingBits - 4 * wholeNybbles};
674 if (wholeNybbles > 0) {
675 std::string fracHex{frac.SHIFTR(trailz + lostBits)
676 .IAND(frac.MASKR(4 * wholeNybbles))
677 .Hexadecimal()};
678 std::size_t field = wholeNybbles;
679 if (fracHex.size() < field) {
680 result += std::string(field - fracHex.size(), '0');
681 }
682 result += fracHex;
683 }
684 if (lostBits > 0) {
685 result += frac.SHIFTR(trailz)
686 .IAND(frac.MASKR(lostBits))
687 .SHIFTL(4 - lostBits)
688 .Hexadecimal();
689 }
690 }
691 result += 'p';
692 int exponent = Exponent() - exponentBias;
693 if (intPart == '0') {
694 exponent += 1;
695 }
696 result += Integer<32>{exponent}.SignedDecimal();
697 return result;
698 }
699}
700
701template <typename W, int P>
702llvm::raw_ostream &Real<W, P>::AsFortran(
703 llvm::raw_ostream &o, int kind, bool minimal) const {
704 if (IsNotANumber()) {
705 o << "(0._" << kind << "/0.)";
706 } else if (IsInfinite()) {
707 if (IsNegative()) {
708 o << "(-1._" << kind << "/0.)";
709 } else {
710 o << "(1._" << kind << "/0.)";
711 }
712 } else {
713 using B = decimal::BinaryFloatingPointNumber<P>;
714 B value{word_.template ToUInt<typename B::RawType>()};
715 char buffer[common::MaxDecimalConversionDigits(P) +
716 EXTRA_DECIMAL_CONVERSION_SPACE];
717 decimal::DecimalConversionFlags flags{}; // default: exact representation
718 if (minimal) {
719 flags = decimal::Minimize;
720 }
721 auto result{decimal::ConvertToDecimal<P>(buffer, sizeof buffer, flags,
722 static_cast<int>(sizeof buffer), decimal::RoundNearest, value)};
723 const char *p{result.str};
724 if (DEREF(p) == '-' || *p == '+') {
725 o << *p++;
726 }
727 int expo{result.decimalExponent};
728 if (*p != '0') {
729 --expo;
730 }
731 o << *p << '.' << (p + 1);
732 if (expo != 0) {
733 o << 'e' << expo;
734 }
735 o << '_' << kind;
736 }
737 return o;
738}
739
740// 16.9.180
741template <typename W, int P> Real<W, P> Real<W, P>::RRSPACING() const {
742 if (IsNotANumber()) {
743 return *this;
744 } else if (IsInfinite()) {
745 return NotANumber();
746 } else {
747 Real result;
748 result.Normalize(false, binaryPrecision + exponentBias - 1, GetFraction());
749 return result;
750 }
751}
752
753// 16.9.180
754template <typename W, int P> Real<W, P> Real<W, P>::SPACING() const {
755 if (IsNotANumber()) {
756 return *this;
757 } else if (IsInfinite()) {
758 return NotANumber();
759 } else if (IsZero() || IsSubnormal()) {
760 return TINY(); // mandated by standard
761 } else {
762 Real result;
763 result.Normalize(false, Exponent(), Fraction::MASKR(1));
764 return result.IsZero() ? TINY() : result;
765 }
766}
767
768// 16.9.171
769template <typename W, int P>
770Real<W, P> Real<W, P>::SET_EXPONENT(std::int64_t expo) const {
771 if (IsNotANumber()) {
772 return *this;
773 } else if (IsInfinite()) {
774 return NotANumber();
775 } else if (IsZero()) {
776 return *this;
777 } else {
778 return SCALE(Integer<64>(expo - UnbiasedExponent() - 1)).value;
779 }
780}
781
782// 16.9.171
783template <typename W, int P> Real<W, P> Real<W, P>::FRACTION() const {
784 return SET_EXPONENT(0);
785}
786
787template class Real<Integer<16>, 11>;
788template class Real<Integer<16>, 8>;
789template class Real<Integer<32>, 24>;
790template class Real<Integer<64>, 53>;
791template class Real<X87IntegerContainer, 64>;
792template class Real<Integer<128>, 113>;
793} // namespace Fortran::evaluate::value
794

source code of flang/lib/Evaluate/real.cpp