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1 // Copyright 2014 the V8 project authors. All rights reserved. | 1 // Copyright 2014 the V8 project authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "src/v8.h" | 5 #include "src/v8.h" |
6 | 6 |
7 #include "src/arguments.h" | 7 #include "src/arguments.h" |
| 8 #include "src/base/bits.h" |
8 #include "src/bootstrapper.h" | 9 #include "src/bootstrapper.h" |
9 #include "src/codegen.h" | 10 #include "src/codegen.h" |
10 #include "src/misc-intrinsics.h" | |
11 #include "src/runtime/runtime.h" | 11 #include "src/runtime/runtime.h" |
12 #include "src/runtime/runtime-utils.h" | 12 #include "src/runtime/runtime-utils.h" |
13 | 13 |
14 | 14 |
15 #ifndef _STLP_VENDOR_CSTD | 15 #ifndef _STLP_VENDOR_CSTD |
16 // STLPort doesn't import fpclassify and isless into the std namespace. | 16 // STLPort doesn't import fpclassify and isless into the std namespace. |
17 using std::fpclassify; | 17 using std::fpclassify; |
18 using std::isless; | 18 using std::isless; |
19 #endif | 19 #endif |
20 | 20 |
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519 100 * 1000 * 1000, 1000 * 1000 * 1000}; | 519 100 * 1000 * 1000, 1000 * 1000 * 1000}; |
520 | 520 |
521 // If the integers have the same number of decimal digits they can be | 521 // If the integers have the same number of decimal digits they can be |
522 // compared directly as the numeric order is the same as the | 522 // compared directly as the numeric order is the same as the |
523 // lexicographic order. If one integer has fewer digits, it is scaled | 523 // lexicographic order. If one integer has fewer digits, it is scaled |
524 // by some power of 10 to have the same number of digits as the longer | 524 // by some power of 10 to have the same number of digits as the longer |
525 // integer. If the scaled integers are equal it means the shorter | 525 // integer. If the scaled integers are equal it means the shorter |
526 // integer comes first in the lexicographic order. | 526 // integer comes first in the lexicographic order. |
527 | 527 |
528 // From http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10 | 528 // From http://graphics.stanford.edu/~seander/bithacks.html#IntegerLog10 |
529 int x_log2 = IntegerLog2(x_scaled); | 529 int x_log2 = 31 - base::bits::CountLeadingZeros32(x_scaled); |
530 int x_log10 = ((x_log2 + 1) * 1233) >> 12; | 530 int x_log10 = ((x_log2 + 1) * 1233) >> 12; |
531 x_log10 -= x_scaled < kPowersOf10[x_log10]; | 531 x_log10 -= x_scaled < kPowersOf10[x_log10]; |
532 | 532 |
533 int y_log2 = IntegerLog2(y_scaled); | 533 int y_log2 = 31 - base::bits::CountLeadingZeros32(y_scaled); |
534 int y_log10 = ((y_log2 + 1) * 1233) >> 12; | 534 int y_log10 = ((y_log2 + 1) * 1233) >> 12; |
535 y_log10 -= y_scaled < kPowersOf10[y_log10]; | 535 y_log10 -= y_scaled < kPowersOf10[y_log10]; |
536 | 536 |
537 int tie = EQUAL; | 537 int tie = EQUAL; |
538 | 538 |
539 if (x_log10 < y_log10) { | 539 if (x_log10 < y_log10) { |
540 // X has fewer digits. We would like to simply scale up X but that | 540 // X has fewer digits. We would like to simply scale up X but that |
541 // might overflow, e.g when comparing 9 with 1_000_000_000, 9 would | 541 // might overflow, e.g when comparing 9 with 1_000_000_000, 9 would |
542 // be scaled up to 9_000_000_000. So we scale up by the next | 542 // be scaled up to 9_000_000_000. So we scale up by the next |
543 // smallest power and scale down Y to drop one digit. It is OK to | 543 // smallest power and scale down Y to drop one digit. It is OK to |
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589 | 589 |
590 RUNTIME_FUNCTION(RuntimeReference_IsNonNegativeSmi) { | 590 RUNTIME_FUNCTION(RuntimeReference_IsNonNegativeSmi) { |
591 SealHandleScope shs(isolate); | 591 SealHandleScope shs(isolate); |
592 DCHECK(args.length() == 1); | 592 DCHECK(args.length() == 1); |
593 CONVERT_ARG_CHECKED(Object, obj, 0); | 593 CONVERT_ARG_CHECKED(Object, obj, 0); |
594 return isolate->heap()->ToBoolean(obj->IsSmi() && | 594 return isolate->heap()->ToBoolean(obj->IsSmi() && |
595 Smi::cast(obj)->value() >= 0); | 595 Smi::cast(obj)->value() >= 0); |
596 } | 596 } |
597 } | 597 } |
598 } // namespace v8::internal | 598 } // namespace v8::internal |
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