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1 // Copyright 2012 the V8 project authors. All rights reserved. | 1 // Copyright 2012 the V8 project authors. All rights reserved. |
2 // Redistribution and use in source and binary forms, with or without | 2 // Redistribution and use in source and binary forms, with or without |
3 // modification, are permitted provided that the following conditions are | 3 // modification, are permitted provided that the following conditions are |
4 // met: | 4 // met: |
5 // | 5 // |
6 // * Redistributions of source code must retain the above copyright | 6 // * Redistributions of source code must retain the above copyright |
7 // notice, this list of conditions and the following disclaimer. | 7 // notice, this list of conditions and the following disclaimer. |
8 // * Redistributions in binary form must reproduce the above | 8 // * Redistributions in binary form must reproduce the above |
9 // copyright notice, this list of conditions and the following | 9 // copyright notice, this list of conditions and the following |
10 // disclaimer in the documentation and/or other materials provided | 10 // disclaimer in the documentation and/or other materials provided |
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1124 | 1124 |
1125 // Theoretically, a variation of the branch-free code for integer division by | 1125 // Theoretically, a variation of the branch-free code for integer division by |
1126 // a power of 2 (calculating the remainder via an additional multiplication | 1126 // a power of 2 (calculating the remainder via an additional multiplication |
1127 // (which gets simplified to an 'and') and subtraction) should be faster, and | 1127 // (which gets simplified to an 'and') and subtraction) should be faster, and |
1128 // this is exactly what GCC and clang emit. Nevertheless, benchmarks seem to | 1128 // this is exactly what GCC and clang emit. Nevertheless, benchmarks seem to |
1129 // indicate that positive dividends are heavily favored, so the branching | 1129 // indicate that positive dividends are heavily favored, so the branching |
1130 // version performs better. | 1130 // version performs better. |
1131 HMod* hmod = instr->hydrogen(); | 1131 HMod* hmod = instr->hydrogen(); |
1132 int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1); | 1132 int32_t mask = divisor < 0 ? -(divisor + 1) : (divisor - 1); |
1133 Label dividend_is_not_negative, done; | 1133 Label dividend_is_not_negative, done; |
1134 if (hmod->left()->CanBeNegative()) { | 1134 if (hmod->CheckFlag(HValue::kLeftCanBeNegative)) { |
1135 __ cmp(dividend, Operand::Zero()); | 1135 __ cmp(dividend, Operand::Zero()); |
1136 __ b(pl, ÷nd_is_not_negative); | 1136 __ b(pl, ÷nd_is_not_negative); |
1137 // Note that this is correct even for kMinInt operands. | 1137 // Note that this is correct even for kMinInt operands. |
1138 __ rsb(dividend, dividend, Operand::Zero()); | 1138 __ rsb(dividend, dividend, Operand::Zero()); |
1139 __ and_(dividend, dividend, Operand(mask)); | 1139 __ and_(dividend, dividend, Operand(mask)); |
1140 __ rsb(dividend, dividend, Operand::Zero(), SetCC); | 1140 __ rsb(dividend, dividend, Operand::Zero(), SetCC); |
1141 if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) { | 1141 if (hmod->CheckFlag(HValue::kBailoutOnMinusZero)) { |
1142 DeoptimizeIf(eq, instr->environment()); | 1142 DeoptimizeIf(eq, instr->environment()); |
1143 } | 1143 } |
1144 __ b(&done); | 1144 __ b(&done); |
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5710 __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index)); | 5710 __ sub(scratch, result, Operand::PointerOffsetFromSmiKey(index)); |
5711 __ ldr(result, FieldMemOperand(scratch, | 5711 __ ldr(result, FieldMemOperand(scratch, |
5712 FixedArray::kHeaderSize - kPointerSize)); | 5712 FixedArray::kHeaderSize - kPointerSize)); |
5713 __ bind(&done); | 5713 __ bind(&done); |
5714 } | 5714 } |
5715 | 5715 |
5716 | 5716 |
5717 #undef __ | 5717 #undef __ |
5718 | 5718 |
5719 } } // namespace v8::internal | 5719 } } // namespace v8::internal |
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