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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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1312 LOperand* dividend = UseFixed(instr->left(), r0); | 1312 LOperand* dividend = UseFixed(instr->left(), r0); |
1313 LOperand* divisor = UseFixed(instr->right(), r1); | 1313 LOperand* divisor = UseFixed(instr->right(), r1); |
1314 return AssignEnvironment(AssignPointerMap( | 1314 return AssignEnvironment(AssignPointerMap( |
1315 DefineFixed(new(zone()) LDivI(dividend, divisor), r0))); | 1315 DefineFixed(new(zone()) LDivI(dividend, divisor), r0))); |
1316 } else { | 1316 } else { |
1317 return DoArithmeticT(Token::DIV, instr); | 1317 return DoArithmeticT(Token::DIV, instr); |
1318 } | 1318 } |
1319 } | 1319 } |
1320 | 1320 |
1321 | 1321 |
1322 bool LChunkBuilder::HasMagicNumberForDivisor(int32_t divisor) { | |
1323 uint32_t divisor_abs = abs(divisor); | |
1324 // Dividing by 0, 1, and powers of 2 is easy. | |
1325 // Note that IsPowerOf2(0) returns true; | |
1326 ASSERT(IsPowerOf2(0) == true); | |
1327 if (IsPowerOf2(divisor_abs)) return true; | |
1328 | |
1329 // We have magic numbers for a few specific divisors. | |
1330 // Details and proofs can be found in: | |
1331 // - Hacker's Delight, Henry S. Warren, Jr. | |
1332 // - The PowerPC Compiler Writer’s Guide | |
1333 // and probably many others. | |
1334 // | |
1335 // We handle | |
1336 // <divisor with magic numbers> * <power of 2> | |
1337 // but not | |
1338 // <divisor with magic numbers> * <other divisor with magic numbers> | |
1339 int32_t power_of_2_factor = | |
1340 CompilerIntrinsics::CountTrailingZeros(divisor_abs); | |
1341 DivMagicNumbers magic_numbers = | |
1342 DivMagicNumberFor(divisor_abs >> power_of_2_factor); | |
1343 if (magic_numbers.M != InvalidDivMagicNumber.M) return true; | |
1344 | |
1345 return false; | |
1346 } | |
1347 | |
1348 | |
1349 HValue* LChunkBuilder::SimplifiedDividendForMathFloorOfDiv(HValue* dividend) { | |
1350 // A change from an integer32 can be replaced by the integer32 value. | |
1351 if (dividend->IsChange() && | |
1352 HChange::cast(dividend)->from().IsInteger32()) { | |
1353 return HChange::cast(dividend)->value(); | |
1354 } | |
1355 // Change representation to integer32 if the constant can be represented as an | |
1356 // integer32 value. | |
1357 if (dividend->IsConstant() && | |
1358 HConstant::cast(dividend)->HasInteger32Value()) { | |
fschneider
2012/04/17 07:41:10
This would only occur is in Math.floor(a/b) both a
Alexandre
2012/04/17 10:01:50
In short: yes we should remove it.
Long:
Division
| |
1359 return HConstant::cast(dividend)->CopyToRepresentation( | |
1360 Representation::Integer32()); | |
1361 } | |
1362 return NULL; | |
1363 } | |
1364 | |
1365 | |
1366 HValue* LChunkBuilder::SimplifiedDivisorForMathFloorOfDiv(HValue* divisor) { | |
1367 // Only optimize when we have magic numbers for the divisor. | |
1368 // The standard integer division routine is usually slower than transitionning | |
1369 // to VFP. | |
1370 if (divisor->IsConstant() && | |
1371 HConstant::cast(divisor)->HasInteger32Value()) { | |
1372 HConstant* constant_val = HConstant::cast(divisor); | |
1373 int32_t int32_val = constant_val->Integer32Value(); | |
1374 if (LChunkBuilder::HasMagicNumberForDivisor(int32_val)) { | |
1375 return constant_val->CopyToRepresentation(Representation::Integer32()); | |
1376 } | |
1377 } | |
1378 return NULL; | |
1379 } | |
1380 | |
1381 | |
1382 LInstruction* LChunkBuilder::DoMathFloorOfDiv(HMathFloorOfDiv* instr) { | |
1383 HValue* right = instr->right(); | |
1384 LOperand* dividend = UseRegister(instr->left()); | |
1385 LOperand* divisor = UseRegisterOrConstant(right); | |
1386 LOperand* remainder = TempRegister(); | |
1387 ASSERT(right->IsConstant() && | |
1388 HConstant::cast(right)->HasInteger32Value() && | |
1389 HasMagicNumberForDivisor(HConstant::cast(right)->Integer32Value())); | |
1390 return AssignEnvironment(DefineAsRegister( | |
1391 new LMathFloorOfDiv(dividend, divisor, remainder))); | |
1392 } | |
1393 | |
1394 | |
1322 LInstruction* LChunkBuilder::DoMod(HMod* instr) { | 1395 LInstruction* LChunkBuilder::DoMod(HMod* instr) { |
1323 if (instr->representation().IsInteger32()) { | 1396 if (instr->representation().IsInteger32()) { |
1324 ASSERT(instr->left()->representation().IsInteger32()); | 1397 ASSERT(instr->left()->representation().IsInteger32()); |
1325 ASSERT(instr->right()->representation().IsInteger32()); | 1398 ASSERT(instr->right()->representation().IsInteger32()); |
1326 | 1399 |
1327 LModI* mod; | 1400 LModI* mod; |
1328 if (instr->HasPowerOf2Divisor()) { | 1401 if (instr->HasPowerOf2Divisor()) { |
1329 ASSERT(!instr->CheckFlag(HValue::kCanBeDivByZero)); | 1402 ASSERT(!instr->CheckFlag(HValue::kCanBeDivByZero)); |
1330 LOperand* value = UseRegisterAtStart(instr->left()); | 1403 LOperand* value = UseRegisterAtStart(instr->left()); |
1331 mod = new(zone()) LModI(value, UseOrConstant(instr->right())); | 1404 mod = new(zone()) LModI(value, UseOrConstant(instr->right())); |
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2315 | 2388 |
2316 | 2389 |
2317 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) { | 2390 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) { |
2318 LOperand* object = UseRegister(instr->object()); | 2391 LOperand* object = UseRegister(instr->object()); |
2319 LOperand* index = UseRegister(instr->index()); | 2392 LOperand* index = UseRegister(instr->index()); |
2320 return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index)); | 2393 return DefineAsRegister(new(zone()) LLoadFieldByIndex(object, index)); |
2321 } | 2394 } |
2322 | 2395 |
2323 | 2396 |
2324 } } // namespace v8::internal | 2397 } } // namespace v8::internal |
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