Modify Bigint _mulAdd, _sqrAdd, _estQuotientDigit, and Montgomery _mulMod

runtime/vm/intrinsifier_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"  // Needed here to get TARGET_ARCH_ARM64.
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/intrinsifier.h"
 
 #include "vm/assembler.h"
@@ skipping 910 matching lines @@
   __ cbnz(&carry_loop, R9);
 
   __ Bind(&done);
   // Returning Object::null() is not required, since this method is private.
   __ ret();
 }
 
 
 void Intrinsifier::Bigint_mulAdd(Assembler* assembler) {
   // Pseudo code:
-  // static void _mulAdd(Uint32List x_digits, int xi,
-  //                     Uint32List m_digits, int i,
-  //                     Uint32List a_digits, int j, int n) {
+  // static int _mulAdd(Uint32List x_digits, int xi,
+  //                    Uint32List m_digits, int i,
+  //                    Uint32List a_digits, int j, int n) {
   //   uint32_t x = x_digits[xi >> 1];  // xi is Smi.
   //   if (x == 0 || n == 0) {
-  //     return;
+  //     return 1;
   //   }
   //   uint32_t* mip = &m_digits[i >> 1];  // i is Smi.
   //   uint32_t* ajp = &a_digits[j >> 1];  // j is Smi.
   //   uint32_t c = 0;
   //   SmiUntag(n);
   //   do {
   //     uint32_t mi = *mip++;
   //     uint32_t aj = *ajp;
   //     uint64_t t = x*mi + aj + c;  // 32-bit * 32-bit -> 64-bit.
   //     *ajp++ = low32(t);
   //     c = high32(t);
   //   } while (--n > 0);
   //   while (c != 0) {
   //     uint64_t t = *ajp + c;
   //     *ajp++ = low32(t);
   //     c = high32(t);  // c == 0 or 1.
   //   }
+  //   return 1;
   // }
 
   Label done;
   // R3 = x, no_op if x == 0
   // R0 = xi as Smi, R1 = x_digits.
   __ ldp(R0, R1, Address(SP, 5 * kWordSize, Address::PairOffset));
   __ add(R1, R1, Operand(R0, LSL, 1));
   __ ldr(R3, FieldAddress(R1, TypedData::data_offset()), kUnsignedWord);
   __ tst(R3, Operand(R3));
   __ b(&done, EQ);
@@ skipping 60 matching lines @@
 
   Label propagate_carry_loop;
   __ Bind(&propagate_carry_loop);
   __ ldr(R0, Address(R5, 0), kUnsignedWord);
   __ addsw(R0, R0, Operand(1));
   __ str(R0, Address(R5, Bigint::kBytesPerDigit, Address::PostIndex),
          kUnsignedWord);
   __ b(&propagate_carry_loop, CS);
 
   __ Bind(&done);
-  // Returning Object::null() is not required, since this method is private.
+  __ LoadImmediate(R0, Smi::RawValue(1), kNoPP);  // One digit processed.
   __ ret();
 }
 
 
 void Intrinsifier::Bigint_sqrAdd(Assembler* assembler) {
   // Pseudo code:
-  // static void _sqrAdd(Uint32List x_digits, int i,
-  //                     Uint32List a_digits, int used) {
+  // static int _sqrAdd(Uint32List x_digits, int i,
+  //                    Uint32List a_digits, int used) {
   //   uint32_t* xip = &x_digits[i >> 1];  // i is Smi.
   //   uint32_t x = *xip++;
-  //   if (x == 0) return;
+  //   if (x == 0) return 1;
   //   uint32_t* ajp = &a_digits[i];  // j == 2*i, i is Smi.
   //   uint32_t aj = *ajp;
   //   uint64_t t = x*x + aj;
   //   *ajp++ = low32(t);
   //   uint64_t c = high32(t);
   //   int n = ((used - i) >> 1) - 1;  // used and i are Smi.
   //   while (--n >= 0) {
   //     uint32_t xi = *xip++;
   //     uint32_t aj = *ajp;
   //     uint96_t t = 2*x*xi + aj + c;  // 2-bit * 32-bit * 32-bit -> 65-bit.
   //     *ajp++ = low32(t);
   //     c = high64(t);  // 33-bit.
   //   }
   //   uint32_t aj = *ajp;
   //   uint64_t t = aj + c;  // 32-bit + 33-bit -> 34-bit.
   //   *ajp++ = low32(t);
   //   *ajp = high32(t);
+  //   return 1;
   // }
 
   // R4 = xip = &x_digits[i >> 1]
   // R2 = i as Smi, R3 = x_digits
   __ ldp(R2, R3, Address(SP, 2 * kWordSize, Address::PairOffset));
   __ add(R3, R3, Operand(R2, LSL, 1));
   __ add(R4, R3, Operand(TypedData::data_offset() - kHeapObjectTag));
 
   // R3 = x = *xip++, return if x == 0
   Label x_zero;
@@ skipping 70 matching lines @@
   __ add(R6, R6, Operand(R0));
 
   // R7 = R6 >> 32.
   __ LsrImmediate(R7, R6, 32);
 
   // *ajp = low32(t) = low32(R6)
   // *(ajp + 1) = high32(t) = low32(R7)
   __ stp(R6, R7, Address(R5, 0, Address::PairOffset), kUnsignedWord);
 
   __ Bind(&x_zero);
-  // Returning Object::null() is not required, since this method is private.
+  __ LoadImmediate(R0, Smi::RawValue(1), kNoPP);  // One digit processed.
   __ ret();
 }
 
 
 void Intrinsifier::Bigint_estQuotientDigit(Assembler* assembler) {
   // Pseudo code:
-  // static void _estQuotientDigit(Uint32List args, Uint32List digits, int i) {
-  //   uint32_t yt = args[_YT];  // _YT == 0.
+  // static int _estQuotientDigit(Uint32List args, Uint32List digits, int i) {
+  //   uint32_t yt = args[_YT];  // _YT == 1.
   //   uint32_t* dp = &digits[i >> 1];  // i is Smi.
   //   uint32_t dh = dp[0];  // dh == digits[i >> 1].
   //   uint32_t qd;
   //   if (dh == yt) {
   //     qd = DIGIT_MASK;
   //   } else {
   //     dl = dp[-1];  // dl == digits[(i - 1) >> 1].
   //     qd = dh:dl / yt;  // No overflow possible, because dh < yt.
   //   }
-  //   args[_QD] = qd;  // _QD == 1;
+  //   args[_QD] = qd;  // _QD == 2.
+  //   return 1;
   // }
 
   // R4 = args
   __ ldr(R4, Address(SP, 2 * kWordSize));  // args
 
-  // R3 = yt = args[0]
-  __ ldr(R3, FieldAddress(R4, TypedData::data_offset()), kUnsignedWord);
+  // R3 = yt = args[1]
+  __ ldr(R3, FieldAddress(R4,
+                          TypedData::data_offset() + Bigint::kBytesPerDigit),
+         kUnsignedWord);
 
   // R2 = dh = digits[i >> 1]
   // R0 = i as Smi, R1 = digits
   __ ldp(R0, R1, Address(SP, 0 * kWordSize, Address::PairOffset));
   __ add(R1, R1, Operand(R0, LSL, 1));
   __ ldr(R2, FieldAddress(R1, TypedData::data_offset()), kUnsignedWord);
 
   // R0 = qd = DIGIT_MASK = -1
   __ movn(R0, Immediate(0), 0);
 
   // Return qd if dh == yt
   Label return_qd;
   __ cmp(R2, Operand(R3));
   __ b(&return_qd, EQ);
 
   // R1 = dl = digits[(i - 1) >> 1]
   __ ldr(R1,
          FieldAddress(R1, TypedData::data_offset() - Bigint::kBytesPerDigit),
          kUnsignedWord);
 
   // R1 = dh:dl
   __ orr(R1, R1, Operand(R2, LSL, 32));
 
   // R0 = qd = dh:dl / yt = R1 / R3
   __ udiv(R0, R1, R3);
 
   __ Bind(&return_qd);
-  // args[1] = qd
+  // args[2] = qd
   __ str(R0,
-         FieldAddress(R4, TypedData::data_offset() + Bigint::kBytesPerDigit),
+         FieldAddress(R4, TypedData::data_offset() + 2*Bigint::kBytesPerDigit),
          kUnsignedWord);
 
-  // Returning Object::null() is not required, since this method is private.
+  __ LoadImmediate(R0, Smi::RawValue(1), kNoPP);  // One digit processed.
   __ ret();
 }
 
 
 void Intrinsifier::Montgomery_mulMod(Assembler* assembler) {
   // Pseudo code:
-  // static void _mulMod(Uint32List args, Uint32List digits, int i) {
-  //   uint32_t rho = args[_RHO];  // _RHO == 0.
+  // static int _mulMod(Uint32List args, Uint32List digits, int i) {
+  //   uint32_t rho = args[_RHO];  // _RHO == 2.
   //   uint32_t d = digits[i >> 1];  // i is Smi.
   //   uint64_t t = rho*d;
-  //   args[_MU] = t mod DIGIT_BASE;  // _MU == 1.
+  //   args[_MU] = t mod DIGIT_BASE;  // _MU == 4.
+  //   args[_MU_HI] = 0;  // _MU_HI == 3.
+  //   return 1;
   // }
 
   // R4 = args
   __ ldr(R4, Address(SP, 2 * kWordSize));  // args
 
-  // R3 = rho = args[0]
-  __ ldr(R3, FieldAddress(R4, TypedData::data_offset()), kUnsignedWord);
+  // R3 = rho = args[2]
+  __ ldr(R3,
+         FieldAddress(R4, TypedData::data_offset() + 2*Bigint::kBytesPerDigit),
+         kUnsignedWord);
 
   // R2 = digits[i >> 1]
   // R0 = i as Smi, R1 = digits
   __ ldp(R0, R1, Address(SP, 0 * kWordSize, Address::PairOffset));
   __ add(R1, R1, Operand(R0, LSL, 1));
   __ ldr(R2, FieldAddress(R1, TypedData::data_offset()), kUnsignedWord);
 
   // X0 = t = rho*d
   __ umaddl(R0, R2, R3, ZR);  // X0 = W2*W3 + 0.
 
-  // args[1] = t mod DIGIT_BASE = low32(t)
+  // args[4] = t mod DIGIT_BASE = low32(t)
   __ str(R0,
-         FieldAddress(R4, TypedData::data_offset() + Bigint::kBytesPerDigit),
-         kWord);
+         FieldAddress(R4, TypedData::data_offset() + 4*Bigint::kBytesPerDigit),
+         kUnsignedWord);
 
-  // Returning Object::null() is not required, since this method is private.
+  __ LoadImmediate(R0, Smi::RawValue(1), kNoPP);  // One digit processed.
   __ ret();
 }
 
 
 // Check if the last argument is a double, jump to label 'is_smi' if smi
 // (easy to convert to double), otherwise jump to label 'not_double_smi',
 // Returns the last argument in R0.
 static void TestLastArgumentIsDouble(Assembler* assembler,
                                      Label* is_smi,
                                      Label* not_double_smi) {
@@ skipping 747 matching lines @@
   Isolate* isolate = Isolate::Current();
   __ LoadImmediate(R1, reinterpret_cast<uword>(isolate), kNoPP);
   // Set return value to Isolate::current_tag_.
   __ ldr(R0, Address(R1, Isolate::current_tag_offset()));
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64