Program: 21013
Project: 21013
Buggy source:
/** 
 * h = f * g Can overlap h with f or g. Preconditions: |f| bounded by 1.65*2^26,1.65*2^25,1.65*2^26,1.65*2^25,etc. |g| bounded by 1.65*2^26,1.65*2^25,1.65*2^26,1.65*2^25,etc. Postconditions: |h| bounded by 1.01*2^25,1.01*2^24,1.01*2^25,1.01*2^24,etc. Notes on implementation strategy: Using schoolbook multiplication. Karatsuba would save a little in some cost models. Most multiplications by 2 and 19 are 32-bit precomputations; cheaper than 64-bit postcomputations. There is one remaining multiplication by 19 in the carry chain; one *19 precomputation can be merged into this, but the resulting data flow is considerably less clean. There are 12 carries below. 10 of them are 2-way parallelizable and vectorizable. Can get away with 11 carries, but then data flow is much deeper. With tighter constraints on inputs can squeeze carries into int32.
 */
public FieldElement multiply(FieldElement val){
  int[] g=((Ed25519FieldElement)val).t;
  int f0=t[0];
  int f1=t[1];
  int f2=t[2];
  int f3=t[3];
  int f4=t[4];
  int f5=t[5];
  int f6=t[6];
  int f7=t[7];
  int f8=t[8];
  int f9=t[9];
  int g0=g[0];
  int g1=g[1];
  int g2=g[2];
  int g3=g[3];
  int g4=g[4];
  int g5=g[5];
  int g6=g[6];
  int g7=g[7];
  int g8=g[8];
  int g9=g[9];
  int g1_19=19 * g1;
  int g2_19=19 * g2;
  int g3_19=19 * g3;
  int g4_19=19 * g4;
  int g5_19=19 * g5;
  int g6_19=19 * g6;
  int g7_19=19 * g7;
  int g8_19=19 * g8;
  int g9_19=19 * g9;
  int f1_2=2 * f1;
  int f3_2=2 * f3;
  int f5_2=2 * f5;
  int f7_2=2 * f7;
  int f9_2=2 * f9;
  long f0g0=f0 * (long)g0;
  long f0g1=f0 * (long)g1;
  long f0g2=f0 * (long)g2;
  long f0g3=f0 * (long)g3;
  long f0g4=f0 * (long)g4;
  long f0g5=f0 * (long)g5;
  long f0g6=f0 * (long)g6;
  long f0g7=f0 * (long)g7;
  long f0g8=f0 * (long)g8;
  long f0g9=f0 * (long)g9;
  long f1g0=f1 * (long)g0;
  long f1g1_2=f1_2 * (long)g1;
  long f1g2=f1 * (long)g2;
  long f1g3_2=f1_2 * (long)g3;
  long f1g4=f1 * (long)g4;
  long f1g5_2=f1_2 * (long)g5;
  long f1g6=f1 * (long)g6;
  long f1g7_2=f1_2 * (long)g7;
  long f1g8=f1 * (long)g8;
  long f1g9_38=f1_2 * (long)g9_19;
  long f2g0=f2 * (long)g0;
  long f2g1=f2 * (long)g1;
  long f2g2=f2 * (long)g2;
  long f2g3=f2 * (long)g3;
  long f2g4=f2 * (long)g4;
  long f2g5=f2 * (long)g5;
  long f2g6=f2 * (long)g6;
  long f2g7=f2 * (long)g7;
  long f2g8_19=f2 * (long)g8_19;
  long f2g9_19=f2 * (long)g9_19;
  long f3g0=f3 * (long)g0;
  long f3g1_2=f3_2 * (long)g1;
  long f3g2=f3 * (long)g2;
  long f3g3_2=f3_2 * (long)g3;
  long f3g4=f3 * (long)g4;
  long f3g5_2=f3_2 * (long)g5;
  long f3g6=f3 * (long)g6;
  long f3g7_38=f3_2 * (long)g7_19;
  long f3g8_19=f3 * (long)g8_19;
  long f3g9_38=f3_2 * (long)g9_19;
  long f4g0=f4 * (long)g0;
  long f4g1=f4 * (long)g1;
  long f4g2=f4 * (long)g2;
  long f4g3=f4 * (long)g3;
  long f4g4=f4 * (long)g4;
  long f4g5=f4 * (long)g5;
  long f4g6_19=f4 * (long)g6_19;
  long f4g7_19=f4 * (long)g7_19;
  long f4g8_19=f4 * (long)g8_19;
  long f4g9_19=f4 * (long)g9_19;
  long f5g0=f5 * (long)g0;
  long f5g1_2=f5_2 * (long)g1;
  long f5g2=f5 * (long)g2;
  long f5g3_2=f5_2 * (long)g3;
  long f5g4=f5 * (long)g4;
  long f5g5_38=f5_2 * (long)g5_19;
  long f5g6_19=f5 * (long)g6_19;
  long f5g7_38=f5_2 * (long)g7_19;
  long f5g8_19=f5 * (long)g8_19;
  long f5g9_38=f5_2 * (long)g9_19;
  long f6g0=f6 * (long)g0;
  long f6g1=f6 * (long)g1;
  long f6g2=f6 * (long)g2;
  long f6g3=f6 * (long)g3;
  long f6g4_19=f6 * (long)g4_19;
  long f6g5_19=f6 * (long)g5_19;
  long f6g6_19=f6 * (long)g6_19;
  long f6g7_19=f6 * (long)g7_19;
  long f6g8_19=f6 * (long)g8_19;
  long f6g9_19=f6 * (long)g9_19;
  long f7g0=f7 * (long)g0;
  long f7g1_2=f7_2 * (long)g1;
  long f7g2=f7 * (long)g2;
  long f7g3_38=f7_2 * (long)g3_19;
  long f7g4_19=f7 * (long)g4_19;
  long f7g5_38=f7_2 * (long)g5_19;
  long f7g6_19=f7 * (long)g6_19;
  long f7g7_38=f7_2 * (long)g7_19;
  long f7g8_19=f7 * (long)g8_19;
  long f7g9_38=f7_2 * (long)g9_19;
  long f8g0=f8 * (long)g0;
  long f8g1=f8 * (long)g1;
  long f8g2_19=f8 * (long)g2_19;
  long f8g3_19=f8 * (long)g3_19;
  long f8g4_19=f8 * (long)g4_19;
  long f8g5_19=f8 * (long)g5_19;
  long f8g6_19=f8 * (long)g6_19;
  long f8g7_19=f8 * (long)g7_19;
  long f8g8_19=f8 * (long)g8_19;
  long f8g9_19=f8 * (long)g9_19;
  long f9g0=f9 * (long)g0;
  long f9g1_38=f9_2 * (long)g1_19;
  long f9g2_19=f9 * (long)g2_19;
  long f9g3_38=f9_2 * (long)g3_19;
  long f9g4_19=f9 * (long)g4_19;
  long f9g5_38=f9_2 * (long)g5_19;
  long f9g6_19=f9 * (long)g6_19;
  long f9g7_38=f9_2 * (long)g7_19;
  long f9g8_19=f9 * (long)g8_19;
  long f9g9_38=f9_2 * (long)g9_19;
  long h0=f0g0 + f1g9_38 + f2g8_19+ f3g7_38+ f4g6_19+ f5g5_38+ f6g4_19+ f7g3_38+ f8g2_19+ f9g1_38;
  long h1=f0g1 + f1g0 + f2g9_19+ f3g8_19+ f4g7_19+ f5g6_19+ f6g5_19+ f7g4_19+ f8g3_19+ f9g2_19;
  long h2=f0g2 + f1g1_2 + f2g0+ f3g9_38+ f4g8_19+ f5g7_38+ f6g6_19+ f7g5_38+ f8g4_19+ f9g3_38;
  long h3=f0g3 + f1g2 + f2g1+ f3g0+ f4g9_19+ f5g8_19+ f6g7_19+ f7g6_19+ f8g5_19+ f9g4_19;
  long h4=f0g4 + f1g3_2 + f2g2+ f3g1_2+ f4g0+ f5g9_38+ f6g8_19+ f7g7_38+ f8g6_19+ f9g5_38;
  long h5=f0g5 + f1g4 + f2g3+ f3g2+ f4g1+ f5g0+ f6g9_19+ f7g8_19+ f8g7_19+ f9g6_19;
  long h6=f0g6 + f1g5_2 + f2g4+ f3g3_2+ f4g2+ f5g1_2+ f6g0+ f7g9_38+ f8g8_19+ f9g7_38;
  long h7=f0g7 + f1g6 + f2g5+ f3g4+ f4g3+ f5g2+ f6g1+ f7g0+ f8g9_19+ f9g8_19;
  long h8=f0g8 + f1g7_2 + f2g6+ f3g5_2+ f4g4+ f5g3_2+ f6g2+ f7g1_2+ f8g0+ f9g9_38;
  long h9=f0g9 + f1g8 + f2g7+ f3g6+ f4g5+ f5g4+ f6g3+ f7g2+ f8g1+ f9g0;
  long carry0;
  long carry1;
  long carry2;
  long carry3;
  long carry4;
  long carry5;
  long carry6;
  long carry7;
  long carry8;
  long carry9;
  carry0=(h0 + (long)(1 << 25)) >> 26;
  h1+=carry0;
  h0-=carry0 << 26;
  carry4=(h4 + (long)(1 << 25)) >> 26;
  h5+=carry4;
  h4-=carry4 << 26;
  carry1=(h1 + (long)(1 << 24)) >> 25;
  h2+=carry1;
  h1-=carry1 << 25;
  carry5=(h5 + (long)(1 << 24)) >> 25;
  h6+=carry5;
  h5-=carry5 << 25;
  carry2=(h2 + (long)(1 << 25)) >> 26;
  h3+=carry2;
  h2-=carry2 << 26;
  carry6=(h6 + (long)(1 << 25)) >> 26;
  h7+=carry6;
  h6-=carry6 << 26;
  carry3=(h3 + (long)(1 << 24)) >> 25;
  h4+=carry3;
  h3-=carry3 << 25;
  carry7=(h7 + (long)(1 << 24)) >> 25;
  h8+=carry7;
  h7-=carry7 << 25;
  carry4=(h4 + (long)(1 << 25)) >> 26;
  h5+=carry4;
  h4-=carry4 << 26;
  carry8=(h8 + (long)(1 << 25)) >> 26;
  h9+=carry8;
  h8-=carry8 << 26;
  carry9=(h9 + (long)(1 << 24)) >> 25;
  h0+=carry9 * 19;
  h9-=carry9 << 25;
  carry0=(h0 + (long)(1 << 25)) >> 26;
  h1+=carry0;
  h0-=carry0 << 26;
  int[] h=new int[10];
  h[0]=(int)h0;
  h[1]=(int)h1;
  h[2]=(int)h2;
  h[3]=(int)h3;
  h[4]=(int)h4;
  h[5]=(int)h5;
  h[6]=(int)h6;
  h[7]=(int)h7;
  h[8]=(int)h8;
  h[9]=(int)h9;
  return new Ed25519FieldElement(f,h);
}

Fixed version (ground truth):
/** 
 * h = f * g Can overlap h with f or g. Preconditions: |f| bounded by 1.65*2^26,1.65*2^25,1.65*2^26,1.65*2^25,etc. |g| bounded by 1.65*2^26,1.65*2^25,1.65*2^26,1.65*2^25,etc. Postconditions: |h| bounded by 1.01*2^25,1.01*2^24,1.01*2^25,1.01*2^24,etc. Notes on implementation strategy: Using schoolbook multiplication. Karatsuba would save a little in some cost models. Most multiplications by 2 and 19 are 32-bit precomputations; cheaper than 64-bit postcomputations. There is one remaining multiplication by 19 in the carry chain; one *19 precomputation can be merged into this, but the resulting data flow is considerably less clean. There are 12 carries below. 10 of them are 2-way parallelizable and vectorizable. Can get away with 11 carries, but then data flow is much deeper. With tighter constraints on inputs can squeeze carries into int32.
 */
public FieldElement multiply(FieldElement val){
  int[] g=((Ed25519FieldElement)val).t;
  int g1_19=19 * g[1];
  int g2_19=19 * g[2];
  int g3_19=19 * g[3];
  int g4_19=19 * g[4];
  int g5_19=19 * g[5];
  int g6_19=19 * g[6];
  int g7_19=19 * g[7];
  int g8_19=19 * g[8];
  int g9_19=19 * g[9];
  int f1_2=2 * t[1];
  int f3_2=2 * t[3];
  int f5_2=2 * t[5];
  int f7_2=2 * t[7];
  int f9_2=2 * t[9];
  long f0g0=t[0] * (long)g[0];
  long f0g1=t[0] * (long)g[1];
  long f0g2=t[0] * (long)g[2];
  long f0g3=t[0] * (long)g[3];
  long f0g4=t[0] * (long)g[4];
  long f0g5=t[0] * (long)g[5];
  long f0g6=t[0] * (long)g[6];
  long f0g7=t[0] * (long)g[7];
  long f0g8=t[0] * (long)g[8];
  long f0g9=t[0] * (long)g[9];
  long f1g0=t[1] * (long)g[0];
  long f1g1_2=f1_2 * (long)g[1];
  long f1g2=t[1] * (long)g[2];
  long f1g3_2=f1_2 * (long)g[3];
  long f1g4=t[1] * (long)g[4];
  long f1g5_2=f1_2 * (long)g[5];
  long f1g6=t[1] * (long)g[6];
  long f1g7_2=f1_2 * (long)g[7];
  long f1g8=t[1] * (long)g[8];
  long f1g9_38=f1_2 * (long)g9_19;
  long f2g0=t[2] * (long)g[0];
  long f2g1=t[2] * (long)g[1];
  long f2g2=t[2] * (long)g[2];
  long f2g3=t[2] * (long)g[3];
  long f2g4=t[2] * (long)g[4];
  long f2g5=t[2] * (long)g[5];
  long f2g6=t[2] * (long)g[6];
  long f2g7=t[2] * (long)g[7];
  long f2g8_19=t[2] * (long)g8_19;
  long f2g9_19=t[2] * (long)g9_19;
  long f3g0=t[3] * (long)g[0];
  long f3g1_2=f3_2 * (long)g[1];
  long f3g2=t[3] * (long)g[2];
  long f3g3_2=f3_2 * (long)g[3];
  long f3g4=t[3] * (long)g[4];
  long f3g5_2=f3_2 * (long)g[5];
  long f3g6=t[3] * (long)g[6];
  long f3g7_38=f3_2 * (long)g7_19;
  long f3g8_19=t[3] * (long)g8_19;
  long f3g9_38=f3_2 * (long)g9_19;
  long f4g0=t[4] * (long)g[0];
  long f4g1=t[4] * (long)g[1];
  long f4g2=t[4] * (long)g[2];
  long f4g3=t[4] * (long)g[3];
  long f4g4=t[4] * (long)g[4];
  long f4g5=t[4] * (long)g[5];
  long f4g6_19=t[4] * (long)g6_19;
  long f4g7_19=t[4] * (long)g7_19;
  long f4g8_19=t[4] * (long)g8_19;
  long f4g9_19=t[4] * (long)g9_19;
  long f5g0=t[5] * (long)g[0];
  long f5g1_2=f5_2 * (long)g[1];
  long f5g2=t[5] * (long)g[2];
  long f5g3_2=f5_2 * (long)g[3];
  long f5g4=t[5] * (long)g[4];
  long f5g5_38=f5_2 * (long)g5_19;
  long f5g6_19=t[5] * (long)g6_19;
  long f5g7_38=f5_2 * (long)g7_19;
  long f5g8_19=t[5] * (long)g8_19;
  long f5g9_38=f5_2 * (long)g9_19;
  long f6g0=t[6] * (long)g[0];
  long f6g1=t[6] * (long)g[1];
  long f6g2=t[6] * (long)g[2];
  long f6g3=t[6] * (long)g[3];
  long f6g4_19=t[6] * (long)g4_19;
  long f6g5_19=t[6] * (long)g5_19;
  long f6g6_19=t[6] * (long)g6_19;
  long f6g7_19=t[6] * (long)g7_19;
  long f6g8_19=t[6] * (long)g8_19;
  long f6g9_19=t[6] * (long)g9_19;
  long f7g0=t[7] * (long)g[0];
  long f7g1_2=f7_2 * (long)g[1];
  long f7g2=t[7] * (long)g[2];
  long f7g3_38=f7_2 * (long)g3_19;
  long f7g4_19=t[7] * (long)g4_19;
  long f7g5_38=f7_2 * (long)g5_19;
  long f7g6_19=t[7] * (long)g6_19;
  long f7g7_38=f7_2 * (long)g7_19;
  long f7g8_19=t[7] * (long)g8_19;
  long f7g9_38=f7_2 * (long)g9_19;
  long f8g0=t[8] * (long)g[0];
  long f8g1=t[8] * (long)g[1];
  long f8g2_19=t[8] * (long)g2_19;
  long f8g3_19=t[8] * (long)g3_19;
  long f8g4_19=t[8] * (long)g4_19;
  long f8g5_19=t[8] * (long)g5_19;
  long f8g6_19=t[8] * (long)g6_19;
  long f8g7_19=t[8] * (long)g7_19;
  long f8g8_19=t[8] * (long)g8_19;
  long f8g9_19=t[8] * (long)g9_19;
  long f9g0=t[9] * (long)g[0];
  long f9g1_38=f9_2 * (long)g1_19;
  long f9g2_19=t[9] * (long)g2_19;
  long f9g3_38=f9_2 * (long)g3_19;
  long f9g4_19=t[9] * (long)g4_19;
  long f9g5_38=f9_2 * (long)g5_19;
  long f9g6_19=t[9] * (long)g6_19;
  long f9g7_38=f9_2 * (long)g7_19;
  long f9g8_19=t[9] * (long)g8_19;
  long f9g9_38=f9_2 * (long)g9_19;
  long h0=f0g0 + f1g9_38 + f2g8_19+ f3g7_38+ f4g6_19+ f5g5_38+ f6g4_19+ f7g3_38+ f8g2_19+ f9g1_38;
  long h1=f0g1 + f1g0 + f2g9_19+ f3g8_19+ f4g7_19+ f5g6_19+ f6g5_19+ f7g4_19+ f8g3_19+ f9g2_19;
  long h2=f0g2 + f1g1_2 + f2g0+ f3g9_38+ f4g8_19+ f5g7_38+ f6g6_19+ f7g5_38+ f8g4_19+ f9g3_38;
  long h3=f0g3 + f1g2 + f2g1+ f3g0+ f4g9_19+ f5g8_19+ f6g7_19+ f7g6_19+ f8g5_19+ f9g4_19;
  long h4=f0g4 + f1g3_2 + f2g2+ f3g1_2+ f4g0+ f5g9_38+ f6g8_19+ f7g7_38+ f8g6_19+ f9g5_38;
  long h5=f0g5 + f1g4 + f2g3+ f3g2+ f4g1+ f5g0+ f6g9_19+ f7g8_19+ f8g7_19+ f9g6_19;
  long h6=f0g6 + f1g5_2 + f2g4+ f3g3_2+ f4g2+ f5g1_2+ f6g0+ f7g9_38+ f8g8_19+ f9g7_38;
  long h7=f0g7 + f1g6 + f2g5+ f3g4+ f4g3+ f5g2+ f6g1+ f7g0+ f8g9_19+ f9g8_19;
  long h8=f0g8 + f1g7_2 + f2g6+ f3g5_2+ f4g4+ f5g3_2+ f6g2+ f7g1_2+ f8g0+ f9g9_38;
  long h9=f0g9 + f1g8 + f2g7+ f3g6+ f4g5+ f5g4+ f6g3+ f7g2+ f8g1+ f9g0;
  long carry0;
  long carry1;
  long carry2;
  long carry3;
  long carry4;
  long carry5;
  long carry6;
  long carry7;
  long carry8;
  long carry9;
  carry0=(h0 + (long)(1 << 25)) >> 26;
  h1+=carry0;
  h0-=carry0 << 26;
  carry4=(h4 + (long)(1 << 25)) >> 26;
  h5+=carry4;
  h4-=carry4 << 26;
  carry1=(h1 + (long)(1 << 24)) >> 25;
  h2+=carry1;
  h1-=carry1 << 25;
  carry5=(h5 + (long)(1 << 24)) >> 25;
  h6+=carry5;
  h5-=carry5 << 25;
  carry2=(h2 + (long)(1 << 25)) >> 26;
  h3+=carry2;
  h2-=carry2 << 26;
  carry6=(h6 + (long)(1 << 25)) >> 26;
  h7+=carry6;
  h6-=carry6 << 26;
  carry3=(h3 + (long)(1 << 24)) >> 25;
  h4+=carry3;
  h3-=carry3 << 25;
  carry7=(h7 + (long)(1 << 24)) >> 25;
  h8+=carry7;
  h7-=carry7 << 25;
  carry4=(h4 + (long)(1 << 25)) >> 26;
  h5+=carry4;
  h4-=carry4 << 26;
  carry8=(h8 + (long)(1 << 25)) >> 26;
  h9+=carry8;
  h8-=carry8 << 26;
  carry9=(h9 + (long)(1 << 24)) >> 25;
  h0+=carry9 * 19;
  h9-=carry9 << 25;
  carry0=(h0 + (long)(1 << 25)) >> 26;
  h1+=carry0;
  h0-=carry0 << 26;
  int[] h=new int[10];
  h[0]=(int)h0;
  h[1]=(int)h1;
  h[2]=(int)h2;
  h[3]=(int)h3;
  h[4]=(int)h4;
  h[5]=(int)h5;
  h[6]=(int)h6;
  h[7]=(int)h7;
  h[8]=(int)h8;
  h[9]=(int)h9;
  return new Ed25519FieldElement(f,h);
}