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8346914: UB issue in scalbnA #25917

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c841ba3
scalbnA => scalbn, remove copysignA
kimbarrett Jun 20, 2025
97e6889
remove unused twom54 constant
kimbarrett Jun 20, 2025
d611f32
update copyrights
kimbarrett Jun 20, 2025
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12 changes: 6 additions & 6 deletions src/hotspot/cpu/aarch64/macroAssembler_aarch64_trig.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -543,7 +543,7 @@ void MacroAssembler::generate__ieee754_rem_pio2(address npio2_hw,
// }
//
// /* compute n */
// z = scalbnA(z,q0); /* actual value of z */
// z = scalbn(z,q0); /* actual value of z */
// z -= 8.0*floor(z*0.125); /* trim off integer >= 8 */
// n = (int) z;
// z -= (double)n;
Expand Down Expand Up @@ -576,7 +576,7 @@ void MacroAssembler::generate__ieee754_rem_pio2(address npio2_hw,
// }
// if(ih==2) {
// z = one - z;
// if(carry!=0) z -= scalbnA(one,q0);
// if(carry!=0) z -= scalbn(one,q0);
// }
// }
//
Expand All @@ -602,7 +602,7 @@ void MacroAssembler::generate__ieee754_rem_pio2(address npio2_hw,
// jz -= 1; q0 -= 24;
// while(iq[jz]==0) { jz--; q0-=24;}
// } else { /* break z into 24-bit if necessary */
// z = scalbnA(z,-q0);
// z = scalbn(z,-q0);
// if(z>=two24B) {
// fw = (double)((int)(twon24*z));
// iq[jz] = (int)(z-two24B*fw);
Expand All @@ -612,7 +612,7 @@ void MacroAssembler::generate__ieee754_rem_pio2(address npio2_hw,
// }
//
// /* convert integer "bit" chunk to floating-point value */
// fw = scalbnA(one,q0);
// fw = scalbn(one,q0);
// for(i=jz;i>=0;i--) {
// q[i] = fw*(double)iq[i]; fw*=twon24;
// }
Expand Down Expand Up @@ -925,7 +925,7 @@ void MacroAssembler::generate__kernel_rem_pio2(address two_over_pi, address pio2
fmovd(v25, 1.0);
fsubd(v18, v25, v18); // z = one - z;
cbzw(rscratch2, IH_HANDLED);
fsubd(v18, v18, v30); // z -= scalbnA(one,q0);
fsubd(v18, v18, v30); // z -= scalbn(one,q0);
}
}
bind(IH_HANDLED);
Expand Down Expand Up @@ -1026,7 +1026,7 @@ void MacroAssembler::generate__kernel_rem_pio2(address two_over_pi, address pio2
bind(Z_ZERO_CHECK_DONE);
// convert integer "bit" chunk to floating-point value
// v17 = twon24
// update v30, which was scalbnA(1.0, <old q0>);
// update v30, which was scalbn(1.0, <old q0>);
addw(tmp2, rscratch1, 1023); // biased exponent
lsl(tmp2, tmp2, 52); // put at correct position
mov(i, jz);
Expand Down
57 changes: 1 addition & 56 deletions src/hotspot/share/runtime/sharedRuntimeMath.hpp
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@@ -1,5 +1,5 @@
/*
* Copyright (c) 2014, 2019, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2014, 2025, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
Expand Down Expand Up @@ -67,64 +67,9 @@ static inline void set_low(double* d, int low) {
*d = conv.d;
}

static double copysignA(double x, double y) {
DoubleIntConv convX;
convX.d = x;
convX.split.hi = (convX.split.hi & 0x7fffffff) | (high(y) & 0x80000000);
return convX.d;
}

/*
* ====================================================
* Copyright (c) 1998 Oracle and/or its affiliates. All rights reserved.
*
* Developed at SunSoft, a Sun Microsystems, Inc. business.
* Permission to use, copy, modify, and distribute this
* software is freely granted, provided that this notice
* is preserved.
* ====================================================
*/

/*
* scalbn (double x, int n)
* scalbn(x,n) returns x* 2**n computed by exponent
* manipulation rather than by actually performing an
* exponentiation or a multiplication.
*/

static const double
two54 = 1.80143985094819840000e+16, /* 0x43500000, 0x00000000 */
twom54 = 5.55111512312578270212e-17, /* 0x3C900000, 0x00000000 */
hugeX = 1.0e+300,
tiny = 1.0e-300;

static double scalbnA(double x, int n) {
int k,hx,lx;
hx = high(x);
lx = low(x);
k = (hx&0x7ff00000)>>20; /* extract exponent */
if (k==0) { /* 0 or subnormal x */
if ((lx|(hx&0x7fffffff))==0) return x; /* +-0 */
x *= two54;
hx = high(x);
k = ((hx&0x7ff00000)>>20) - 54;
if (n< -50000) return tiny*x; /*underflow*/
}
if (k==0x7ff) return x+x; /* NaN or Inf */
k = k+n;
if (k > 0x7fe) return hugeX*copysignA(hugeX,x); /* overflow */
if (k > 0) { /* normal result */
set_high(&x, (hx&0x800fffff)|(k<<20));
return x;
}
if (k <= -54) {
if (n > 50000) /* in case integer overflow in n+k */
return hugeX*copysignA(hugeX,x); /*overflow*/
else return tiny*copysignA(tiny,x); /*underflow*/
}
k += 54; /* subnormal result */
set_high(&x, (hx&0x800fffff)|(k<<20));
return x*twom54;
}

#endif // SHARE_RUNTIME_SHAREDRUNTIMEMATH_HPP
2 changes: 1 addition & 1 deletion src/hotspot/share/runtime/sharedRuntimeTrans.cpp
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Expand Up @@ -657,7 +657,7 @@ static double __ieee754_pow(double x, double y) {
z = one-(r-z);
j = high(z);
j += (n<<20);
if((j>>20)<=0) z = scalbnA(z,n); /* subnormal output */
if((j>>20)<=0) z = scalbn(z,n); /* subnormal output */
else set_high(&z, high(z) + (n<<20));
return s*z;
}
Expand Down
8 changes: 4 additions & 4 deletions src/hotspot/share/runtime/sharedRuntimeTrig.cpp
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Expand Up @@ -200,7 +200,7 @@ static int __kernel_rem_pio2(double *x, double *y, int e0, int nx, int prec, con
}

/* compute n */
z = scalbnA(z,q0); /* actual value of z */
z = scalbn(z,q0); /* actual value of z */
z -= 8.0*floor(z*0.125); /* trim off integer >= 8 */
n = (int) z;
z -= (double)n;
Expand Down Expand Up @@ -233,7 +233,7 @@ static int __kernel_rem_pio2(double *x, double *y, int e0, int nx, int prec, con
}
if(ih==2) {
z = one - z;
if(carry!=0) z -= scalbnA(one,q0);
if(carry!=0) z -= scalbn(one,q0);
}
}

Expand All @@ -259,7 +259,7 @@ static int __kernel_rem_pio2(double *x, double *y, int e0, int nx, int prec, con
jz -= 1; q0 -= 24;
while(iq[jz]==0) { jz--; q0-=24;}
} else { /* break z into 24-bit if necessary */
z = scalbnA(z,-q0);
z = scalbn(z,-q0);
if(z>=two24B) {
fw = (double)((int)(twon24*z));
iq[jz] = (int)(z-two24B*fw);
Expand All @@ -269,7 +269,7 @@ static int __kernel_rem_pio2(double *x, double *y, int e0, int nx, int prec, con
}

/* convert integer "bit" chunk to floating-point value */
fw = scalbnA(one,q0);
fw = scalbn(one,q0);
for(i=jz;i>=0;i--) {
q[i] = fw*(double)iq[i]; fw*=twon24;
}
Expand Down