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gh-133304: workaround for RISC-V in PyFloat_Pack4/Unpack4() (#133328)

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Sergey B Kirpichev 2025-05-03 18:07:52 +03:00 • committed by GitHub
parent 84a08f8629
commit f16f06f336
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3 changed files with 46 additions and 3 deletions
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41
Objects/floatobject.c
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@ -2196,12 +2196,33 @@ PyFloat_Pack4(double x, char *data, int le)
uint64_t v;
memcpy(&v, &x, 8);
#ifndef __riscv
if ((v & (1ULL << 51)) == 0) {
uint32_t u32;
memcpy(&u32, &y, 4);
u32 &= ~(1 << 22); /* make sNaN */
memcpy(&y, &u32, 4);
}
#else
uint32_t u32;
memcpy(&u32, &y, 4);
if ((v & (1ULL << 51)) == 0) {
u32 &= ~(1 << 22);
}
/* Workaround RISC-V: "If a NaN value is converted to a
* different floating-point type, the result is the
* canonical NaN of the new type". The canonical NaN here
* is a positive qNaN with zero payload. */
if (v & (1ULL << 63)) {
u32 |= (1 << 31); /* set sign */
}
/* add payload */
u32 -= (u32 & 0x3fffff);
u32 += (uint32_t)((v & 0x7ffffffffffffULL) >> 29);
memcpy(&y, &u32, 4);
#endif
}
unsigned char s[sizeof(float)];
@ -2493,6 +2514,7 @@ PyFloat_Unpack4(const char *data, int le)
uint32_t v;
memcpy(&v, &x, 4);
#ifndef __riscv
if ((v & (1 << 22)) == 0) {
double y = x; /* will make qNaN double */
uint64_t u64;
@ -2501,6 +2523,25 @@ PyFloat_Unpack4(const char *data, int le)
memcpy(&y, &u64, 8);
return y;
}
#else
double y = x;
uint64_t u64;
memcpy(&u64, &y, 8);
if ((v & (1 << 22)) == 0) {
u64 &= ~(1ULL << 51);
}
/* Workaround RISC-V, see PyFloat_Pack4() */
if (v & (1 << 31)) {
u64 |= (1ULL << 63); /* set sign */
}
/* add payload */
u64 -= (u64 & 0x7ffffffffffffULL);
u64 += ((v & 0x3fffffULL) << 29);
memcpy(&y, &u64, 8);
return y;
#endif
}
return x;