newlib: Fix long double for unsupported rounding modes and exceptions
Commit Message
RISC-V newlib fails to build for soft float multilibs since long double
support was enabled in:
commit 04798b7bb69571452d2cfc7e0b052a9bbd3b619d
Author: Kito Cheng <kito.cheng@sifive.com>
Date: Mon Dec 4 15:41:39 2023 +0800
RISC-V: Support long double math
Long double for RISC-V is using 128 bit IEEE 754 format like Aarch64,
so we reference AArch64 to support that.
The RISC-V soft floating point environment only supports the
FE_TONEAREST rounding mode and does not support exceptions. Guard long
double rounding and exception support with ifdefs based on the presence
of the relevant rounding modes and exceptions.
Tested on gcc/g++ testsuite using RISC-V GNU Newlib Toolchain built by
riscv-gnu-toolchain with multilibs:
riscv-sim/-march=rv32i/-mabi=ilp32/-mcmodel=medlow
riscv-sim/-march=rv32iac/-mabi=ilp32/-mcmodel=medlow
riscv-sim/-march=rv32im/-mabi=ilp32/-mcmodel=medlow
riscv-sim/-march=rv32imac/-mabi=ilp32/-mcmodel=medlow
riscv-sim/-march=rv32imafc/-mabi=ilp32f/-mcmodel=medlow
riscv-sim/-march=rv64imac/-mabi=lp64/-mcmodel=medlow
Co-authored-by: Simon Cook <simon.cook@embecosm.com>
---
newlib/libm/ld/s_fmal.c | 14 ++++++++++++--
newlib/libm/ld/s_lrint.c | 2 ++
newlib/libm/ld/s_lround.c | 2 ++
3 files changed, 16 insertions(+), 2 deletions(-)
@@ -199,27 +199,37 @@ fmal(long double x, long double y, long double z)
* modes other than FE_TONEAREST are painful.
*/
if (spread < -LDBL_MANT_DIG) {
+#ifdef FE_INEXACT
feraiseexcept(FE_INEXACT);
+#endif
+#ifdef FE_UNDERFLOW
if (!isnormal(z))
feraiseexcept(FE_UNDERFLOW);
+#endif
switch (oround) {
- case FE_TONEAREST:
+ default: /* FE_TONEAREST */
return (z);
+#ifdef FE_TOWARDZERO
case FE_TOWARDZERO:
if (x > 0.0 ^ y < 0.0 ^ z < 0.0)
return (z);
else
return (nextafterl(z, 0));
+#endif
+#ifdef FE_DOWNWARD
case FE_DOWNWARD:
if (x > 0.0 ^ y < 0.0)
return (z);
else
return (nextafterl(z, -INFINITY));
- default: /* FE_UPWARD */
+#endif
+#ifdef FE_UPWARD
+ case FE_UPWARD:
if (x > 0.0 ^ y < 0.0)
return (nextafterl(z, INFINITY));
else
return (z);
+#endif
}
}
if (spread <= LDBL_MANT_DIG * 2)
@@ -53,8 +53,10 @@ fn(type x)
feholdexcept(&env);
d = (dtype)roundit(x);
+#if defined(FE_INVALID) && defined(FE_INEXACT)
if (fetestexcept(FE_INVALID))
feclearexcept(FE_INEXACT);
+#endif
feupdateenv(&env);
return (d);
}
@@ -64,7 +64,9 @@ fn(type x)
x = roundit(x);
return ((dtype)x);
} else {
+#ifdef FE_INVALID
feraiseexcept(FE_INVALID);
+#endif
return (DTYPE_MAX);
}
}