https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110748
--- Comment #11 from Vineet Gupta <vineetg at gcc dot gnu.org> ---
There's a variation which can be optimized as well and seems non trivial to
implement
Now it is the negative constant -0.0 to be stored to mem. In bit notation this
has a single sign bit set thus can be optimized using a bseti if rv64gc_zbs.
void znd(double *d) { *d = -0.0; }
void znf(float *f) { *f = -0.0; }
llvm optim these to
znd(double*):
bseti a1, zero, 63
sd a1, 0(a0)
ret
znf(float*):
lui a1, 0x80000
sw a1, 0(a0)
ret
While gcc resorts to constant pool for both
lui a5,%hi(.LANCHOR0)
fld fa5,%lo(.LANCHOR0)(a5)
fsd fa5,0(a0)
ret
.set .LANCHOR0,. + 0
.LC0:
.word 0
.word -2147483648
