nir/lower_int64: Fix float16 to int64 conversions.

Currently float16 to int64 conversions don't work correctly, because
the "div" variable has an infinite value, since 2^32 isn't
representable as a 16-bit float, which causes the result of of rem(x,
div) to be NaN for all inputs, leading to an incorrect result.  Since
no values of magnitude greater than 2^32 are representable as a
float16 we don't actually need to do the fdiv/frem operations, the
conversion is equivalent to f2u32 with the result padded to 64 bits.

Rework:
 * Jordan: Handle f16 in if/else rather than conditional

Fixes: 936c58c8fc ("nir: Extend nir_lower_int64() to support i2f/f2i lowering")
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19391>
This commit is contained in:
Francisco Jerez
2022-10-28 16:27:17 -07:00
committed by Marge Bot
parent ec9b9ff971
commit e14f85366e

View File

@@ -813,10 +813,15 @@ lower_f2(nir_builder *b, nir_ssa_def *x, bool dst_is_signed)
if (dst_is_signed)
x = nir_fabs(b, x);
nir_ssa_def *div = nir_imm_floatN_t(b, 1ULL << 32, x->bit_size);
nir_ssa_def *res_hi = nir_f2u32(b, nir_fdiv(b, x, div));
nir_ssa_def *res_lo = nir_f2u32(b, nir_frem(b, x, div));
nir_ssa_def *res = nir_pack_64_2x32_split(b, res_lo, res_hi);
nir_ssa_def *res;
if (x->bit_size < 32) {
res = nir_pack_64_2x32_split(b, nir_f2u32(b, x), nir_imm_int(b, 0));
} else {
nir_ssa_def *div = nir_imm_floatN_t(b, 1ULL << 32, x->bit_size);
nir_ssa_def *res_hi = nir_f2u32(b, nir_fdiv(b, x, div));
nir_ssa_def *res_lo = nir_f2u32(b, nir_frem(b, x, div));
res = nir_pack_64_2x32_split(b, res_lo, res_hi);
}
if (dst_is_signed)
res = nir_bcsel(b, nir_flt(b, x_sign, nir_imm_floatN_t(b, 0, x->bit_size)),