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Add integer to f16 conversions
These are not present in LLVM's `compiler-rt` but LLVM does emit them in some cases [1]. [1]: rust-lang/rust#132614 (comment)
1 parent e344295 commit 7230b09

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5 files changed

+150
-26
lines changed

5 files changed

+150
-26
lines changed

‎README.md‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -233,11 +233,17 @@ of being added to Rust.
233233
- [x] fixunstfdi.c
234234
- [x] fixunstfsi.c
235235
- [x] fixunstfti.c
236+
- [x] floatdihf.c (not yet in `compiler-rt` but emitted by LLVM)
236237
- [x] floatditf.c
238+
- [x] floatsihf.c (not yet in `compiler-rt` but emitted by LLVM)
237239
- [x] floatsitf.c
240+
- [x] floattihf.c (not yet in `compiler-rt` but emitted by LLVM)
238241
- [x] floattitf.c
242+
- [x] floatundihf.c (not yet in `compiler-rt` but emitted by LLVM)
239243
- [x] floatunditf.c
244+
- [x] floatunsihf.c (not yet in `compiler-rt` but emitted by LLVM)
240245
- [x] floatunsitf.c
246+
- [x] floatuntihf.c (not yet in `compiler-rt` but emitted by LLVM)
241247
- [x] floatuntitf.c
242248
- [x] multf3.c
243249
- [x] powitf2.c

‎src/float/conv.rs‎

Lines changed: 125 additions & 24 deletions
Original file line numberDiff line numberDiff line change
@@ -79,6 +79,25 @@ mod int_to_float {
7979
F::from_bits(conv(i.unsigned_abs()) | sign_bit)
8080
}
8181

82+
pub fn u32_to_f16_bits(i: u32) -> u16 {
83+
let n = i.leading_zeros();
84+
let i_m = i.wrapping_shl(n);
85+
// Mantissa with implicit bit set
86+
let m_base: u16 = (i_m >> shift_f_lt_i::<u32, f16>()) as u16;
87+
// The entire lower half of `i` will be truncated (masked portion), plus the
88+
// next `EXPONENT_BITS` bits.
89+
let adj = (i_m >> f16::EXPONENT_BITS | i_m & 0xFF) as u16;
90+
let m = m_adj::<f16>(m_base, adj);
91+
let e = if i == 0 { 0 } else { exp::<u32, f16>(n) - 1 };
92+
// Any int can have an exponent out of range for `f16`, unlike other float types.
93+
// Clamp this.
94+
if e >= f16::EXPONENT_MAX as u16 - 1 {
95+
f16::INFINITY.to_bits()
96+
} else {
97+
repr::<f16>(e, m)
98+
}
99+
}
100+
82101
pub fn u32_to_f32_bits(i: u32) -> u32 {
83102
if i == 0 {
84103
return 0;
@@ -122,6 +141,32 @@ mod int_to_float {
122141
(h as u128) << 64
123142
}
124143

144+
pub fn u64_to_f16_bits(i: u64) -> u16 {
145+
let n = i.leading_zeros();
146+
let i_m = i.wrapping_shl(n); // Mantissa, shifted so the first bit is nonzero
147+
let m_base: u16 = (i_m >> shift_f_lt_i::<u64, f16>()) as u16;
148+
149+
// Within the upper `F::BITS`, everything except for the signifcand
150+
// gets truncated
151+
let d1: u16 = (i_m >> (u64::BITS - f16::BITS - f16::SIGNIFICAND_BITS - 1)).cast();
152+
153+
// The entire rest of `i_m` gets truncated. Zero the upper `F::BITS` then just
154+
// check if it is nonzero.
155+
let d2: u16 = (i_m << f16::BITS >> f16::BITS != 0).into();
156+
let adj = d1 | d2;
157+
158+
// Mantissa with implicit bit set
159+
let m = m_adj::<f16>(m_base, adj);
160+
let e = if i == 0 { 0 } else { exp::<u64, f16>(n) - 1 };
161+
162+
// Clamp to infinity if the exponent is out of range
163+
if e >= f16::EXPONENT_MAX as u16 - 1 {
164+
f16::INFINITY.to_bits()
165+
} else {
166+
repr::<f16>(e, m)
167+
}
168+
}
169+
125170
pub fn u64_to_f32_bits(i: u64) -> u32 {
126171
let n = i.leading_zeros();
127172
let i_m = i.wrapping_shl(n);
@@ -160,6 +205,32 @@ mod int_to_float {
160205
repr::<f128>(e, m)
161206
}
162207

208+
pub fn u128_to_f16_bits(i: u128) -> u16 {
209+
let n = i.leading_zeros();
210+
let i_m = i.wrapping_shl(n); // Mantissa, shifted so the first bit is nonzero
211+
let m_base: u16 = (i_m >> shift_f_lt_i::<u128, f16>()) as u16;
212+
213+
// Within the upper `F::BITS`, everything except for the signifcand
214+
// gets truncated
215+
let d1: u16 = (i_m >> (u128::BITS - f16::BITS - f16::SIGNIFICAND_BITS - 1)).cast();
216+
217+
// The entire rest of `i_m` gets truncated. Zero the upper `F::BITS` then just
218+
// check if it is nonzero.
219+
let d2: u16 = (i_m << f16::BITS >> f16::BITS != 0).into();
220+
let adj = d1 | d2;
221+
222+
// Mantissa with implicit bit set
223+
let m = m_adj::<f16>(m_base, adj);
224+
let e = if i == 0 { 0 } else { exp::<u128, f16>(n) - 1 };
225+
226+
// Clamp to infinity if the exponent is out of range
227+
if e >= f16::EXPONENT_MAX as u16 - 1 {
228+
f16::INFINITY.to_bits()
229+
} else {
230+
repr::<f16>(e, m)
231+
}
232+
}
233+
163234
pub fn u128_to_f32_bits(i: u128) -> u32 {
164235
let n = i.leading_zeros();
165236
let i_m = i.wrapping_shl(n); // Mantissa, shifted so the first bit is nonzero
@@ -210,6 +281,11 @@ mod int_to_float {
210281

211282
// Conversions from unsigned integers to floats.
212283
intrinsics! {
284+
#[cfg(f16_enabled)]
285+
pub extern "C" fn __floatunsihf(i: u32) -> f16 {
286+
f16::from_bits(int_to_float::u32_to_f16_bits(i))
287+
}
288+
213289
#[arm_aeabi_alias = __aeabi_ui2f]
214290
pub extern "C" fn __floatunsisf(i: u32) -> f32 {
215291
f32::from_bits(int_to_float::u32_to_f32_bits(i))
@@ -220,6 +296,17 @@ intrinsics! {
220296
f64::from_bits(int_to_float::u32_to_f64_bits(i))
221297
}
222298

299+
#[ppc_alias = __floatunsikf]
300+
#[cfg(f128_enabled)]
301+
pub extern "C" fn __floatunsitf(i: u32) -> f128 {
302+
f128::from_bits(int_to_float::u32_to_f128_bits(i))
303+
}
304+
305+
#[cfg(f16_enabled)]
306+
pub extern "C" fn __floatundihf(i: u64) -> f16 {
307+
f16::from_bits(int_to_float::u64_to_f16_bits(i))
308+
}
309+
223310
#[arm_aeabi_alias = __aeabi_ul2f]
224311
pub extern "C" fn __floatundisf(i: u64) -> f32 {
225312
f32::from_bits(int_to_float::u64_to_f32_bits(i))
@@ -230,6 +317,17 @@ intrinsics! {
230317
f64::from_bits(int_to_float::u64_to_f64_bits(i))
231318
}
232319

320+
#[ppc_alias = __floatundikf]
321+
#[cfg(f128_enabled)]
322+
pub extern "C" fn __floatunditf(i: u64) -> f128 {
323+
f128::from_bits(int_to_float::u64_to_f128_bits(i))
324+
}
325+
326+
#[cfg(f16_enabled)]
327+
pub extern "C" fn __floatuntihf(i: u128) -> f16 {
328+
f16::from_bits(int_to_float::u128_to_f16_bits(i))
329+
}
330+
233331
#[cfg_attr(target_os = "uefi", unadjusted_on_win64)]
234332
pub extern "C" fn __floatuntisf(i: u128) -> f32 {
235333
f32::from_bits(int_to_float::u128_to_f32_bits(i))
@@ -240,18 +338,6 @@ intrinsics! {
240338
f64::from_bits(int_to_float::u128_to_f64_bits(i))
241339
}
242340

243-
#[ppc_alias = __floatunsikf]
244-
#[cfg(f128_enabled)]
245-
pub extern "C" fn __floatunsitf(i: u32) -> f128 {
246-
f128::from_bits(int_to_float::u32_to_f128_bits(i))
247-
}
248-
249-
#[ppc_alias = __floatundikf]
250-
#[cfg(f128_enabled)]
251-
pub extern "C" fn __floatunditf(i: u64) -> f128 {
252-
f128::from_bits(int_to_float::u64_to_f128_bits(i))
253-
}
254-
255341
#[ppc_alias = __floatuntikf]
256342
#[cfg(f128_enabled)]
257343
pub extern "C" fn __floatuntitf(i: u128) -> f128 {
@@ -261,6 +347,11 @@ intrinsics! {
261347

262348
// Conversions from signed integers to floats.
263349
intrinsics! {
350+
#[cfg(f16_enabled)]
351+
pub extern "C" fn __floatsihf(i: i32) -> f16 {
352+
int_to_float::signed(i, int_to_float::u32_to_f16_bits)
353+
}
354+
264355
#[arm_aeabi_alias = __aeabi_i2f]
265356
pub extern "C" fn __floatsisf(i: i32) -> f32 {
266357
int_to_float::signed(i, int_to_float::u32_to_f32_bits)
@@ -271,6 +362,17 @@ intrinsics! {
271362
int_to_float::signed(i, int_to_float::u32_to_f64_bits)
272363
}
273364

365+
#[ppc_alias = __floatsikf]
366+
#[cfg(f128_enabled)]
367+
pub extern "C" fn __floatsitf(i: i32) -> f128 {
368+
int_to_float::signed(i, int_to_float::u32_to_f128_bits)
369+
}
370+
371+
#[cfg(f16_enabled)]
372+
pub extern "C" fn __floatdihf(i: i64) -> f16 {
373+
int_to_float::signed(i, int_to_float::u64_to_f16_bits)
374+
}
375+
274376
#[arm_aeabi_alias = __aeabi_l2f]
275377
pub extern "C" fn __floatdisf(i: i64) -> f32 {
276378
int_to_float::signed(i, int_to_float::u64_to_f32_bits)
@@ -281,6 +383,17 @@ intrinsics! {
281383
int_to_float::signed(i, int_to_float::u64_to_f64_bits)
282384
}
283385

386+
#[ppc_alias = __floatdikf]
387+
#[cfg(f128_enabled)]
388+
pub extern "C" fn __floatditf(i: i64) -> f128 {
389+
int_to_float::signed(i, int_to_float::u64_to_f128_bits)
390+
}
391+
392+
#[cfg(f16_enabled)]
393+
pub extern "C" fn __floattihf(i: i128) -> f16 {
394+
int_to_float::signed(i, int_to_float::u128_to_f16_bits)
395+
}
396+
284397
#[cfg_attr(target_os = "uefi", unadjusted_on_win64)]
285398
pub extern "C" fn __floattisf(i: i128) -> f32 {
286399
int_to_float::signed(i, int_to_float::u128_to_f32_bits)
@@ -291,18 +404,6 @@ intrinsics! {
291404
int_to_float::signed(i, int_to_float::u128_to_f64_bits)
292405
}
293406

294-
#[ppc_alias = __floatsikf]
295-
#[cfg(f128_enabled)]
296-
pub extern "C" fn __floatsitf(i: i32) -> f128 {
297-
int_to_float::signed(i, int_to_float::u32_to_f128_bits)
298-
}
299-
300-
#[ppc_alias = __floatdikf]
301-
#[cfg(f128_enabled)]
302-
pub extern "C" fn __floatditf(i: i64) -> f128 {
303-
int_to_float::signed(i, int_to_float::u64_to_f128_bits)
304-
}
305-
306407
#[ppc_alias = __floattikf]
307408
#[cfg(f128_enabled)]
308409
pub extern "C" fn __floattitf(i: i128) -> f128 {

‎testcrate/Cargo.toml‎

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -39,9 +39,10 @@ no-f16-f128 = ["compiler_builtins/no-f16-f128"]
3939
mem = ["compiler_builtins/mem"]
4040
mangled-names = ["compiler_builtins/mangled-names"]
4141
# Skip tests that rely on f128 symbols being available on the system
42-
no-sys-f128 = ["no-sys-f128-int-convert", "no-sys-f16-f128-convert"]
42+
no-sys-f128 = ["no-sys-f16-int-convert", "no-sys-f128-int-convert", "no-sys-f16-f128-convert"]
4343
# Some platforms have some f128 functions but everything except integer conversions
4444
no-sys-f128-int-convert = []
45+
no-sys-f16-int-convert = []
4546
no-sys-f16-f128-convert = []
4647
# Skip tests that rely on f16 symbols being available on the system
4748
no-sys-f16 = []

‎testcrate/build.rs‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -6,6 +6,7 @@ enum Feature {
66
NoSysF128,
77
NoSysF128IntConvert,
88
NoSysF16,
9+
NoSysF16IntConvert,
910
NoSysF16F128Convert,
1011
}
1112

@@ -40,6 +41,7 @@ fn main() {
4041
{
4142
features.insert(Feature::NoSysF128);
4243
features.insert(Feature::NoSysF128IntConvert);
44+
features.insert(Feature::NoSysF16IntConvert);
4345
features.insert(Feature::NoSysF16F128Convert);
4446
}
4547

@@ -76,6 +78,10 @@ fn main() {
7678
"no-sys-f128-int-convert",
7779
"using apfloat fallback for f128 <-> int conversions",
7880
),
81+
Feature::NoSysF16IntConvert => (
82+
"no-sys-f16-int-convert",
83+
"using apfloat fallback for f16 <-> int conversions",
84+
),
7985
Feature::NoSysF16F128Convert => (
8086
"no-sys-f16-f128-convert",
8187
"using apfloat fallback for f16 <-> f128 conversions",

‎testcrate/tests/conv.rs‎

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -34,7 +34,7 @@ mod i_to_f {
3434
FloatTy::from_u128(x.try_into().unwrap()).value
3535
};
3636

37-
<$f_ty>::from_bits(apf.to_bits())
37+
<$f_ty>::from_bits(apf.to_bits().try_into().unwrap())
3838
},
3939
x
4040
);
@@ -100,6 +100,16 @@ mod i_to_f {
100100
};
101101
}
102102

103+
#[cfg(f16_enabled)]
104+
i_to_f! { f16, Half, not(feature = "no-sys-f16-int-convert"),
105+
u32, __floatunsihf;
106+
i32, __floatsihf;
107+
u64, __floatundihf;
108+
i64, __floatdihf;
109+
u128, __floatuntihf;
110+
i128, __floattihf;
111+
}
112+
103113
i_to_f! { f32, Single, all(),
104114
u32, __floatunsisf;
105115
i32, __floatsisf;

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