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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)
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5 files changed

+146
-26
lines changed

5 files changed

+146
-26
lines changed

‎README.md

+6
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

+121-24
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 +141,30 @@ 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+
if e >= f16::EXPONENT_MAX as u16 - 1 {
162+
f16::INFINITY.to_bits()
163+
} else {
164+
repr::<f16>(e, m)
165+
}
166+
}
167+
125168
pub fn u64_to_f32_bits(i: u64) -> u32 {
126169
let n = i.leading_zeros();
127170
let i_m = i.wrapping_shl(n);
@@ -160,6 +203,30 @@ mod int_to_float {
160203
repr::<f128>(e, m)
161204
}
162205

206+
pub fn u128_to_f16_bits(i: u128) -> u16 {
207+
let n = i.leading_zeros();
208+
let i_m = i.wrapping_shl(n); // Mantissa, shifted so the first bit is nonzero
209+
let m_base: u16 = (i_m >> shift_f_lt_i::<u128, f16>()) as u16;
210+
211+
// Within the upper `F::BITS`, everything except for the signifcand
212+
// gets truncated
213+
let d1: u16 = (i_m >> (u128::BITS - f16::BITS - f16::SIGNIFICAND_BITS - 1)).cast();
214+
215+
// The entire rest of `i_m` gets truncated. Zero the upper `F::BITS` then just
216+
// check if it is nonzero.
217+
let d2: u16 = (i_m << f16::BITS >> f16::BITS != 0).into();
218+
let adj = d1 | d2;
219+
220+
// Mantissa with implicit bit set
221+
let m = m_adj::<f16>(m_base, adj);
222+
let e = if i == 0 { 0 } else { exp::<u128, f16>(n) - 1 };
223+
if e >= f16::EXPONENT_MAX as u16 - 1 {
224+
f16::INFINITY.to_bits()
225+
} else {
226+
repr::<f16>(e, m)
227+
}
228+
}
229+
163230
pub fn u128_to_f32_bits(i: u128) -> u32 {
164231
let n = i.leading_zeros();
165232
let i_m = i.wrapping_shl(n); // Mantissa, shifted so the first bit is nonzero
@@ -210,6 +277,11 @@ mod int_to_float {
210277

211278
// Conversions from unsigned integers to floats.
212279
intrinsics! {
280+
#[cfg(f16_enabled)]
281+
pub extern "C" fn __floatunsihf(i: u32) -> f16 {
282+
f16::from_bits(int_to_float::u32_to_f16_bits(i))
283+
}
284+
213285
#[arm_aeabi_alias = __aeabi_ui2f]
214286
pub extern "C" fn __floatunsisf(i: u32) -> f32 {
215287
f32::from_bits(int_to_float::u32_to_f32_bits(i))
@@ -220,6 +292,17 @@ intrinsics! {
220292
f64::from_bits(int_to_float::u32_to_f64_bits(i))
221293
}
222294

295+
#[ppc_alias = __floatunsikf]
296+
#[cfg(f128_enabled)]
297+
pub extern "C" fn __floatunsitf(i: u32) -> f128 {
298+
f128::from_bits(int_to_float::u32_to_f128_bits(i))
299+
}
300+
301+
#[cfg(f16_enabled)]
302+
pub extern "C" fn __floatundihf(i: u64) -> f16 {
303+
f16::from_bits(int_to_float::u64_to_f16_bits(i))
304+
}
305+
223306
#[arm_aeabi_alias = __aeabi_ul2f]
224307
pub extern "C" fn __floatundisf(i: u64) -> f32 {
225308
f32::from_bits(int_to_float::u64_to_f32_bits(i))
@@ -230,6 +313,17 @@ intrinsics! {
230313
f64::from_bits(int_to_float::u64_to_f64_bits(i))
231314
}
232315

316+
#[ppc_alias = __floatundikf]
317+
#[cfg(f128_enabled)]
318+
pub extern "C" fn __floatunditf(i: u64) -> f128 {
319+
f128::from_bits(int_to_float::u64_to_f128_bits(i))
320+
}
321+
322+
#[cfg(f16_enabled)]
323+
pub extern "C" fn __floatuntihf(i: u128) -> f16 {
324+
f16::from_bits(int_to_float::u128_to_f16_bits(i))
325+
}
326+
233327
#[cfg_attr(target_os = "uefi", unadjusted_on_win64)]
234328
pub extern "C" fn __floatuntisf(i: u128) -> f32 {
235329
f32::from_bits(int_to_float::u128_to_f32_bits(i))
@@ -240,18 +334,6 @@ intrinsics! {
240334
f64::from_bits(int_to_float::u128_to_f64_bits(i))
241335
}
242336

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-
255337
#[ppc_alias = __floatuntikf]
256338
#[cfg(f128_enabled)]
257339
pub extern "C" fn __floatuntitf(i: u128) -> f128 {
@@ -261,6 +343,11 @@ intrinsics! {
261343

262344
// Conversions from signed integers to floats.
263345
intrinsics! {
346+
#[cfg(f16_enabled)]
347+
pub extern "C" fn __floatsihf(i: i32) -> f16 {
348+
int_to_float::signed(i, int_to_float::u32_to_f16_bits)
349+
}
350+
264351
#[arm_aeabi_alias = __aeabi_i2f]
265352
pub extern "C" fn __floatsisf(i: i32) -> f32 {
266353
int_to_float::signed(i, int_to_float::u32_to_f32_bits)
@@ -271,6 +358,17 @@ intrinsics! {
271358
int_to_float::signed(i, int_to_float::u32_to_f64_bits)
272359
}
273360

361+
#[ppc_alias = __floatsikf]
362+
#[cfg(f128_enabled)]
363+
pub extern "C" fn __floatsitf(i: i32) -> f128 {
364+
int_to_float::signed(i, int_to_float::u32_to_f128_bits)
365+
}
366+
367+
#[cfg(f16_enabled)]
368+
pub extern "C" fn __floatdihf(i: i64) -> f16 {
369+
int_to_float::signed(i, int_to_float::u64_to_f16_bits)
370+
}
371+
274372
#[arm_aeabi_alias = __aeabi_l2f]
275373
pub extern "C" fn __floatdisf(i: i64) -> f32 {
276374
int_to_float::signed(i, int_to_float::u64_to_f32_bits)
@@ -281,6 +379,17 @@ intrinsics! {
281379
int_to_float::signed(i, int_to_float::u64_to_f64_bits)
282380
}
283381

382+
#[ppc_alias = __floatdikf]
383+
#[cfg(f128_enabled)]
384+
pub extern "C" fn __floatditf(i: i64) -> f128 {
385+
int_to_float::signed(i, int_to_float::u64_to_f128_bits)
386+
}
387+
388+
#[cfg(f16_enabled)]
389+
pub extern "C" fn __floattihf(i: i128) -> f16 {
390+
int_to_float::signed(i, int_to_float::u128_to_f16_bits)
391+
}
392+
284393
#[cfg_attr(target_os = "uefi", unadjusted_on_win64)]
285394
pub extern "C" fn __floattisf(i: i128) -> f32 {
286395
int_to_float::signed(i, int_to_float::u128_to_f32_bits)
@@ -291,18 +400,6 @@ intrinsics! {
291400
int_to_float::signed(i, int_to_float::u128_to_f64_bits)
292401
}
293402

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-
306403
#[ppc_alias = __floattikf]
307404
#[cfg(f128_enabled)]
308405
pub extern "C" fn __floattitf(i: i128) -> f128 {

‎testcrate/Cargo.toml

+2-1
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

+6
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

+11-1
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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