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Commit | Line | Data |
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60c5eb7d XL |
1 | use super::operand::{OperandRef, OperandValue}; |
2 | use super::place::PlaceRef; | |
dfeec247 | 3 | use super::{FunctionCx, LocalRef}; |
60c5eb7d XL |
4 | |
5 | use crate::base; | |
dfeec247 | 6 | use crate::common::{self, IntPredicate, RealPredicate}; |
60c5eb7d | 7 | use crate::traits::*; |
dfeec247 | 8 | use crate::MemFlags; |
60c5eb7d | 9 | |
dfeec247 | 10 | use rustc_apfloat::{ieee, Float, Round, Status}; |
ba9703b0 XL |
11 | use rustc_hir::lang_items::ExchangeMallocFnLangItem; |
12 | use rustc_middle::mir; | |
13 | use rustc_middle::ty::cast::{CastTy, IntTy}; | |
14 | use rustc_middle::ty::layout::HasTyCtxt; | |
15 | use rustc_middle::ty::{self, adjustment::PointerCast, Instance, Ty, TyCtxt}; | |
dfeec247 XL |
16 | use rustc_span::source_map::{Span, DUMMY_SP}; |
17 | use rustc_span::symbol::sym; | |
ba9703b0 | 18 | use rustc_target::abi::{Abi, Int, LayoutOf, Variants}; |
92a42be0 | 19 | |
dc9dc135 | 20 | impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { |
a1dfa0c6 XL |
21 | pub fn codegen_rvalue( |
22 | &mut self, | |
23 | mut bx: Bx, | |
24 | dest: PlaceRef<'tcx, Bx::Value>, | |
dfeec247 | 25 | rvalue: &mir::Rvalue<'tcx>, |
a1dfa0c6 | 26 | ) -> Bx { |
dfeec247 | 27 | debug!("codegen_rvalue(dest.llval={:?}, rvalue={:?})", dest.llval, rvalue); |
92a42be0 SL |
28 | |
29 | match *rvalue { | |
dfeec247 XL |
30 | mir::Rvalue::Use(ref operand) => { |
31 | let cg_operand = self.codegen_operand(&mut bx, operand); | |
32 | // FIXME: consider not copying constants through stack. (Fixable by codegen'ing | |
33 | // constants into `OperandValue::Ref`; why don’t we do that yet if we don’t?) | |
34 | cg_operand.val.store(&mut bx, dest); | |
35 | bx | |
36 | } | |
92a42be0 | 37 | |
48663c56 | 38 | mir::Rvalue::Cast(mir::CastKind::Pointer(PointerCast::Unsize), ref source, _) => { |
ff7c6d11 XL |
39 | // The destination necessarily contains a fat pointer, so if |
40 | // it's a scalar pair, it's a fat pointer or newtype thereof. | |
a1dfa0c6 | 41 | if bx.cx().is_backend_scalar_pair(dest.layout) { |
60c5eb7d | 42 | // Into-coerce of a thin pointer to a fat pointer -- just |
92a42be0 | 43 | // use the operand path. |
a1dfa0c6 XL |
44 | let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue); |
45 | temp.val.store(&mut bx, dest); | |
2c00a5a8 | 46 | return bx; |
92a42be0 SL |
47 | } |
48 | ||
49 | // Unsize of a nontrivial struct. I would prefer for | |
94b46f34 | 50 | // this to be eliminated by MIR building, but |
92a42be0 SL |
51 | // `CoerceUnsized` can be passed by a where-clause, |
52 | // so the (generic) MIR may not be able to expand it. | |
a1dfa0c6 | 53 | let operand = self.codegen_operand(&mut bx, source); |
ff7c6d11 | 54 | match operand.val { |
dfeec247 | 55 | OperandValue::Pair(..) | OperandValue::Immediate(_) => { |
60c5eb7d | 56 | // Unsize from an immediate structure. We don't |
32a655c1 SL |
57 | // really need a temporary alloca here, but |
58 | // avoiding it would require us to have | |
60c5eb7d | 59 | // `coerce_unsized_into` use `extractvalue` to |
32a655c1 SL |
60 | // index into the struct, and this case isn't |
61 | // important enough for it. | |
94b46f34 | 62 | debug!("codegen_rvalue: creating ugly alloca"); |
e1599b0c | 63 | let scratch = PlaceRef::alloca(&mut bx, operand.layout); |
a1dfa0c6 XL |
64 | scratch.storage_live(&mut bx); |
65 | operand.val.store(&mut bx, scratch); | |
66 | base::coerce_unsized_into(&mut bx, scratch, dest); | |
67 | scratch.storage_dead(&mut bx); | |
32a655c1 | 68 | } |
b7449926 | 69 | OperandValue::Ref(llref, None, align) => { |
e1599b0c | 70 | let source = PlaceRef::new_sized_aligned(llref, operand.layout, align); |
a1dfa0c6 | 71 | base::coerce_unsized_into(&mut bx, source, dest); |
92a42be0 | 72 | } |
b7449926 | 73 | OperandValue::Ref(_, Some(_), _) => { |
60c5eb7d | 74 | bug!("unsized coercion on an unsized rvalue"); |
b7449926 | 75 | } |
ff7c6d11 | 76 | } |
2c00a5a8 | 77 | bx |
92a42be0 SL |
78 | } |
79 | ||
ea8adc8c | 80 | mir::Rvalue::Repeat(ref elem, count) => { |
a1dfa0c6 | 81 | let cg_elem = self.codegen_operand(&mut bx, elem); |
3b2f2976 | 82 | |
ff7c6d11 XL |
83 | // Do not generate the loop for zero-sized elements or empty arrays. |
84 | if dest.layout.is_zst() { | |
2c00a5a8 | 85 | return bx; |
3b2f2976 | 86 | } |
3b2f2976 | 87 | |
94b46f34 | 88 | if let OperandValue::Immediate(v) = cg_elem.val { |
532ac7d7 XL |
89 | let zero = bx.const_usize(0); |
90 | let start = dest.project_index(&mut bx, zero).llval; | |
91 | let size = bx.const_usize(dest.layout.size.bytes()); | |
ff7c6d11 | 92 | |
3b2f2976 | 93 | // Use llvm.memset.p0i8.* to initialize all zero arrays |
e74abb32 | 94 | if bx.cx().const_to_opt_uint(v) == Some(0) { |
a1dfa0c6 XL |
95 | let fill = bx.cx().const_u8(0); |
96 | bx.memset(start, fill, size, dest.align, MemFlags::empty()); | |
2c00a5a8 | 97 | return bx; |
3b2f2976 XL |
98 | } |
99 | ||
100 | // Use llvm.memset.p0i8.* to initialize byte arrays | |
a1dfa0c6 XL |
101 | let v = base::from_immediate(&mut bx, v); |
102 | if bx.cx().val_ty(v) == bx.cx().type_i8() { | |
103 | bx.memset(start, v, size, dest.align, MemFlags::empty()); | |
2c00a5a8 | 104 | return bx; |
3b2f2976 XL |
105 | } |
106 | } | |
107 | ||
ba9703b0 XL |
108 | let count = |
109 | self.monomorphize(&count).eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all()); | |
110 | ||
532ac7d7 | 111 | bx.write_operand_repeatedly(cg_elem, count, dest) |
92a42be0 SL |
112 | } |
113 | ||
9cc50fc6 | 114 | mir::Rvalue::Aggregate(ref kind, ref operands) => { |
ff7c6d11 | 115 | let (dest, active_field_index) = match **kind { |
b7449926 | 116 | mir::AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => { |
a1dfa0c6 | 117 | dest.codegen_set_discr(&mut bx, variant_index); |
ff7c6d11 | 118 | if adt_def.is_enum() { |
a1dfa0c6 | 119 | (dest.project_downcast(&mut bx, variant_index), active_field_index) |
ff7c6d11 XL |
120 | } else { |
121 | (dest, active_field_index) | |
9cc50fc6 SL |
122 | } |
123 | } | |
dfeec247 | 124 | _ => (dest, None), |
ff7c6d11 XL |
125 | }; |
126 | for (i, operand) in operands.iter().enumerate() { | |
a1dfa0c6 | 127 | let op = self.codegen_operand(&mut bx, operand); |
ff7c6d11 XL |
128 | // Do not generate stores and GEPis for zero-sized fields. |
129 | if !op.layout.is_zst() { | |
130 | let field_index = active_field_index.unwrap_or(i); | |
a1dfa0c6 XL |
131 | let field = dest.project_field(&mut bx, field_index); |
132 | op.val.store(&mut bx, field); | |
ff7c6d11 | 133 | } |
92a42be0 | 134 | } |
2c00a5a8 | 135 | bx |
92a42be0 SL |
136 | } |
137 | ||
92a42be0 | 138 | _ => { |
416331ca | 139 | assert!(self.rvalue_creates_operand(rvalue, DUMMY_SP)); |
a1dfa0c6 XL |
140 | let (mut bx, temp) = self.codegen_rvalue_operand(bx, rvalue); |
141 | temp.val.store(&mut bx, dest); | |
2c00a5a8 | 142 | bx |
92a42be0 SL |
143 | } |
144 | } | |
145 | } | |
146 | ||
a1dfa0c6 XL |
147 | pub fn codegen_rvalue_unsized( |
148 | &mut self, | |
149 | mut bx: Bx, | |
150 | indirect_dest: PlaceRef<'tcx, Bx::Value>, | |
151 | rvalue: &mir::Rvalue<'tcx>, | |
152 | ) -> Bx { | |
dfeec247 XL |
153 | debug!( |
154 | "codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})", | |
155 | indirect_dest.llval, rvalue | |
156 | ); | |
b7449926 XL |
157 | |
158 | match *rvalue { | |
159 | mir::Rvalue::Use(ref operand) => { | |
a1dfa0c6 XL |
160 | let cg_operand = self.codegen_operand(&mut bx, operand); |
161 | cg_operand.val.store_unsized(&mut bx, indirect_dest); | |
b7449926 XL |
162 | bx |
163 | } | |
164 | ||
60c5eb7d | 165 | _ => bug!("unsized assignment other than `Rvalue::Use`"), |
b7449926 XL |
166 | } |
167 | } | |
168 | ||
a1dfa0c6 XL |
169 | pub fn codegen_rvalue_operand( |
170 | &mut self, | |
171 | mut bx: Bx, | |
dfeec247 | 172 | rvalue: &mir::Rvalue<'tcx>, |
a1dfa0c6 | 173 | ) -> (Bx, OperandRef<'tcx, Bx::Value>) { |
416331ca XL |
174 | assert!( |
175 | self.rvalue_creates_operand(rvalue, DUMMY_SP), | |
176 | "cannot codegen {:?} to operand", | |
177 | rvalue, | |
178 | ); | |
92a42be0 SL |
179 | |
180 | match *rvalue { | |
ff7c6d11 | 181 | mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => { |
a1dfa0c6 | 182 | let operand = self.codegen_operand(&mut bx, source); |
54a0048b | 183 | debug!("cast operand is {:?}", operand); |
a1dfa0c6 | 184 | let cast = bx.cx().layout_of(self.monomorphize(&mir_cast_ty)); |
92a42be0 SL |
185 | |
186 | let val = match *kind { | |
48663c56 | 187 | mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => { |
e74abb32 | 188 | match operand.layout.ty.kind { |
b7449926 | 189 | ty::FnDef(def_id, substs) => { |
48663c56 XL |
190 | if bx.cx().tcx().has_attr(def_id, sym::rustc_args_required_const) { |
191 | bug!("reifying a fn ptr that requires const arguments"); | |
2c00a5a8 | 192 | } |
54a0048b | 193 | OperandValue::Immediate( |
e74abb32 XL |
194 | bx.get_fn_addr( |
195 | ty::Instance::resolve_for_fn_ptr( | |
196 | bx.tcx(), | |
197 | ty::ParamEnv::reveal_all(), | |
198 | def_id, | |
dfeec247 XL |
199 | substs, |
200 | ) | |
201 | .unwrap(), | |
202 | ), | |
e74abb32 | 203 | ) |
54a0048b | 204 | } |
dfeec247 | 205 | _ => bug!("{} cannot be reified to a fn ptr", operand.layout.ty), |
54a0048b SL |
206 | } |
207 | } | |
48663c56 | 208 | mir::CastKind::Pointer(PointerCast::ClosureFnPointer(_)) => { |
e74abb32 | 209 | match operand.layout.ty.kind { |
b7449926 | 210 | ty::Closure(def_id, substs) => { |
dc9dc135 | 211 | let instance = Instance::resolve_closure( |
e74abb32 XL |
212 | bx.cx().tcx(), |
213 | def_id, | |
214 | substs, | |
dfeec247 XL |
215 | ty::ClosureKind::FnOnce, |
216 | ); | |
e74abb32 | 217 | OperandValue::Immediate(bx.cx().get_fn_addr(instance)) |
8bb4bdeb | 218 | } |
dfeec247 | 219 | _ => bug!("{} cannot be cast to a fn ptr", operand.layout.ty), |
8bb4bdeb XL |
220 | } |
221 | } | |
48663c56 | 222 | mir::CastKind::Pointer(PointerCast::UnsafeFnPointer) => { |
60c5eb7d | 223 | // This is a no-op at the LLVM level. |
92a42be0 SL |
224 | operand.val |
225 | } | |
48663c56 | 226 | mir::CastKind::Pointer(PointerCast::Unsize) => { |
a1dfa0c6 | 227 | assert!(bx.cx().is_backend_scalar_pair(cast)); |
92a42be0 | 228 | match operand.val { |
3157f602 | 229 | OperandValue::Pair(lldata, llextra) => { |
60c5eb7d | 230 | // unsize from a fat pointer -- this is a |
92a42be0 | 231 | // "trait-object-to-supertrait" coercion, for |
60c5eb7d | 232 | // example, `&'a fmt::Debug + Send => &'a fmt::Debug`. |
ff7c6d11 XL |
233 | |
234 | // HACK(eddyb) have to bitcast pointers | |
235 | // until LLVM removes pointee types. | |
dfeec247 XL |
236 | let lldata = bx.pointercast( |
237 | lldata, | |
238 | bx.cx().scalar_pair_element_backend_type(cast, 0, true), | |
239 | ); | |
3157f602 | 240 | OperandValue::Pair(lldata, llextra) |
92a42be0 SL |
241 | } |
242 | OperandValue::Immediate(lldata) => { | |
243 | // "standard" unsize | |
dfeec247 XL |
244 | let (lldata, llextra) = base::unsize_thin_ptr( |
245 | &mut bx, | |
246 | lldata, | |
247 | operand.layout.ty, | |
248 | cast.ty, | |
249 | ); | |
3157f602 | 250 | OperandValue::Pair(lldata, llextra) |
92a42be0 | 251 | } |
32a655c1 | 252 | OperandValue::Ref(..) => { |
dfeec247 | 253 | bug!("by-ref operand {:?} in `codegen_rvalue_operand`", operand); |
92a42be0 SL |
254 | } |
255 | } | |
256 | } | |
dfeec247 XL |
257 | mir::CastKind::Pointer(PointerCast::MutToConstPointer) |
258 | | mir::CastKind::Misc | |
259 | if bx.cx().is_backend_scalar_pair(operand.layout) => | |
260 | { | |
ff7c6d11 | 261 | if let OperandValue::Pair(data_ptr, meta) = operand.val { |
a1dfa0c6 | 262 | if bx.cx().is_backend_scalar_pair(cast) { |
dfeec247 XL |
263 | let data_cast = bx.pointercast( |
264 | data_ptr, | |
265 | bx.cx().scalar_pair_element_backend_type(cast, 0, true), | |
266 | ); | |
ff7c6d11 | 267 | OperandValue::Pair(data_cast, meta) |
dfeec247 XL |
268 | } else { |
269 | // cast to thin-ptr | |
5bcae85e SL |
270 | // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and |
271 | // pointer-cast of that pointer to desired pointer type. | |
a1dfa0c6 | 272 | let llcast_ty = bx.cx().immediate_backend_type(cast); |
2c00a5a8 | 273 | let llval = bx.pointercast(data_ptr, llcast_ty); |
5bcae85e SL |
274 | OperandValue::Immediate(llval) |
275 | } | |
276 | } else { | |
60c5eb7d | 277 | bug!("unexpected non-pair operand"); |
5bcae85e SL |
278 | } |
279 | } | |
ba9703b0 XL |
280 | mir::CastKind::Pointer( |
281 | PointerCast::MutToConstPointer | PointerCast::ArrayToPointer, | |
282 | ) | |
dfeec247 | 283 | | mir::CastKind::Misc => { |
a1dfa0c6 XL |
284 | assert!(bx.cx().is_backend_immediate(cast)); |
285 | let ll_t_out = bx.cx().immediate_backend_type(cast); | |
0bf4aa26 | 286 | if operand.layout.abi.is_uninhabited() { |
a1dfa0c6 | 287 | let val = OperandValue::Immediate(bx.cx().const_undef(ll_t_out)); |
dfeec247 | 288 | return (bx, OperandRef { val, layout: cast }); |
83c7162d | 289 | } |
dfeec247 XL |
290 | let r_t_in = |
291 | CastTy::from_ty(operand.layout.ty).expect("bad input type for cast"); | |
ff7c6d11 | 292 | let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast"); |
a1dfa0c6 | 293 | let ll_t_in = bx.cx().immediate_backend_type(operand.layout); |
83c7162d | 294 | match operand.layout.variants { |
ba9703b0 | 295 | Variants::Single { index } => { |
48663c56 XL |
296 | if let Some(discr) = |
297 | operand.layout.ty.discriminant_for_variant(bx.tcx(), index) | |
298 | { | |
ba9703b0 XL |
299 | let discr_layout = bx.cx().layout_of(discr.ty); |
300 | let discr_t = bx.cx().immediate_backend_type(discr_layout); | |
301 | let discr_val = bx.cx().const_uint_big(discr_t, discr.val); | |
302 | let discr_val = | |
303 | bx.intcast(discr_val, ll_t_out, discr.ty.is_signed()); | |
304 | ||
dfeec247 XL |
305 | return ( |
306 | bx, | |
307 | OperandRef { | |
308 | val: OperandValue::Immediate(discr_val), | |
309 | layout: cast, | |
310 | }, | |
311 | ); | |
83c7162d XL |
312 | } |
313 | } | |
ba9703b0 | 314 | Variants::Multiple { .. } => {} |
83c7162d | 315 | } |
32a655c1 | 316 | let llval = operand.immediate(); |
c30ab7b3 | 317 | |
ff7c6d11 | 318 | let mut signed = false; |
ba9703b0 XL |
319 | if let Abi::Scalar(ref scalar) = operand.layout.abi { |
320 | if let Int(_, s) = scalar.value { | |
94b46f34 | 321 | // We use `i1` for bytes that are always `0` or `1`, |
0731742a | 322 | // e.g., `#[repr(i8)] enum E { A, B }`, but we can't |
94b46f34 | 323 | // let LLVM interpret the `i1` as signed, because |
0731742a | 324 | // then `i1 1` (i.e., E::B) is effectively `i8 -1`. |
94b46f34 | 325 | signed = !scalar.is_bool() && s; |
ff7c6d11 | 326 | |
a1dfa0c6 | 327 | let er = scalar.valid_range_exclusive(bx.cx()); |
dfeec247 XL |
328 | if er.end != er.start |
329 | && scalar.valid_range.end() > scalar.valid_range.start() | |
330 | { | |
ff7c6d11 XL |
331 | // We want `table[e as usize]` to not |
332 | // have bound checks, and this is the most | |
333 | // convenient place to put the `assume`. | |
a1dfa0c6 XL |
334 | let ll_t_in_const = |
335 | bx.cx().const_uint_big(ll_t_in, *scalar.valid_range.end()); | |
dfeec247 | 336 | let cmp = bx.icmp(IntPredicate::IntULE, llval, ll_t_in_const); |
a1dfa0c6 | 337 | bx.assume(cmp); |
ff7c6d11 XL |
338 | } |
339 | } | |
340 | } | |
9cc50fc6 SL |
341 | |
342 | let newval = match (r_t_in, r_t_out) { | |
dfeec247 | 343 | (CastTy::Int(_), CastTy::Int(_)) => bx.intcast(llval, ll_t_out, signed), |
9cc50fc6 | 344 | (CastTy::Float, CastTy::Float) => { |
a1dfa0c6 XL |
345 | let srcsz = bx.cx().float_width(ll_t_in); |
346 | let dstsz = bx.cx().float_width(ll_t_out); | |
9cc50fc6 | 347 | if dstsz > srcsz { |
2c00a5a8 | 348 | bx.fpext(llval, ll_t_out) |
9cc50fc6 | 349 | } else if srcsz > dstsz { |
2c00a5a8 | 350 | bx.fptrunc(llval, ll_t_out) |
9cc50fc6 SL |
351 | } else { |
352 | llval | |
353 | } | |
354 | } | |
dfeec247 XL |
355 | (CastTy::Int(_), CastTy::Float) => { |
356 | if signed { | |
357 | bx.sitofp(llval, ll_t_out) | |
358 | } else { | |
359 | bx.uitofp(llval, ll_t_out) | |
360 | } | |
361 | } | |
ba9703b0 | 362 | (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Ptr(_)) => { |
dfeec247 XL |
363 | bx.pointercast(llval, ll_t_out) |
364 | } | |
ba9703b0 | 365 | (CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Int(_)) => { |
dfeec247 XL |
366 | bx.ptrtoint(llval, ll_t_out) |
367 | } | |
2c00a5a8 | 368 | (CastTy::Int(_), CastTy::Ptr(_)) => { |
a1dfa0c6 | 369 | let usize_llval = bx.intcast(llval, bx.cx().type_isize(), signed); |
2c00a5a8 XL |
370 | bx.inttoptr(usize_llval, ll_t_out) |
371 | } | |
dfeec247 XL |
372 | (CastTy::Float, CastTy::Int(IntTy::I)) => { |
373 | cast_float_to_int(&mut bx, true, llval, ll_t_in, ll_t_out) | |
374 | } | |
375 | (CastTy::Float, CastTy::Int(_)) => { | |
376 | cast_float_to_int(&mut bx, false, llval, ll_t_in, ll_t_out) | |
377 | } | |
378 | _ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty), | |
9cc50fc6 SL |
379 | }; |
380 | OperandValue::Immediate(newval) | |
381 | } | |
92a42be0 | 382 | }; |
dfeec247 | 383 | (bx, OperandRef { val, layout: cast }) |
92a42be0 SL |
384 | } |
385 | ||
ba9703b0 | 386 | mir::Rvalue::Ref(_, bk, place) => { |
dfeec247 XL |
387 | let mk_ref = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| { |
388 | tcx.mk_ref( | |
389 | tcx.lifetimes.re_erased, | |
390 | ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() }, | |
391 | ) | |
392 | }; | |
393 | self.codegen_place_to_pointer(bx, place, mk_ref) | |
394 | } | |
92a42be0 | 395 | |
ba9703b0 | 396 | mir::Rvalue::AddressOf(mutability, place) => { |
dfeec247 | 397 | let mk_ptr = move |tcx: TyCtxt<'tcx>, ty: Ty<'tcx>| { |
74b04a01 | 398 | tcx.mk_ptr(ty::TypeAndMut { ty, mutbl: mutability }) |
7453a54e | 399 | }; |
dfeec247 | 400 | self.codegen_place_to_pointer(bx, place, mk_ptr) |
92a42be0 SL |
401 | } |
402 | ||
ba9703b0 | 403 | mir::Rvalue::Len(place) => { |
a1dfa0c6 | 404 | let size = self.evaluate_array_len(&mut bx, place); |
7453a54e | 405 | let operand = OperandRef { |
3b2f2976 | 406 | val: OperandValue::Immediate(size), |
a1dfa0c6 | 407 | layout: bx.cx().layout_of(bx.tcx().types.usize), |
7453a54e | 408 | }; |
2c00a5a8 | 409 | (bx, operand) |
92a42be0 SL |
410 | } |
411 | ||
412 | mir::Rvalue::BinaryOp(op, ref lhs, ref rhs) => { | |
a1dfa0c6 XL |
413 | let lhs = self.codegen_operand(&mut bx, lhs); |
414 | let rhs = self.codegen_operand(&mut bx, rhs); | |
ff7c6d11 | 415 | let llresult = match (lhs.val, rhs.val) { |
dfeec247 XL |
416 | ( |
417 | OperandValue::Pair(lhs_addr, lhs_extra), | |
418 | OperandValue::Pair(rhs_addr, rhs_extra), | |
419 | ) => self.codegen_fat_ptr_binop( | |
420 | &mut bx, | |
421 | op, | |
422 | lhs_addr, | |
423 | lhs_extra, | |
424 | rhs_addr, | |
425 | rhs_extra, | |
426 | lhs.layout.ty, | |
427 | ), | |
428 | ||
429 | (OperandValue::Immediate(lhs_val), OperandValue::Immediate(rhs_val)) => { | |
a1dfa0c6 | 430 | self.codegen_scalar_binop(&mut bx, op, lhs_val, rhs_val, lhs.layout.ty) |
ff7c6d11 XL |
431 | } |
432 | ||
dfeec247 | 433 | _ => bug!(), |
92a42be0 | 434 | }; |
7453a54e | 435 | let operand = OperandRef { |
92a42be0 | 436 | val: OperandValue::Immediate(llresult), |
dfeec247 | 437 | layout: bx.cx().layout_of(op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)), |
7453a54e | 438 | }; |
2c00a5a8 | 439 | (bx, operand) |
92a42be0 | 440 | } |
3157f602 | 441 | mir::Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => { |
a1dfa0c6 XL |
442 | let lhs = self.codegen_operand(&mut bx, lhs); |
443 | let rhs = self.codegen_operand(&mut bx, rhs); | |
dfeec247 XL |
444 | let result = self.codegen_scalar_checked_binop( |
445 | &mut bx, | |
446 | op, | |
447 | lhs.immediate(), | |
448 | rhs.immediate(), | |
449 | lhs.layout.ty, | |
450 | ); | |
2c00a5a8 | 451 | let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty); |
0531ce1d | 452 | let operand_ty = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]); |
dfeec247 | 453 | let operand = OperandRef { val: result, layout: bx.cx().layout_of(operand_ty) }; |
3157f602 | 454 | |
2c00a5a8 | 455 | (bx, operand) |
3157f602 | 456 | } |
92a42be0 SL |
457 | |
458 | mir::Rvalue::UnaryOp(op, ref operand) => { | |
a1dfa0c6 | 459 | let operand = self.codegen_operand(&mut bx, operand); |
92a42be0 | 460 | let lloperand = operand.immediate(); |
dc9dc135 | 461 | let is_float = operand.layout.ty.is_floating_point(); |
92a42be0 | 462 | let llval = match op { |
2c00a5a8 | 463 | mir::UnOp::Not => bx.not(lloperand), |
dfeec247 XL |
464 | mir::UnOp::Neg => { |
465 | if is_float { | |
466 | bx.fneg(lloperand) | |
467 | } else { | |
468 | bx.neg(lloperand) | |
469 | } | |
92a42be0 SL |
470 | } |
471 | }; | |
dfeec247 | 472 | (bx, OperandRef { val: OperandValue::Immediate(llval), layout: operand.layout }) |
92a42be0 SL |
473 | } |
474 | ||
ff7c6d11 | 475 | mir::Rvalue::Discriminant(ref place) => { |
60c5eb7d | 476 | let discr_ty = rvalue.ty(*self.mir, bx.tcx()); |
dfeec247 | 477 | let discr = self |
74b04a01 | 478 | .codegen_place(&mut bx, place.as_ref()) |
a1dfa0c6 | 479 | .codegen_get_discr(&mut bx, discr_ty); |
dfeec247 XL |
480 | ( |
481 | bx, | |
482 | OperandRef { | |
483 | val: OperandValue::Immediate(discr), | |
484 | layout: self.cx.layout_of(discr_ty), | |
485 | }, | |
486 | ) | |
8bb4bdeb XL |
487 | } |
488 | ||
7cac9316 | 489 | mir::Rvalue::NullaryOp(mir::NullOp::SizeOf, ty) => { |
a1dfa0c6 XL |
490 | assert!(bx.cx().type_is_sized(ty)); |
491 | let val = bx.cx().const_usize(bx.cx().layout_of(ty).size.bytes()); | |
492 | let tcx = self.cx.tcx(); | |
dfeec247 XL |
493 | ( |
494 | bx, | |
495 | OperandRef { | |
496 | val: OperandValue::Immediate(val), | |
497 | layout: self.cx.layout_of(tcx.types.usize), | |
498 | }, | |
499 | ) | |
7cac9316 XL |
500 | } |
501 | ||
502 | mir::Rvalue::NullaryOp(mir::NullOp::Box, content_ty) => { | |
a1dfa0c6 XL |
503 | let content_ty = self.monomorphize(&content_ty); |
504 | let content_layout = bx.cx().layout_of(content_ty); | |
505 | let llsize = bx.cx().const_usize(content_layout.size.bytes()); | |
506 | let llalign = bx.cx().const_usize(content_layout.align.abi.bytes()); | |
507 | let box_layout = bx.cx().layout_of(bx.tcx().mk_box(content_ty)); | |
508 | let llty_ptr = bx.cx().backend_type(box_layout); | |
32a655c1 SL |
509 | |
510 | // Allocate space: | |
2c00a5a8 | 511 | let def_id = match bx.tcx().lang_items().require(ExchangeMallocFnLangItem) { |
32a655c1 SL |
512 | Ok(id) => id, |
513 | Err(s) => { | |
a1dfa0c6 | 514 | bx.cx().sess().fatal(&format!("allocation of `{}` {}", box_layout.ty, s)); |
32a655c1 SL |
515 | } |
516 | }; | |
2c00a5a8 | 517 | let instance = ty::Instance::mono(bx.tcx(), def_id); |
e74abb32 | 518 | let r = bx.cx().get_fn_addr(instance); |
a1dfa0c6 XL |
519 | let call = bx.call(r, &[llsize, llalign], None); |
520 | let val = bx.pointercast(call, llty_ptr); | |
32a655c1 | 521 | |
dfeec247 | 522 | let operand = OperandRef { val: OperandValue::Immediate(val), layout: box_layout }; |
2c00a5a8 | 523 | (bx, operand) |
92a42be0 | 524 | } |
a7813a04 | 525 | mir::Rvalue::Use(ref operand) => { |
a1dfa0c6 | 526 | let operand = self.codegen_operand(&mut bx, operand); |
2c00a5a8 | 527 | (bx, operand) |
a7813a04 | 528 | } |
dfeec247 | 529 | mir::Rvalue::Repeat(..) | mir::Rvalue::Aggregate(..) => { |
cc61c64b XL |
530 | // According to `rvalue_creates_operand`, only ZST |
531 | // aggregate rvalues are allowed to be operands. | |
60c5eb7d | 532 | let ty = rvalue.ty(*self.mir, self.cx.tcx()); |
dfeec247 XL |
533 | let operand = |
534 | OperandRef::new_zst(&mut bx, self.cx.layout_of(self.monomorphize(&ty))); | |
532ac7d7 | 535 | (bx, operand) |
92a42be0 SL |
536 | } |
537 | } | |
538 | } | |
539 | ||
ba9703b0 | 540 | fn evaluate_array_len(&mut self, bx: &mut Bx, place: mir::Place<'tcx>) -> Bx::Value { |
3b2f2976 | 541 | // ZST are passed as operands and require special handling |
94b46f34 | 542 | // because codegen_place() panics if Local is operand. |
e74abb32 | 543 | if let Some(index) = place.as_local() { |
3b2f2976 | 544 | if let LocalRef::Operand(Some(op)) = self.locals[index] { |
e74abb32 | 545 | if let ty::Array(_, n) = op.layout.ty.kind { |
416331ca | 546 | let n = n.eval_usize(bx.cx().tcx(), ty::ParamEnv::reveal_all()); |
a1dfa0c6 | 547 | return bx.cx().const_usize(n); |
3b2f2976 XL |
548 | } |
549 | } | |
550 | } | |
551 | // use common size calculation for non zero-sized types | |
74b04a01 | 552 | let cg_value = self.codegen_place(bx, place.as_ref()); |
416331ca | 553 | cg_value.len(bx.cx()) |
3b2f2976 XL |
554 | } |
555 | ||
dfeec247 XL |
556 | /// Codegen an `Rvalue::AddressOf` or `Rvalue::Ref` |
557 | fn codegen_place_to_pointer( | |
558 | &mut self, | |
559 | mut bx: Bx, | |
ba9703b0 | 560 | place: mir::Place<'tcx>, |
dfeec247 XL |
561 | mk_ptr_ty: impl FnOnce(TyCtxt<'tcx>, Ty<'tcx>) -> Ty<'tcx>, |
562 | ) -> (Bx, OperandRef<'tcx, Bx::Value>) { | |
74b04a01 | 563 | let cg_place = self.codegen_place(&mut bx, place.as_ref()); |
dfeec247 XL |
564 | |
565 | let ty = cg_place.layout.ty; | |
566 | ||
567 | // Note: places are indirect, so storing the `llval` into the | |
568 | // destination effectively creates a reference. | |
569 | let val = if !bx.cx().type_has_metadata(ty) { | |
570 | OperandValue::Immediate(cg_place.llval) | |
571 | } else { | |
572 | OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap()) | |
573 | }; | |
574 | (bx, OperandRef { val, layout: self.cx.layout_of(mk_ptr_ty(self.cx.tcx(), ty)) }) | |
575 | } | |
576 | ||
b7449926 XL |
577 | pub fn codegen_scalar_binop( |
578 | &mut self, | |
a1dfa0c6 | 579 | bx: &mut Bx, |
b7449926 | 580 | op: mir::BinOp, |
a1dfa0c6 XL |
581 | lhs: Bx::Value, |
582 | rhs: Bx::Value, | |
b7449926 | 583 | input_ty: Ty<'tcx>, |
a1dfa0c6 | 584 | ) -> Bx::Value { |
dc9dc135 | 585 | let is_float = input_ty.is_floating_point(); |
92a42be0 SL |
586 | let is_signed = input_ty.is_signed(); |
587 | match op { | |
dfeec247 XL |
588 | mir::BinOp::Add => { |
589 | if is_float { | |
590 | bx.fadd(lhs, rhs) | |
591 | } else { | |
592 | bx.add(lhs, rhs) | |
593 | } | |
594 | } | |
595 | mir::BinOp::Sub => { | |
596 | if is_float { | |
597 | bx.fsub(lhs, rhs) | |
598 | } else { | |
599 | bx.sub(lhs, rhs) | |
600 | } | |
601 | } | |
602 | mir::BinOp::Mul => { | |
603 | if is_float { | |
604 | bx.fmul(lhs, rhs) | |
605 | } else { | |
606 | bx.mul(lhs, rhs) | |
607 | } | |
608 | } | |
609 | mir::BinOp::Div => { | |
610 | if is_float { | |
611 | bx.fdiv(lhs, rhs) | |
612 | } else if is_signed { | |
613 | bx.sdiv(lhs, rhs) | |
614 | } else { | |
615 | bx.udiv(lhs, rhs) | |
616 | } | |
617 | } | |
618 | mir::BinOp::Rem => { | |
619 | if is_float { | |
620 | bx.frem(lhs, rhs) | |
621 | } else if is_signed { | |
622 | bx.srem(lhs, rhs) | |
623 | } else { | |
624 | bx.urem(lhs, rhs) | |
625 | } | |
626 | } | |
2c00a5a8 XL |
627 | mir::BinOp::BitOr => bx.or(lhs, rhs), |
628 | mir::BinOp::BitAnd => bx.and(lhs, rhs), | |
629 | mir::BinOp::BitXor => bx.xor(lhs, rhs), | |
630 | mir::BinOp::Offset => bx.inbounds_gep(lhs, &[rhs]), | |
631 | mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs), | |
632 | mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs), | |
dfeec247 XL |
633 | mir::BinOp::Ne |
634 | | mir::BinOp::Lt | |
635 | | mir::BinOp::Gt | |
636 | | mir::BinOp::Eq | |
637 | | mir::BinOp::Le | |
638 | | mir::BinOp::Ge => { | |
639 | if is_float { | |
640 | bx.fcmp(base::bin_op_to_fcmp_predicate(op.to_hir_binop()), lhs, rhs) | |
641 | } else { | |
642 | bx.icmp(base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed), lhs, rhs) | |
643 | } | |
c30ab7b3 SL |
644 | } |
645 | } | |
646 | } | |
647 | ||
b7449926 XL |
648 | pub fn codegen_fat_ptr_binop( |
649 | &mut self, | |
a1dfa0c6 | 650 | bx: &mut Bx, |
b7449926 | 651 | op: mir::BinOp, |
a1dfa0c6 XL |
652 | lhs_addr: Bx::Value, |
653 | lhs_extra: Bx::Value, | |
654 | rhs_addr: Bx::Value, | |
655 | rhs_extra: Bx::Value, | |
b7449926 | 656 | _input_ty: Ty<'tcx>, |
a1dfa0c6 | 657 | ) -> Bx::Value { |
c30ab7b3 SL |
658 | match op { |
659 | mir::BinOp::Eq => { | |
a1dfa0c6 XL |
660 | let lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr); |
661 | let rhs = bx.icmp(IntPredicate::IntEQ, lhs_extra, rhs_extra); | |
662 | bx.and(lhs, rhs) | |
c30ab7b3 SL |
663 | } |
664 | mir::BinOp::Ne => { | |
a1dfa0c6 XL |
665 | let lhs = bx.icmp(IntPredicate::IntNE, lhs_addr, rhs_addr); |
666 | let rhs = bx.icmp(IntPredicate::IntNE, lhs_extra, rhs_extra); | |
667 | bx.or(lhs, rhs) | |
c30ab7b3 | 668 | } |
dfeec247 | 669 | mir::BinOp::Le | mir::BinOp::Lt | mir::BinOp::Ge | mir::BinOp::Gt => { |
c30ab7b3 SL |
670 | // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1) |
671 | let (op, strict_op) = match op { | |
a1dfa0c6 XL |
672 | mir::BinOp::Lt => (IntPredicate::IntULT, IntPredicate::IntULT), |
673 | mir::BinOp::Le => (IntPredicate::IntULE, IntPredicate::IntULT), | |
674 | mir::BinOp::Gt => (IntPredicate::IntUGT, IntPredicate::IntUGT), | |
675 | mir::BinOp::Ge => (IntPredicate::IntUGE, IntPredicate::IntUGT), | |
c30ab7b3 SL |
676 | _ => bug!(), |
677 | }; | |
a1dfa0c6 XL |
678 | let lhs = bx.icmp(strict_op, lhs_addr, rhs_addr); |
679 | let and_lhs = bx.icmp(IntPredicate::IntEQ, lhs_addr, rhs_addr); | |
680 | let and_rhs = bx.icmp(op, lhs_extra, rhs_extra); | |
681 | let rhs = bx.and(and_lhs, and_rhs); | |
682 | bx.or(lhs, rhs) | |
c30ab7b3 SL |
683 | } |
684 | _ => { | |
685 | bug!("unexpected fat ptr binop"); | |
92a42be0 SL |
686 | } |
687 | } | |
688 | } | |
3157f602 | 689 | |
a1dfa0c6 XL |
690 | pub fn codegen_scalar_checked_binop( |
691 | &mut self, | |
692 | bx: &mut Bx, | |
693 | op: mir::BinOp, | |
694 | lhs: Bx::Value, | |
695 | rhs: Bx::Value, | |
dfeec247 | 696 | input_ty: Ty<'tcx>, |
a1dfa0c6 | 697 | ) -> OperandValue<Bx::Value> { |
3157f602 XL |
698 | // This case can currently arise only from functions marked |
699 | // with #[rustc_inherit_overflow_checks] and inlined from | |
700 | // another crate (mostly core::num generic/#[inline] fns), | |
701 | // while the current crate doesn't use overflow checks. | |
a1dfa0c6 | 702 | if !bx.cx().check_overflow() { |
94b46f34 | 703 | let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty); |
a1dfa0c6 | 704 | return OperandValue::Pair(val, bx.cx().const_bool(false)); |
3157f602 XL |
705 | } |
706 | ||
3157f602 XL |
707 | let (val, of) = match op { |
708 | // These are checked using intrinsics | |
709 | mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => { | |
710 | let oop = match op { | |
711 | mir::BinOp::Add => OverflowOp::Add, | |
712 | mir::BinOp::Sub => OverflowOp::Sub, | |
713 | mir::BinOp::Mul => OverflowOp::Mul, | |
dfeec247 | 714 | _ => unreachable!(), |
3157f602 | 715 | }; |
a1dfa0c6 | 716 | bx.checked_binop(oop, input_ty, lhs, rhs) |
3157f602 XL |
717 | } |
718 | mir::BinOp::Shl | mir::BinOp::Shr => { | |
a1dfa0c6 XL |
719 | let lhs_llty = bx.cx().val_ty(lhs); |
720 | let rhs_llty = bx.cx().val_ty(rhs); | |
721 | let invert_mask = common::shift_mask_val(bx, lhs_llty, rhs_llty, true); | |
2c00a5a8 | 722 | let outer_bits = bx.and(rhs, invert_mask); |
3157f602 | 723 | |
a1dfa0c6 | 724 | let of = bx.icmp(IntPredicate::IntNE, outer_bits, bx.cx().const_null(rhs_llty)); |
94b46f34 | 725 | let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty); |
3157f602 XL |
726 | |
727 | (val, of) | |
728 | } | |
dfeec247 | 729 | _ => bug!("Operator `{:?}` is not a checkable operator", op), |
3157f602 XL |
730 | }; |
731 | ||
732 | OperandValue::Pair(val, of) | |
733 | } | |
a1dfa0c6 | 734 | } |
92a42be0 | 735 | |
dc9dc135 | 736 | impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { |
416331ca | 737 | pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>, span: Span) -> bool { |
cc61c64b XL |
738 | match *rvalue { |
739 | mir::Rvalue::Ref(..) | | |
dfeec247 | 740 | mir::Rvalue::AddressOf(..) | |
cc61c64b XL |
741 | mir::Rvalue::Len(..) | |
742 | mir::Rvalue::Cast(..) | // (*) | |
743 | mir::Rvalue::BinaryOp(..) | | |
744 | mir::Rvalue::CheckedBinaryOp(..) | | |
745 | mir::Rvalue::UnaryOp(..) | | |
746 | mir::Rvalue::Discriminant(..) | | |
7cac9316 | 747 | mir::Rvalue::NullaryOp(..) | |
cc61c64b XL |
748 | mir::Rvalue::Use(..) => // (*) |
749 | true, | |
750 | mir::Rvalue::Repeat(..) | | |
751 | mir::Rvalue::Aggregate(..) => { | |
60c5eb7d | 752 | let ty = rvalue.ty(*self.mir, self.cx.tcx()); |
cc61c64b | 753 | let ty = self.monomorphize(&ty); |
416331ca | 754 | self.cx.spanned_layout_of(ty, span).is_zst() |
cc61c64b XL |
755 | } |
756 | } | |
92a42be0 | 757 | |
cc61c64b XL |
758 | // (*) this is only true if the type is suitable |
759 | } | |
92a42be0 | 760 | } |
3157f602 | 761 | |
dc9dc135 | 762 | fn cast_float_to_int<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>( |
a1dfa0c6 XL |
763 | bx: &mut Bx, |
764 | signed: bool, | |
765 | x: Bx::Value, | |
766 | float_ty: Bx::Type, | |
dfeec247 | 767 | int_ty: Bx::Type, |
a1dfa0c6 | 768 | ) -> Bx::Value { |
dfeec247 | 769 | let fptosui_result = if signed { bx.fptosi(x, int_ty) } else { bx.fptoui(x, int_ty) }; |
abe05a73 | 770 | |
a1dfa0c6 | 771 | if !bx.cx().sess().opts.debugging_opts.saturating_float_casts { |
abe05a73 XL |
772 | return fptosui_result; |
773 | } | |
a1dfa0c6 XL |
774 | |
775 | let int_width = bx.cx().int_width(int_ty); | |
776 | let float_width = bx.cx().float_width(float_ty); | |
abe05a73 XL |
777 | // LLVM's fpto[su]i returns undef when the input x is infinite, NaN, or does not fit into the |
778 | // destination integer type after rounding towards zero. This `undef` value can cause UB in | |
779 | // safe code (see issue #10184), so we implement a saturating conversion on top of it: | |
780 | // Semantically, the mathematical value of the input is rounded towards zero to the next | |
781 | // mathematical integer, and then the result is clamped into the range of the destination | |
782 | // integer type. Positive and negative infinity are mapped to the maximum and minimum value of | |
783 | // the destination integer type. NaN is mapped to 0. | |
784 | // | |
785 | // Define f_min and f_max as the largest and smallest (finite) floats that are exactly equal to | |
786 | // a value representable in int_ty. | |
787 | // They are exactly equal to int_ty::{MIN,MAX} if float_ty has enough significand bits. | |
788 | // Otherwise, int_ty::MAX must be rounded towards zero, as it is one less than a power of two. | |
789 | // int_ty::MIN, however, is either zero or a negative power of two and is thus exactly | |
0531ce1d | 790 | // representable. Note that this only works if float_ty's exponent range is sufficiently large. |
abe05a73 XL |
791 | // f16 or 256 bit integers would break this property. Right now the smallest float type is f32 |
792 | // with exponents ranging up to 127, which is barely enough for i128::MIN = -2^127. | |
793 | // On the other hand, f_max works even if int_ty::MAX is greater than float_ty::MAX. Because | |
794 | // we're rounding towards zero, we just get float_ty::MAX (which is always an integer). | |
795 | // This already happens today with u128::MAX = 2^128 - 1 > f32::MAX. | |
a1dfa0c6 XL |
796 | let int_max = |signed: bool, int_width: u64| -> u128 { |
797 | let shift_amount = 128 - int_width; | |
dfeec247 | 798 | if signed { i128::MAX as u128 >> shift_amount } else { u128::MAX >> shift_amount } |
a1dfa0c6 XL |
799 | }; |
800 | let int_min = |signed: bool, int_width: u64| -> i128 { | |
dfeec247 | 801 | if signed { i128::MIN >> (128 - int_width) } else { 0 } |
a1dfa0c6 XL |
802 | }; |
803 | ||
dfeec247 | 804 | let compute_clamp_bounds_single = |signed: bool, int_width: u64| -> (u128, u128) { |
a1dfa0c6 XL |
805 | let rounded_min = ieee::Single::from_i128_r(int_min(signed, int_width), Round::TowardZero); |
806 | assert_eq!(rounded_min.status, Status::OK); | |
807 | let rounded_max = ieee::Single::from_u128_r(int_max(signed, int_width), Round::TowardZero); | |
808 | assert!(rounded_max.value.is_finite()); | |
809 | (rounded_min.value.to_bits(), rounded_max.value.to_bits()) | |
810 | }; | |
dfeec247 | 811 | let compute_clamp_bounds_double = |signed: bool, int_width: u64| -> (u128, u128) { |
a1dfa0c6 XL |
812 | let rounded_min = ieee::Double::from_i128_r(int_min(signed, int_width), Round::TowardZero); |
813 | assert_eq!(rounded_min.status, Status::OK); | |
814 | let rounded_max = ieee::Double::from_u128_r(int_max(signed, int_width), Round::TowardZero); | |
815 | assert!(rounded_max.value.is_finite()); | |
816 | (rounded_min.value.to_bits(), rounded_max.value.to_bits()) | |
817 | }; | |
818 | ||
819 | let mut float_bits_to_llval = |bits| { | |
dfeec247 | 820 | let bits_llval = match float_width { |
a1dfa0c6 XL |
821 | 32 => bx.cx().const_u32(bits as u32), |
822 | 64 => bx.cx().const_u64(bits as u64), | |
abe05a73 XL |
823 | n => bug!("unsupported float width {}", n), |
824 | }; | |
a1dfa0c6 | 825 | bx.bitcast(bits_llval, float_ty) |
abe05a73 | 826 | }; |
a1dfa0c6 XL |
827 | let (f_min, f_max) = match float_width { |
828 | 32 => compute_clamp_bounds_single(signed, int_width), | |
829 | 64 => compute_clamp_bounds_double(signed, int_width), | |
abe05a73 XL |
830 | n => bug!("unsupported float width {}", n), |
831 | }; | |
832 | let f_min = float_bits_to_llval(f_min); | |
833 | let f_max = float_bits_to_llval(f_max); | |
834 | // To implement saturation, we perform the following steps: | |
835 | // | |
836 | // 1. Cast x to an integer with fpto[su]i. This may result in undef. | |
837 | // 2. Compare x to f_min and f_max, and use the comparison results to select: | |
838 | // a) int_ty::MIN if x < f_min or x is NaN | |
839 | // b) int_ty::MAX if x > f_max | |
840 | // c) the result of fpto[su]i otherwise | |
841 | // 3. If x is NaN, return 0.0, otherwise return the result of step 2. | |
842 | // | |
843 | // This avoids resulting undef because values in range [f_min, f_max] by definition fit into the | |
844 | // destination type. It creates an undef temporary, but *producing* undef is not UB. Our use of | |
845 | // undef does not introduce any non-determinism either. | |
846 | // More importantly, the above procedure correctly implements saturating conversion. | |
847 | // Proof (sketch): | |
848 | // If x is NaN, 0 is returned by definition. | |
849 | // Otherwise, x is finite or infinite and thus can be compared with f_min and f_max. | |
850 | // This yields three cases to consider: | |
851 | // (1) if x in [f_min, f_max], the result of fpto[su]i is returned, which agrees with | |
852 | // saturating conversion for inputs in that range. | |
853 | // (2) if x > f_max, then x is larger than int_ty::MAX. This holds even if f_max is rounded | |
854 | // (i.e., if f_max < int_ty::MAX) because in those cases, nextUp(f_max) is already larger | |
855 | // than int_ty::MAX. Because x is larger than int_ty::MAX, the return value of int_ty::MAX | |
856 | // is correct. | |
857 | // (3) if x < f_min, then x is smaller than int_ty::MIN. As shown earlier, f_min exactly equals | |
858 | // int_ty::MIN and therefore the return value of int_ty::MIN is correct. | |
859 | // QED. | |
860 | ||
861 | // Step 1 was already performed above. | |
862 | ||
863 | // Step 2: We use two comparisons and two selects, with %s1 being the result: | |
864 | // %less_or_nan = fcmp ult %x, %f_min | |
865 | // %greater = fcmp olt %x, %f_max | |
866 | // %s0 = select %less_or_nan, int_ty::MIN, %fptosi_result | |
867 | // %s1 = select %greater, int_ty::MAX, %s0 | |
868 | // Note that %less_or_nan uses an *unordered* comparison. This comparison is true if the | |
869 | // operands are not comparable (i.e., if x is NaN). The unordered comparison ensures that s1 | |
870 | // becomes int_ty::MIN if x is NaN. | |
871 | // Performance note: Unordered comparison can be lowered to a "flipped" comparison and a | |
872 | // negation, and the negation can be merged into the select. Therefore, it not necessarily any | |
873 | // more expensive than a ordered ("normal") comparison. Whether these optimizations will be | |
874 | // performed is ultimately up to the backend, but at least x86 does perform them. | |
a1dfa0c6 XL |
875 | let less_or_nan = bx.fcmp(RealPredicate::RealULT, x, f_min); |
876 | let greater = bx.fcmp(RealPredicate::RealOGT, x, f_max); | |
877 | let int_max = bx.cx().const_uint_big(int_ty, int_max(signed, int_width)); | |
878 | let int_min = bx.cx().const_uint_big(int_ty, int_min(signed, int_width) as u128); | |
2c00a5a8 XL |
879 | let s0 = bx.select(less_or_nan, int_min, fptosui_result); |
880 | let s1 = bx.select(greater, int_max, s0); | |
abe05a73 XL |
881 | |
882 | // Step 3: NaN replacement. | |
883 | // For unsigned types, the above step already yielded int_ty::MIN == 0 if x is NaN. | |
884 | // Therefore we only need to execute this step for signed integer types. | |
885 | if signed { | |
886 | // LLVM has no isNaN predicate, so we use (x == x) instead | |
a1dfa0c6 XL |
887 | let zero = bx.cx().const_uint(int_ty, 0); |
888 | let cmp = bx.fcmp(RealPredicate::RealOEQ, x, x); | |
889 | bx.select(cmp, s1, zero) | |
abe05a73 XL |
890 | } else { |
891 | s1 | |
892 | } | |
893 | } |