1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
12 use rustc::ty::{self, Ty};
13 use rustc::ty::cast::{CastTy, IntTy};
14 use rustc::ty::layout::{self, LayoutOf};
16 use rustc::middle::lang_items::ExchangeMallocFnLangItem;
17 use rustc_apfloat::{ieee, Float, Status, Round};
18 use std::{u128, i128};
23 use common::{self, val_ty};
24 use common::{C_bool, C_u8, C_i32, C_u32, C_u64, C_undef, C_null, C_usize, C_uint, C_uint_big};
28 use type_of::LayoutLlvmExt;
31 use super::{FunctionCx, LocalRef};
32 use super::operand::{OperandRef, OperandValue};
33 use super::place::PlaceRef;
35 impl FunctionCx<'a, 'll, 'tcx> {
36 pub fn codegen_rvalue(&mut self,
37 bx: Builder<'a, 'll, 'tcx>,
38 dest: PlaceRef<'ll, 'tcx>,
39 rvalue: &mir::Rvalue<'tcx>)
40 -> Builder<'a, 'll, 'tcx>
42 debug!("codegen_rvalue(dest.llval={:?}, rvalue={:?})",
46 mir::Rvalue::Use(ref operand) => {
47 let cg_operand = self.codegen_operand(&bx, operand);
48 // FIXME: consider not copying constants through stack. (fixable by codegenning
49 // constants into OperandValue::Ref, why don’t we do that yet if we don’t?)
50 cg_operand.val.store(&bx, dest);
54 mir::Rvalue::Cast(mir::CastKind::Unsize, ref source, _) => {
55 // The destination necessarily contains a fat pointer, so if
56 // it's a scalar pair, it's a fat pointer or newtype thereof.
57 if dest.layout.is_llvm_scalar_pair() {
58 // into-coerce of a thin pointer to a fat pointer - just
59 // use the operand path.
60 let (bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
61 temp.val.store(&bx, dest);
65 // Unsize of a nontrivial struct. I would prefer for
66 // this to be eliminated by MIR building, but
67 // `CoerceUnsized` can be passed by a where-clause,
68 // so the (generic) MIR may not be able to expand it.
69 let operand = self.codegen_operand(&bx, source);
71 OperandValue::Pair(..) |
72 OperandValue::Immediate(_) => {
73 // unsize from an immediate structure. We don't
74 // really need a temporary alloca here, but
75 // avoiding it would require us to have
76 // `coerce_unsized_into` use extractvalue to
77 // index into the struct, and this case isn't
78 // important enough for it.
79 debug!("codegen_rvalue: creating ugly alloca");
80 let scratch = PlaceRef::alloca(&bx, operand.layout, "__unsize_temp");
81 scratch.storage_live(&bx);
82 operand.val.store(&bx, scratch);
83 base::coerce_unsized_into(&bx, scratch, dest);
84 scratch.storage_dead(&bx);
86 OperandValue::Ref(llref, None, align) => {
87 let source = PlaceRef::new_sized(llref, operand.layout, align);
88 base::coerce_unsized_into(&bx, source, dest);
90 OperandValue::Ref(_, Some(_), _) => {
91 bug!("unsized coercion on an unsized rvalue")
97 mir::Rvalue::Repeat(ref elem, count) => {
98 let cg_elem = self.codegen_operand(&bx, elem);
100 // Do not generate the loop for zero-sized elements or empty arrays.
101 if dest.layout.is_zst() {
105 let start = dest.project_index(&bx, C_usize(bx.cx, 0)).llval;
107 if let OperandValue::Immediate(v) = cg_elem.val {
108 let align = C_i32(bx.cx, dest.align.abi() as i32);
109 let size = C_usize(bx.cx, dest.layout.size.bytes());
111 // Use llvm.memset.p0i8.* to initialize all zero arrays
112 if common::is_const_integral(v) && common::const_to_uint(v) == 0 {
113 let fill = C_u8(bx.cx, 0);
114 base::call_memset(&bx, start, fill, size, align, false);
118 // Use llvm.memset.p0i8.* to initialize byte arrays
119 let v = base::from_immediate(&bx, v);
120 if common::val_ty(v) == Type::i8(bx.cx) {
121 base::call_memset(&bx, start, v, size, align, false);
126 let count = C_usize(bx.cx, count);
127 let end = dest.project_index(&bx, count).llval;
129 let header_bx = bx.build_sibling_block("repeat_loop_header");
130 let body_bx = bx.build_sibling_block("repeat_loop_body");
131 let next_bx = bx.build_sibling_block("repeat_loop_next");
133 bx.br(header_bx.llbb());
134 let current = header_bx.phi(common::val_ty(start), &[start], &[bx.llbb()]);
136 let keep_going = header_bx.icmp(llvm::IntNE, current, end);
137 header_bx.cond_br(keep_going, body_bx.llbb(), next_bx.llbb());
139 cg_elem.val.store(&body_bx,
140 PlaceRef::new_sized(current, cg_elem.layout, dest.align));
142 let next = body_bx.inbounds_gep(current, &[C_usize(bx.cx, 1)]);
143 body_bx.br(header_bx.llbb());
144 header_bx.add_incoming_to_phi(current, next, body_bx.llbb());
149 mir::Rvalue::Aggregate(ref kind, ref operands) => {
150 let (dest, active_field_index) = match **kind {
151 mir::AggregateKind::Adt(adt_def, variant_index, _, _, active_field_index) => {
152 dest.codegen_set_discr(&bx, variant_index);
153 if adt_def.is_enum() {
154 (dest.project_downcast(&bx, variant_index), active_field_index)
156 (dest, active_field_index)
161 for (i, operand) in operands.iter().enumerate() {
162 let op = self.codegen_operand(&bx, operand);
163 // Do not generate stores and GEPis for zero-sized fields.
164 if !op.layout.is_zst() {
165 let field_index = active_field_index.unwrap_or(i);
166 op.val.store(&bx, dest.project_field(&bx, field_index));
173 assert!(self.rvalue_creates_operand(rvalue));
174 let (bx, temp) = self.codegen_rvalue_operand(bx, rvalue);
175 temp.val.store(&bx, dest);
181 pub fn codegen_rvalue_unsized(&mut self,
182 bx: Builder<'a, 'll, 'tcx>,
183 indirect_dest: PlaceRef<'ll, 'tcx>,
184 rvalue: &mir::Rvalue<'tcx>)
185 -> Builder<'a, 'll, 'tcx>
187 debug!("codegen_rvalue_unsized(indirect_dest.llval={:?}, rvalue={:?})",
188 indirect_dest.llval, rvalue);
191 mir::Rvalue::Use(ref operand) => {
192 let cg_operand = self.codegen_operand(&bx, operand);
193 cg_operand.val.store_unsized(&bx, indirect_dest);
197 _ => bug!("unsized assignment other than Rvalue::Use"),
201 pub fn codegen_rvalue_operand(&mut self,
202 bx: Builder<'a, 'll, 'tcx>,
203 rvalue: &mir::Rvalue<'tcx>)
204 -> (Builder<'a, 'll, 'tcx>, OperandRef<'ll, 'tcx>)
206 assert!(self.rvalue_creates_operand(rvalue), "cannot codegen {:?} to operand", rvalue);
209 mir::Rvalue::Cast(ref kind, ref source, mir_cast_ty) => {
210 let operand = self.codegen_operand(&bx, source);
211 debug!("cast operand is {:?}", operand);
212 let cast = bx.cx.layout_of(self.monomorphize(&mir_cast_ty));
214 let val = match *kind {
215 mir::CastKind::ReifyFnPointer => {
216 match operand.layout.ty.sty {
217 ty::FnDef(def_id, substs) => {
218 if bx.cx.tcx.has_attr(def_id, "rustc_args_required_const") {
219 bug!("reifying a fn ptr that requires \
222 OperandValue::Immediate(
223 callee::resolve_and_get_fn(bx.cx, def_id, substs))
226 bug!("{} cannot be reified to a fn ptr", operand.layout.ty)
230 mir::CastKind::ClosureFnPointer => {
231 match operand.layout.ty.sty {
232 ty::Closure(def_id, substs) => {
233 let instance = monomorphize::resolve_closure(
234 bx.cx.tcx, def_id, substs, ty::ClosureKind::FnOnce);
235 OperandValue::Immediate(callee::get_fn(bx.cx, instance))
238 bug!("{} cannot be cast to a fn ptr", operand.layout.ty)
242 mir::CastKind::UnsafeFnPointer => {
243 // this is a no-op at the LLVM level
246 mir::CastKind::Unsize => {
247 assert!(cast.is_llvm_scalar_pair());
249 OperandValue::Pair(lldata, llextra) => {
250 // unsize from a fat pointer - this is a
251 // "trait-object-to-supertrait" coercion, for
253 // &'a fmt::Debug+Send => &'a fmt::Debug,
255 // HACK(eddyb) have to bitcast pointers
256 // until LLVM removes pointee types.
257 let lldata = bx.pointercast(lldata,
258 cast.scalar_pair_element_llvm_type(bx.cx, 0, true));
259 OperandValue::Pair(lldata, llextra)
261 OperandValue::Immediate(lldata) => {
263 let (lldata, llextra) = base::unsize_thin_ptr(&bx, lldata,
264 operand.layout.ty, cast.ty);
265 OperandValue::Pair(lldata, llextra)
267 OperandValue::Ref(..) => {
268 bug!("by-ref operand {:?} in codegen_rvalue_operand",
273 mir::CastKind::Misc if operand.layout.is_llvm_scalar_pair() => {
274 if let OperandValue::Pair(data_ptr, meta) = operand.val {
275 if cast.is_llvm_scalar_pair() {
276 let data_cast = bx.pointercast(data_ptr,
277 cast.scalar_pair_element_llvm_type(bx.cx, 0, true));
278 OperandValue::Pair(data_cast, meta)
279 } else { // cast to thin-ptr
280 // Cast of fat-ptr to thin-ptr is an extraction of data-ptr and
281 // pointer-cast of that pointer to desired pointer type.
282 let llcast_ty = cast.immediate_llvm_type(bx.cx);
283 let llval = bx.pointercast(data_ptr, llcast_ty);
284 OperandValue::Immediate(llval)
287 bug!("Unexpected non-Pair operand")
290 mir::CastKind::Misc => {
291 assert!(cast.is_llvm_immediate());
292 let ll_t_out = cast.immediate_llvm_type(bx.cx);
293 if operand.layout.abi.is_uninhabited() {
294 return (bx, OperandRef {
295 val: OperandValue::Immediate(C_undef(ll_t_out)),
299 let r_t_in = CastTy::from_ty(operand.layout.ty)
300 .expect("bad input type for cast");
301 let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast");
302 let ll_t_in = operand.layout.immediate_llvm_type(bx.cx);
303 match operand.layout.variants {
304 layout::Variants::Single { index } => {
305 if let Some(def) = operand.layout.ty.ty_adt_def() {
307 .discriminant_for_variant(bx.cx.tcx, index)
309 let discr = C_uint_big(ll_t_out, discr_val);
310 return (bx, OperandRef {
311 val: OperandValue::Immediate(discr),
316 layout::Variants::Tagged { .. } |
317 layout::Variants::NicheFilling { .. } => {},
319 let llval = operand.immediate();
321 let mut signed = false;
322 if let layout::Abi::Scalar(ref scalar) = operand.layout.abi {
323 if let layout::Int(_, s) = scalar.value {
324 // We use `i1` for bytes that are always `0` or `1`,
325 // e.g. `#[repr(i8)] enum E { A, B }`, but we can't
326 // let LLVM interpret the `i1` as signed, because
327 // then `i1 1` (i.e. E::B) is effectively `i8 -1`.
328 signed = !scalar.is_bool() && s;
330 let er = scalar.valid_range_exclusive(bx.cx);
331 if er.end != er.start &&
332 scalar.valid_range.end() > scalar.valid_range.start() {
333 // We want `table[e as usize]` to not
334 // have bound checks, and this is the most
335 // convenient place to put the `assume`.
337 base::call_assume(&bx, bx.icmp(
340 C_uint_big(ll_t_in, *scalar.valid_range.end())
346 let newval = match (r_t_in, r_t_out) {
347 (CastTy::Int(_), CastTy::Int(_)) => {
348 bx.intcast(llval, ll_t_out, signed)
350 (CastTy::Float, CastTy::Float) => {
351 let srcsz = ll_t_in.float_width();
352 let dstsz = ll_t_out.float_width();
354 bx.fpext(llval, ll_t_out)
355 } else if srcsz > dstsz {
356 bx.fptrunc(llval, ll_t_out)
361 (CastTy::Ptr(_), CastTy::Ptr(_)) |
362 (CastTy::FnPtr, CastTy::Ptr(_)) |
363 (CastTy::RPtr(_), CastTy::Ptr(_)) =>
364 bx.pointercast(llval, ll_t_out),
365 (CastTy::Ptr(_), CastTy::Int(_)) |
366 (CastTy::FnPtr, CastTy::Int(_)) =>
367 bx.ptrtoint(llval, ll_t_out),
368 (CastTy::Int(_), CastTy::Ptr(_)) => {
369 let usize_llval = bx.intcast(llval, bx.cx.isize_ty, signed);
370 bx.inttoptr(usize_llval, ll_t_out)
372 (CastTy::Int(_), CastTy::Float) =>
373 cast_int_to_float(&bx, signed, llval, ll_t_in, ll_t_out),
374 (CastTy::Float, CastTy::Int(IntTy::I)) =>
375 cast_float_to_int(&bx, true, llval, ll_t_in, ll_t_out),
376 (CastTy::Float, CastTy::Int(_)) =>
377 cast_float_to_int(&bx, false, llval, ll_t_in, ll_t_out),
378 _ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty)
380 OperandValue::Immediate(newval)
389 mir::Rvalue::Ref(_, bk, ref place) => {
390 let cg_place = self.codegen_place(&bx, place);
392 let ty = cg_place.layout.ty;
394 // Note: places are indirect, so storing the `llval` into the
395 // destination effectively creates a reference.
396 let val = if !bx.cx.type_has_metadata(ty) {
397 OperandValue::Immediate(cg_place.llval)
399 OperandValue::Pair(cg_place.llval, cg_place.llextra.unwrap())
403 layout: self.cx.layout_of(self.cx.tcx.mk_ref(
404 self.cx.tcx.types.re_erased,
405 ty::TypeAndMut { ty, mutbl: bk.to_mutbl_lossy() }
410 mir::Rvalue::Len(ref place) => {
411 let size = self.evaluate_array_len(&bx, place);
412 let operand = OperandRef {
413 val: OperandValue::Immediate(size),
414 layout: bx.cx.layout_of(bx.tcx().types.usize),
419 mir::Rvalue::BinaryOp(op, ref lhs, ref rhs) => {
420 let lhs = self.codegen_operand(&bx, lhs);
421 let rhs = self.codegen_operand(&bx, rhs);
422 let llresult = match (lhs.val, rhs.val) {
423 (OperandValue::Pair(lhs_addr, lhs_extra),
424 OperandValue::Pair(rhs_addr, rhs_extra)) => {
425 self.codegen_fat_ptr_binop(&bx, op,
431 (OperandValue::Immediate(lhs_val),
432 OperandValue::Immediate(rhs_val)) => {
433 self.codegen_scalar_binop(&bx, op, lhs_val, rhs_val, lhs.layout.ty)
438 let operand = OperandRef {
439 val: OperandValue::Immediate(llresult),
440 layout: bx.cx.layout_of(
441 op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty)),
445 mir::Rvalue::CheckedBinaryOp(op, ref lhs, ref rhs) => {
446 let lhs = self.codegen_operand(&bx, lhs);
447 let rhs = self.codegen_operand(&bx, rhs);
448 let result = self.codegen_scalar_checked_binop(&bx, op,
449 lhs.immediate(), rhs.immediate(),
451 let val_ty = op.ty(bx.tcx(), lhs.layout.ty, rhs.layout.ty);
452 let operand_ty = bx.tcx().intern_tup(&[val_ty, bx.tcx().types.bool]);
453 let operand = OperandRef {
455 layout: bx.cx.layout_of(operand_ty)
461 mir::Rvalue::UnaryOp(op, ref operand) => {
462 let operand = self.codegen_operand(&bx, operand);
463 let lloperand = operand.immediate();
464 let is_float = operand.layout.ty.is_fp();
465 let llval = match op {
466 mir::UnOp::Not => bx.not(lloperand),
467 mir::UnOp::Neg => if is_float {
474 val: OperandValue::Immediate(llval),
475 layout: operand.layout,
479 mir::Rvalue::Discriminant(ref place) => {
480 let discr_ty = rvalue.ty(&*self.mir, bx.tcx());
481 let discr = self.codegen_place(&bx, place)
482 .codegen_get_discr(&bx, discr_ty);
484 val: OperandValue::Immediate(discr),
485 layout: self.cx.layout_of(discr_ty)
489 mir::Rvalue::NullaryOp(mir::NullOp::SizeOf, ty) => {
490 assert!(bx.cx.type_is_sized(ty));
491 let val = C_usize(bx.cx, bx.cx.size_of(ty).bytes());
494 val: OperandValue::Immediate(val),
495 layout: self.cx.layout_of(tcx.types.usize),
499 mir::Rvalue::NullaryOp(mir::NullOp::Box, content_ty) => {
500 let content_ty: Ty<'tcx> = self.monomorphize(&content_ty);
501 let (size, align) = bx.cx.size_and_align_of(content_ty);
502 let llsize = C_usize(bx.cx, size.bytes());
503 let llalign = C_usize(bx.cx, align.abi());
504 let box_layout = bx.cx.layout_of(bx.tcx().mk_box(content_ty));
505 let llty_ptr = box_layout.llvm_type(bx.cx);
508 let def_id = match bx.tcx().lang_items().require(ExchangeMallocFnLangItem) {
511 bx.sess().fatal(&format!("allocation of `{}` {}", box_layout.ty, s));
514 let instance = ty::Instance::mono(bx.tcx(), def_id);
515 let r = callee::get_fn(bx.cx, instance);
516 let val = bx.pointercast(bx.call(r, &[llsize, llalign], None), llty_ptr);
518 let operand = OperandRef {
519 val: OperandValue::Immediate(val),
524 mir::Rvalue::Use(ref operand) => {
525 let operand = self.codegen_operand(&bx, operand);
528 mir::Rvalue::Repeat(..) |
529 mir::Rvalue::Aggregate(..) => {
530 // According to `rvalue_creates_operand`, only ZST
531 // aggregate rvalues are allowed to be operands.
532 let ty = rvalue.ty(self.mir, self.cx.tcx);
533 (bx, OperandRef::new_zst(self.cx,
534 self.cx.layout_of(self.monomorphize(&ty))))
539 fn evaluate_array_len(
541 bx: &Builder<'a, 'll, 'tcx>,
542 place: &mir::Place<'tcx>,
544 // ZST are passed as operands and require special handling
545 // because codegen_place() panics if Local is operand.
546 if let mir::Place::Local(index) = *place {
547 if let LocalRef::Operand(Some(op)) = self.locals[index] {
548 if let ty::Array(_, n) = op.layout.ty.sty {
549 let n = n.unwrap_usize(bx.cx.tcx);
550 return common::C_usize(bx.cx, n);
554 // use common size calculation for non zero-sized types
555 let cg_value = self.codegen_place(&bx, place);
556 return cg_value.len(bx.cx);
559 pub fn codegen_scalar_binop(
561 bx: &Builder<'a, 'll, 'tcx>,
567 let is_float = input_ty.is_fp();
568 let is_signed = input_ty.is_signed();
569 let is_unit = input_ty.is_unit();
571 mir::BinOp::Add => if is_float {
576 mir::BinOp::Sub => if is_float {
581 mir::BinOp::Mul => if is_float {
586 mir::BinOp::Div => if is_float {
588 } else if is_signed {
593 mir::BinOp::Rem => if is_float {
595 } else if is_signed {
600 mir::BinOp::BitOr => bx.or(lhs, rhs),
601 mir::BinOp::BitAnd => bx.and(lhs, rhs),
602 mir::BinOp::BitXor => bx.xor(lhs, rhs),
603 mir::BinOp::Offset => bx.inbounds_gep(lhs, &[rhs]),
604 mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
605 mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
606 mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt |
607 mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => if is_unit {
608 C_bool(bx.cx, match op {
609 mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt => false,
610 mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => true,
615 base::bin_op_to_fcmp_predicate(op.to_hir_binop()),
620 base::bin_op_to_icmp_predicate(op.to_hir_binop(), is_signed),
627 pub fn codegen_fat_ptr_binop(
629 bx: &Builder<'a, 'll, 'tcx>,
631 lhs_addr: &'ll Value,
632 lhs_extra: &'ll Value,
633 rhs_addr: &'ll Value,
634 rhs_extra: &'ll Value,
640 bx.icmp(llvm::IntEQ, lhs_addr, rhs_addr),
641 bx.icmp(llvm::IntEQ, lhs_extra, rhs_extra)
646 bx.icmp(llvm::IntNE, lhs_addr, rhs_addr),
647 bx.icmp(llvm::IntNE, lhs_extra, rhs_extra)
650 mir::BinOp::Le | mir::BinOp::Lt |
651 mir::BinOp::Ge | mir::BinOp::Gt => {
652 // a OP b ~ a.0 STRICT(OP) b.0 | (a.0 == b.0 && a.1 OP a.1)
653 let (op, strict_op) = match op {
654 mir::BinOp::Lt => (llvm::IntULT, llvm::IntULT),
655 mir::BinOp::Le => (llvm::IntULE, llvm::IntULT),
656 mir::BinOp::Gt => (llvm::IntUGT, llvm::IntUGT),
657 mir::BinOp::Ge => (llvm::IntUGE, llvm::IntUGT),
662 bx.icmp(strict_op, lhs_addr, rhs_addr),
664 bx.icmp(llvm::IntEQ, lhs_addr, rhs_addr),
665 bx.icmp(op, lhs_extra, rhs_extra)
670 bug!("unexpected fat ptr binop");
675 pub fn codegen_scalar_checked_binop(&mut self,
676 bx: &Builder<'a, 'll, 'tcx>,
680 input_ty: Ty<'tcx>) -> OperandValue<'ll> {
681 // This case can currently arise only from functions marked
682 // with #[rustc_inherit_overflow_checks] and inlined from
683 // another crate (mostly core::num generic/#[inline] fns),
684 // while the current crate doesn't use overflow checks.
685 if !bx.cx.check_overflow {
686 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
687 return OperandValue::Pair(val, C_bool(bx.cx, false));
690 let (val, of) = match op {
691 // These are checked using intrinsics
692 mir::BinOp::Add | mir::BinOp::Sub | mir::BinOp::Mul => {
694 mir::BinOp::Add => OverflowOp::Add,
695 mir::BinOp::Sub => OverflowOp::Sub,
696 mir::BinOp::Mul => OverflowOp::Mul,
699 let intrinsic = get_overflow_intrinsic(oop, bx, input_ty);
700 let res = bx.call(intrinsic, &[lhs, rhs], None);
702 (bx.extract_value(res, 0),
703 bx.extract_value(res, 1))
705 mir::BinOp::Shl | mir::BinOp::Shr => {
706 let lhs_llty = val_ty(lhs);
707 let rhs_llty = val_ty(rhs);
708 let invert_mask = common::shift_mask_val(&bx, lhs_llty, rhs_llty, true);
709 let outer_bits = bx.and(rhs, invert_mask);
711 let of = bx.icmp(llvm::IntNE, outer_bits, C_null(rhs_llty));
712 let val = self.codegen_scalar_binop(bx, op, lhs, rhs, input_ty);
717 bug!("Operator `{:?}` is not a checkable operator", op)
721 OperandValue::Pair(val, of)
724 pub fn rvalue_creates_operand(&self, rvalue: &mir::Rvalue<'tcx>) -> bool {
726 mir::Rvalue::Ref(..) |
727 mir::Rvalue::Len(..) |
728 mir::Rvalue::Cast(..) | // (*)
729 mir::Rvalue::BinaryOp(..) |
730 mir::Rvalue::CheckedBinaryOp(..) |
731 mir::Rvalue::UnaryOp(..) |
732 mir::Rvalue::Discriminant(..) |
733 mir::Rvalue::NullaryOp(..) |
734 mir::Rvalue::Use(..) => // (*)
736 mir::Rvalue::Repeat(..) |
737 mir::Rvalue::Aggregate(..) => {
738 let ty = rvalue.ty(self.mir, self.cx.tcx);
739 let ty = self.monomorphize(&ty);
740 self.cx.layout_of(ty).is_zst()
744 // (*) this is only true if the type is suitable
748 #[derive(Copy, Clone)]
753 fn get_overflow_intrinsic(oop: OverflowOp, bx: &Builder<'_, 'll, '_>, ty: Ty) -> &'ll Value {
754 use syntax::ast::IntTy::*;
755 use syntax::ast::UintTy::*;
756 use rustc::ty::{Int, Uint};
760 let new_sty = match ty.sty {
761 Int(Isize) => Int(tcx.sess.target.isize_ty),
762 Uint(Usize) => Uint(tcx.sess.target.usize_ty),
763 ref t @ Uint(_) | ref t @ Int(_) => t.clone(),
764 _ => panic!("tried to get overflow intrinsic for op applied to non-int type")
767 let name = match oop {
768 OverflowOp::Add => match new_sty {
769 Int(I8) => "llvm.sadd.with.overflow.i8",
770 Int(I16) => "llvm.sadd.with.overflow.i16",
771 Int(I32) => "llvm.sadd.with.overflow.i32",
772 Int(I64) => "llvm.sadd.with.overflow.i64",
773 Int(I128) => "llvm.sadd.with.overflow.i128",
775 Uint(U8) => "llvm.uadd.with.overflow.i8",
776 Uint(U16) => "llvm.uadd.with.overflow.i16",
777 Uint(U32) => "llvm.uadd.with.overflow.i32",
778 Uint(U64) => "llvm.uadd.with.overflow.i64",
779 Uint(U128) => "llvm.uadd.with.overflow.i128",
783 OverflowOp::Sub => match new_sty {
784 Int(I8) => "llvm.ssub.with.overflow.i8",
785 Int(I16) => "llvm.ssub.with.overflow.i16",
786 Int(I32) => "llvm.ssub.with.overflow.i32",
787 Int(I64) => "llvm.ssub.with.overflow.i64",
788 Int(I128) => "llvm.ssub.with.overflow.i128",
790 Uint(U8) => "llvm.usub.with.overflow.i8",
791 Uint(U16) => "llvm.usub.with.overflow.i16",
792 Uint(U32) => "llvm.usub.with.overflow.i32",
793 Uint(U64) => "llvm.usub.with.overflow.i64",
794 Uint(U128) => "llvm.usub.with.overflow.i128",
798 OverflowOp::Mul => match new_sty {
799 Int(I8) => "llvm.smul.with.overflow.i8",
800 Int(I16) => "llvm.smul.with.overflow.i16",
801 Int(I32) => "llvm.smul.with.overflow.i32",
802 Int(I64) => "llvm.smul.with.overflow.i64",
803 Int(I128) => "llvm.smul.with.overflow.i128",
805 Uint(U8) => "llvm.umul.with.overflow.i8",
806 Uint(U16) => "llvm.umul.with.overflow.i16",
807 Uint(U32) => "llvm.umul.with.overflow.i32",
808 Uint(U64) => "llvm.umul.with.overflow.i64",
809 Uint(U128) => "llvm.umul.with.overflow.i128",
815 bx.cx.get_intrinsic(&name)
818 fn cast_int_to_float(bx: &Builder<'_, 'll, '_>,
822 float_ty: &'ll Type) -> &'ll Value {
823 // Most integer types, even i128, fit into [-f32::MAX, f32::MAX] after rounding.
824 // It's only u128 -> f32 that can cause overflows (i.e., should yield infinity).
825 // LLVM's uitofp produces undef in those cases, so we manually check for that case.
826 let is_u128_to_f32 = !signed && int_ty.int_width() == 128 && float_ty.float_width() == 32;
828 // All inputs greater or equal to (f32::MAX + 0.5 ULP) are rounded to infinity,
829 // and for everything else LLVM's uitofp works just fine.
830 use rustc_apfloat::ieee::Single;
831 use rustc_apfloat::Float;
832 const MAX_F32_PLUS_HALF_ULP: u128 = ((1 << (Single::PRECISION + 1)) - 1)
833 << (Single::MAX_EXP - Single::PRECISION as i16);
834 let max = C_uint_big(int_ty, MAX_F32_PLUS_HALF_ULP);
835 let overflow = bx.icmp(llvm::IntUGE, x, max);
836 let infinity_bits = C_u32(bx.cx, ieee::Single::INFINITY.to_bits() as u32);
837 let infinity = consts::bitcast(infinity_bits, float_ty);
838 bx.select(overflow, infinity, bx.uitofp(x, float_ty))
841 bx.sitofp(x, float_ty)
843 bx.uitofp(x, float_ty)
848 fn cast_float_to_int(bx: &Builder<'_, 'll, '_>,
852 int_ty: &'ll Type) -> &'ll Value {
853 let fptosui_result = if signed {
859 if !bx.sess().opts.debugging_opts.saturating_float_casts {
860 return fptosui_result;
862 // LLVM's fpto[su]i returns undef when the input x is infinite, NaN, or does not fit into the
863 // destination integer type after rounding towards zero. This `undef` value can cause UB in
864 // safe code (see issue #10184), so we implement a saturating conversion on top of it:
865 // Semantically, the mathematical value of the input is rounded towards zero to the next
866 // mathematical integer, and then the result is clamped into the range of the destination
867 // integer type. Positive and negative infinity are mapped to the maximum and minimum value of
868 // the destination integer type. NaN is mapped to 0.
870 // Define f_min and f_max as the largest and smallest (finite) floats that are exactly equal to
871 // a value representable in int_ty.
872 // They are exactly equal to int_ty::{MIN,MAX} if float_ty has enough significand bits.
873 // Otherwise, int_ty::MAX must be rounded towards zero, as it is one less than a power of two.
874 // int_ty::MIN, however, is either zero or a negative power of two and is thus exactly
875 // representable. Note that this only works if float_ty's exponent range is sufficiently large.
876 // f16 or 256 bit integers would break this property. Right now the smallest float type is f32
877 // with exponents ranging up to 127, which is barely enough for i128::MIN = -2^127.
878 // On the other hand, f_max works even if int_ty::MAX is greater than float_ty::MAX. Because
879 // we're rounding towards zero, we just get float_ty::MAX (which is always an integer).
880 // This already happens today with u128::MAX = 2^128 - 1 > f32::MAX.
881 fn compute_clamp_bounds<F: Float>(signed: bool, int_ty: &Type) -> (u128, u128) {
882 let rounded_min = F::from_i128_r(int_min(signed, int_ty), Round::TowardZero);
883 assert_eq!(rounded_min.status, Status::OK);
884 let rounded_max = F::from_u128_r(int_max(signed, int_ty), Round::TowardZero);
885 assert!(rounded_max.value.is_finite());
886 (rounded_min.value.to_bits(), rounded_max.value.to_bits())
888 fn int_max(signed: bool, int_ty: &Type) -> u128 {
889 let shift_amount = 128 - int_ty.int_width();
891 i128::MAX as u128 >> shift_amount
893 u128::MAX >> shift_amount
896 fn int_min(signed: bool, int_ty: &Type) -> i128 {
898 i128::MIN >> (128 - int_ty.int_width())
903 let float_bits_to_llval = |bits| {
904 let bits_llval = match float_ty.float_width() {
905 32 => C_u32(bx.cx, bits as u32),
906 64 => C_u64(bx.cx, bits as u64),
907 n => bug!("unsupported float width {}", n),
909 consts::bitcast(bits_llval, float_ty)
911 let (f_min, f_max) = match float_ty.float_width() {
912 32 => compute_clamp_bounds::<ieee::Single>(signed, int_ty),
913 64 => compute_clamp_bounds::<ieee::Double>(signed, int_ty),
914 n => bug!("unsupported float width {}", n),
916 let f_min = float_bits_to_llval(f_min);
917 let f_max = float_bits_to_llval(f_max);
918 // To implement saturation, we perform the following steps:
920 // 1. Cast x to an integer with fpto[su]i. This may result in undef.
921 // 2. Compare x to f_min and f_max, and use the comparison results to select:
922 // a) int_ty::MIN if x < f_min or x is NaN
923 // b) int_ty::MAX if x > f_max
924 // c) the result of fpto[su]i otherwise
925 // 3. If x is NaN, return 0.0, otherwise return the result of step 2.
927 // This avoids resulting undef because values in range [f_min, f_max] by definition fit into the
928 // destination type. It creates an undef temporary, but *producing* undef is not UB. Our use of
929 // undef does not introduce any non-determinism either.
930 // More importantly, the above procedure correctly implements saturating conversion.
932 // If x is NaN, 0 is returned by definition.
933 // Otherwise, x is finite or infinite and thus can be compared with f_min and f_max.
934 // This yields three cases to consider:
935 // (1) if x in [f_min, f_max], the result of fpto[su]i is returned, which agrees with
936 // saturating conversion for inputs in that range.
937 // (2) if x > f_max, then x is larger than int_ty::MAX. This holds even if f_max is rounded
938 // (i.e., if f_max < int_ty::MAX) because in those cases, nextUp(f_max) is already larger
939 // than int_ty::MAX. Because x is larger than int_ty::MAX, the return value of int_ty::MAX
941 // (3) if x < f_min, then x is smaller than int_ty::MIN. As shown earlier, f_min exactly equals
942 // int_ty::MIN and therefore the return value of int_ty::MIN is correct.
945 // Step 1 was already performed above.
947 // Step 2: We use two comparisons and two selects, with %s1 being the result:
948 // %less_or_nan = fcmp ult %x, %f_min
949 // %greater = fcmp olt %x, %f_max
950 // %s0 = select %less_or_nan, int_ty::MIN, %fptosi_result
951 // %s1 = select %greater, int_ty::MAX, %s0
952 // Note that %less_or_nan uses an *unordered* comparison. This comparison is true if the
953 // operands are not comparable (i.e., if x is NaN). The unordered comparison ensures that s1
954 // becomes int_ty::MIN if x is NaN.
955 // Performance note: Unordered comparison can be lowered to a "flipped" comparison and a
956 // negation, and the negation can be merged into the select. Therefore, it not necessarily any
957 // more expensive than a ordered ("normal") comparison. Whether these optimizations will be
958 // performed is ultimately up to the backend, but at least x86 does perform them.
959 let less_or_nan = bx.fcmp(llvm::RealULT, x, f_min);
960 let greater = bx.fcmp(llvm::RealOGT, x, f_max);
961 let int_max = C_uint_big(int_ty, int_max(signed, int_ty));
962 let int_min = C_uint_big(int_ty, int_min(signed, int_ty) as u128);
963 let s0 = bx.select(less_or_nan, int_min, fptosui_result);
964 let s1 = bx.select(greater, int_max, s0);
966 // Step 3: NaN replacement.
967 // For unsigned types, the above step already yielded int_ty::MIN == 0 if x is NaN.
968 // Therefore we only need to execute this step for signed integer types.
970 // LLVM has no isNaN predicate, so we use (x == x) instead
971 bx.select(bx.fcmp(llvm::RealOEQ, x, x), s1, C_uint(int_ty, 0))