diff options
Diffstat (limited to 'compiler/rustc_mir_transform/src')
| -rw-r--r-- | compiler/rustc_mir_transform/src/dataflow_const_prop.rs | 52 | ||||
| -rw-r--r-- | compiler/rustc_mir_transform/src/gvn.rs | 82 |
2 files changed, 115 insertions, 19 deletions
diff --git a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs index 6a37047a693..86e99a8a5b5 100644 --- a/compiler/rustc_mir_transform/src/dataflow_const_prop.rs +++ b/compiler/rustc_mir_transform/src/dataflow_const_prop.rs @@ -2,7 +2,9 @@ //! //! Currently, this pass only propagates scalar values. -use rustc_const_eval::interpret::{ImmTy, Immediate, InterpCx, OpTy, PlaceTy, Projectable}; +use rustc_const_eval::interpret::{ + ImmTy, Immediate, InterpCx, OpTy, PlaceTy, PointerArithmetic, Projectable, +}; use rustc_data_structures::fx::FxHashMap; use rustc_hir::def::DefKind; use rustc_middle::mir::interpret::{AllocId, ConstAllocation, InterpResult, Scalar}; @@ -936,12 +938,50 @@ impl<'mir, 'tcx: 'mir> rustc_const_eval::interpret::Machine<'mir, 'tcx> for Dumm } fn binary_ptr_op( - _ecx: &InterpCx<'mir, 'tcx, Self>, - _bin_op: BinOp, - _left: &rustc_const_eval::interpret::ImmTy<'tcx, Self::Provenance>, - _right: &rustc_const_eval::interpret::ImmTy<'tcx, Self::Provenance>, + ecx: &InterpCx<'mir, 'tcx, Self>, + bin_op: BinOp, + left: &rustc_const_eval::interpret::ImmTy<'tcx, Self::Provenance>, + right: &rustc_const_eval::interpret::ImmTy<'tcx, Self::Provenance>, ) -> interpret::InterpResult<'tcx, (ImmTy<'tcx, Self::Provenance>, bool)> { - throw_machine_stop_str!("can't do pointer arithmetic"); + use rustc_middle::mir::BinOp::*; + Ok(match bin_op { + Eq | Ne | Lt | Le | Gt | Ge => { + // Types can differ, e.g. fn ptrs with different `for`. + assert_eq!(left.layout.abi, right.layout.abi); + let size = ecx.pointer_size(); + // Just compare the bits. ScalarPairs are compared lexicographically. + // We thus always compare pairs and simply fill scalars up with 0. + // If the pointer has provenance, `to_bits` will return `Err` and we bail out. + let left = match **left { + Immediate::Scalar(l) => (l.to_bits(size)?, 0), + Immediate::ScalarPair(l1, l2) => (l1.to_bits(size)?, l2.to_bits(size)?), + Immediate::Uninit => panic!("we should never see uninit data here"), + }; + let right = match **right { + Immediate::Scalar(r) => (r.to_bits(size)?, 0), + Immediate::ScalarPair(r1, r2) => (r1.to_bits(size)?, r2.to_bits(size)?), + Immediate::Uninit => panic!("we should never see uninit data here"), + }; + let res = match bin_op { + Eq => left == right, + Ne => left != right, + Lt => left < right, + Le => left <= right, + Gt => left > right, + Ge => left >= right, + _ => bug!(), + }; + (ImmTy::from_bool(res, *ecx.tcx), false) + } + + // Some more operations are possible with atomics. + // The return value always has the provenance of the *left* operand. + Add | Sub | BitOr | BitAnd | BitXor => { + throw_machine_stop_str!("pointer arithmetic is not handled") + } + + _ => span_bug!(ecx.cur_span(), "Invalid operator on pointers: {:?}", bin_op), + }) } fn expose_ptr( diff --git a/compiler/rustc_mir_transform/src/gvn.rs b/compiler/rustc_mir_transform/src/gvn.rs index 36c441a3945..2c7ae53055f 100644 --- a/compiler/rustc_mir_transform/src/gvn.rs +++ b/compiler/rustc_mir_transform/src/gvn.rs @@ -93,7 +93,6 @@ use rustc_index::IndexVec; use rustc_middle::mir::interpret::GlobalAlloc; use rustc_middle::mir::visit::*; use rustc_middle::mir::*; -use rustc_middle::ty::adjustment::PointerCoercion; use rustc_middle::ty::layout::LayoutOf; use rustc_middle::ty::{self, Ty, TyCtxt, TypeAndMut}; use rustc_span::def_id::DefId; @@ -552,6 +551,29 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { } value.offset(Size::ZERO, to, &self.ecx).ok()? } + CastKind::PointerCoercion(ty::adjustment::PointerCoercion::Unsize) => { + let src = self.evaluated[value].as_ref()?; + let to = self.ecx.layout_of(to).ok()?; + let dest = self.ecx.allocate(to, MemoryKind::Stack).ok()?; + self.ecx.unsize_into(src, to, &dest.clone().into()).ok()?; + self.ecx + .alloc_mark_immutable(dest.ptr().provenance.unwrap().alloc_id()) + .ok()?; + dest.into() + } + CastKind::FnPtrToPtr + | CastKind::PtrToPtr + | CastKind::PointerCoercion( + ty::adjustment::PointerCoercion::MutToConstPointer + | ty::adjustment::PointerCoercion::ArrayToPointer + | ty::adjustment::PointerCoercion::UnsafeFnPointer, + ) => { + let src = self.evaluated[value].as_ref()?; + let src = self.ecx.read_immediate(src).ok()?; + let to = self.ecx.layout_of(to).ok()?; + let ret = self.ecx.ptr_to_ptr(&src, to).ok()?; + ret.into() + } _ => return None, }, }; @@ -778,18 +800,8 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { // Operations. Rvalue::Len(ref mut place) => return self.simplify_len(place, location), - Rvalue::Cast(kind, ref mut value, to) => { - let from = value.ty(self.local_decls, self.tcx); - let value = self.simplify_operand(value, location)?; - if let CastKind::PointerCoercion( - PointerCoercion::ReifyFnPointer | PointerCoercion::ClosureFnPointer(_), - ) = kind - { - // Each reification of a generic fn may get a different pointer. - // Do not try to merge them. - return self.new_opaque(); - } - Value::Cast { kind, value, from, to } + Rvalue::Cast(ref mut kind, ref mut value, to) => { + return self.simplify_cast(kind, value, to, location); } Rvalue::BinaryOp(op, box (ref mut lhs, ref mut rhs)) => { let ty = lhs.ty(self.local_decls, self.tcx); @@ -1035,6 +1047,50 @@ impl<'body, 'tcx> VnState<'body, 'tcx> { } } + fn simplify_cast( + &mut self, + kind: &mut CastKind, + operand: &mut Operand<'tcx>, + to: Ty<'tcx>, + location: Location, + ) -> Option<VnIndex> { + use rustc_middle::ty::adjustment::PointerCoercion::*; + use CastKind::*; + + let mut from = operand.ty(self.local_decls, self.tcx); + let mut value = self.simplify_operand(operand, location)?; + if from == to { + return Some(value); + } + + if let CastKind::PointerCoercion(ReifyFnPointer | ClosureFnPointer(_)) = kind { + // Each reification of a generic fn may get a different pointer. + // Do not try to merge them. + return self.new_opaque(); + } + + if let PtrToPtr | PointerCoercion(MutToConstPointer) = kind + && let Value::Cast { kind: inner_kind, value: inner_value, from: inner_from, to: _ } = + *self.get(value) + && let PtrToPtr | PointerCoercion(MutToConstPointer) = inner_kind + { + from = inner_from; + value = inner_value; + *kind = PtrToPtr; + if inner_from == to { + return Some(inner_value); + } + if let Some(const_) = self.try_as_constant(value) { + *operand = Operand::Constant(Box::new(const_)); + } else if let Some(local) = self.try_as_local(value, location) { + *operand = Operand::Copy(local.into()); + self.reused_locals.insert(local); + } + } + + Some(self.insert(Value::Cast { kind: *kind, value, from, to })) + } + fn simplify_len(&mut self, place: &mut Place<'tcx>, location: Location) -> Option<VnIndex> { // Trivial case: we are fetching a statically known length. let place_ty = place.ty(self.local_decls, self.tcx).ty; |