| //! This implements the VCode container: a CFG of Insts that have been lowered. |
| //! |
| //! VCode is virtual-register code. An instruction in VCode is almost a machine |
| //! instruction; however, its register slots can refer to virtual registers in |
| //! addition to real machine registers. |
| //! |
| //! VCode is structured with traditional basic blocks, and |
| //! each block must be terminated by an unconditional branch (one target), a |
| //! conditional branch (two targets), or a return (no targets). Note that this |
| //! slightly differs from the machine code of most ISAs: in most ISAs, a |
| //! conditional branch has one target (and the not-taken case falls through). |
| //! However, we expect that machine backends will elide branches to the following |
| //! block (i.e., zero-offset jumps), and will be able to codegen a branch-cond / |
| //! branch-uncond pair if *both* targets are not fallthrough. This allows us to |
| //! play with layout prior to final binary emission, as well, if we want. |
| //! |
| //! See the main module comment in `mod.rs` for more details on the VCode-based |
| //! backend pipeline. |
| |
| use crate::fx::FxHashMap; |
| use crate::fx::FxHashSet; |
| use crate::ir::RelSourceLoc; |
| use crate::ir::{self, types, Constant, ConstantData, DynamicStackSlot, LabelValueLoc, ValueLabel}; |
| use crate::machinst::*; |
| use crate::timing; |
| use crate::trace; |
| use crate::CodegenError; |
| use crate::ValueLocRange; |
| use regalloc2::{ |
| Edit, Function as RegallocFunction, InstOrEdit, InstRange, Operand, OperandKind, PReg, PRegSet, |
| RegClass, VReg, |
| }; |
| |
| use alloc::vec::Vec; |
| use cranelift_entity::{entity_impl, Keys, PrimaryMap}; |
| use std::collections::hash_map::Entry; |
| use std::collections::HashMap; |
| use std::fmt; |
| |
| /// Index referring to an instruction in VCode. |
| pub type InsnIndex = regalloc2::Inst; |
| |
| /// Index referring to a basic block in VCode. |
| pub type BlockIndex = regalloc2::Block; |
| |
| /// VCodeInst wraps all requirements for a MachInst to be in VCode: it must be |
| /// a `MachInst` and it must be able to emit itself at least to a `SizeCodeSink`. |
| pub trait VCodeInst: MachInst + MachInstEmit {} |
| impl<I: MachInst + MachInstEmit> VCodeInst for I {} |
| |
| /// A function in "VCode" (virtualized-register code) form, after |
| /// lowering. This is essentially a standard CFG of basic blocks, |
| /// where each basic block consists of lowered instructions produced |
| /// by the machine-specific backend. |
| /// |
| /// Note that the VCode is immutable once produced, and is not |
| /// modified by register allocation in particular. Rather, register |
| /// allocation on the `VCode` produces a separate `regalloc2::Output` |
| /// struct, and this can be passed to `emit`. `emit` in turn does not |
| /// modify the vcode, but produces an `EmitResult`, which contains the |
| /// machine code itself, and the associated disassembly and/or |
| /// metadata as requested. |
| pub struct VCode<I: VCodeInst> { |
| /// VReg IR-level types. |
| vreg_types: Vec<Type>, |
| |
| /// Lowered machine instructions in order corresponding to the original IR. |
| insts: Vec<I>, |
| |
| /// Operands: pre-regalloc references to virtual registers with |
| /// constraints, in one flattened array. This allows the regalloc |
| /// to efficiently access all operands without requiring expensive |
| /// matches or method invocations on insts. |
| operands: Vec<Operand>, |
| |
| /// Operand index ranges: for each instruction in `insts`, there |
| /// is a tuple here providing the range in `operands` for that |
| /// instruction's operands. |
| operand_ranges: Vec<(u32, u32)>, |
| |
| /// Clobbers: a sparse map from instruction indices to clobber masks. |
| clobbers: FxHashMap<InsnIndex, PRegSet>, |
| |
| /// Move information: for a given InsnIndex, (src, dst) operand pair. |
| is_move: FxHashMap<InsnIndex, (Operand, Operand)>, |
| |
| /// Source locations for each instruction. (`SourceLoc` is a `u32`, so it is |
| /// reasonable to keep one of these per instruction.) |
| srclocs: Vec<RelSourceLoc>, |
| |
| /// Entry block. |
| entry: BlockIndex, |
| |
| /// Block instruction indices. |
| block_ranges: Vec<(InsnIndex, InsnIndex)>, |
| |
| /// Block successors: index range in the `block_succs_preds` list. |
| block_succ_range: Vec<(u32, u32)>, |
| |
| /// Block predecessors: index range in the `block_succs_preds` list. |
| block_pred_range: Vec<(u32, u32)>, |
| |
| /// Block successor and predecessor lists, concatenated into one |
| /// Vec. The `block_succ_range` and `block_pred_range` lists of |
| /// tuples above give (start, end) ranges within this list that |
| /// correspond to each basic block's successors or predecessors, |
| /// respectively. |
| block_succs_preds: Vec<regalloc2::Block>, |
| |
| /// Block parameters: index range in `block_params` below. |
| block_params_range: Vec<(u32, u32)>, |
| |
| /// Block parameter lists, concatenated into one vec. The |
| /// `block_params_range` list of tuples above gives (start, end) |
| /// ranges within this list that correspond to each basic block's |
| /// blockparam vregs. |
| block_params: Vec<regalloc2::VReg>, |
| |
| /// Outgoing block arguments on branch instructions, concatenated |
| /// into one list. |
| /// |
| /// Note that this is conceptually a 3D array: we have a VReg list |
| /// per block, per successor. We flatten those three dimensions |
| /// into this 1D vec, then store index ranges in two levels of |
| /// indirection. |
| /// |
| /// Indexed by the indices in `branch_block_arg_succ_range`. |
| branch_block_args: Vec<regalloc2::VReg>, |
| |
| /// Array of sequences of (start, end) tuples in |
| /// `branch_block_args`, one for each successor; these sequences |
| /// for each block are concatenated. |
| /// |
| /// Indexed by the indices in `branch_block_arg_succ_range`. |
| branch_block_arg_range: Vec<(u32, u32)>, |
| |
| /// For a given block, indices in `branch_block_arg_range` |
| /// corresponding to all of its successors. |
| branch_block_arg_succ_range: Vec<(u32, u32)>, |
| |
| /// VReg aliases. Each key in this table is translated to its |
| /// value when gathering Operands from instructions. Aliases are |
| /// not chased transitively (we do not further look up the |
| /// translated reg to see if it is another alias). |
| /// |
| /// We use these aliases to rename an instruction's expected |
| /// result vregs to the returned vregs from lowering, which are |
| /// usually freshly-allocated temps. |
| /// |
| /// Operands and branch arguments will already have been |
| /// translated through this alias table; but it helps to make |
| /// sense of instructions when pretty-printed, for example. |
| vreg_aliases: FxHashMap<regalloc2::VReg, regalloc2::VReg>, |
| |
| /// Block-order information. |
| block_order: BlockLoweringOrder, |
| |
| /// ABI object. |
| pub(crate) abi: Callee<I::ABIMachineSpec>, |
| |
| /// Constant information used during code emission. This should be |
| /// immutable across function compilations within the same module. |
| emit_info: I::Info, |
| |
| /// Reference-typed `regalloc2::VReg`s. The regalloc requires |
| /// these in a dense slice (as opposed to querying the |
| /// reftype-status of each vreg) for efficient iteration. |
| reftyped_vregs: Vec<VReg>, |
| |
| /// Constants. |
| constants: VCodeConstants, |
| |
| /// Value labels for debuginfo attached to vregs. |
| debug_value_labels: Vec<(VReg, InsnIndex, InsnIndex, u32)>, |
| |
| pub(crate) sigs: SigSet, |
| } |
| |
| /// The result of `VCode::emit`. Contains all information computed |
| /// during emission: actual machine code, optionally a disassembly, |
| /// and optionally metadata about the code layout. |
| pub struct EmitResult<I: VCodeInst> { |
| /// The MachBuffer containing the machine code. |
| pub buffer: MachBuffer<I>, |
| |
| /// Offset of each basic block, recorded during emission. Computed |
| /// only if `debug_value_labels` is non-empty. |
| pub bb_offsets: Vec<CodeOffset>, |
| |
| /// Final basic-block edges, in terms of code offsets of |
| /// bb-starts. Computed only if `debug_value_labels` is non-empty. |
| pub bb_edges: Vec<(CodeOffset, CodeOffset)>, |
| |
| /// Final instruction offsets, recorded during emission. Computed |
| /// only if `debug_value_labels` is non-empty. |
| pub inst_offsets: Vec<CodeOffset>, |
| |
| /// Final length of function body. |
| pub func_body_len: CodeOffset, |
| |
| /// The pretty-printed disassembly, if any. This uses the same |
| /// pretty-printing for MachInsts as the pre-regalloc VCode Debug |
| /// implementation, but additionally includes the prologue and |
| /// epilogue(s), and makes use of the regalloc results. |
| pub disasm: Option<String>, |
| |
| /// Offsets of sized stackslots. |
| pub sized_stackslot_offsets: PrimaryMap<StackSlot, u32>, |
| |
| /// Offsets of dynamic stackslots. |
| pub dynamic_stackslot_offsets: PrimaryMap<DynamicStackSlot, u32>, |
| |
| /// Value-labels information (debug metadata). |
| pub value_labels_ranges: ValueLabelsRanges, |
| |
| /// Stack frame size. |
| pub frame_size: u32, |
| |
| /// The alignment requirement for pc-relative loads. |
| pub alignment: u32, |
| } |
| |
| /// A builder for a VCode function body. |
| /// |
| /// This builder has the ability to accept instructions in either |
| /// forward or reverse order, depending on the pass direction that |
| /// produces the VCode. The lowering from CLIF to VCode<MachInst> |
| /// ordinarily occurs in reverse order (in order to allow instructions |
| /// to be lowered only if used, and not merged) so a reversal will |
| /// occur at the end of lowering to ensure the VCode is in machine |
| /// order. |
| /// |
| /// If built in reverse, block and instruction indices used once the |
| /// VCode is built are relative to the final (reversed) order, not the |
| /// order of construction. Note that this means we do not know the |
| /// final block or instruction indices when building, so we do not |
| /// hand them out. (The user is assumed to know them when appending |
| /// terminator instructions with successor blocks.) |
| pub struct VCodeBuilder<I: VCodeInst> { |
| /// In-progress VCode. |
| pub(crate) vcode: VCode<I>, |
| |
| /// In what direction is the build occuring? |
| direction: VCodeBuildDirection, |
| |
| /// Index of the last block-start in the vcode. |
| block_start: usize, |
| |
| /// Start of succs for the current block in the concatenated succs list. |
| succ_start: usize, |
| |
| /// Start of blockparams for the current block in the concatenated |
| /// blockparams list. |
| block_params_start: usize, |
| |
| /// Start of successor blockparam arg list entries in |
| /// the concatenated branch_block_arg_range list. |
| branch_block_arg_succ_start: usize, |
| |
| /// Current source location. |
| cur_srcloc: RelSourceLoc, |
| |
| /// Debug-value label in-progress map, keyed by label. For each |
| /// label, we keep disjoint ranges mapping to vregs. We'll flatten |
| /// this into (vreg, range, label) tuples when done. |
| debug_info: FxHashMap<ValueLabel, Vec<(InsnIndex, InsnIndex, VReg)>>, |
| } |
| |
| /// Direction in which a VCodeBuilder builds VCode. |
| #[derive(Clone, Copy, Debug, PartialEq, Eq)] |
| pub enum VCodeBuildDirection { |
| // TODO: add `Forward` once we need it and can test it adequately. |
| /// Backward-build pass: we expect the producer to call `emit()` |
| /// with instructions in reverse program order within each block. |
| Backward, |
| } |
| |
| impl<I: VCodeInst> VCodeBuilder<I> { |
| /// Create a new VCodeBuilder. |
| pub fn new( |
| sigs: SigSet, |
| abi: Callee<I::ABIMachineSpec>, |
| emit_info: I::Info, |
| block_order: BlockLoweringOrder, |
| constants: VCodeConstants, |
| direction: VCodeBuildDirection, |
| ) -> VCodeBuilder<I> { |
| let vcode = VCode::new(sigs, abi, emit_info, block_order, constants); |
| |
| VCodeBuilder { |
| vcode, |
| direction, |
| block_start: 0, |
| succ_start: 0, |
| block_params_start: 0, |
| branch_block_arg_succ_start: 0, |
| cur_srcloc: Default::default(), |
| debug_info: FxHashMap::default(), |
| } |
| } |
| |
| pub fn init_abi(&mut self, temps: Vec<Writable<Reg>>) { |
| self.vcode.abi.init(&self.vcode.sigs, temps); |
| } |
| |
| /// Access the ABI object. |
| pub fn abi(&self) -> &Callee<I::ABIMachineSpec> { |
| &self.vcode.abi |
| } |
| |
| /// Access the ABI object. |
| pub fn abi_mut(&mut self) -> &mut Callee<I::ABIMachineSpec> { |
| &mut self.vcode.abi |
| } |
| |
| pub fn sigs(&self) -> &SigSet { |
| &self.vcode.sigs |
| } |
| |
| pub fn sigs_mut(&mut self) -> &mut SigSet { |
| &mut self.vcode.sigs |
| } |
| |
| /// Access to the BlockLoweringOrder object. |
| pub fn block_order(&self) -> &BlockLoweringOrder { |
| &self.vcode.block_order |
| } |
| |
| /// Set the current block as the entry block. |
| pub fn set_entry(&mut self, block: BlockIndex) { |
| self.vcode.entry = block; |
| } |
| |
| /// End the current basic block. Must be called after emitting vcode insts |
| /// for IR insts and prior to ending the function (building the VCode). |
| pub fn end_bb(&mut self) { |
| let start_idx = self.block_start; |
| let end_idx = self.vcode.insts.len(); |
| self.block_start = end_idx; |
| // Add the instruction index range to the list of blocks. |
| self.vcode |
| .block_ranges |
| .push((InsnIndex::new(start_idx), InsnIndex::new(end_idx))); |
| // End the successors list. |
| let succ_end = self.vcode.block_succs_preds.len(); |
| self.vcode |
| .block_succ_range |
| .push((self.succ_start as u32, succ_end as u32)); |
| self.succ_start = succ_end; |
| // End the blockparams list. |
| let block_params_end = self.vcode.block_params.len(); |
| self.vcode |
| .block_params_range |
| .push((self.block_params_start as u32, block_params_end as u32)); |
| self.block_params_start = block_params_end; |
| // End the branch blockparam args list. |
| let branch_block_arg_succ_end = self.vcode.branch_block_arg_range.len(); |
| self.vcode.branch_block_arg_succ_range.push(( |
| self.branch_block_arg_succ_start as u32, |
| branch_block_arg_succ_end as u32, |
| )); |
| self.branch_block_arg_succ_start = branch_block_arg_succ_end; |
| } |
| |
| pub fn add_block_param(&mut self, param: VirtualReg) { |
| self.vcode.block_params.push(param.into()); |
| } |
| |
| fn add_branch_args_for_succ(&mut self, args: &[Reg]) { |
| let start = self.vcode.branch_block_args.len(); |
| self.vcode |
| .branch_block_args |
| .extend(args.iter().map(|&arg| VReg::from(arg))); |
| let end = self.vcode.branch_block_args.len(); |
| self.vcode |
| .branch_block_arg_range |
| .push((start as u32, end as u32)); |
| } |
| |
| /// Push an instruction for the current BB and current IR inst |
| /// within the BB. |
| pub fn push(&mut self, insn: I) { |
| self.vcode.insts.push(insn); |
| self.vcode.srclocs.push(self.cur_srcloc); |
| } |
| |
| /// Add a successor block with branch args. |
| pub fn add_succ(&mut self, block: BlockIndex, args: &[Reg]) { |
| self.vcode.block_succs_preds.push(block); |
| self.add_branch_args_for_succ(args); |
| } |
| |
| /// Set the current source location. |
| pub fn set_srcloc(&mut self, srcloc: RelSourceLoc) { |
| self.cur_srcloc = srcloc; |
| } |
| |
| /// Add a debug value label to a register. |
| pub fn add_value_label(&mut self, reg: Reg, label: ValueLabel) { |
| // We'll fix up labels in reverse(). Because we're generating |
| // code bottom-to-top, the liverange of the label goes *from* |
| // the last index at which was defined (or 0, which is the end |
| // of the eventual function) *to* just this instruction, and |
| // no further. |
| let inst = InsnIndex::new(self.vcode.insts.len()); |
| let labels = self.debug_info.entry(label).or_insert_with(|| vec![]); |
| let last = labels |
| .last() |
| .map(|(_start, end, _vreg)| *end) |
| .unwrap_or(InsnIndex::new(0)); |
| labels.push((last, inst, reg.into())); |
| } |
| |
| pub fn set_vreg_alias(&mut self, from: Reg, to: Reg) { |
| let from = from.into(); |
| let resolved_to = self.resolve_vreg_alias(to.into()); |
| // Disallow cycles (see below). |
| assert_ne!(resolved_to, from); |
| self.vcode.vreg_aliases.insert(from, resolved_to); |
| } |
| |
| pub fn resolve_vreg_alias(&self, from: regalloc2::VReg) -> regalloc2::VReg { |
| Self::resolve_vreg_alias_impl(&self.vcode.vreg_aliases, from) |
| } |
| |
| fn resolve_vreg_alias_impl( |
| aliases: &FxHashMap<regalloc2::VReg, regalloc2::VReg>, |
| from: regalloc2::VReg, |
| ) -> regalloc2::VReg { |
| // We prevent cycles from existing by resolving targets of |
| // aliases eagerly before setting them. If the target resolves |
| // to the origin of the alias, then a cycle would be created |
| // and the alias is disallowed. Because of the structure of |
| // SSA code (one instruction can refer to another's defs but |
| // not vice-versa, except indirectly through |
| // phis/blockparams), cycles should not occur as we use |
| // aliases to redirect vregs to the temps that actually define |
| // them. |
| |
| let mut vreg = from; |
| while let Some(to) = aliases.get(&vreg) { |
| vreg = *to; |
| } |
| vreg |
| } |
| |
| /// Access the constants. |
| pub fn constants(&mut self) -> &mut VCodeConstants { |
| &mut self.vcode.constants |
| } |
| |
| fn compute_preds_from_succs(&mut self) { |
| // Compute predecessors from successors. In order to gather |
| // all preds for a block into a contiguous sequence, we build |
| // a list of (succ, pred) tuples and then sort. |
| let mut succ_pred_edges: Vec<(BlockIndex, BlockIndex)> = |
| Vec::with_capacity(self.vcode.block_succs_preds.len()); |
| for (pred, &(start, end)) in self.vcode.block_succ_range.iter().enumerate() { |
| let pred = BlockIndex::new(pred); |
| for i in start..end { |
| let succ = BlockIndex::new(self.vcode.block_succs_preds[i as usize].index()); |
| succ_pred_edges.push((succ, pred)); |
| } |
| } |
| succ_pred_edges.sort_unstable(); |
| |
| let mut i = 0; |
| for succ in 0..self.vcode.num_blocks() { |
| let succ = BlockIndex::new(succ); |
| let start = self.vcode.block_succs_preds.len(); |
| while i < succ_pred_edges.len() && succ_pred_edges[i].0 == succ { |
| let pred = succ_pred_edges[i].1; |
| self.vcode.block_succs_preds.push(pred); |
| i += 1; |
| } |
| let end = self.vcode.block_succs_preds.len(); |
| self.vcode.block_pred_range.push((start as u32, end as u32)); |
| } |
| } |
| |
| /// Called once, when a build in Backward order is complete, to |
| /// perform the overall reversal (into final forward order) and |
| /// finalize metadata accordingly. |
| fn reverse_and_finalize(&mut self) { |
| let n_insts = self.vcode.insts.len(); |
| if n_insts == 0 { |
| return; |
| } |
| |
| // Reverse the per-block and per-inst sequences. |
| self.vcode.block_ranges.reverse(); |
| // block_params_range is indexed by block (and blocks were |
| // traversed in reverse) so we reverse it; but block-param |
| // sequences in the concatenated vec can remain in reverse |
| // order (it is effectively an arena of arbitrarily-placed |
| // referenced sequences). |
| self.vcode.block_params_range.reverse(); |
| // Likewise, we reverse block_succ_range, but the block_succ |
| // concatenated array can remain as-is. |
| self.vcode.block_succ_range.reverse(); |
| self.vcode.insts.reverse(); |
| self.vcode.srclocs.reverse(); |
| // Likewise, branch_block_arg_succ_range is indexed by block |
| // so must be reversed. |
| self.vcode.branch_block_arg_succ_range.reverse(); |
| |
| // To translate an instruction index *endpoint* in reversed |
| // order to forward order, compute `n_insts - i`. |
| // |
| // Why not `n_insts - 1 - i`? That would be correct to |
| // translate an individual instruction index (for ten insts 0 |
| // to 9 inclusive, inst 0 becomes 9, and inst 9 becomes |
| // 0). But for the usual inclusive-start, exclusive-end range |
| // idiom, inclusive starts become exclusive ends and |
| // vice-versa, so e.g. an (inclusive) start of 0 becomes an |
| // (exclusive) end of 10. |
| let translate = |inst: InsnIndex| InsnIndex::new(n_insts - inst.index()); |
| |
| // Edit the block-range instruction indices. |
| for tuple in &mut self.vcode.block_ranges { |
| let (start, end) = *tuple; |
| *tuple = (translate(end), translate(start)); // Note reversed order. |
| } |
| |
| // Generate debug-value labels based on per-label maps. |
| for (label, tuples) in &self.debug_info { |
| for &(start, end, vreg) in tuples { |
| let vreg = self.resolve_vreg_alias(vreg); |
| let fwd_start = translate(end); |
| let fwd_end = translate(start); |
| self.vcode |
| .debug_value_labels |
| .push((vreg, fwd_start, fwd_end, label.as_u32())); |
| } |
| } |
| |
| // Now sort debug value labels by VReg, as required |
| // by regalloc2. |
| self.vcode |
| .debug_value_labels |
| .sort_unstable_by_key(|(vreg, _, _, _)| *vreg); |
| } |
| |
| fn collect_operands(&mut self, allocatable: PRegSet) { |
| for (i, insn) in self.vcode.insts.iter().enumerate() { |
| // Push operands from the instruction onto the operand list. |
| // |
| // We rename through the vreg alias table as we collect |
| // the operands. This is better than a separate post-pass |
| // over operands, because it has more cache locality: |
| // operands only need to pass through L1 once. This is |
| // also better than renaming instructions' |
| // operands/registers while lowering, because here we only |
| // need to do the `match` over the instruction to visit |
| // its register fields (which is slow, branchy code) once. |
| |
| let vreg_aliases = &self.vcode.vreg_aliases; |
| let mut op_collector = |
| OperandCollector::new(&mut self.vcode.operands, allocatable, |vreg| { |
| Self::resolve_vreg_alias_impl(vreg_aliases, vreg) |
| }); |
| insn.get_operands(&mut op_collector); |
| let (ops, clobbers) = op_collector.finish(); |
| self.vcode.operand_ranges.push(ops); |
| |
| if clobbers != PRegSet::default() { |
| self.vcode.clobbers.insert(InsnIndex::new(i), clobbers); |
| } |
| |
| if let Some((dst, src)) = insn.is_move() { |
| // We should never see non-virtual registers present in move |
| // instructions. |
| assert!( |
| src.is_virtual(), |
| "the real register {:?} was used as the source of a move instruction", |
| src |
| ); |
| assert!( |
| dst.to_reg().is_virtual(), |
| "the real register {:?} was used as the destination of a move instruction", |
| dst.to_reg() |
| ); |
| |
| let src = Operand::reg_use(Self::resolve_vreg_alias_impl(vreg_aliases, src.into())); |
| let dst = Operand::reg_def(Self::resolve_vreg_alias_impl( |
| vreg_aliases, |
| dst.to_reg().into(), |
| )); |
| |
| // Note that regalloc2 requires these in (src, dst) order. |
| self.vcode.is_move.insert(InsnIndex::new(i), (src, dst)); |
| } |
| } |
| |
| // Translate blockparam args via the vreg aliases table as well. |
| for arg in &mut self.vcode.branch_block_args { |
| let new_arg = Self::resolve_vreg_alias_impl(&self.vcode.vreg_aliases, *arg); |
| trace!("operandcollector: block arg {:?} -> {:?}", arg, new_arg); |
| *arg = new_arg; |
| } |
| } |
| |
| /// Build the final VCode. |
| pub fn build(mut self, allocatable: PRegSet, vregs: VRegAllocator<I>) -> VCode<I> { |
| self.vcode.vreg_types = vregs.vreg_types; |
| self.vcode.reftyped_vregs = vregs.reftyped_vregs; |
| |
| if self.direction == VCodeBuildDirection::Backward { |
| self.reverse_and_finalize(); |
| } |
| self.collect_operands(allocatable); |
| |
| // Apply register aliases to the `reftyped_vregs` list since this list |
| // will be returned directly to `regalloc2` eventually and all |
| // operands/results of instructions will use the alias-resolved vregs |
| // from `regalloc2`'s perspective. |
| // |
| // Also note that `reftyped_vregs` can't have duplicates, so after the |
| // aliases are applied duplicates are removed. |
| for reg in self.vcode.reftyped_vregs.iter_mut() { |
| *reg = Self::resolve_vreg_alias_impl(&self.vcode.vreg_aliases, *reg); |
| } |
| self.vcode.reftyped_vregs.sort(); |
| self.vcode.reftyped_vregs.dedup(); |
| |
| self.compute_preds_from_succs(); |
| self.vcode.debug_value_labels.sort_unstable(); |
| self.vcode |
| } |
| } |
| |
| /// Is this type a reference type? |
| fn is_reftype(ty: Type) -> bool { |
| ty == types::R64 || ty == types::R32 |
| } |
| |
| impl<I: VCodeInst> VCode<I> { |
| /// New empty VCode. |
| fn new( |
| sigs: SigSet, |
| abi: Callee<I::ABIMachineSpec>, |
| emit_info: I::Info, |
| block_order: BlockLoweringOrder, |
| constants: VCodeConstants, |
| ) -> VCode<I> { |
| let n_blocks = block_order.lowered_order().len(); |
| VCode { |
| sigs, |
| vreg_types: vec![], |
| insts: Vec::with_capacity(10 * n_blocks), |
| operands: Vec::with_capacity(30 * n_blocks), |
| operand_ranges: Vec::with_capacity(10 * n_blocks), |
| clobbers: FxHashMap::default(), |
| is_move: FxHashMap::default(), |
| srclocs: Vec::with_capacity(10 * n_blocks), |
| entry: BlockIndex::new(0), |
| block_ranges: Vec::with_capacity(n_blocks), |
| block_succ_range: Vec::with_capacity(n_blocks), |
| block_succs_preds: Vec::with_capacity(2 * n_blocks), |
| block_pred_range: Vec::with_capacity(n_blocks), |
| block_params_range: Vec::with_capacity(n_blocks), |
| block_params: Vec::with_capacity(5 * n_blocks), |
| branch_block_args: Vec::with_capacity(10 * n_blocks), |
| branch_block_arg_range: Vec::with_capacity(2 * n_blocks), |
| branch_block_arg_succ_range: Vec::with_capacity(n_blocks), |
| block_order, |
| abi, |
| emit_info, |
| reftyped_vregs: vec![], |
| constants, |
| debug_value_labels: vec![], |
| vreg_aliases: FxHashMap::with_capacity_and_hasher(10 * n_blocks, Default::default()), |
| } |
| } |
| |
| /// Get the number of blocks. Block indices will be in the range `0 .. |
| /// (self.num_blocks() - 1)`. |
| pub fn num_blocks(&self) -> usize { |
| self.block_ranges.len() |
| } |
| |
| /// The number of lowered instructions. |
| pub fn num_insts(&self) -> usize { |
| self.insts.len() |
| } |
| |
| /// Get the successors for a block. |
| pub fn succs(&self, block: BlockIndex) -> &[BlockIndex] { |
| let (start, end) = self.block_succ_range[block.index()]; |
| &self.block_succs_preds[start as usize..end as usize] |
| } |
| |
| fn compute_clobbers(&self, regalloc: ®alloc2::Output) -> Vec<Writable<RealReg>> { |
| // Compute clobbered registers. |
| let mut clobbered = vec![]; |
| let mut clobbered_set = FxHashSet::default(); |
| |
| // All moves are included in clobbers. |
| for edit in ®alloc.edits { |
| let Edit::Move { to, .. } = edit.1; |
| if let Some(preg) = to.as_reg() { |
| let reg = RealReg::from(preg); |
| if clobbered_set.insert(reg) { |
| clobbered.push(Writable::from_reg(reg)); |
| } |
| } |
| } |
| |
| for (i, (start, end)) in self.operand_ranges.iter().enumerate() { |
| // Skip this instruction if not "included in clobbers" as |
| // per the MachInst. (Some backends use this to implement |
| // ABI specifics; e.g., excluding calls of the same ABI as |
| // the current function from clobbers, because by |
| // definition everything clobbered by the call can be |
| // clobbered by this function without saving as well.) |
| if !self.insts[i].is_included_in_clobbers() { |
| continue; |
| } |
| |
| let start = *start as usize; |
| let end = *end as usize; |
| let operands = &self.operands[start..end]; |
| let allocs = ®alloc.allocs[start..end]; |
| for (operand, alloc) in operands.iter().zip(allocs.iter()) { |
| // We're interested only in writes (Mods or Defs). |
| if operand.kind() == OperandKind::Use { |
| continue; |
| } |
| if let Some(preg) = alloc.as_reg() { |
| let reg = RealReg::from(preg); |
| if clobbered_set.insert(reg) { |
| clobbered.push(Writable::from_reg(reg)); |
| } |
| } |
| } |
| |
| // Also add explicitly-clobbered registers. |
| for preg in self |
| .clobbers |
| .get(&InsnIndex::new(i)) |
| .cloned() |
| .unwrap_or_default() |
| { |
| let reg = RealReg::from(preg); |
| if clobbered_set.insert(reg) { |
| clobbered.push(Writable::from_reg(reg)); |
| } |
| } |
| } |
| |
| clobbered |
| } |
| |
| /// Emit the instructions to a `MachBuffer`, containing fixed-up |
| /// code and external reloc/trap/etc. records ready for use. Takes |
| /// the regalloc results as well. |
| /// |
| /// Returns the machine code itself, and optionally metadata |
| /// and/or a disassembly, as an `EmitResult`. The `VCode` itself |
| /// is consumed by the emission process. |
| pub fn emit( |
| mut self, |
| regalloc: ®alloc2::Output, |
| want_disasm: bool, |
| want_metadata: bool, |
| ) -> EmitResult<I> |
| where |
| I: VCodeInst, |
| { |
| // To write into disasm string. |
| use core::fmt::Write; |
| |
| let _tt = timing::vcode_emit(); |
| let mut buffer = MachBuffer::new(); |
| let mut bb_starts: Vec<Option<CodeOffset>> = vec![]; |
| |
| // The first M MachLabels are reserved for block indices, the next N MachLabels for |
| // constants. |
| buffer.reserve_labels_for_blocks(self.num_blocks()); |
| buffer.reserve_labels_for_constants(&self.constants); |
| |
| // Construct the final order we emit code in: cold blocks at the end. |
| let mut final_order: SmallVec<[BlockIndex; 16]> = smallvec![]; |
| let mut cold_blocks: SmallVec<[BlockIndex; 16]> = smallvec![]; |
| for block in 0..self.num_blocks() { |
| let block = BlockIndex::new(block); |
| if self.block_order.is_cold(block) { |
| cold_blocks.push(block); |
| } else { |
| final_order.push(block); |
| } |
| } |
| final_order.extend(cold_blocks.clone()); |
| |
| // Compute/save info we need for the prologue: clobbers and |
| // number of spillslots. |
| // |
| // We clone `abi` here because we will mutate it as we |
| // generate the prologue and set other info, but we can't |
| // mutate `VCode`. The info it usually carries prior to |
| // setting clobbers is fairly minimal so this should be |
| // relatively cheap. |
| let clobbers = self.compute_clobbers(regalloc); |
| self.abi.set_num_spillslots(regalloc.num_spillslots); |
| self.abi.set_clobbered(clobbers); |
| |
| // We need to generate the prologue in order to get the ABI |
| // object into the right state first. We'll emit it when we |
| // hit the right block below. |
| let prologue_insts = self.abi.gen_prologue(&self.sigs); |
| |
| // Emit blocks. |
| let mut cur_srcloc = None; |
| let mut last_offset = None; |
| let mut inst_offsets = vec![]; |
| let mut state = I::State::new(&self.abi); |
| |
| let mut disasm = String::new(); |
| |
| if !self.debug_value_labels.is_empty() { |
| inst_offsets.resize(self.insts.len(), 0); |
| } |
| |
| // Count edits per block ahead of time; this is needed for |
| // lookahead island emission. (We could derive it per-block |
| // with binary search in the edit list, but it's more |
| // efficient to do it in one pass here.) |
| let mut ra_edits_per_block: SmallVec<[u32; 64]> = smallvec![]; |
| let mut edit_idx = 0; |
| for block in 0..self.num_blocks() { |
| let end_inst = self.block_ranges[block].1; |
| let start_edit_idx = edit_idx; |
| while edit_idx < regalloc.edits.len() && regalloc.edits[edit_idx].0.inst() < end_inst { |
| edit_idx += 1; |
| } |
| let end_edit_idx = edit_idx; |
| ra_edits_per_block.push((end_edit_idx - start_edit_idx) as u32); |
| } |
| |
| let is_forward_edge_cfi_enabled = self.abi.is_forward_edge_cfi_enabled(); |
| |
| for (block_order_idx, &block) in final_order.iter().enumerate() { |
| trace!("emitting block {:?}", block); |
| let new_offset = I::align_basic_block(buffer.cur_offset()); |
| while new_offset > buffer.cur_offset() { |
| // Pad with NOPs up to the aligned block offset. |
| let nop = I::gen_nop((new_offset - buffer.cur_offset()) as usize); |
| nop.emit(&[], &mut buffer, &self.emit_info, &mut Default::default()); |
| } |
| assert_eq!(buffer.cur_offset(), new_offset); |
| |
| let do_emit = |inst: &I, |
| allocs: &[Allocation], |
| disasm: &mut String, |
| buffer: &mut MachBuffer<I>, |
| state: &mut I::State| { |
| if want_disasm && !inst.is_args() { |
| let mut s = state.clone(); |
| writeln!(disasm, " {}", inst.pretty_print_inst(allocs, &mut s)).unwrap(); |
| } |
| inst.emit(allocs, buffer, &self.emit_info, state); |
| }; |
| |
| // Is this the first block? Emit the prologue directly if so. |
| if block == self.entry { |
| trace!(" -> entry block"); |
| buffer.start_srcloc(Default::default()); |
| state.pre_sourceloc(Default::default()); |
| for inst in &prologue_insts { |
| do_emit(&inst, &[], &mut disasm, &mut buffer, &mut state); |
| } |
| buffer.end_srcloc(); |
| } |
| |
| // Now emit the regular block body. |
| |
| buffer.bind_label(MachLabel::from_block(block)); |
| |
| if want_disasm { |
| writeln!(&mut disasm, "block{}:", block.index()).unwrap(); |
| } |
| |
| if want_metadata { |
| // Track BB starts. If we have backed up due to MachBuffer |
| // branch opts, note that the removed blocks were removed. |
| let cur_offset = buffer.cur_offset(); |
| if last_offset.is_some() && cur_offset <= last_offset.unwrap() { |
| for i in (0..bb_starts.len()).rev() { |
| if bb_starts[i].is_some() && cur_offset > bb_starts[i].unwrap() { |
| break; |
| } |
| bb_starts[i] = None; |
| } |
| } |
| bb_starts.push(Some(cur_offset)); |
| last_offset = Some(cur_offset); |
| } |
| |
| if let Some(block_start) = I::gen_block_start( |
| self.block_order.is_indirect_branch_target(block), |
| is_forward_edge_cfi_enabled, |
| ) { |
| do_emit(&block_start, &[], &mut disasm, &mut buffer, &mut state); |
| } |
| |
| for inst_or_edit in regalloc.block_insts_and_edits(&self, block) { |
| match inst_or_edit { |
| InstOrEdit::Inst(iix) => { |
| if !self.debug_value_labels.is_empty() { |
| // If we need to produce debug info, |
| // record the offset of each instruction |
| // so that we can translate value-label |
| // ranges to machine-code offsets. |
| |
| // Cold blocks violate monotonicity |
| // assumptions elsewhere (that |
| // instructions in inst-index order are in |
| // order in machine code), so we omit |
| // their offsets here. Value-label range |
| // generation below will skip empty ranges |
| // and ranges with to-offsets of zero. |
| if !self.block_order.is_cold(block) { |
| inst_offsets[iix.index()] = buffer.cur_offset(); |
| } |
| } |
| |
| if self.insts[iix.index()].is_move().is_some() { |
| // Skip moves in the pre-regalloc program; |
| // all of these are incorporated by the |
| // regalloc into its unified move handling |
| // and they come out the other end, if |
| // still needed (not elided), as |
| // regalloc-inserted moves. |
| continue; |
| } |
| |
| // Update the srcloc at this point in the buffer. |
| let srcloc = self.srclocs[iix.index()]; |
| if cur_srcloc != Some(srcloc) { |
| if cur_srcloc.is_some() { |
| buffer.end_srcloc(); |
| } |
| buffer.start_srcloc(srcloc); |
| cur_srcloc = Some(srcloc); |
| } |
| state.pre_sourceloc(cur_srcloc.unwrap_or_default()); |
| |
| // If this is a safepoint, compute a stack map |
| // and pass it to the emit state. |
| if self.insts[iix.index()].is_safepoint() { |
| let mut safepoint_slots: SmallVec<[SpillSlot; 8]> = smallvec![]; |
| // Find the contiguous range of |
| // (progpoint, allocation) safepoint slot |
| // records in `regalloc.safepoint_slots` |
| // for this instruction index. |
| let safepoint_slots_start = regalloc |
| .safepoint_slots |
| .binary_search_by(|(progpoint, _alloc)| { |
| if progpoint.inst() >= iix { |
| std::cmp::Ordering::Greater |
| } else { |
| std::cmp::Ordering::Less |
| } |
| }) |
| .unwrap_err(); |
| |
| for (_, alloc) in regalloc.safepoint_slots[safepoint_slots_start..] |
| .iter() |
| .take_while(|(progpoint, _)| progpoint.inst() == iix) |
| { |
| let slot = alloc.as_stack().unwrap(); |
| safepoint_slots.push(slot); |
| } |
| if !safepoint_slots.is_empty() { |
| let stack_map = self |
| .abi |
| .spillslots_to_stack_map(&safepoint_slots[..], &state); |
| state.pre_safepoint(stack_map); |
| } |
| } |
| |
| // Get the allocations for this inst from the regalloc result. |
| let allocs = regalloc.inst_allocs(iix); |
| |
| // If the instruction we are about to emit is |
| // a return, place an epilogue at this point |
| // (and don't emit the return; the actual |
| // epilogue will contain it). |
| if self.insts[iix.index()].is_term() == MachTerminator::Ret { |
| for inst in self.abi.gen_epilogue() { |
| do_emit(&inst, &[], &mut disasm, &mut buffer, &mut state); |
| } |
| } else { |
| // Emit the instruction! |
| do_emit( |
| &self.insts[iix.index()], |
| allocs, |
| &mut disasm, |
| &mut buffer, |
| &mut state, |
| ); |
| } |
| } |
| |
| InstOrEdit::Edit(Edit::Move { from, to }) => { |
| // Create a move/spill/reload instruction and |
| // immediately emit it. |
| match (from.as_reg(), to.as_reg()) { |
| (Some(from), Some(to)) => { |
| // Reg-to-reg move. |
| let from_rreg = Reg::from(from); |
| let to_rreg = Writable::from_reg(Reg::from(to)); |
| debug_assert_eq!(from.class(), to.class()); |
| let ty = I::canonical_type_for_rc(from.class()); |
| let mv = I::gen_move(to_rreg, from_rreg, ty); |
| do_emit(&mv, &[], &mut disasm, &mut buffer, &mut state); |
| } |
| (Some(from), None) => { |
| // Spill from register to spillslot. |
| let to = to.as_stack().unwrap(); |
| let from_rreg = RealReg::from(from); |
| let spill = self.abi.gen_spill(to, from_rreg); |
| do_emit(&spill, &[], &mut disasm, &mut buffer, &mut state); |
| } |
| (None, Some(to)) => { |
| // Load from spillslot to register. |
| let from = from.as_stack().unwrap(); |
| let to_rreg = Writable::from_reg(RealReg::from(to)); |
| let reload = self.abi.gen_reload(to_rreg, from); |
| do_emit(&reload, &[], &mut disasm, &mut buffer, &mut state); |
| } |
| (None, None) => { |
| panic!("regalloc2 should have eliminated stack-to-stack moves!"); |
| } |
| } |
| } |
| } |
| } |
| |
| if cur_srcloc.is_some() { |
| buffer.end_srcloc(); |
| cur_srcloc = None; |
| } |
| |
| // Do we need an island? Get the worst-case size of the |
| // next BB and see if, having emitted that many bytes, we |
| // will be beyond the deadline. |
| if block_order_idx < final_order.len() - 1 { |
| let next_block = final_order[block_order_idx + 1]; |
| let next_block_range = self.block_ranges[next_block.index()]; |
| let next_block_size = |
| (next_block_range.1.index() - next_block_range.0.index()) as u32; |
| let next_block_ra_insertions = ra_edits_per_block[next_block.index()]; |
| let worst_case_next_bb = |
| I::worst_case_size() * (next_block_size + next_block_ra_insertions); |
| if buffer.island_needed(worst_case_next_bb) { |
| buffer.emit_island(worst_case_next_bb); |
| } |
| } |
| } |
| |
| // Emit the constants used by the function. |
| let mut alignment = 1; |
| for (constant, data) in self.constants.iter() { |
| alignment = data.alignment().max(alignment); |
| |
| let label = buffer.get_label_for_constant(constant); |
| buffer.defer_constant(label, data.alignment(), data.as_slice(), u32::max_value()); |
| } |
| |
| let func_body_len = buffer.cur_offset(); |
| |
| // Create `bb_edges` and final (filtered) `bb_starts`. |
| let mut bb_edges = vec![]; |
| let mut bb_offsets = vec![]; |
| if want_metadata { |
| for block in 0..self.num_blocks() { |
| if bb_starts[block].is_none() { |
| // Block was deleted by MachBuffer; skip. |
| continue; |
| } |
| let from = bb_starts[block].unwrap(); |
| |
| bb_offsets.push(from); |
| // Resolve each `succ` label and add edges. |
| let succs = self.block_succs(BlockIndex::new(block)); |
| for &succ in succs.iter() { |
| let to = buffer.resolve_label_offset(MachLabel::from_block(succ)); |
| bb_edges.push((from, to)); |
| } |
| } |
| } |
| |
| let value_labels_ranges = |
| self.compute_value_labels_ranges(regalloc, &inst_offsets[..], func_body_len); |
| let frame_size = self.abi.frame_size(); |
| |
| EmitResult { |
| buffer, |
| bb_offsets, |
| bb_edges, |
| inst_offsets, |
| func_body_len, |
| disasm: if want_disasm { Some(disasm) } else { None }, |
| sized_stackslot_offsets: self.abi.sized_stackslot_offsets().clone(), |
| dynamic_stackslot_offsets: self.abi.dynamic_stackslot_offsets().clone(), |
| value_labels_ranges, |
| frame_size, |
| alignment, |
| } |
| } |
| |
| fn compute_value_labels_ranges( |
| &self, |
| regalloc: ®alloc2::Output, |
| inst_offsets: &[CodeOffset], |
| func_body_len: u32, |
| ) -> ValueLabelsRanges { |
| if self.debug_value_labels.is_empty() { |
| return ValueLabelsRanges::default(); |
| } |
| |
| let mut value_labels_ranges: ValueLabelsRanges = HashMap::new(); |
| for &(label, from, to, alloc) in ®alloc.debug_locations { |
| let ranges = value_labels_ranges |
| .entry(ValueLabel::from_u32(label)) |
| .or_insert_with(|| vec![]); |
| let from_offset = inst_offsets[from.inst().index()]; |
| let to_offset = if to.inst().index() == inst_offsets.len() { |
| func_body_len |
| } else { |
| inst_offsets[to.inst().index()] |
| }; |
| |
| // Empty range or to-offset of zero can happen because of |
| // cold blocks (see above). |
| if to_offset == 0 || from_offset == to_offset { |
| continue; |
| } |
| |
| let loc = if let Some(preg) = alloc.as_reg() { |
| LabelValueLoc::Reg(Reg::from(preg)) |
| } else { |
| // We can't translate spillslot locations at the |
| // moment because ValueLabelLoc requires an |
| // instantaneous SP offset, and this can *change* |
| // within the range we have here because of callsites |
| // adjusting SP temporarily. To avoid the complexity |
| // of accurately plumbing through nominal-SP |
| // adjustment sites, we just omit debug info for |
| // values that are spilled. Not ideal, but debug info |
| // is best-effort. |
| continue; |
| }; |
| |
| ranges.push(ValueLocRange { |
| loc, |
| // ValueLocRanges are recorded by *instruction-end |
| // offset*. `from_offset` is the *start* of the |
| // instruction; that is the same as the end of another |
| // instruction, so we only want to begin coverage once |
| // we are past the previous instruction's end. |
| start: from_offset + 1, |
| // Likewise, `end` is exclusive, but we want to |
| // *include* the end of the last |
| // instruction. `to_offset` is the start of the |
| // `to`-instruction, which is the exclusive end, i.e., |
| // the first instruction not covered. That |
| // instruction's start is the same as the end of the |
| // last instruction that is included, so we go one |
| // byte further to be sure to include it. |
| end: to_offset + 1, |
| }); |
| } |
| |
| value_labels_ranges |
| } |
| |
| /// Get the IR block for a BlockIndex, if one exists. |
| pub fn bindex_to_bb(&self, block: BlockIndex) -> Option<ir::Block> { |
| self.block_order.lowered_order()[block.index()].orig_block() |
| } |
| |
| #[inline] |
| fn assert_no_vreg_aliases<'a>(&self, list: &'a [VReg]) -> &'a [VReg] { |
| for vreg in list { |
| self.assert_not_vreg_alias(*vreg); |
| } |
| list |
| } |
| |
| #[inline] |
| fn assert_not_vreg_alias(&self, vreg: VReg) -> VReg { |
| debug_assert!(VCodeBuilder::<I>::resolve_vreg_alias_impl(&self.vreg_aliases, vreg) == vreg); |
| vreg |
| } |
| |
| #[inline] |
| fn assert_operand_not_vreg_alias(&self, op: Operand) -> Operand { |
| // It should be true by construction that `Operand`s do not contain any |
| // aliased vregs since they're all collected and mapped when the VCode |
| // is itself constructed. |
| self.assert_not_vreg_alias(op.vreg()); |
| op |
| } |
| } |
| |
| impl<I: VCodeInst> RegallocFunction for VCode<I> { |
| fn num_insts(&self) -> usize { |
| self.insts.len() |
| } |
| |
| fn num_blocks(&self) -> usize { |
| self.block_ranges.len() |
| } |
| |
| fn entry_block(&self) -> BlockIndex { |
| self.entry |
| } |
| |
| fn block_insns(&self, block: BlockIndex) -> InstRange { |
| let (start, end) = self.block_ranges[block.index()]; |
| InstRange::forward(start, end) |
| } |
| |
| fn block_succs(&self, block: BlockIndex) -> &[BlockIndex] { |
| let (start, end) = self.block_succ_range[block.index()]; |
| &self.block_succs_preds[start as usize..end as usize] |
| } |
| |
| fn block_preds(&self, block: BlockIndex) -> &[BlockIndex] { |
| let (start, end) = self.block_pred_range[block.index()]; |
| &self.block_succs_preds[start as usize..end as usize] |
| } |
| |
| fn block_params(&self, block: BlockIndex) -> &[VReg] { |
| // As a special case we don't return block params for the entry block, as all the arguments |
| // will be defined by the `Inst::Args` instruction. |
| if block == self.entry { |
| return &[]; |
| } |
| |
| let (start, end) = self.block_params_range[block.index()]; |
| let ret = &self.block_params[start as usize..end as usize]; |
| // Currently block params are never aliased to another vreg, but |
| // double-check just to be sure. |
| self.assert_no_vreg_aliases(ret) |
| } |
| |
| fn branch_blockparams(&self, block: BlockIndex, _insn: InsnIndex, succ_idx: usize) -> &[VReg] { |
| let (succ_range_start, succ_range_end) = self.branch_block_arg_succ_range[block.index()]; |
| let succ_ranges = |
| &self.branch_block_arg_range[succ_range_start as usize..succ_range_end as usize]; |
| let (branch_block_args_start, branch_block_args_end) = succ_ranges[succ_idx]; |
| let ret = &self.branch_block_args |
| [branch_block_args_start as usize..branch_block_args_end as usize]; |
| self.assert_no_vreg_aliases(ret) |
| } |
| |
| fn is_ret(&self, insn: InsnIndex) -> bool { |
| match self.insts[insn.index()].is_term() { |
| // We treat blocks terminated by an unconditional trap like a return for regalloc. |
| MachTerminator::None => self.insts[insn.index()].is_trap(), |
| MachTerminator::Ret => true, |
| _ => false, |
| } |
| } |
| |
| fn is_branch(&self, insn: InsnIndex) -> bool { |
| match self.insts[insn.index()].is_term() { |
| MachTerminator::Cond | MachTerminator::Uncond | MachTerminator::Indirect => true, |
| _ => false, |
| } |
| } |
| |
| fn requires_refs_on_stack(&self, insn: InsnIndex) -> bool { |
| self.insts[insn.index()].is_safepoint() |
| } |
| |
| fn is_move(&self, insn: InsnIndex) -> Option<(Operand, Operand)> { |
| let (a, b) = self.is_move.get(&insn)?; |
| Some(( |
| self.assert_operand_not_vreg_alias(*a), |
| self.assert_operand_not_vreg_alias(*b), |
| )) |
| } |
| |
| fn inst_operands(&self, insn: InsnIndex) -> &[Operand] { |
| let (start, end) = self.operand_ranges[insn.index()]; |
| let ret = &self.operands[start as usize..end as usize]; |
| for op in ret { |
| self.assert_operand_not_vreg_alias(*op); |
| } |
| ret |
| } |
| |
| fn inst_clobbers(&self, insn: InsnIndex) -> PRegSet { |
| self.clobbers.get(&insn).cloned().unwrap_or_default() |
| } |
| |
| fn num_vregs(&self) -> usize { |
| std::cmp::max(self.vreg_types.len(), first_user_vreg_index()) |
| } |
| |
| fn reftype_vregs(&self) -> &[VReg] { |
| self.assert_no_vreg_aliases(&self.reftyped_vregs[..]) |
| } |
| |
| fn debug_value_labels(&self) -> &[(VReg, InsnIndex, InsnIndex, u32)] { |
| // VRegs here are inserted into `debug_value_labels` after code is |
| // generated and aliases are fully defined, so no double-check that |
| // aliases are not lingering. |
| for (vreg, ..) in self.debug_value_labels.iter() { |
| self.assert_not_vreg_alias(*vreg); |
| } |
| &self.debug_value_labels[..] |
| } |
| |
| fn is_pinned_vreg(&self, vreg: VReg) -> Option<PReg> { |
| pinned_vreg_to_preg(vreg) |
| } |
| |
| fn spillslot_size(&self, regclass: RegClass) -> usize { |
| self.abi.get_spillslot_size(regclass) as usize |
| } |
| |
| fn allow_multiple_vreg_defs(&self) -> bool { |
| // At least the s390x backend requires this, because the |
| // `Loop` pseudo-instruction aggregates all Operands so pinned |
| // vregs (RealRegs) may occur more than once. |
| true |
| } |
| } |
| |
| impl<I: VCodeInst> fmt::Debug for VCode<I> { |
| fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { |
| writeln!(f, "VCode {{")?; |
| writeln!(f, " Entry block: {}", self.entry.index())?; |
| |
| let mut state = Default::default(); |
| |
| let mut alias_keys = self.vreg_aliases.keys().cloned().collect::<Vec<_>>(); |
| alias_keys.sort_unstable(); |
| for key in alias_keys { |
| let dest = self.vreg_aliases.get(&key).unwrap(); |
| writeln!(f, " {:?} := {:?}", Reg::from(key), Reg::from(*dest))?; |
| } |
| |
| for block in 0..self.num_blocks() { |
| let block = BlockIndex::new(block); |
| writeln!(f, "Block {}:", block.index())?; |
| if let Some(bb) = self.bindex_to_bb(block) { |
| writeln!(f, " (original IR block: {})", bb)?; |
| } |
| for succ in self.succs(block) { |
| writeln!(f, " (successor: Block {})", succ.index())?; |
| } |
| let (start, end) = self.block_ranges[block.index()]; |
| writeln!( |
| f, |
| " (instruction range: {} .. {})", |
| start.index(), |
| end.index() |
| )?; |
| for inst in start.index()..end.index() { |
| writeln!( |
| f, |
| " Inst {}: {}", |
| inst, |
| self.insts[inst].pretty_print_inst(&[], &mut state) |
| )?; |
| } |
| } |
| |
| writeln!(f, "}}")?; |
| Ok(()) |
| } |
| } |
| |
| /// This structure manages VReg allocation during the lifetime of the VCodeBuilder. |
| pub struct VRegAllocator<I> { |
| /// Next virtual register number to allocate. |
| next_vreg: usize, |
| |
| /// VReg IR-level types. |
| vreg_types: Vec<Type>, |
| |
| /// A set with the same contents as `reftyped_vregs`, in order to |
| /// avoid inserting more than once. |
| reftyped_vregs_set: FxHashSet<VReg>, |
| |
| /// Reference-typed `regalloc2::VReg`s. The regalloc requires |
| /// these in a dense slice (as opposed to querying the |
| /// reftype-status of each vreg) for efficient iteration. |
| reftyped_vregs: Vec<VReg>, |
| |
| /// The type of instruction that this allocator makes registers for. |
| _inst: core::marker::PhantomData<I>, |
| } |
| |
| impl<I: VCodeInst> VRegAllocator<I> { |
| /// Make a new VRegAllocator. |
| pub fn new() -> Self { |
| Self { |
| next_vreg: first_user_vreg_index(), |
| vreg_types: vec![], |
| reftyped_vregs_set: FxHashSet::default(), |
| reftyped_vregs: vec![], |
| _inst: core::marker::PhantomData::default(), |
| } |
| } |
| |
| /// Allocate a fresh ValueRegs. |
| pub fn alloc(&mut self, ty: Type) -> CodegenResult<ValueRegs<Reg>> { |
| let v = self.next_vreg; |
| let (regclasses, tys) = I::rc_for_type(ty)?; |
| self.next_vreg += regclasses.len(); |
| if self.next_vreg >= VReg::MAX { |
| return Err(CodegenError::CodeTooLarge); |
| } |
| |
| let regs: ValueRegs<Reg> = match regclasses { |
| &[rc0] => ValueRegs::one(VReg::new(v, rc0).into()), |
| &[rc0, rc1] => ValueRegs::two(VReg::new(v, rc0).into(), VReg::new(v + 1, rc1).into()), |
| // We can extend this if/when we support 32-bit targets; e.g., |
| // an i128 on a 32-bit machine will need up to four machine regs |
| // for a `Value`. |
| _ => panic!("Value must reside in 1 or 2 registers"), |
| }; |
| for (®_ty, ®) in tys.iter().zip(regs.regs().iter()) { |
| self.set_vreg_type(reg.to_virtual_reg().unwrap(), reg_ty); |
| } |
| Ok(regs) |
| } |
| |
| /// Set the type of this virtual register. |
| pub fn set_vreg_type(&mut self, vreg: VirtualReg, ty: Type) { |
| if self.vreg_types.len() <= vreg.index() { |
| self.vreg_types.resize(vreg.index() + 1, ir::types::INVALID); |
| } |
| self.vreg_types[vreg.index()] = ty; |
| if is_reftype(ty) { |
| let vreg: VReg = vreg.into(); |
| if self.reftyped_vregs_set.insert(vreg) { |
| self.reftyped_vregs.push(vreg); |
| } |
| } |
| } |
| } |
| |
| /// This structure tracks the large constants used in VCode that will be emitted separately by the |
| /// [MachBuffer]. |
| /// |
| /// First, during the lowering phase, constants are inserted using |
| /// [VCodeConstants.insert]; an intermediate handle, [VCodeConstant], tracks what constants are |
| /// used in this phase. Some deduplication is performed, when possible, as constant |
| /// values are inserted. |
| /// |
| /// Secondly, during the emission phase, the [MachBuffer] assigns [MachLabel]s for each of the |
| /// constants so that instructions can refer to the value's memory location. The [MachBuffer] |
| /// then writes the constant values to the buffer. |
| #[derive(Default)] |
| pub struct VCodeConstants { |
| constants: PrimaryMap<VCodeConstant, VCodeConstantData>, |
| pool_uses: HashMap<Constant, VCodeConstant>, |
| well_known_uses: HashMap<*const [u8], VCodeConstant>, |
| u64s: HashMap<[u8; 8], VCodeConstant>, |
| } |
| impl VCodeConstants { |
| /// Initialize the structure with the expected number of constants. |
| pub fn with_capacity(expected_num_constants: usize) -> Self { |
| Self { |
| constants: PrimaryMap::with_capacity(expected_num_constants), |
| pool_uses: HashMap::with_capacity(expected_num_constants), |
| well_known_uses: HashMap::new(), |
| u64s: HashMap::new(), |
| } |
| } |
| |
| /// Insert a constant; using this method indicates that a constant value will be used and thus |
| /// will be emitted to the `MachBuffer`. The current implementation can deduplicate constants |
| /// that are [VCodeConstantData::Pool] or [VCodeConstantData::WellKnown] but not |
| /// [VCodeConstantData::Generated]. |
| pub fn insert(&mut self, data: VCodeConstantData) -> VCodeConstant { |
| match data { |
| VCodeConstantData::Generated(_) => self.constants.push(data), |
| VCodeConstantData::Pool(constant, _) => match self.pool_uses.get(&constant) { |
| None => { |
| let vcode_constant = self.constants.push(data); |
| self.pool_uses.insert(constant, vcode_constant); |
| vcode_constant |
| } |
| Some(&vcode_constant) => vcode_constant, |
| }, |
| VCodeConstantData::WellKnown(data_ref) => { |
| match self.well_known_uses.entry(data_ref as *const [u8]) { |
| Entry::Vacant(v) => { |
| let vcode_constant = self.constants.push(data); |
| v.insert(vcode_constant); |
| vcode_constant |
| } |
| Entry::Occupied(o) => *o.get(), |
| } |
| } |
| VCodeConstantData::U64(value) => match self.u64s.entry(value) { |
| Entry::Vacant(v) => { |
| let vcode_constant = self.constants.push(data); |
| v.insert(vcode_constant); |
| vcode_constant |
| } |
| Entry::Occupied(o) => *o.get(), |
| }, |
| } |
| } |
| |
| /// Return the number of constants inserted. |
| pub fn len(&self) -> usize { |
| self.constants.len() |
| } |
| |
| /// Iterate over the [VCodeConstant] keys inserted in this structure. |
| pub fn keys(&self) -> Keys<VCodeConstant> { |
| self.constants.keys() |
| } |
| |
| /// Iterate over the [VCodeConstant] keys and the data (as a byte slice) inserted in this |
| /// structure. |
| pub fn iter(&self) -> impl Iterator<Item = (VCodeConstant, &VCodeConstantData)> { |
| self.constants.iter() |
| } |
| } |
| |
| /// A use of a constant by one or more VCode instructions; see [VCodeConstants]. |
| #[derive(Clone, Copy, Debug, PartialEq, Eq)] |
| pub struct VCodeConstant(u32); |
| entity_impl!(VCodeConstant); |
| |
| /// Identify the different types of constant that can be inserted into [VCodeConstants]. Tracking |
| /// these separately instead of as raw byte buffers allows us to avoid some duplication. |
| pub enum VCodeConstantData { |
| /// A constant already present in the Cranelift IR |
| /// [ConstantPool](crate::ir::constant::ConstantPool). |
| Pool(Constant, ConstantData), |
| /// A reference to a well-known constant value that is statically encoded within the compiler. |
| WellKnown(&'static [u8]), |
| /// A constant value generated during lowering; the value may depend on the instruction context |
| /// which makes it difficult to de-duplicate--if possible, use other variants. |
| Generated(ConstantData), |
| /// A constant of at most 64 bits. These are deduplicated as |
| /// well. Stored as a fixed-size array of `u8` so that we do not |
| /// encounter endianness problems when cross-compiling. |
| U64([u8; 8]), |
| } |
| impl VCodeConstantData { |
| /// Retrieve the constant data as a byte slice. |
| pub fn as_slice(&self) -> &[u8] { |
| match self { |
| VCodeConstantData::Pool(_, d) | VCodeConstantData::Generated(d) => d.as_slice(), |
| VCodeConstantData::WellKnown(d) => d, |
| VCodeConstantData::U64(value) => &value[..], |
| } |
| } |
| |
| /// Calculate the alignment of the constant data. |
| pub fn alignment(&self) -> u32 { |
| if self.as_slice().len() <= 8 { |
| 8 |
| } else { |
| 16 |
| } |
| } |
| } |
| |
| #[cfg(test)] |
| mod test { |
| use super::*; |
| use std::mem::size_of; |
| |
| #[test] |
| fn size_of_constant_structs() { |
| assert_eq!(size_of::<Constant>(), 4); |
| assert_eq!(size_of::<VCodeConstant>(), 4); |
| assert_eq!(size_of::<ConstantData>(), 24); |
| assert_eq!(size_of::<VCodeConstantData>(), 32); |
| assert_eq!( |
| size_of::<PrimaryMap<VCodeConstant, VCodeConstantData>>(), |
| 24 |
| ); |
| // TODO The VCodeConstants structure's memory size could be further optimized. |
| // With certain versions of Rust, each `HashMap` in `VCodeConstants` occupied at |
| // least 48 bytes, making an empty `VCodeConstants` cost 120 bytes. |
| } |
| } |
