fune/third_party/rust/cranelift-frontend/src/frontend.rs
Chris Fallin 35cf81d389 Bug 1648885 and Bug 1649432: vendor latest Cranelift to get Spectre mitigations and fix fuzzbug. r=bbouvier
This patch pulls in Cranelift revision
47a218f908e6bdeb7a0fb65ed74e58a0b608080d, which incorporates several
relevant changes:

- It includes the Spectre mitigation for explicit heap bounds checks
  merged in PR bytecodealliance/wasmtime#1930, resolving Bug 1648885.

- It includes the fix for an out-of-bounds subtraction on large shift
  amounts merged in PR bytecodealliance/wasmtime#1954, resolving Bug
  1649432.

We need to temporarily disable the `wasm/limits.js` jit-test on
Cranelift configurations because it now needs shared memory to work, and
the Cranelift backend does not support this yet. Given that this should
be ready in the next month at most (requires atomics support on AArch64,
which is currently being examined), it seems simpler to temporarily
disable the test on aarch64 than to try to disentangle the bits that
depend on shared memories explicitly.

This patch also edits the `regexp/bug1445907.js` jit-test to run only if
Wasm debugging is supported. This is needed for the test not to fail
with `--wasm-compiler=cranelift` (which disables Baseline, the only Wasm
compiler that supports debugging).

Differential Revision: https://phabricator.services.mozilla.com/D81936
2020-07-02 15:47:56 +00:00

1310 lines
47 KiB
Rust

//! A frontend for building Cranelift IR from other languages.
use crate::ssa::{SSABuilder, SideEffects};
use crate::variable::Variable;
use cranelift_codegen::cursor::{Cursor, FuncCursor};
use cranelift_codegen::entity::{EntitySet, SecondaryMap};
use cranelift_codegen::ir;
use cranelift_codegen::ir::function::DisplayFunction;
use cranelift_codegen::ir::{
types, AbiParam, Block, DataFlowGraph, ExtFuncData, ExternalName, FuncRef, Function,
GlobalValue, GlobalValueData, Heap, HeapData, Inst, InstBuilder, InstBuilderBase,
InstructionData, JumpTable, JumpTableData, LibCall, MemFlags, SigRef, Signature, StackSlot,
StackSlotData, Type, Value, ValueLabel, ValueLabelAssignments, ValueLabelStart,
};
use cranelift_codegen::isa::{TargetFrontendConfig, TargetIsa};
use cranelift_codegen::packed_option::PackedOption;
/// Structure used for translating a series of functions into Cranelift IR.
///
/// In order to reduce memory reallocations when compiling multiple functions,
/// `FunctionBuilderContext` holds various data structures which are cleared between
/// functions, rather than dropped, preserving the underlying allocations.
pub struct FunctionBuilderContext {
ssa: SSABuilder,
blocks: SecondaryMap<Block, BlockData>,
types: SecondaryMap<Variable, Type>,
}
/// Temporary object used to build a single Cranelift IR `Function`.
pub struct FunctionBuilder<'a> {
/// The function currently being built.
/// This field is public so the function can be re-borrowed.
pub func: &'a mut Function,
/// Source location to assign to all new instructions.
srcloc: ir::SourceLoc,
func_ctx: &'a mut FunctionBuilderContext,
position: PackedOption<Block>,
}
#[derive(Clone, Default)]
struct BlockData {
/// A Block is "pristine" iff no instructions have been added since the last
/// call to `switch_to_block()`.
pristine: bool,
/// A Block is "filled" iff a terminator instruction has been inserted since
/// the last call to `switch_to_block()`.
///
/// A filled block cannot be pristine.
filled: bool,
/// Count of parameters not supplied implicitly by the SSABuilder.
user_param_count: usize,
}
impl FunctionBuilderContext {
/// Creates a FunctionBuilderContext structure. The structure is automatically cleared after
/// each [`FunctionBuilder`](struct.FunctionBuilder.html) completes translating a function.
pub fn new() -> Self {
Self {
ssa: SSABuilder::new(),
blocks: SecondaryMap::new(),
types: SecondaryMap::new(),
}
}
fn clear(&mut self) {
self.ssa.clear();
self.blocks.clear();
self.types.clear();
}
fn is_empty(&self) -> bool {
self.ssa.is_empty() && self.blocks.is_empty() && self.types.is_empty()
}
}
/// Implementation of the [`InstBuilder`](cranelift_codegen::ir::InstBuilder) that has
/// one convenience method per Cranelift IR instruction.
pub struct FuncInstBuilder<'short, 'long: 'short> {
builder: &'short mut FunctionBuilder<'long>,
block: Block,
}
impl<'short, 'long> FuncInstBuilder<'short, 'long> {
fn new(builder: &'short mut FunctionBuilder<'long>, block: Block) -> Self {
Self { builder, block }
}
}
impl<'short, 'long> InstBuilderBase<'short> for FuncInstBuilder<'short, 'long> {
fn data_flow_graph(&self) -> &DataFlowGraph {
&self.builder.func.dfg
}
fn data_flow_graph_mut(&mut self) -> &mut DataFlowGraph {
&mut self.builder.func.dfg
}
// This implementation is richer than `InsertBuilder` because we use the data of the
// instruction being inserted to add related info to the DFG and the SSA building system,
// and perform debug sanity checks.
fn build(self, data: InstructionData, ctrl_typevar: Type) -> (Inst, &'short mut DataFlowGraph) {
// We only insert the Block in the layout when an instruction is added to it
self.builder.ensure_inserted_block();
let inst = self.builder.func.dfg.make_inst(data.clone());
self.builder.func.dfg.make_inst_results(inst, ctrl_typevar);
self.builder.func.layout.append_inst(inst, self.block);
if !self.builder.srcloc.is_default() {
self.builder.func.srclocs[inst] = self.builder.srcloc;
}
if data.opcode().is_branch() {
match data.branch_destination() {
Some(dest_block) => {
// If the user has supplied jump arguments we must adapt the arguments of
// the destination block
self.builder.declare_successor(dest_block, inst);
}
None => {
// branch_destination() doesn't detect jump_tables
// If jump table we declare all entries successor
if let InstructionData::BranchTable {
table, destination, ..
} = data
{
// Unlike all other jumps/branches, jump tables are
// capable of having the same successor appear
// multiple times, so we must deduplicate.
let mut unique = EntitySet::<Block>::new();
for dest_block in self
.builder
.func
.jump_tables
.get(table)
.expect("you are referencing an undeclared jump table")
.iter()
.filter(|&dest_block| unique.insert(*dest_block))
{
// Call `declare_block_predecessor` instead of `declare_successor` for
// avoiding the borrow checker.
self.builder.func_ctx.ssa.declare_block_predecessor(
*dest_block,
self.builder.position.unwrap(),
inst,
);
}
self.builder.declare_successor(destination, inst);
}
}
}
}
if data.opcode().is_terminator() {
self.builder.fill_current_block()
}
(inst, &mut self.builder.func.dfg)
}
}
/// This module allows you to create a function in Cranelift IR in a straightforward way, hiding
/// all the complexity of its internal representation.
///
/// The module is parametrized by one type which is the representation of variables in your
/// origin language. It offers a way to conveniently append instruction to your program flow.
/// You are responsible to split your instruction flow into extended blocks (declared with
/// `create_block`) whose properties are:
///
/// - branch and jump instructions can only point at the top of extended blocks;
/// - the last instruction of each block is a terminator instruction which has no natural successor,
/// and those instructions can only appear at the end of extended blocks.
///
/// The parameters of Cranelift IR instructions are Cranelift IR values, which can only be created
/// as results of other Cranelift IR instructions. To be able to create variables redefined multiple
/// times in your program, use the `def_var` and `use_var` command, that will maintain the
/// correspondence between your variables and Cranelift IR SSA values.
///
/// The first block for which you call `switch_to_block` will be assumed to be the beginning of
/// the function.
///
/// At creation, a `FunctionBuilder` instance borrows an already allocated `Function` which it
/// modifies with the information stored in the mutable borrowed
/// [`FunctionBuilderContext`](struct.FunctionBuilderContext.html). The function passed in
/// argument should be newly created with
/// [`Function::with_name_signature()`](Function::with_name_signature), whereas the
/// `FunctionBuilderContext` can be kept as is between two function translations.
///
/// # Errors
///
/// The functions below will panic in debug mode whenever you try to modify the Cranelift IR
/// function in a way that violate the coherence of the code. For instance: switching to a new
/// `Block` when you haven't filled the current one with a terminator instruction, inserting a
/// return instruction with arguments that don't match the function's signature.
impl<'a> FunctionBuilder<'a> {
/// Creates a new FunctionBuilder structure that will operate on a `Function` using a
/// `FunctionBuilderContext`.
pub fn new(func: &'a mut Function, func_ctx: &'a mut FunctionBuilderContext) -> Self {
debug_assert!(func_ctx.is_empty());
Self {
func,
srcloc: Default::default(),
func_ctx,
position: Default::default(),
}
}
/// Get the block that this builder is currently at.
pub fn current_block(&self) -> Option<Block> {
self.position.expand()
}
/// Set the source location that should be assigned to all new instructions.
pub fn set_srcloc(&mut self, srcloc: ir::SourceLoc) {
self.srcloc = srcloc;
}
/// Creates a new `Block` and returns its reference.
pub fn create_block(&mut self) -> Block {
let block = self.func.dfg.make_block();
self.func_ctx.ssa.declare_block(block);
self.func_ctx.blocks[block] = BlockData {
filled: false,
pristine: true,
user_param_count: 0,
};
block
}
/// Insert `block` in the layout *after* the existing block `after`.
pub fn insert_block_after(&mut self, block: Block, after: Block) {
self.func.layout.insert_block_after(block, after);
}
/// After the call to this function, new instructions will be inserted into the designated
/// block, in the order they are declared. You must declare the types of the Block arguments
/// you will use here.
///
/// When inserting the terminator instruction (which doesn't have a fallthrough to its immediate
/// successor), the block will be declared filled and it will not be possible to append
/// instructions to it.
pub fn switch_to_block(&mut self, block: Block) {
// First we check that the previous block has been filled.
debug_assert!(
self.position.is_none()
|| self.is_unreachable()
|| self.is_pristine()
|| self.is_filled(),
"you have to fill your block before switching"
);
// We cannot switch to a filled block
debug_assert!(
!self.func_ctx.blocks[block].filled,
"you cannot switch to a block which is already filled"
);
// Then we change the cursor position.
self.position = PackedOption::from(block);
}
/// Declares that all the predecessors of this block are known.
///
/// Function to call with `block` as soon as the last branch instruction to `block` has been
/// created. Forgetting to call this method on every block will cause inconsistencies in the
/// produced functions.
pub fn seal_block(&mut self, block: Block) {
let side_effects = self.func_ctx.ssa.seal_block(block, self.func);
self.handle_ssa_side_effects(side_effects);
}
/// Effectively calls seal_block on all unsealed blocks in the function.
///
/// It's more efficient to seal `Block`s as soon as possible, during
/// translation, but for frontends where this is impractical to do, this
/// function can be used at the end of translating all blocks to ensure
/// that everything is sealed.
pub fn seal_all_blocks(&mut self) {
let side_effects = self.func_ctx.ssa.seal_all_blocks(self.func);
self.handle_ssa_side_effects(side_effects);
}
/// In order to use a variable in a `use_var`, you need to declare its type with this method.
pub fn declare_var(&mut self, var: Variable, ty: Type) {
debug_assert_eq!(
self.func_ctx.types[var],
types::INVALID,
"variable {:?} is declared twice",
var
);
self.func_ctx.types[var] = ty;
}
/// Returns the Cranelift IR value corresponding to the utilization at the current program
/// position of a previously defined user variable.
pub fn use_var(&mut self, var: Variable) -> Value {
let (val, side_effects) = {
let ty = *self.func_ctx.types.get(var).unwrap_or_else(|| {
panic!(
"variable {:?} is used but its type has not been declared",
var
)
});
debug_assert_ne!(
ty,
types::INVALID,
"variable {:?} is used but its type has not been declared",
var
);
self.func_ctx
.ssa
.use_var(self.func, var, ty, self.position.unwrap())
};
self.handle_ssa_side_effects(side_effects);
val
}
/// Register a new definition of a user variable. The type of the value must be
/// the same as the type registered for the variable.
pub fn def_var(&mut self, var: Variable, val: Value) {
debug_assert_eq!(
*self.func_ctx.types.get(var).unwrap_or_else(|| panic!(
"variable {:?} is used but its type has not been declared",
var
)),
self.func.dfg.value_type(val),
"declared type of variable {:?} doesn't match type of value {}",
var,
val
);
self.func_ctx.ssa.def_var(var, val, self.position.unwrap());
}
/// Set label for Value
///
/// This will not do anything unless `func.dfg.collect_debug_info` is called first.
pub fn set_val_label(&mut self, val: Value, label: ValueLabel) {
if let Some(values_labels) = self.func.dfg.values_labels.as_mut() {
use crate::hash_map::Entry;
let start = ValueLabelStart {
from: self.srcloc,
label,
};
match values_labels.entry(val) {
Entry::Occupied(mut e) => match e.get_mut() {
ValueLabelAssignments::Starts(starts) => starts.push(start),
_ => panic!("Unexpected ValueLabelAssignments at this stage"),
},
Entry::Vacant(e) => {
e.insert(ValueLabelAssignments::Starts(vec![start]));
}
}
}
}
/// Creates a jump table in the function, to be used by `br_table` instructions.
pub fn create_jump_table(&mut self, data: JumpTableData) -> JumpTable {
self.func.create_jump_table(data)
}
/// Creates a stack slot in the function, to be used by `stack_load`, `stack_store` and
/// `stack_addr` instructions.
pub fn create_stack_slot(&mut self, data: StackSlotData) -> StackSlot {
self.func.create_stack_slot(data)
}
/// Adds a signature which can later be used to declare an external function import.
pub fn import_signature(&mut self, signature: Signature) -> SigRef {
self.func.import_signature(signature)
}
/// Declare an external function import.
pub fn import_function(&mut self, data: ExtFuncData) -> FuncRef {
self.func.import_function(data)
}
/// Declares a global value accessible to the function.
pub fn create_global_value(&mut self, data: GlobalValueData) -> GlobalValue {
self.func.create_global_value(data)
}
/// Declares a heap accessible to the function.
pub fn create_heap(&mut self, data: HeapData) -> Heap {
self.func.create_heap(data)
}
/// Returns an object with the [`InstBuilder`](cranelift_codegen::ir::InstBuilder)
/// trait that allows to conveniently append an instruction to the current `Block` being built.
pub fn ins<'short>(&'short mut self) -> FuncInstBuilder<'short, 'a> {
let block = self
.position
.expect("Please call switch_to_block before inserting instructions");
FuncInstBuilder::new(self, block)
}
/// Make sure that the current block is inserted in the layout.
pub fn ensure_inserted_block(&mut self) {
let block = self.position.unwrap();
if self.func_ctx.blocks[block].pristine {
if !self.func.layout.is_block_inserted(block) {
self.func.layout.append_block(block);
}
self.func_ctx.blocks[block].pristine = false;
} else {
debug_assert!(
!self.func_ctx.blocks[block].filled,
"you cannot add an instruction to a block already filled"
);
}
}
/// Returns a `FuncCursor` pointed at the current position ready for inserting instructions.
///
/// This can be used to insert SSA code that doesn't need to access locals and that doesn't
/// need to know about `FunctionBuilder` at all.
pub fn cursor(&mut self) -> FuncCursor {
self.ensure_inserted_block();
FuncCursor::new(self.func)
.with_srcloc(self.srcloc)
.at_bottom(self.position.unwrap())
}
/// Append parameters to the given `Block` corresponding to the function
/// parameters. This can be used to set up the block parameters for the
/// entry block.
pub fn append_block_params_for_function_params(&mut self, block: Block) {
debug_assert!(
!self.func_ctx.ssa.has_any_predecessors(block),
"block parameters for function parameters should only be added to the entry block"
);
// These parameters count as "user" parameters here because they aren't
// inserted by the SSABuilder.
let user_param_count = &mut self.func_ctx.blocks[block].user_param_count;
for argtyp in &self.func.signature.params {
*user_param_count += 1;
self.func.dfg.append_block_param(block, argtyp.value_type);
}
}
/// Append parameters to the given `Block` corresponding to the function
/// return values. This can be used to set up the block parameters for a
/// function exit block.
pub fn append_block_params_for_function_returns(&mut self, block: Block) {
// These parameters count as "user" parameters here because they aren't
// inserted by the SSABuilder.
let user_param_count = &mut self.func_ctx.blocks[block].user_param_count;
for argtyp in &self.func.signature.returns {
*user_param_count += 1;
self.func.dfg.append_block_param(block, argtyp.value_type);
}
}
/// Declare that translation of the current function is complete. This
/// resets the state of the `FunctionBuilder` in preparation to be used
/// for another function.
pub fn finalize(&mut self) {
// Check that all the `Block`s are filled and sealed.
debug_assert!(
self.func_ctx.blocks.iter().all(
|(block, block_data)| block_data.pristine || self.func_ctx.ssa.is_sealed(block)
),
"all blocks should be sealed before dropping a FunctionBuilder"
);
debug_assert!(
self.func_ctx
.blocks
.values()
.all(|block_data| block_data.pristine || block_data.filled),
"all blocks should be filled before dropping a FunctionBuilder"
);
// In debug mode, check that all blocks are valid basic blocks.
#[cfg(debug_assertions)]
{
// Iterate manually to provide more helpful error messages.
for block in self.func_ctx.blocks.keys() {
if let Err((inst, _msg)) = self.func.is_block_basic(block) {
let inst_str = self.func.dfg.display_inst(inst, None);
panic!("{} failed basic block invariants on {}", block, inst_str);
}
}
}
// Clear the state (but preserve the allocated buffers) in preparation
// for translation another function.
self.func_ctx.clear();
// Reset srcloc and position to initial states.
self.srcloc = Default::default();
self.position = Default::default();
}
}
/// All the functions documented in the previous block are write-only and help you build a valid
/// Cranelift IR functions via multiple debug asserts. However, you might need to improve the
/// performance of your translation perform more complex transformations to your Cranelift IR
/// function. The functions below help you inspect the function you're creating and modify it
/// in ways that can be unsafe if used incorrectly.
impl<'a> FunctionBuilder<'a> {
/// Retrieves all the parameters for a `Block` currently inferred from the jump instructions
/// inserted that target it and the SSA construction.
pub fn block_params(&self, block: Block) -> &[Value] {
self.func.dfg.block_params(block)
}
/// Retrieves the signature with reference `sigref` previously added with `import_signature`.
pub fn signature(&self, sigref: SigRef) -> Option<&Signature> {
self.func.dfg.signatures.get(sigref)
}
/// Creates a parameter for a specific `Block` by appending it to the list of already existing
/// parameters.
///
/// **Note:** this function has to be called at the creation of the `Block` before adding
/// instructions to it, otherwise this could interfere with SSA construction.
pub fn append_block_param(&mut self, block: Block, ty: Type) -> Value {
debug_assert!(
self.func_ctx.blocks[block].pristine,
"You can't add block parameters after adding any instruction"
);
debug_assert_eq!(
self.func_ctx.blocks[block].user_param_count,
self.func.dfg.num_block_params(block)
);
self.func_ctx.blocks[block].user_param_count += 1;
self.func.dfg.append_block_param(block, ty)
}
/// Returns the result values of an instruction.
pub fn inst_results(&self, inst: Inst) -> &[Value] {
self.func.dfg.inst_results(inst)
}
/// Changes the destination of a jump instruction after creation.
///
/// **Note:** You are responsible for maintaining the coherence with the arguments of
/// other jump instructions.
pub fn change_jump_destination(&mut self, inst: Inst, new_dest: Block) {
let old_dest = self.func.dfg[inst]
.branch_destination_mut()
.expect("you want to change the jump destination of a non-jump instruction");
let pred = self.func_ctx.ssa.remove_block_predecessor(*old_dest, inst);
*old_dest = new_dest;
self.func_ctx
.ssa
.declare_block_predecessor(new_dest, pred, inst);
}
/// Returns `true` if and only if the current `Block` is sealed and has no predecessors declared.
///
/// The entry block of a function is never unreachable.
pub fn is_unreachable(&self) -> bool {
let is_entry = match self.func.layout.entry_block() {
None => false,
Some(entry) => self.position.unwrap() == entry,
};
!is_entry
&& self.func_ctx.ssa.is_sealed(self.position.unwrap())
&& !self
.func_ctx
.ssa
.has_any_predecessors(self.position.unwrap())
}
/// Returns `true` if and only if no instructions have been added since the last call to
/// `switch_to_block`.
pub fn is_pristine(&self) -> bool {
self.func_ctx.blocks[self.position.unwrap()].pristine
}
/// Returns `true` if and only if a terminator instruction has been inserted since the
/// last call to `switch_to_block`.
pub fn is_filled(&self) -> bool {
self.func_ctx.blocks[self.position.unwrap()].filled
}
/// Returns a displayable object for the function as it is.
///
/// Useful for debug purposes. Use it with `None` for standard printing.
// Clippy thinks the lifetime that follows is needless, but rustc needs it
#[cfg_attr(feature = "cargo-clippy", allow(clippy::needless_lifetimes))]
pub fn display<'b, I: Into<Option<&'b dyn TargetIsa>>>(&'b self, isa: I) -> DisplayFunction {
self.func.display(isa)
}
}
/// Helper functions
impl<'a> FunctionBuilder<'a> {
/// Calls libc.memcpy
///
/// Copies the `size` bytes from `src` to `dest`, assumes that `src + size`
/// won't overlap onto `dest`. If `dest` and `src` overlap, the behavior is
/// undefined. Applications in which `dest` and `src` might overlap should
/// use `call_memmove` instead.
pub fn call_memcpy(
&mut self,
config: TargetFrontendConfig,
dest: Value,
src: Value,
size: Value,
) {
let pointer_type = config.pointer_type();
let signature = {
let mut s = Signature::new(config.default_call_conv);
s.params.push(AbiParam::new(pointer_type));
s.params.push(AbiParam::new(pointer_type));
s.params.push(AbiParam::new(pointer_type));
self.import_signature(s)
};
let libc_memcpy = self.import_function(ExtFuncData {
name: ExternalName::LibCall(LibCall::Memcpy),
signature,
colocated: false,
});
self.ins().call(libc_memcpy, &[dest, src, size]);
}
/// Optimised memcpy or memmove for small copies.
///
/// # Codegen safety
///
/// The following properties must hold to prevent UB:
///
/// * `src_align` and `dest_align` are an upper-bound on the alignment of `src` respectively `dest`.
/// * If `non_overlapping` is true, then this must be correct.
pub fn emit_small_memory_copy(
&mut self,
config: TargetFrontendConfig,
dest: Value,
src: Value,
size: u64,
dest_align: u8,
src_align: u8,
non_overlapping: bool,
) {
// Currently the result of guess work, not actual profiling.
const THRESHOLD: u64 = 4;
if size == 0 {
return;
}
let access_size = greatest_divisible_power_of_two(size);
assert!(
access_size.is_power_of_two(),
"`size` is not a power of two"
);
assert!(
access_size >= u64::from(::core::cmp::min(src_align, dest_align)),
"`size` is smaller than `dest` and `src`'s alignment value."
);
let (access_size, int_type) = if access_size <= 8 {
(access_size, Type::int((access_size * 8) as u16).unwrap())
} else {
(8, types::I64)
};
let load_and_store_amount = size / access_size;
if load_and_store_amount > THRESHOLD {
let size_value = self.ins().iconst(config.pointer_type(), size as i64);
if non_overlapping {
self.call_memcpy(config, dest, src, size_value);
} else {
self.call_memmove(config, dest, src, size_value);
}
return;
}
let mut flags = MemFlags::new();
flags.set_aligned();
// Load all of the memory first. This is necessary in case `dest` overlaps.
// It can also improve performance a bit.
let registers: smallvec::SmallVec<[_; THRESHOLD as usize]> = (0..load_and_store_amount)
.map(|i| {
let offset = (access_size * i) as i32;
(self.ins().load(int_type, flags, src, offset), offset)
})
.collect();
for (value, offset) in registers {
self.ins().store(flags, value, dest, offset);
}
}
/// Calls libc.memset
///
/// Writes `size` bytes of i8 value `ch` to memory starting at `buffer`.
pub fn call_memset(
&mut self,
config: TargetFrontendConfig,
buffer: Value,
ch: Value,
size: Value,
) {
let pointer_type = config.pointer_type();
let signature = {
let mut s = Signature::new(config.default_call_conv);
s.params.push(AbiParam::new(pointer_type));
s.params.push(AbiParam::new(types::I32));
s.params.push(AbiParam::new(pointer_type));
self.import_signature(s)
};
let libc_memset = self.import_function(ExtFuncData {
name: ExternalName::LibCall(LibCall::Memset),
signature,
colocated: false,
});
let ch = self.ins().uextend(types::I32, ch);
self.ins().call(libc_memset, &[buffer, ch, size]);
}
/// Calls libc.memset
///
/// Writes `size` bytes of value `ch` to memory starting at `buffer`.
pub fn emit_small_memset(
&mut self,
config: TargetFrontendConfig,
buffer: Value,
ch: u8,
size: u64,
buffer_align: u8,
) {
// Currently the result of guess work, not actual profiling.
const THRESHOLD: u64 = 4;
if size == 0 {
return;
}
let access_size = greatest_divisible_power_of_two(size);
assert!(
access_size.is_power_of_two(),
"`size` is not a power of two"
);
assert!(
access_size >= u64::from(buffer_align),
"`size` is smaller than `dest` and `src`'s alignment value."
);
let (access_size, int_type) = if access_size <= 8 {
(access_size, Type::int((access_size * 8) as u16).unwrap())
} else {
(8, types::I64)
};
let load_and_store_amount = size / access_size;
if load_and_store_amount > THRESHOLD {
let ch = self.ins().iconst(types::I8, i64::from(ch));
let size = self.ins().iconst(config.pointer_type(), size as i64);
self.call_memset(config, buffer, ch, size);
} else {
let mut flags = MemFlags::new();
flags.set_aligned();
let ch = u64::from(ch);
let raw_value = if int_type == types::I64 {
(ch << 32) | (ch << 16) | (ch << 8) | ch
} else if int_type == types::I32 {
(ch << 16) | (ch << 8) | ch
} else if int_type == types::I16 {
(ch << 8) | ch
} else {
assert_eq!(int_type, types::I8);
ch
};
let value = self.ins().iconst(int_type, raw_value as i64);
for i in 0..load_and_store_amount {
let offset = (access_size * i) as i32;
self.ins().store(flags, value, buffer, offset);
}
}
}
/// Calls libc.memmove
///
/// Copies `size` bytes from memory starting at `source` to memory starting
/// at `dest`. `source` is always read before writing to `dest`.
pub fn call_memmove(
&mut self,
config: TargetFrontendConfig,
dest: Value,
source: Value,
size: Value,
) {
let pointer_type = config.pointer_type();
let signature = {
let mut s = Signature::new(config.default_call_conv);
s.params.push(AbiParam::new(pointer_type));
s.params.push(AbiParam::new(pointer_type));
s.params.push(AbiParam::new(pointer_type));
self.import_signature(s)
};
let libc_memmove = self.import_function(ExtFuncData {
name: ExternalName::LibCall(LibCall::Memmove),
signature,
colocated: false,
});
self.ins().call(libc_memmove, &[dest, source, size]);
}
}
fn greatest_divisible_power_of_two(size: u64) -> u64 {
(size as i64 & -(size as i64)) as u64
}
// Helper functions
impl<'a> FunctionBuilder<'a> {
/// A Block is 'filled' when a terminator instruction is present.
fn fill_current_block(&mut self) {
self.func_ctx.blocks[self.position.unwrap()].filled = true;
}
fn declare_successor(&mut self, dest_block: Block, jump_inst: Inst) {
self.func_ctx
.ssa
.declare_block_predecessor(dest_block, self.position.unwrap(), jump_inst);
}
fn handle_ssa_side_effects(&mut self, side_effects: SideEffects) {
for split_block in side_effects.split_blocks_created {
self.func_ctx.blocks[split_block].filled = true
}
for modified_block in side_effects.instructions_added_to_blocks {
self.func_ctx.blocks[modified_block].pristine = false
}
}
}
#[cfg(test)]
mod tests {
use super::greatest_divisible_power_of_two;
use crate::frontend::{FunctionBuilder, FunctionBuilderContext};
use crate::Variable;
use alloc::string::ToString;
use cranelift_codegen::entity::EntityRef;
use cranelift_codegen::ir::types::*;
use cranelift_codegen::ir::{AbiParam, ExternalName, Function, InstBuilder, Signature};
use cranelift_codegen::isa::CallConv;
use cranelift_codegen::settings;
use cranelift_codegen::verifier::verify_function;
fn sample_function(lazy_seal: bool) {
let mut sig = Signature::new(CallConv::SystemV);
sig.returns.push(AbiParam::new(I32));
sig.params.push(AbiParam::new(I32));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let block1 = builder.create_block();
let block2 = builder.create_block();
let block3 = builder.create_block();
let x = Variable::new(0);
let y = Variable::new(1);
let z = Variable::new(2);
builder.declare_var(x, I32);
builder.declare_var(y, I32);
builder.declare_var(z, I32);
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
if !lazy_seal {
builder.seal_block(block0);
}
{
let tmp = builder.block_params(block0)[0]; // the first function parameter
builder.def_var(x, tmp);
}
{
let tmp = builder.ins().iconst(I32, 2);
builder.def_var(y, tmp);
}
{
let arg1 = builder.use_var(x);
let arg2 = builder.use_var(y);
let tmp = builder.ins().iadd(arg1, arg2);
builder.def_var(z, tmp);
}
builder.ins().jump(block1, &[]);
builder.switch_to_block(block1);
{
let arg1 = builder.use_var(y);
let arg2 = builder.use_var(z);
let tmp = builder.ins().iadd(arg1, arg2);
builder.def_var(z, tmp);
}
{
let arg = builder.use_var(y);
builder.ins().brnz(arg, block3, &[]);
}
builder.ins().jump(block2, &[]);
builder.switch_to_block(block2);
if !lazy_seal {
builder.seal_block(block2);
}
{
let arg1 = builder.use_var(z);
let arg2 = builder.use_var(x);
let tmp = builder.ins().isub(arg1, arg2);
builder.def_var(z, tmp);
}
{
let arg = builder.use_var(y);
builder.ins().return_(&[arg]);
}
builder.switch_to_block(block3);
if !lazy_seal {
builder.seal_block(block3);
}
{
let arg1 = builder.use_var(y);
let arg2 = builder.use_var(x);
let tmp = builder.ins().isub(arg1, arg2);
builder.def_var(y, tmp);
}
builder.ins().jump(block1, &[]);
if !lazy_seal {
builder.seal_block(block1);
}
if lazy_seal {
builder.seal_all_blocks();
}
builder.finalize();
}
let flags = settings::Flags::new(settings::builder());
// println!("{}", func.display(None));
if let Err(errors) = verify_function(&func, &flags) {
panic!("{}\n{}", func.display(None), errors)
}
}
#[test]
fn sample() {
sample_function(false)
}
#[test]
fn sample_with_lazy_seal() {
sample_function(true)
}
#[test]
fn memcpy() {
use core::str::FromStr;
use cranelift_codegen::{isa, settings};
let shared_builder = settings::builder();
let shared_flags = settings::Flags::new(shared_builder);
let triple = ::target_lexicon::Triple::from_str("arm").expect("Couldn't create arm triple");
let target = isa::lookup(triple)
.ok()
.map(|b| b.finish(shared_flags))
.expect("This test requires arm support.");
let mut sig = Signature::new(target.default_call_conv());
sig.returns.push(AbiParam::new(I32));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let x = Variable::new(0);
let y = Variable::new(1);
let z = Variable::new(2);
builder.declare_var(x, target.pointer_type());
builder.declare_var(y, target.pointer_type());
builder.declare_var(z, I32);
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
let src = builder.use_var(x);
let dest = builder.use_var(y);
let size = builder.use_var(y);
builder.call_memcpy(target.frontend_config(), dest, src, size);
builder.ins().return_(&[size]);
builder.seal_all_blocks();
builder.finalize();
}
assert_eq!(
func.display(None).to_string(),
"function %sample() -> i32 system_v {
sig0 = (i32, i32, i32) system_v
fn0 = %Memcpy sig0
block0:
v3 = iconst.i32 0
v1 -> v3
v2 = iconst.i32 0
v0 -> v2
call fn0(v1, v0, v1)
return v1
}
"
);
}
#[test]
fn small_memcpy() {
use core::str::FromStr;
use cranelift_codegen::{isa, settings};
let shared_builder = settings::builder();
let shared_flags = settings::Flags::new(shared_builder);
let triple = ::target_lexicon::Triple::from_str("arm").expect("Couldn't create arm triple");
let target = isa::lookup(triple)
.ok()
.map(|b| b.finish(shared_flags))
.expect("This test requires arm support.");
let mut sig = Signature::new(target.default_call_conv());
sig.returns.push(AbiParam::new(I32));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let x = Variable::new(0);
let y = Variable::new(16);
builder.declare_var(x, target.pointer_type());
builder.declare_var(y, target.pointer_type());
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
let src = builder.use_var(x);
let dest = builder.use_var(y);
let size = 8;
builder.emit_small_memory_copy(target.frontend_config(), dest, src, size, 8, 8, true);
builder.ins().return_(&[dest]);
builder.seal_all_blocks();
builder.finalize();
}
assert_eq!(
func.display(None).to_string(),
"function %sample() -> i32 system_v {
block0:
v4 = iconst.i32 0
v1 -> v4
v3 = iconst.i32 0
v0 -> v3
v2 = load.i64 aligned v0
store aligned v2, v1
return v1
}
"
);
}
#[test]
fn not_so_small_memcpy() {
use core::str::FromStr;
use cranelift_codegen::{isa, settings};
let shared_builder = settings::builder();
let shared_flags = settings::Flags::new(shared_builder);
let triple = ::target_lexicon::Triple::from_str("arm").expect("Couldn't create arm triple");
let target = isa::lookup(triple)
.ok()
.map(|b| b.finish(shared_flags))
.expect("This test requires arm support.");
let mut sig = Signature::new(target.default_call_conv());
sig.returns.push(AbiParam::new(I32));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let x = Variable::new(0);
let y = Variable::new(16);
builder.declare_var(x, target.pointer_type());
builder.declare_var(y, target.pointer_type());
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
let src = builder.use_var(x);
let dest = builder.use_var(y);
let size = 8192;
builder.emit_small_memory_copy(target.frontend_config(), dest, src, size, 8, 8, true);
builder.ins().return_(&[dest]);
builder.seal_all_blocks();
builder.finalize();
}
assert_eq!(
func.display(None).to_string(),
"function %sample() -> i32 system_v {
sig0 = (i32, i32, i32) system_v
fn0 = %Memcpy sig0
block0:
v4 = iconst.i32 0
v1 -> v4
v3 = iconst.i32 0
v0 -> v3
v2 = iconst.i32 8192
call fn0(v1, v0, v2)
return v1
}
"
);
}
#[test]
fn small_memset() {
use core::str::FromStr;
use cranelift_codegen::{isa, settings};
let shared_builder = settings::builder();
let shared_flags = settings::Flags::new(shared_builder);
let triple = ::target_lexicon::Triple::from_str("arm").expect("Couldn't create arm triple");
let target = isa::lookup(triple)
.ok()
.map(|b| b.finish(shared_flags))
.expect("This test requires arm support.");
let mut sig = Signature::new(target.default_call_conv());
sig.returns.push(AbiParam::new(I32));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let y = Variable::new(16);
builder.declare_var(y, target.pointer_type());
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
let dest = builder.use_var(y);
let size = 8;
builder.emit_small_memset(target.frontend_config(), dest, 1, size, 8);
builder.ins().return_(&[dest]);
builder.seal_all_blocks();
builder.finalize();
}
assert_eq!(
func.display(None).to_string(),
"function %sample() -> i32 system_v {
block0:
v2 = iconst.i32 0
v0 -> v2
v1 = iconst.i64 0x0001_0001_0101
store aligned v1, v0
return v0
}
"
);
}
#[test]
fn not_so_small_memset() {
use core::str::FromStr;
use cranelift_codegen::{isa, settings};
let shared_builder = settings::builder();
let shared_flags = settings::Flags::new(shared_builder);
let triple = ::target_lexicon::Triple::from_str("arm").expect("Couldn't create arm triple");
let target = isa::lookup(triple)
.ok()
.map(|b| b.finish(shared_flags))
.expect("This test requires arm support.");
let mut sig = Signature::new(target.default_call_conv());
sig.returns.push(AbiParam::new(I32));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let y = Variable::new(16);
builder.declare_var(y, target.pointer_type());
builder.append_block_params_for_function_params(block0);
builder.switch_to_block(block0);
let dest = builder.use_var(y);
let size = 8192;
builder.emit_small_memset(target.frontend_config(), dest, 1, size, 8);
builder.ins().return_(&[dest]);
builder.seal_all_blocks();
builder.finalize();
}
assert_eq!(
func.display(None).to_string(),
"function %sample() -> i32 system_v {
sig0 = (i32, i32, i32) system_v
fn0 = %Memset sig0
block0:
v4 = iconst.i32 0
v0 -> v4
v1 = iconst.i8 1
v2 = iconst.i32 8192
v3 = uextend.i32 v1
call fn0(v0, v3, v2)
return v0
}
"
);
}
#[test]
fn undef_vector_vars() {
let mut sig = Signature::new(CallConv::SystemV);
sig.returns.push(AbiParam::new(I8X16));
sig.returns.push(AbiParam::new(B8X16));
sig.returns.push(AbiParam::new(F32X4));
let mut fn_ctx = FunctionBuilderContext::new();
let mut func = Function::with_name_signature(ExternalName::testcase("sample"), sig);
{
let mut builder = FunctionBuilder::new(&mut func, &mut fn_ctx);
let block0 = builder.create_block();
let a = Variable::new(0);
let b = Variable::new(1);
let c = Variable::new(2);
builder.declare_var(a, I8X16);
builder.declare_var(b, B8X16);
builder.declare_var(c, F32X4);
builder.switch_to_block(block0);
let a = builder.use_var(a);
let b = builder.use_var(b);
let c = builder.use_var(c);
builder.ins().return_(&[a, b, c]);
builder.seal_all_blocks();
builder.finalize();
}
assert_eq!(
func.display(None).to_string(),
"function %sample() -> i8x16, b8x16, f32x4 system_v {
const0 = 0x00000000000000000000000000000000
block0:
v5 = f32const 0.0
v6 = splat.f32x4 v5
v2 -> v6
v4 = vconst.b8x16 const0
v1 -> v4
v3 = vconst.i8x16 const0
v0 -> v3
return v0, v1, v2
}
"
);
}
#[test]
fn test_greatest_divisible_power_of_two() {
assert_eq!(64, greatest_divisible_power_of_two(64));
assert_eq!(16, greatest_divisible_power_of_two(48));
assert_eq!(8, greatest_divisible_power_of_two(24));
assert_eq!(1, greatest_divisible_power_of_two(25));
}
}