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cranelift: Add stack support to the interpreter with virtual addresses (#3187)

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* cranelift: Add stack support to the interpreter

We also change the approach for heap loads and stores.

Previously we would use the offset as the address to the heap. However,
this approach does not allow using the load/store instructions to
read/write from both the heap and the stack.

This commit changes the addressing mechanism of the interpreter. We now
return the real addresses from the addressing instructions
(stack_addr/heap_addr), and instead check if the address passed into
the load/store instructions points to an area in the heap or the stack.

* cranelift: Add virtual addresses to cranelift interpreter

Adds a  Virtual Addressing scheme that was discussed as a better
alternative to returning the real addresses.

The virtual addresses are split into 4 regions (stack, heap, tables and
global values), and the address itself is composed of an `entry` field
and an `offset` field. In general the `entry` field corresponds to the
instance of the resource (e.g. table5 is entry 5) and the `offset` field
is a byte offset inside that entry.

There is one exception to this which is the stack, where due to only
having one stack, the whole address is an offset field.

The number of bits in entry vs offset fields is variable with respect to
the `region` and the address size (32bits vs 64bits). This is done
because with 32 bit addresses we would have to compromise on heap size,
or have a small number of global values / tables. With 64 bit addresses
we do not have to compromise on this, but we need to support 32 bit
addresses.

* cranelift: Remove interpreter trap codes

* cranelift: Calculate frame_offset when entering or exiting a frame

* cranelift: Add safe read/write interface to DataValue

* cranelift: DataValue write full 128bit slot for booleans

* cranelift: Use DataValue accessors for trampoline.
This commit is contained in:
Afonso Bordado
2021-08-24 17:29:11 +01:00
committed by GitHub
parent f4ff7c350a
commit 2776074dfc
13 changed files with 1094 additions and 157 deletions
Download Patch File Download Diff File Expand all files Collapse all files

108
cranelift/interpreter/src/step.rs
View File

@@ -1,8 +1,10 @@
//! The [step] function interprets a single Cranelift instruction given its [State] and
//! [InstructionContext]; the interpretation is generic over [Value]s.
use crate::address::{Address, AddressSize};
use crate::instruction::InstructionContext;
use crate::state::{MemoryError, State};
use crate::value::{Value, ValueConversionKind, ValueError, ValueResult};
use cranelift_codegen::data_value::DataValue;
use cranelift_codegen::ir::condcodes::{FloatCC, IntCC};
use cranelift_codegen::ir::{
types, Block, FuncRef, Function, InstructionData, Opcode, TrapCode, Value as ValueRef,
@@ -87,6 +89,37 @@ where
Err(e) => Err(e),
};
let memerror_to_trap = |e: MemoryError| match e {
MemoryError::InvalidAddress(_) => TrapCode::HeapOutOfBounds,
MemoryError::InvalidAddressType(_) => TrapCode::HeapOutOfBounds,
MemoryError::InvalidOffset { .. } => TrapCode::HeapOutOfBounds,
MemoryError::InvalidEntry { .. } => TrapCode::HeapOutOfBounds,
MemoryError::OutOfBoundsStore { .. } => TrapCode::HeapOutOfBounds,
MemoryError::OutOfBoundsLoad { .. } => TrapCode::HeapOutOfBounds,
};
// Assigns or traps depending on the value of the result
let assign_or_memtrap = |res| match res {
Ok(v) => assign(v),
Err(e) => ControlFlow::Trap(CraneliftTrap::User(memerror_to_trap(e))),
};
// Continues or traps depending on the value of the result
let continue_or_memtrap = |res| match res {
Ok(_) => ControlFlow::Continue,
Err(e) => ControlFlow::Trap(CraneliftTrap::User(memerror_to_trap(e))),
};
let calculate_addr = |imm: V, args: SmallVec<[V; 1]>| -> ValueResult<u64> {
let imm = imm.convert(ValueConversionKind::ZeroExtend(ctrl_ty))?;
let args = args
.into_iter()
.map(|v| v.convert(ValueConversionKind::ZeroExtend(ctrl_ty)))
.collect::<ValueResult<SmallVec<[V; 1]>>>()?;
Ok(sum(imm, args)? as u64)
};
// Interpret a binary instruction with the given `op`, assigning the resulting value to the
// instruction's results.
let binary = |op: fn(V, V) -> ValueResult<V>,
@@ -250,7 +283,6 @@ where
| Opcode::Uload32x2Complex
| Opcode::Sload32x2
| Opcode::Sload32x2Complex => {
let address = sum(imm(), args()?)? as usize;
let ctrl_ty = inst_context.controlling_type().unwrap();
let (load_ty, kind) = match inst.opcode() {
Opcode::Load | Opcode::LoadComplex => (ctrl_ty, None),
@@ -286,13 +318,20 @@ where
| Opcode::Sload32x2Complex => unimplemented!(),
_ => unreachable!(),
};
let loaded = state.load_heap(address, load_ty)?;
let extended = if let Some(c) = kind {
loaded.convert(c)?
} else {
loaded
};
ControlFlow::Assign(smallvec!(extended))
let addr_value = calculate_addr(imm(), args()?)?;
let loaded = assign_or_memtrap(
Address::try_from(addr_value).and_then(|addr| state.checked_load(addr, load_ty)),
);
match (loaded, kind) {
(ControlFlow::Assign(ret), Some(c)) => ControlFlow::Assign(
ret.into_iter()
.map(|loaded| loaded.convert(c.clone()))
.collect::<ValueResult<SmallVec<[V; 1]>>>()?,
),
(cf, _) => cf,
}
}
Opcode::Store
| Opcode::StoreComplex
@@ -302,7 +341,6 @@ where
| Opcode::Istore16Complex
| Opcode::Istore32
| Opcode::Istore32Complex => {
let address = sum(imm(), args_range(1..)?)? as usize;
let kind = match inst.opcode() {
Opcode::Store | Opcode::StoreComplex => None,
Opcode::Istore8 | Opcode::Istore8Complex => {
@@ -316,27 +354,49 @@ where
}
_ => unreachable!(),
};
let addr_value = calculate_addr(imm(), args_range(1..)?)?;
let reduced = if let Some(c) = kind {
arg(0)?.convert(c)?
} else {
arg(0)?
};
state.store_heap(address, reduced)?;
ControlFlow::Continue
continue_or_memtrap(
Address::try_from(addr_value).and_then(|addr| state.checked_store(addr, reduced)),
)
}
Opcode::StackLoad => {
let address = sum(imm(), args_range(1..)?)? as usize;
let load_ty = inst_context.controlling_type().unwrap();
let loaded = state.load_stack(address, load_ty)?;
ControlFlow::Assign(smallvec!(loaded))
let slot = inst.stack_slot().unwrap();
let offset = sum(imm(), args()?)? as u64;
assign_or_memtrap({
state
.stack_address(AddressSize::_64, slot, offset)
.and_then(|addr| state.checked_load(addr, load_ty))
})
}
Opcode::StackStore => {
let address = sum(imm(), args_range(1..)?)? as usize;
let arg0 = arg(0)?;
state.store_stack(address, arg0)?;
ControlFlow::Continue
let arg = arg(0)?;
let slot = inst.stack_slot().unwrap();
let offset = sum(imm(), args_range(1..)?)? as u64;
continue_or_memtrap({
state
.stack_address(AddressSize::_64, slot, offset)
.and_then(|addr| state.checked_store(addr, arg))
})
}
Opcode::StackAddr => {
let load_ty = inst_context.controlling_type().unwrap();
let slot = inst.stack_slot().unwrap();
let offset = sum(imm(), args()?)? as u64;
assign_or_memtrap({
AddressSize::try_from(load_ty).and_then(|addr_size| {
let addr = state.stack_address(addr_size, slot, offset)?;
let dv = DataValue::try_from(addr)?;
Ok(dv.into())
})
})
}
Opcode::StackAddr => unimplemented!("StackAddr"),
Opcode::GlobalValue => unimplemented!("GlobalValue"),
Opcode::SymbolValue => unimplemented!("SymbolValue"),
Opcode::TlsValue => unimplemented!("TlsValue"),
@@ -724,6 +784,16 @@ impl<'a, V> ControlFlow<'a, V> {
panic!("expected the control flow to be in the return state")
}
}
/// For convenience, we can unwrap the [ControlFlow] state assuming that it is a
/// [ControlFlow::Trap], panicking otherwise.
pub fn unwrap_trap(self) -> CraneliftTrap {
if let ControlFlow::Trap(trap) = self {
trap
} else {
panic!("expected the control flow to be a trap")
}
}
}
#[derive(Error, Debug, PartialEq)]