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Auto merge of #66646 - RalfJung:unwind_to_block, r=oli-obk

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refactor goto_block and also add unwind_to_block

r? @oli-obk
This commit is contained in:
bors 2019-11-26 20:38:47 +00:00
commit a7d791b450
6 changed files with 137 additions and 136 deletions
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15
src/librustc_mir/const_eval.rs
View File

@ -323,8 +323,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
ecx: &mut InterpCx<'mir, 'tcx, Self>,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx>],
dest: Option<PlaceTy<'tcx>>,
ret: Option<mir::BasicBlock>,
ret: Option<(PlaceTy<'tcx>, mir::BasicBlock)>,
_unwind: Option<mir::BasicBlock> // unwinding is not supported in consts
) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>> {
debug!("eval_fn_call: {:?}", instance);
@ -337,8 +336,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
// Some functions we support even if they are non-const -- but avoid testing
// that for const fn! We certainly do *not* want to actually call the fn
// though, so be sure we return here.
return if ecx.hook_panic_fn(instance, args, dest)? {
ecx.goto_block(ret)?; // fully evaluated and done
return if ecx.hook_panic_fn(instance, args, ret)? {
Ok(None)
} else {
throw_unsup_format!("calling non-const function `{}`", instance)
@ -364,8 +362,8 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
fn_val: !,
_args: &[OpTy<'tcx>],
_dest: Option<PlaceTy<'tcx>>,
_ret: Option<mir::BasicBlock>,
_ret: Option<(PlaceTy<'tcx>, mir::BasicBlock)>,
_unwind: Option<mir::BasicBlock>
) -> InterpResult<'tcx> {
match fn_val {}
}
@ -375,11 +373,10 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
span: Span,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx>],
dest: Option<PlaceTy<'tcx>>,
_ret: Option<mir::BasicBlock>,
ret: Option<(PlaceTy<'tcx>, mir::BasicBlock)>,
_unwind: Option<mir::BasicBlock>
) -> InterpResult<'tcx> {
if ecx.emulate_intrinsic(span, instance, args, dest)? {
if ecx.emulate_intrinsic(span, instance, args, ret)? {
return Ok(());
}
// An intrinsic that we do not support

38
src/librustc_mir/interpret/eval_context.rs
View File

@ -555,6 +555,37 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
}
/// Jump to the given block.
#[inline]
pub fn go_to_block(&mut self, target: mir::BasicBlock) {
let frame = self.frame_mut();
frame.block = Some(target);
frame.stmt = 0;
}
/// *Return* to the given `target` basic block.
/// Do *not* use for unwinding! Use `unwind_to_block` instead.
///
/// If `target` is `None`, that indicates the function cannot return, so we raise UB.
pub fn return_to_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> {
if let Some(target) = target {
Ok(self.go_to_block(target))
} else {
throw_ub!(Unreachable)
}
}
/// *Unwind* to the given `target` basic block.
/// Do *not* use for returning! Use `return_to_block` instead.
///
/// If `target` is `None`, that indicates the function does not need cleanup during
/// unwinding, and we will just keep propagating that upwards.
pub fn unwind_to_block(&mut self, target: Option<mir::BasicBlock>) {
let frame = self.frame_mut();
frame.block = target;
frame.stmt = 0;
}
/// Pops the current frame from the stack, deallocating the
/// memory for allocated locals.
///
@ -630,10 +661,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
if cur_unwinding {
// Follow the unwind edge.
let unwind = next_block.expect("Encounted StackPopCleanup::None when unwinding!");
let next_frame = self.frame_mut();
// If `unwind` is `None`, we'll leave that function immediately again.
next_frame.block = unwind;
next_frame.stmt = 0;
self.unwind_to_block(unwind);
} else {
// Follow the normal return edge.
// Validate the return value. Do this after deallocating so that we catch dangling
@ -660,7 +688,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// Jump to new block -- *after* validation so that the spans make more sense.
if let Some(ret) = next_block {
self.goto_block(ret)?;
self.return_to_block(ret)?;
}
}

77
src/librustc_mir/interpret/intrinsics.rs
View File

@ -9,8 +9,10 @@ use rustc::ty::layout::{LayoutOf, Primitive, Size};
use rustc::ty::subst::SubstsRef;
use rustc::hir::def_id::DefId;
use rustc::ty::TyCtxt;
use rustc::mir::BinOp;
use rustc::mir::interpret::{InterpResult, Scalar, GlobalId, ConstValue};
use rustc::mir::{
self, BinOp,
interpret::{InterpResult, Scalar, GlobalId, ConstValue}
};
use super::{
Machine, PlaceTy, OpTy, InterpCx, ImmTy,
@ -91,17 +93,21 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
span: Span,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx, M::PointerTag>],
dest: Option<PlaceTy<'tcx, M::PointerTag>>,
ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
) -> InterpResult<'tcx, bool> {
let substs = instance.substs;
// We currently do not handle any diverging intrinsics.
let dest = match dest {
Some(dest) => dest,
None => return Ok(false)
};
let intrinsic_name = &*self.tcx.item_name(instance.def_id()).as_str();
// We currently do not handle any intrinsics that are *allowed* to diverge,
// but `transmute` could lack a return place in case of UB.
let (dest, ret) = match ret {
Some(p) => p,
None => match intrinsic_name {
"transmute" => throw_ub!(Unreachable),
_ => return Ok(false),
}
};
match intrinsic_name {
"caller_location" => {
let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
@ -268,34 +274,39 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
// exception from the exception.)
// This is the dual to the special exception for offset-by-0
// in the inbounds pointer offset operation (see the Miri code, `src/operator.rs`).
if a.is_bits() && b.is_bits() {
//
// Control flow is weird because we cannot early-return (to reach the
// `go_to_block` at the end).
let done = if a.is_bits() && b.is_bits() {
let a = a.to_machine_usize(self)?;
let b = b.to_machine_usize(self)?;
if a == b && a != 0 {
self.write_scalar(Scalar::from_int(0, isize_layout.size), dest)?;
return Ok(true);
}
}
true
} else { false }
} else { false };
// General case: we need two pointers.
let a = self.force_ptr(a)?;
let b = self.force_ptr(b)?;
if a.alloc_id != b.alloc_id {
throw_ub_format!(
"ptr_offset_from cannot compute offset of pointers into different \
allocations.",
);
if !done {
// General case: we need two pointers.
let a = self.force_ptr(a)?;
let b = self.force_ptr(b)?;
if a.alloc_id != b.alloc_id {
throw_ub_format!(
"ptr_offset_from cannot compute offset of pointers into different \
allocations.",
);
}
let usize_layout = self.layout_of(self.tcx.types.usize)?;
let a_offset = ImmTy::from_uint(a.offset.bytes(), usize_layout);
let b_offset = ImmTy::from_uint(b.offset.bytes(), usize_layout);
let (val, _overflowed, _ty) = self.overflowing_binary_op(
BinOp::Sub, a_offset, b_offset,
)?;
let pointee_layout = self.layout_of(substs.type_at(0))?;
let val = ImmTy::from_scalar(val, isize_layout);
let size = ImmTy::from_int(pointee_layout.size.bytes(), isize_layout);
self.exact_div(val, size, dest)?;
}
let usize_layout = self.layout_of(self.tcx.types.usize)?;
let a_offset = ImmTy::from_uint(a.offset.bytes(), usize_layout);
let b_offset = ImmTy::from_uint(b.offset.bytes(), usize_layout);
let (val, _overflowed, _ty) = self.overflowing_binary_op(
BinOp::Sub, a_offset, b_offset,
)?;
let pointee_layout = self.layout_of(substs.type_at(0))?;
let val = ImmTy::from_scalar(val, isize_layout);
let size = ImmTy::from_int(pointee_layout.size.bytes(), isize_layout);
self.exact_div(val, size, dest)?;
}
"transmute" => {
@ -350,6 +361,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
_ => return Ok(false),
}
self.dump_place(*dest);
self.go_to_block(ret);
Ok(true)
}
@ -360,7 +373,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
&mut self,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx, M::PointerTag>],
_dest: Option<PlaceTy<'tcx, M::PointerTag>>,
_ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
) -> InterpResult<'tcx, bool> {
let def_id = instance.def_id();
if Some(def_id) == self.tcx.lang_items().panic_fn() {

20
src/librustc_mir/interpret/machine.rs
View File

@ -141,7 +141,7 @@ pub trait Machine<'mir, 'tcx>: Sized {
/// Returns either the mir to use for the call, or `None` if execution should
/// just proceed (which usually means this hook did all the work that the
/// called function should usually have done). In the latter case, it is
/// this hook's responsibility to call `goto_block(ret)` to advance the instruction pointer!
/// this hook's responsibility to advance the instruction pointer!
/// (This is to support functions like `__rust_maybe_catch_panic` that neither find a MIR
/// nor just jump to `ret`, but instead push their own stack frame.)
/// Passing `dest`and `ret` in the same `Option` proved very annoying when only one of them
@ -150,30 +150,28 @@ pub trait Machine<'mir, 'tcx>: Sized {
ecx: &mut InterpCx<'mir, 'tcx, Self>,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx, Self::PointerTag>],
dest: Option<PlaceTy<'tcx, Self::PointerTag>>,
ret: Option<mir::BasicBlock>,
unwind: Option<mir::BasicBlock>
ret: Option<(PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
unwind: Option<mir::BasicBlock>,
) -> InterpResult<'tcx, Option<&'mir mir::Body<'tcx>>>;
/// Execute `fn_val`. it is the hook's responsibility to advance the instruction
/// Execute `fn_val`. It is the hook's responsibility to advance the instruction
/// pointer as appropriate.
fn call_extra_fn(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
fn_val: Self::ExtraFnVal,
args: &[OpTy<'tcx, Self::PointerTag>],
dest: Option<PlaceTy<'tcx, Self::PointerTag>>,
ret: Option<mir::BasicBlock>,
ret: Option<(PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
unwind: Option<mir::BasicBlock>,
) -> InterpResult<'tcx>;
/// Directly process an intrinsic without pushing a stack frame.
/// If this returns successfully, the engine will take care of jumping to the next block.
/// Directly process an intrinsic without pushing a stack frame. It is the hook's
/// responsibility to advance the instruction pointer as appropriate.
fn call_intrinsic(
ecx: &mut InterpCx<'mir, 'tcx, Self>,
span: Span,
instance: ty::Instance<'tcx>,
args: &[OpTy<'tcx, Self::PointerTag>],
dest: Option<PlaceTy<'tcx, Self::PointerTag>>,
ret: Option<mir::BasicBlock>,
ret: Option<(PlaceTy<'tcx, Self::PointerTag>, mir::BasicBlock)>,
unwind: Option<mir::BasicBlock>,
) -> InterpResult<'tcx>;

113
src/librustc_mir/interpret/terminator.rs
View File

@ -12,17 +12,6 @@ use super::{
};
impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
#[inline]
pub fn goto_block(&mut self, target: Option<mir::BasicBlock>) -> InterpResult<'tcx> {
if let Some(target) = target {
self.frame_mut().block = Some(target);
self.frame_mut().stmt = 0;
Ok(())
} else {
throw_ub!(Unreachable)
}
}
pub(super) fn eval_terminator(
&mut self,
terminator: &mir::Terminator<'tcx>,
@ -34,7 +23,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
self.pop_stack_frame(/* unwinding */ false)?
}
Goto { target } => self.goto_block(Some(target))?,
Goto { target } => self.go_to_block(target),
SwitchInt {
ref discr,
@ -60,7 +49,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
}
self.goto_block(Some(target_block))?;
self.go_to_block(target_block);
}
Call {
@ -70,11 +59,6 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
ref cleanup,
..
} => {
let (dest, ret) = match *destination {
Some((ref lv, target)) => (Some(self.eval_place(lv)?), Some(target)),
None => (None, None),
};
let func = self.eval_operand(func, None)?;
let (fn_val, abi) = match func.layout.ty.kind {
ty::FnPtr(sig) => {
@ -92,12 +76,15 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
}
};
let args = self.eval_operands(args)?;
let ret = match destination {
Some((dest, ret)) => Some((self.eval_place(dest)?, *ret)),
None => None,
};
self.eval_fn_call(
fn_val,
terminator.source_info.span,
abi,
&args[..],
dest,
ret,
*cleanup
)?;
@ -133,7 +120,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let cond_val = self.read_immediate(self.eval_operand(cond, None)?)?
.to_scalar()?.to_bool()?;
if expected == cond_val {
self.goto_block(Some(target))?;
self.go_to_block(target);
} else {
// Compute error message
use rustc::mir::interpret::PanicInfo::*;
@ -249,8 +236,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
span: Span,
caller_abi: Abi,
args: &[OpTy<'tcx, M::PointerTag>],
dest: Option<PlaceTy<'tcx, M::PointerTag>>,
ret: Option<mir::BasicBlock>,
ret: Option<(PlaceTy<'tcx, M::PointerTag>, mir::BasicBlock)>,
unwind: Option<mir::BasicBlock>
) -> InterpResult<'tcx> {
trace!("eval_fn_call: {:#?}", fn_val);
@ -258,32 +244,38 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
let instance = match fn_val {
FnVal::Instance(instance) => instance,
FnVal::Other(extra) => {
return M::call_extra_fn(self, extra, args, dest, ret);
return M::call_extra_fn(self, extra, args, ret, unwind);
}
};
// ABI check
{
let callee_abi = {
let instance_ty = instance.ty(*self.tcx);
match instance_ty.kind {
ty::FnDef(..) =>
instance_ty.fn_sig(*self.tcx).abi(),
ty::Closure(..) => Abi::RustCall,
ty::Generator(..) => Abi::Rust,
_ => bug!("unexpected callee ty: {:?}", instance_ty),
}
};
let normalize_abi = |abi| match abi {
Abi::Rust | Abi::RustCall | Abi::RustIntrinsic | Abi::PlatformIntrinsic =>
// These are all the same ABI, really.
Abi::Rust,
abi =>
abi,
};
if normalize_abi(caller_abi) != normalize_abi(callee_abi) {
throw_unsup!(FunctionAbiMismatch(caller_abi, callee_abi))
}
}
match instance.def {
ty::InstanceDef::Intrinsic(..) => {
assert!(caller_abi == Abi::RustIntrinsic || caller_abi == Abi::PlatformIntrinsic);
let old_stack = self.cur_frame();
let old_bb = self.frame().block;
M::call_intrinsic(self, span, instance, args, dest, ret, unwind)?;
// No stack frame gets pushed, the main loop will just act as if the
// call completed.
if ret.is_some() {
self.goto_block(ret)?;
} else {
// If this intrinsic call doesn't have a ret block,
// then the intrinsic implementation should have
// changed the stack frame (otherwise, we'll end
// up trying to execute this intrinsic call again)
debug_assert!(self.cur_frame() != old_stack || self.frame().block != old_bb);
}
if let Some(dest) = dest {
self.dump_place(*dest)
}
Ok(())
return M::call_intrinsic(self, span, instance, args, ret, unwind);
}
ty::InstanceDef::VtableShim(..) |
ty::InstanceDef::ReifyShim(..) |
@ -292,32 +284,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
ty::InstanceDef::DropGlue(..) |
ty::InstanceDef::CloneShim(..) |
ty::InstanceDef::Item(_) => {
// ABI check
{
let callee_abi = {
let instance_ty = instance.ty(*self.tcx);
match instance_ty.kind {
ty::FnDef(..) =>
instance_ty.fn_sig(*self.tcx).abi(),
ty::Closure(..) => Abi::RustCall,
ty::Generator(..) => Abi::Rust,
_ => bug!("unexpected callee ty: {:?}", instance_ty),
}
};
let normalize_abi = |abi| match abi {
Abi::Rust | Abi::RustCall | Abi::RustIntrinsic | Abi::PlatformIntrinsic =>
// These are all the same ABI, really.
Abi::Rust,
abi =>
abi,
};
if normalize_abi(caller_abi) != normalize_abi(callee_abi) {
throw_unsup!(FunctionAbiMismatch(caller_abi, callee_abi))
}
}
// We need MIR for this fn
let body = match M::find_fn(self, instance, args, dest, ret, unwind)? {
let body = match M::find_fn(self, instance, args, ret, unwind)? {
Some(body) => body,
None => return Ok(()),
};
@ -326,8 +294,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
instance,
span,
body,
dest,
StackPopCleanup::Goto { ret, unwind }
ret.map(|p| p.0),
StackPopCleanup::Goto { ret: ret.map(|p| p.1), unwind }
)?;
// We want to pop this frame again in case there was an error, to put
@ -410,7 +378,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
throw_unsup!(FunctionArgCountMismatch)
}
// Don't forget to check the return type!
if let Some(caller_ret) = dest {
if let Some((caller_ret, _)) = ret {
let callee_ret = self.eval_place(
&mir::Place::return_place()
)?;
@ -476,7 +444,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
});
trace!("Patched self operand to {:#?}", args[0]);
// recurse with concrete function
self.eval_fn_call(drop_fn, span, caller_abi, &args, dest, ret, unwind)
self.eval_fn_call(drop_fn, span, caller_abi, &args, ret, unwind)
}
}
}
@ -516,8 +484,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
span,
Abi::Rust,
&[arg.into()],
Some(dest.into()),
Some(target),
Some((dest.into(), target)),
unwind
)
}

10
src/librustc_mir/transform/const_prop.rs
View File

@ -144,8 +144,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine {
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
_instance: ty::Instance<'tcx>,
_args: &[OpTy<'tcx>],
_dest: Option<PlaceTy<'tcx>>,
_ret: Option<BasicBlock>,
_ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
_unwind: Option<BasicBlock>,
) -> InterpResult<'tcx, Option<&'mir Body<'tcx>>> {
Ok(None)
@ -155,8 +154,8 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine {
_ecx: &mut InterpCx<'mir, 'tcx, Self>,
fn_val: !,
_args: &[OpTy<'tcx>],
_dest: Option<PlaceTy<'tcx>>,
_ret: Option<BasicBlock>,
_ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
_unwind: Option<BasicBlock>
) -> InterpResult<'tcx> {
match fn_val {}
}
@ -166,8 +165,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for ConstPropMachine {
_span: Span,
_instance: ty::Instance<'tcx>,
_args: &[OpTy<'tcx>],
_dest: Option<PlaceTy<'tcx>>,
_ret: Option<BasicBlock>,
_ret: Option<(PlaceTy<'tcx>, BasicBlock)>,
_unwind: Option<BasicBlock>
) -> InterpResult<'tcx> {
throw_unsup_format!("calling intrinsics isn't supported in ConstProp");