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block.rs
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block.rs
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use super::operand::OperandRef;
use super::operand::OperandValue::{Immediate, Pair, Ref, ZeroSized};
use super::place::PlaceRef;
use super::{CachedLlbb, FunctionCx, LocalRef};
use crate::base;
use crate::common::{self, IntPredicate};
use crate::meth;
use crate::traits::*;
use crate::MemFlags;
use rustc_ast as ast;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_hir::lang_items::LangItem;
use rustc_middle::mir::{self, AssertKind, BasicBlock, SwitchTargets, UnwindTerminateReason};
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
use rustc_middle::ty::{self, Instance, Ty};
use rustc_session::config::OptLevel;
use rustc_span::{source_map::Spanned, sym, Span};
use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode, Reg};
use rustc_target::abi::{self, HasDataLayout, WrappingRange};
use rustc_target::spec::abi::Abi;
use std::cmp;
// Indicates if we are in the middle of merging a BB's successor into it. This
// can happen when BB jumps directly to its successor and the successor has no
// other predecessors.
#[derive(Debug, PartialEq)]
enum MergingSucc {
False,
True,
}
/// Used by `FunctionCx::codegen_terminator` for emitting common patterns
/// e.g., creating a basic block, calling a function, etc.
struct TerminatorCodegenHelper<'tcx> {
bb: mir::BasicBlock,
terminator: &'tcx mir::Terminator<'tcx>,
}
impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
/// Returns the appropriate `Funclet` for the current funclet, if on MSVC,
/// either already previously cached, or newly created, by `landing_pad_for`.
fn funclet<'b, Bx: BuilderMethods<'a, 'tcx>>(
&self,
fx: &'b mut FunctionCx<'a, 'tcx, Bx>,
) -> Option<&'b Bx::Funclet> {
let cleanup_kinds = fx.cleanup_kinds.as_ref()?;
let funclet_bb = cleanup_kinds[self.bb].funclet_bb(self.bb)?;
// If `landing_pad_for` hasn't been called yet to create the `Funclet`,
// it has to be now. This may not seem necessary, as RPO should lead
// to all the unwind edges being visited (and so to `landing_pad_for`
// getting called for them), before building any of the blocks inside
// the funclet itself - however, if MIR contains edges that end up not
// being needed in the LLVM IR after monomorphization, the funclet may
// be unreachable, and we don't have yet a way to skip building it in
// such an eventuality (which may be a better solution than this).
if fx.funclets[funclet_bb].is_none() {
fx.landing_pad_for(funclet_bb);
}
Some(
fx.funclets[funclet_bb]
.as_ref()
.expect("landing_pad_for didn't also create funclets entry"),
)
}
/// Get a basic block (creating it if necessary), possibly with cleanup
/// stuff in it or next to it.
fn llbb_with_cleanup<Bx: BuilderMethods<'a, 'tcx>>(
&self,
fx: &mut FunctionCx<'a, 'tcx, Bx>,
target: mir::BasicBlock,
) -> Bx::BasicBlock {
let (needs_landing_pad, is_cleanupret) = self.llbb_characteristics(fx, target);
let mut lltarget = fx.llbb(target);
if needs_landing_pad {
lltarget = fx.landing_pad_for(target);
}
if is_cleanupret {
// Cross-funclet jump - need a trampoline
debug_assert!(base::wants_new_eh_instructions(fx.cx.tcx().sess));
debug!("llbb_with_cleanup: creating cleanup trampoline for {:?}", target);
let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
let trampoline_llbb = Bx::append_block(fx.cx, fx.llfn, name);
let mut trampoline_bx = Bx::build(fx.cx, trampoline_llbb);
trampoline_bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
trampoline_llbb
} else {
lltarget
}
}
fn llbb_characteristics<Bx: BuilderMethods<'a, 'tcx>>(
&self,
fx: &mut FunctionCx<'a, 'tcx, Bx>,
target: mir::BasicBlock,
) -> (bool, bool) {
if let Some(ref cleanup_kinds) = fx.cleanup_kinds {
let funclet_bb = cleanup_kinds[self.bb].funclet_bb(self.bb);
let target_funclet = cleanup_kinds[target].funclet_bb(target);
let (needs_landing_pad, is_cleanupret) = match (funclet_bb, target_funclet) {
(None, None) => (false, false),
(None, Some(_)) => (true, false),
(Some(f), Some(t_f)) => (f != t_f, f != t_f),
(Some(_), None) => {
let span = self.terminator.source_info.span;
span_bug!(span, "{:?} - jump out of cleanup?", self.terminator);
}
};
(needs_landing_pad, is_cleanupret)
} else {
let needs_landing_pad = !fx.mir[self.bb].is_cleanup && fx.mir[target].is_cleanup;
let is_cleanupret = false;
(needs_landing_pad, is_cleanupret)
}
}
fn funclet_br<Bx: BuilderMethods<'a, 'tcx>>(
&self,
fx: &mut FunctionCx<'a, 'tcx, Bx>,
bx: &mut Bx,
target: mir::BasicBlock,
mergeable_succ: bool,
) -> MergingSucc {
let (needs_landing_pad, is_cleanupret) = self.llbb_characteristics(fx, target);
if mergeable_succ && !needs_landing_pad && !is_cleanupret {
// We can merge the successor into this bb, so no need for a `br`.
MergingSucc::True
} else {
let mut lltarget = fx.llbb(target);
if needs_landing_pad {
lltarget = fx.landing_pad_for(target);
}
if is_cleanupret {
// micro-optimization: generate a `ret` rather than a jump
// to a trampoline.
bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
} else {
bx.br(lltarget);
}
MergingSucc::False
}
}
/// Call `fn_ptr` of `fn_abi` with the arguments `llargs`, the optional
/// return destination `destination` and the unwind action `unwind`.
fn do_call<Bx: BuilderMethods<'a, 'tcx>>(
&self,
fx: &mut FunctionCx<'a, 'tcx, Bx>,
bx: &mut Bx,
fn_abi: &'tcx FnAbi<'tcx, Ty<'tcx>>,
fn_ptr: Bx::Value,
llargs: &[Bx::Value],
destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
mut unwind: mir::UnwindAction,
copied_constant_arguments: &[PlaceRef<'tcx, <Bx as BackendTypes>::Value>],
mergeable_succ: bool,
) -> MergingSucc {
// If there is a cleanup block and the function we're calling can unwind, then
// do an invoke, otherwise do a call.
let fn_ty = bx.fn_decl_backend_type(fn_abi);
let fn_attrs = if bx.tcx().def_kind(fx.instance.def_id()).has_codegen_attrs() {
Some(bx.tcx().codegen_fn_attrs(fx.instance.def_id()))
} else {
None
};
if !fn_abi.can_unwind {
unwind = mir::UnwindAction::Unreachable;
}
let unwind_block = match unwind {
mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
mir::UnwindAction::Continue => None,
mir::UnwindAction::Unreachable => None,
mir::UnwindAction::Terminate(reason) => {
if fx.mir[self.bb].is_cleanup && base::wants_new_eh_instructions(fx.cx.tcx().sess) {
// MSVC SEH will abort automatically if an exception tries to
// propagate out from cleanup.
// FIXME(@mirkootter): For wasm, we currently do not support terminate during
// cleanup, because this requires a few more changes: The current code
// caches the `terminate_block` for each function; funclet based code - however -
// requires a different terminate_block for each funclet
// Until this is implemented, we just do not unwind inside cleanup blocks
None
} else {
Some(fx.terminate_block(reason))
}
}
};
if let Some(unwind_block) = unwind_block {
let ret_llbb = if let Some((_, target)) = destination {
fx.llbb(target)
} else {
fx.unreachable_block()
};
let invokeret = bx.invoke(
fn_ty,
fn_attrs,
Some(fn_abi),
fn_ptr,
llargs,
ret_llbb,
unwind_block,
self.funclet(fx),
);
if fx.mir[self.bb].is_cleanup {
bx.apply_attrs_to_cleanup_callsite(invokeret);
}
if let Some((ret_dest, target)) = destination {
bx.switch_to_block(fx.llbb(target));
fx.set_debug_loc(bx, self.terminator.source_info);
for tmp in copied_constant_arguments {
bx.lifetime_end(tmp.llval, tmp.layout.size);
}
fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
}
MergingSucc::False
} else {
let llret = bx.call(fn_ty, fn_attrs, Some(fn_abi), fn_ptr, llargs, self.funclet(fx));
if fx.mir[self.bb].is_cleanup {
bx.apply_attrs_to_cleanup_callsite(llret);
}
if let Some((ret_dest, target)) = destination {
for tmp in copied_constant_arguments {
bx.lifetime_end(tmp.llval, tmp.layout.size);
}
fx.store_return(bx, ret_dest, &fn_abi.ret, llret);
self.funclet_br(fx, bx, target, mergeable_succ)
} else {
bx.unreachable();
MergingSucc::False
}
}
}
/// Generates inline assembly with optional `destination` and `unwind`.
fn do_inlineasm<Bx: BuilderMethods<'a, 'tcx>>(
&self,
fx: &mut FunctionCx<'a, 'tcx, Bx>,
bx: &mut Bx,
template: &[InlineAsmTemplatePiece],
operands: &[InlineAsmOperandRef<'tcx, Bx>],
options: InlineAsmOptions,
line_spans: &[Span],
destination: Option<mir::BasicBlock>,
unwind: mir::UnwindAction,
instance: Instance<'_>,
mergeable_succ: bool,
) -> MergingSucc {
let unwind_target = match unwind {
mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
mir::UnwindAction::Terminate(reason) => Some(fx.terminate_block(reason)),
mir::UnwindAction::Continue => None,
mir::UnwindAction::Unreachable => None,
};
if operands.iter().any(|x| matches!(x, InlineAsmOperandRef::Label { .. })) {
assert!(unwind_target.is_none());
let ret_llbb = if let Some(target) = destination {
fx.llbb(target)
} else {
fx.unreachable_block()
};
bx.codegen_inline_asm(
template,
operands,
options,
line_spans,
instance,
Some(ret_llbb),
None,
);
MergingSucc::False
} else if let Some(cleanup) = unwind_target {
let ret_llbb = if let Some(target) = destination {
fx.llbb(target)
} else {
fx.unreachable_block()
};
bx.codegen_inline_asm(
template,
operands,
options,
line_spans,
instance,
Some(ret_llbb),
Some((cleanup, self.funclet(fx))),
);
MergingSucc::False
} else {
bx.codegen_inline_asm(template, operands, options, line_spans, instance, None, None);
if let Some(target) = destination {
self.funclet_br(fx, bx, target, mergeable_succ)
} else {
bx.unreachable();
MergingSucc::False
}
}
}
}
/// Codegen implementations for some terminator variants.
impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
/// Generates code for a `Resume` terminator.
fn codegen_resume_terminator(&mut self, helper: TerminatorCodegenHelper<'tcx>, bx: &mut Bx) {
if let Some(funclet) = helper.funclet(self) {
bx.cleanup_ret(funclet, None);
} else {
let slot = self.get_personality_slot(bx);
let exn0 = slot.project_field(bx, 0);
let exn0 = bx.load_operand(exn0).immediate();
let exn1 = slot.project_field(bx, 1);
let exn1 = bx.load_operand(exn1).immediate();
slot.storage_dead(bx);
bx.resume(exn0, exn1);
}
}
fn codegen_switchint_terminator(
&mut self,
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
discr: &mir::Operand<'tcx>,
targets: &SwitchTargets,
) {
let discr = self.codegen_operand(bx, discr);
let discr_value = discr.immediate();
let switch_ty = discr.layout.ty;
// If our discriminant is a constant we can branch directly
if let Some(const_discr) = bx.const_to_opt_u128(discr_value, false) {
let target = targets.target_for_value(const_discr);
bx.br(helper.llbb_with_cleanup(self, target));
return;
};
let mut target_iter = targets.iter();
if target_iter.len() == 1 {
// If there are two targets (one conditional, one fallback), emit `br` instead of
// `switch`.
let (test_value, target) = target_iter.next().unwrap();
let lltrue = helper.llbb_with_cleanup(self, target);
let llfalse = helper.llbb_with_cleanup(self, targets.otherwise());
if switch_ty == bx.tcx().types.bool {
// Don't generate trivial icmps when switching on bool.
match test_value {
0 => bx.cond_br(discr_value, llfalse, lltrue),
1 => bx.cond_br(discr_value, lltrue, llfalse),
_ => bug!(),
}
} else {
let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
let llval = bx.const_uint_big(switch_llty, test_value);
let cmp = bx.icmp(IntPredicate::IntEQ, discr_value, llval);
bx.cond_br(cmp, lltrue, llfalse);
}
} else if self.cx.sess().opts.optimize == OptLevel::No
&& target_iter.len() == 2
&& self.mir[targets.otherwise()].is_empty_unreachable()
{
// In unoptimized builds, if there are two normal targets and the `otherwise` target is
// an unreachable BB, emit `br` instead of `switch`. This leaves behind the unreachable
// BB, which will usually (but not always) be dead code.
//
// Why only in unoptimized builds?
// - In unoptimized builds LLVM uses FastISel which does not support switches, so it
// must fall back to the to the slower SelectionDAG isel. Therefore, using `br` gives
// significant compile time speedups for unoptimized builds.
// - In optimized builds the above doesn't hold, and using `br` sometimes results in
// worse generated code because LLVM can no longer tell that the value being switched
// on can only have two values, e.g. 0 and 1.
//
let (test_value1, target1) = target_iter.next().unwrap();
let (_test_value2, target2) = target_iter.next().unwrap();
let ll1 = helper.llbb_with_cleanup(self, target1);
let ll2 = helper.llbb_with_cleanup(self, target2);
let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
let llval = bx.const_uint_big(switch_llty, test_value1);
let cmp = bx.icmp(IntPredicate::IntEQ, discr_value, llval);
bx.cond_br(cmp, ll1, ll2);
} else {
bx.switch(
discr_value,
helper.llbb_with_cleanup(self, targets.otherwise()),
target_iter.map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
);
}
}
fn codegen_return_terminator(&mut self, bx: &mut Bx) {
// Call `va_end` if this is the definition of a C-variadic function.
if self.fn_abi.c_variadic {
// The `VaList` "spoofed" argument is just after all the real arguments.
let va_list_arg_idx = self.fn_abi.args.len();
match self.locals[mir::Local::from_usize(1 + va_list_arg_idx)] {
LocalRef::Place(va_list) => {
bx.va_end(va_list.llval);
}
_ => bug!("C-variadic function must have a `VaList` place"),
}
}
if self.fn_abi.ret.layout.abi.is_uninhabited() {
// Functions with uninhabited return values are marked `noreturn`,
// so we should make sure that we never actually do.
// We play it safe by using a well-defined `abort`, but we could go for immediate UB
// if that turns out to be helpful.
bx.abort();
// `abort` does not terminate the block, so we still need to generate
// an `unreachable` terminator after it.
bx.unreachable();
return;
}
let llval = match &self.fn_abi.ret.mode {
PassMode::Ignore | PassMode::Indirect { .. } => {
bx.ret_void();
return;
}
PassMode::Direct(_) | PassMode::Pair(..) => {
let op = self.codegen_consume(bx, mir::Place::return_place().as_ref());
if let Ref(llval, _, align) = op.val {
bx.load(bx.backend_type(op.layout), llval, align)
} else {
op.immediate_or_packed_pair(bx)
}
}
PassMode::Cast { cast: cast_ty, pad_i32: _ } => {
let op = match self.locals[mir::RETURN_PLACE] {
LocalRef::Operand(op) => op,
LocalRef::PendingOperand => bug!("use of return before def"),
LocalRef::Place(cg_place) => OperandRef {
val: Ref(cg_place.llval, None, cg_place.align),
layout: cg_place.layout,
},
LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
};
let llslot = match op.val {
Immediate(_) | Pair(..) => {
let scratch = PlaceRef::alloca(bx, self.fn_abi.ret.layout);
op.val.store(bx, scratch);
scratch.llval
}
Ref(llval, _, align) => {
assert_eq!(align, op.layout.align.abi, "return place is unaligned!");
llval
}
ZeroSized => bug!("ZST return value shouldn't be in PassMode::Cast"),
};
let ty = bx.cast_backend_type(cast_ty);
bx.load(ty, llslot, self.fn_abi.ret.layout.align.abi)
}
};
bx.ret(llval);
}
#[tracing::instrument(level = "trace", skip(self, helper, bx))]
fn codegen_drop_terminator(
&mut self,
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
location: mir::Place<'tcx>,
target: mir::BasicBlock,
unwind: mir::UnwindAction,
mergeable_succ: bool,
) -> MergingSucc {
let ty = location.ty(self.mir, bx.tcx()).ty;
let ty = self.monomorphize(ty);
let drop_fn = Instance::resolve_drop_in_place(bx.tcx(), ty);
if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
// we don't actually need to drop anything.
return helper.funclet_br(self, bx, target, mergeable_succ);
}
let place = self.codegen_place(bx, location.as_ref());
let (args1, args2);
let mut args = if let Some(llextra) = place.llextra {
args2 = [place.llval, llextra];
&args2[..]
} else {
args1 = [place.llval];
&args1[..]
};
let (drop_fn, fn_abi) =
match ty.kind() {
// FIXME(eddyb) perhaps move some of this logic into
// `Instance::resolve_drop_in_place`?
ty::Dynamic(_, _, ty::Dyn) => {
// IN THIS ARM, WE HAVE:
// ty = *mut (dyn Trait)
// which is: exists<T> ( *mut T, Vtable<T: Trait> )
// args[0] args[1]
//
// args = ( Data, Vtable )
// |
// v
// /-------\
// | ... |
// \-------/
//
let virtual_drop = Instance {
def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
args: drop_fn.args,
};
debug!("ty = {:?}", ty);
debug!("drop_fn = {:?}", drop_fn);
debug!("args = {:?}", args);
let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
let vtable = args[1];
// Truncate vtable off of args list
args = &args[..1];
(
meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
.get_fn(bx, vtable, ty, fn_abi),
fn_abi,
)
}
ty::Dynamic(_, _, ty::DynStar) => {
// IN THIS ARM, WE HAVE:
// ty = *mut (dyn* Trait)
// which is: *mut exists<T: sizeof(T) == sizeof(usize)> (T, Vtable<T: Trait>)
//
// args = [ * ]
// |
// v
// ( Data, Vtable )
// |
// v
// /-------\
// | ... |
// \-------/
//
//
// WE CAN CONVERT THIS INTO THE ABOVE LOGIC BY DOING
//
// data = &(*args[0]).0 // gives a pointer to Data above (really the same pointer)
// vtable = (*args[0]).1 // loads the vtable out
// (data, vtable) // an equivalent Rust `*mut dyn Trait`
//
// SO THEN WE CAN USE THE ABOVE CODE.
let virtual_drop = Instance {
def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
args: drop_fn.args,
};
debug!("ty = {:?}", ty);
debug!("drop_fn = {:?}", drop_fn);
debug!("args = {:?}", args);
let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
let meta_ptr = place.project_field(bx, 1);
let meta = bx.load_operand(meta_ptr);
// Truncate vtable off of args list
args = &args[..1];
debug!("args' = {:?}", args);
(
meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
.get_fn(bx, meta.immediate(), ty, fn_abi),
fn_abi,
)
}
_ => (bx.get_fn_addr(drop_fn), bx.fn_abi_of_instance(drop_fn, ty::List::empty())),
};
helper.do_call(
self,
bx,
fn_abi,
drop_fn,
args,
Some((ReturnDest::Nothing, target)),
unwind,
&[],
mergeable_succ,
)
}
fn codegen_assert_terminator(
&mut self,
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
terminator: &mir::Terminator<'tcx>,
cond: &mir::Operand<'tcx>,
expected: bool,
msg: &mir::AssertMessage<'tcx>,
target: mir::BasicBlock,
unwind: mir::UnwindAction,
mergeable_succ: bool,
) -> MergingSucc {
let span = terminator.source_info.span;
let cond = self.codegen_operand(bx, cond).immediate();
let mut const_cond = bx.const_to_opt_u128(cond, false).map(|c| c == 1);
// This case can currently arise only from functions marked
// with #[rustc_inherit_overflow_checks] and inlined from
// another crate (mostly core::num generic/#[inline] fns),
// while the current crate doesn't use overflow checks.
if !bx.cx().check_overflow() && msg.is_optional_overflow_check() {
const_cond = Some(expected);
}
// Don't codegen the panic block if success if known.
if const_cond == Some(expected) {
return helper.funclet_br(self, bx, target, mergeable_succ);
}
// Pass the condition through llvm.expect for branch hinting.
let cond = bx.expect(cond, expected);
// Create the failure block and the conditional branch to it.
let lltarget = helper.llbb_with_cleanup(self, target);
let panic_block = bx.append_sibling_block("panic");
if expected {
bx.cond_br(cond, lltarget, panic_block);
} else {
bx.cond_br(cond, panic_block, lltarget);
}
// After this point, bx is the block for the call to panic.
bx.switch_to_block(panic_block);
self.set_debug_loc(bx, terminator.source_info);
// Get the location information.
let location = self.get_caller_location(bx, terminator.source_info).immediate();
// Put together the arguments to the panic entry point.
let (lang_item, args) = match msg {
AssertKind::BoundsCheck { ref len, ref index } => {
let len = self.codegen_operand(bx, len).immediate();
let index = self.codegen_operand(bx, index).immediate();
// It's `fn panic_bounds_check(index: usize, len: usize)`,
// and `#[track_caller]` adds an implicit third argument.
(LangItem::PanicBoundsCheck, vec![index, len, location])
}
AssertKind::MisalignedPointerDereference { ref required, ref found } => {
let required = self.codegen_operand(bx, required).immediate();
let found = self.codegen_operand(bx, found).immediate();
// It's `fn panic_misaligned_pointer_dereference(required: usize, found: usize)`,
// and `#[track_caller]` adds an implicit third argument.
(LangItem::PanicMisalignedPointerDereference, vec![required, found, location])
}
_ => {
let msg = bx.const_str(msg.description());
// It's `pub fn panic(expr: &str)`, with the wide reference being passed
// as two arguments, and `#[track_caller]` adds an implicit third argument.
(LangItem::Panic, vec![msg.0, msg.1, location])
}
};
let (fn_abi, llfn) = common::build_langcall(bx, Some(span), lang_item);
// Codegen the actual panic invoke/call.
let merging_succ = helper.do_call(self, bx, fn_abi, llfn, &args, None, unwind, &[], false);
assert_eq!(merging_succ, MergingSucc::False);
MergingSucc::False
}
fn codegen_terminate_terminator(
&mut self,
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
terminator: &mir::Terminator<'tcx>,
reason: UnwindTerminateReason,
) {
let span = terminator.source_info.span;
self.set_debug_loc(bx, terminator.source_info);
// Obtain the panic entry point.
let (fn_abi, llfn) = common::build_langcall(bx, Some(span), reason.lang_item());
// Codegen the actual panic invoke/call.
let merging_succ = helper.do_call(
self,
bx,
fn_abi,
llfn,
&[],
None,
mir::UnwindAction::Unreachable,
&[],
false,
);
assert_eq!(merging_succ, MergingSucc::False);
}
/// Returns `Some` if this is indeed a panic intrinsic and codegen is done.
fn codegen_panic_intrinsic(
&mut self,
helper: &TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
intrinsic: Option<ty::IntrinsicDef>,
instance: Option<Instance<'tcx>>,
source_info: mir::SourceInfo,
target: Option<mir::BasicBlock>,
unwind: mir::UnwindAction,
mergeable_succ: bool,
) -> Option<MergingSucc> {
// Emit a panic or a no-op for `assert_*` intrinsics.
// These are intrinsics that compile to panics so that we can get a message
// which mentions the offending type, even from a const context.
let panic_intrinsic = intrinsic.and_then(|i| ValidityRequirement::from_intrinsic(i.name));
if let Some(requirement) = panic_intrinsic {
let ty = instance.unwrap().args.type_at(0);
let do_panic = !bx
.tcx()
.check_validity_requirement((requirement, bx.param_env().and(ty)))
.expect("expect to have layout during codegen");
let layout = bx.layout_of(ty);
Some(if do_panic {
let msg_str = with_no_visible_paths!({
with_no_trimmed_paths!({
if layout.abi.is_uninhabited() {
// Use this error even for the other intrinsics as it is more precise.
format!("attempted to instantiate uninhabited type `{ty}`")
} else if requirement == ValidityRequirement::Zero {
format!("attempted to zero-initialize type `{ty}`, which is invalid")
} else {
format!(
"attempted to leave type `{ty}` uninitialized, which is invalid"
)
}
})
});
let msg = bx.const_str(&msg_str);
// Obtain the panic entry point.
let (fn_abi, llfn) =
common::build_langcall(bx, Some(source_info.span), LangItem::PanicNounwind);
// Codegen the actual panic invoke/call.
helper.do_call(
self,
bx,
fn_abi,
llfn,
&[msg.0, msg.1],
target.as_ref().map(|bb| (ReturnDest::Nothing, *bb)),
unwind,
&[],
mergeable_succ,
)
} else {
// a NOP
let target = target.unwrap();
helper.funclet_br(self, bx, target, mergeable_succ)
})
} else {
None
}
}
fn codegen_call_terminator(
&mut self,
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
terminator: &mir::Terminator<'tcx>,
func: &mir::Operand<'tcx>,
args: &[Spanned<mir::Operand<'tcx>>],
destination: mir::Place<'tcx>,
target: Option<mir::BasicBlock>,
unwind: mir::UnwindAction,
fn_span: Span,
mergeable_succ: bool,
) -> MergingSucc {
let source_info = terminator.source_info;
let span = source_info.span;
// Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
let callee = self.codegen_operand(bx, func);
let (instance, mut llfn) = match *callee.layout.ty.kind() {
ty::FnDef(def_id, args) => (
Some(
ty::Instance::expect_resolve(
bx.tcx(),
ty::ParamEnv::reveal_all(),
def_id,
args,
)
.polymorphize(bx.tcx()),
),
None,
),
ty::FnPtr(_) => (None, Some(callee.immediate())),
_ => bug!("{} is not callable", callee.layout.ty),
};
let def = instance.map(|i| i.def);
if let Some(ty::InstanceDef::DropGlue(_, None)) = def {
// Empty drop glue; a no-op.
let target = target.unwrap();
return helper.funclet_br(self, bx, target, mergeable_succ);
}
// FIXME(eddyb) avoid computing this if possible, when `instance` is
// available - right now `sig` is only needed for getting the `abi`
// and figuring out how many extra args were passed to a C-variadic `fn`.
let sig = callee.layout.ty.fn_sig(bx.tcx());
let abi = sig.abi();
// Handle intrinsics old codegen wants Expr's for, ourselves.
let intrinsic = match def {
Some(ty::InstanceDef::Intrinsic(def_id)) => Some(bx.tcx().intrinsic(def_id).unwrap()),
_ => None,
};
let extra_args = &args[sig.inputs().skip_binder().len()..];
let extra_args = bx.tcx().mk_type_list_from_iter(extra_args.iter().map(|op_arg| {
let op_ty = op_arg.node.ty(self.mir, bx.tcx());
self.monomorphize(op_ty)
}));
let fn_abi = match instance {
Some(instance) => bx.fn_abi_of_instance(instance, extra_args),
None => bx.fn_abi_of_fn_ptr(sig, extra_args),
};
if let Some(merging_succ) = self.codegen_panic_intrinsic(
&helper,
bx,
intrinsic,
instance,
source_info,
target,
unwind,
mergeable_succ,
) {
return merging_succ;
}
// The arguments we'll be passing. Plus one to account for outptr, if used.
let arg_count = fn_abi.args.len() + fn_abi.ret.is_indirect() as usize;
if matches!(intrinsic, Some(ty::IntrinsicDef { name: sym::caller_location, .. })) {
return if let Some(target) = target {
let location =
self.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
let mut llargs = Vec::with_capacity(arg_count);
let ret_dest = self.make_return_dest(
bx,
destination,
&fn_abi.ret,
&mut llargs,
intrinsic,
Some(target),
);
assert_eq!(llargs, []);
if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
location.val.store(bx, tmp);
}
self.store_return(bx, ret_dest, &fn_abi.ret, location.immediate());
helper.funclet_br(self, bx, target, mergeable_succ)
} else {
MergingSucc::False
};
}
let instance = match intrinsic {
None => instance,
Some(intrinsic) => {
let mut llargs = Vec::with_capacity(1);
let ret_dest = self.make_return_dest(
bx,
destination,
&fn_abi.ret,
&mut llargs,
Some(intrinsic),
target,
);
let dest = match ret_dest {
_ if fn_abi.ret.is_indirect() => llargs[0],
ReturnDest::Nothing => bx.const_undef(bx.type_ptr()),
ReturnDest::IndirectOperand(dst, _) | ReturnDest::Store(dst) => dst.llval,
ReturnDest::DirectOperand(_) => {
bug!("Cannot use direct operand with an intrinsic call")
}
};
let args: Vec<_> = args
.iter()
.enumerate()
.map(|(i, arg)| {
// The indices passed to simd_shuffle in the
// third argument must be constant. This is
// checked by the type-checker.
if i == 2 && intrinsic.name == sym::simd_shuffle {
if let mir::Operand::Constant(constant) = &arg.node {
let (llval, ty) = self.simd_shuffle_indices(bx, constant);
return OperandRef {
val: Immediate(llval),
layout: bx.layout_of(ty),
};
} else {
span_bug!(span, "shuffle indices must be constant");
}
}
self.codegen_operand(bx, &arg.node)
})
.collect();
let instance = *instance.as_ref().unwrap();
match Self::codegen_intrinsic_call(bx, instance, fn_abi, &args, dest, span) {
Ok(()) => {
if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
self.store_return(bx, ret_dest, &fn_abi.ret, dst.llval);
}
return if let Some(target) = target {
helper.funclet_br(self, bx, target, mergeable_succ)
} else {
bx.unreachable();
MergingSucc::False
};
}
Err(instance) => {
if intrinsic.must_be_overridden {
span_bug!(
span,
"intrinsic {} must be overridden by codegen backend, but isn't",
intrinsic.name,
);
}
Some(instance)
}
}
}
};
let mut llargs = Vec::with_capacity(arg_count);
let destination = target.as_ref().map(|&target| {
(
self.make_return_dest(
bx,
destination,
&fn_abi.ret,
&mut llargs,
None,
Some(target),
),
target,
)
});
// Split the rust-call tupled arguments off.
let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
let (tup, args) = args.split_last().unwrap();
(args, Some(tup))
} else {
(args, None)
};
let mut copied_constant_arguments = vec![];
'make_args: for (i, arg) in first_args.iter().enumerate() {
let mut op = self.codegen_operand(bx, &arg.node);
if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
match op.val {
Pair(data_ptr, meta) => {
// In the case of Rc<Self>, we need to explicitly pass a
// *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
// that is understood elsewhere in the compiler as a method on
// `dyn Trait`.
// To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
// we get a value of a built-in pointer type.
//
// This is also relevant for `Pin<&mut Self>`, where we need to peel the `Pin`.
while !op.layout.ty.is_unsafe_ptr() && !op.layout.ty.is_ref() {
let (idx, _) = op.layout.non_1zst_field(bx).expect(
"not exactly one non-1-ZST field in a `DispatchFromDyn` type",
);
op = op.extract_field(bx, idx);
}
// now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
// data pointer and vtable. Look up the method in the vtable, and pass
// the data pointer as the first argument
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
bx,
meta,
op.layout.ty,
fn_abi,
));
llargs.push(data_ptr);
continue 'make_args;