use std::cmp;
use rustc_abi::{BackendRepr, ExternAbi, HasDataLayout, Reg, WrappingRange};
use rustc_ast as ast;
use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
use rustc_data_structures::packed::Pu128;
use rustc_hir::lang_items::LangItem;
use rustc_middle::mir::{self, AssertKind, InlineAsmMacro, 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_middle::{bug, span_bug};
use rustc_session::config::OptLevel;
use rustc_span::source_map::Spanned;
use rustc_span::{Span, sym};
use rustc_target::callconv::{ArgAbi, FnAbi, PassMode};
use tracing::{debug, info};
use super::operand::OperandRef;
use super::operand::OperandValue::{Immediate, Pair, Ref, ZeroSized};
use super::place::{PlaceRef, PlaceValue};
use super::{CachedLlbb, FunctionCx, LocalRef};
use crate::base::{self, is_call_from_compiler_builtins_to_upstream_monomorphization};
use crate::common::{self, IntPredicate};
use crate::errors::CompilerBuiltinsCannotCall;
use crate::traits::*;
use crate::{MemFlags, meth};
// 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
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>],
instance: Option<Instance<'tcx>>,
mergeable_succ: bool,
) -> MergingSucc {
let tcx = bx.tcx();
if let Some(instance) = instance {
if is_call_from_compiler_builtins_to_upstream_monomorphization(tcx, instance) {
if destination.is_some() {
let caller_def = fx.instance.def_id();
let e = CompilerBuiltinsCannotCall {
span: tcx.def_span(caller_def),
caller: with_no_trimmed_paths!(tcx.def_path_str(caller_def)),
callee: with_no_trimmed_paths!(tcx.def_path_str(instance.def_id())),
};
tcx.dcx().emit_err(e);
} else {
info!(
"compiler_builtins call to diverging function {:?} replaced with abort",
instance.def_id()
);
bx.abort();
bx.unreachable();
return MergingSucc::False;
}
}
}
// 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),
instance,
);
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.val.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), instance);
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.val.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> {
fn codegen_tail_call_terminator(
&mut self,
bx: &mut Bx,
func: &mir::Operand<'tcx>,
args: &[Spanned<mir::Operand<'tcx>>],
fn_span: Span,
) {
// We don't need source_info as we already have fn_span for diagnostics
let func = self.codegen_operand(bx, func);
let fn_ty = func.layout.ty;
// Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
let (fn_ptr, fn_abi, instance) = match *fn_ty.kind() {
ty::FnDef(def_id, substs) => {
let instance = ty::Instance::expect_resolve(
bx.tcx(),
bx.typing_env(),
def_id,
substs,
fn_span,
);
let fn_ptr = bx.get_fn_addr(instance);
let fn_abi = bx.fn_abi_of_instance(instance, ty::List::empty());
(fn_ptr, fn_abi, Some(instance))
}
ty::FnPtr(..) => {
let sig = fn_ty.fn_sig(bx.tcx());
let extra_args = bx.tcx().mk_type_list(&[]);
let fn_ptr = func.immediate();
let fn_abi = bx.fn_abi_of_fn_ptr(sig, extra_args);
(fn_ptr, fn_abi, None)
}
_ => bug!("{} is not callable", func.layout.ty),
};
let mut llargs = Vec::with_capacity(args.len());
// Process arguments
for arg in args {
let op = self.codegen_operand(bx, &arg.node);
let arg_idx = llargs.len();
if arg_idx < fn_abi.args.len() {
self.codegen_argument(bx, op, &mut llargs, &fn_abi.args[arg_idx]);
} else {
// This can happen in case of C-variadic functions
let is_immediate = match op.val {
Immediate(_) => true,
_ => false,
};
if is_immediate {
llargs.push(op.immediate());
} else {
let temp = PlaceRef::alloca(bx, op.layout);
op.val.store(bx, temp);
llargs.push(bx.load(
bx.backend_type(op.layout),
temp.val.llval,
temp.val.align,
));
}
}
}
// Call the function
let fn_ty = bx.fn_decl_backend_type(fn_abi);
let fn_attrs = if let Some(instance) = instance
&& bx.tcx().def_kind(instance.def_id()).has_codegen_attrs()
{
Some(bx.tcx().codegen_fn_attrs(instance.def_id()))
} else {
None
};
// Perform the actual function call
let llret = bx.call(fn_ty, fn_attrs, Some(fn_abi), fn_ptr, &llargs, None, instance);
// Mark as tail call - this is the critical part
bx.set_tail_call(llret);
// Return the result
bx.ret(llret);
}
/// 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 otherwise = targets.otherwise();
let lltarget = helper.llbb_with_cleanup(self, target);
let llotherwise = helper.llbb_with_cleanup(self, otherwise);
let target_cold = self.cold_blocks[target];
let otherwise_cold = self.cold_blocks[otherwise];
// If `target_cold == otherwise_cold`, the branches have the same weight
// so there is no expectation. If they differ, the `target` branch is expected
// when the `otherwise` branch is cold.
let expect = if target_cold == otherwise_cold { None } else { Some(otherwise_cold) };
if switch_ty == bx.tcx().types.bool {
// Don't generate trivial icmps when switching on bool.
match test_value {
0 => {
let expect = expect.map(|e| !e);
bx.cond_br_with_expect(discr_value, llotherwise, lltarget, expect);
}
1 => {
bx.cond_br_with_expect(discr_value, lltarget, llotherwise, expect);
}
_ => 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_with_expect(cmp, lltarget, llotherwise, expect);
}
} else if target_iter.len() == 2
&& self.mir[targets.otherwise()].is_empty_unreachable()
&& targets.all_values().contains(&Pu128(0))
&& targets.all_values().contains(&Pu128(1))
{
// This is the really common case for `bool`, `Option`, etc.
// By using `trunc nuw` we communicate that other values are
// impossible without needing `switch` or `assume`s.
let true_bb = targets.target_for_value(1);
let false_bb = targets.target_for_value(0);
let true_ll = helper.llbb_with_cleanup(self, true_bb);
let false_ll = helper.llbb_with_cleanup(self, false_bb);
let expected_cond_value = if self.cx.sess().opts.optimize == OptLevel::No {
None
} else {
match (self.cold_blocks[true_bb], self.cold_blocks[false_bb]) {
// Same coldness, no expectation
(true, true) | (false, false) => None,
// Different coldness, expect the non-cold one
(true, false) => Some(false),
(false, true) => Some(true),
}
};
let bool_ty = bx.tcx().types.bool;
let cond = if switch_ty == bool_ty {
discr_value
} else {
let bool_llty = bx.immediate_backend_type(bx.layout_of(bool_ty));
bx.unchecked_utrunc(discr_value, bool_llty)
};
bx.cond_br_with_expect(cond, true_ll, false_ll, expected_cond_value);
} 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 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 {
let otherwise = targets.otherwise();
let otherwise_cold = self.cold_blocks[otherwise];
let otherwise_unreachable = self.mir[otherwise].is_empty_unreachable();
let cold_count = targets.iter().filter(|(_, target)| self.cold_blocks[*target]).count();
let none_cold = cold_count == 0;
let all_cold = cold_count == targets.iter().len();
if (none_cold && (!otherwise_cold || otherwise_unreachable))
|| (all_cold && (otherwise_cold || otherwise_unreachable))
{
// All targets have the same weight,
// or `otherwise` is unreachable and it's the only target with a different weight.
bx.switch(
discr_value,
helper.llbb_with_cleanup(self, targets.otherwise()),
target_iter
.map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
);
} else {
// Targets have different weights
bx.switch_with_weights(
discr_value,
helper.llbb_with_cleanup(self, targets.otherwise()),
otherwise_cold,
target_iter.map(|(value, target)| {
(value, helper.llbb_with_cleanup(self, target), self.cold_blocks[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.val.llval);
}
_ => bug!("C-variadic function must have a `VaList` place"),
}
}
if self.fn_abi.ret.layout.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(place_val) = op.val {
bx.load_from_place(bx.backend_type(op.layout), place_val)
} 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.val), 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.val.llval
}
Ref(place_val) => {
assert_eq!(
place_val.align, op.layout.align.abi,
"return place is unaligned!"
);
place_val.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,
source_info: &mir::SourceInfo,
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::InstanceKind::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.val.llextra {
args2 = [place.val.llval, llextra];
&args2[..]
} else {
args1 = [place.val.llval];
&args1[..]
};
let (maybe_null, drop_fn, fn_abi, drop_instance) = 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::InstanceKind::Virtual(drop_fn.def_id(), 0), // idx 0: the drop function
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];
(
true,
meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
.get_optional_fn(bx, vtable, ty, fn_abi),
fn_abi,
virtual_drop,
)
}
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::InstanceKind::Virtual(drop_fn.def_id(), 0), // idx 0: the drop function
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);
(
true,
meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
.get_optional_fn(bx, meta.immediate(), ty, fn_abi),
fn_abi,
virtual_drop,
)
}
_ => (
false,
bx.get_fn_addr(drop_fn),
bx.fn_abi_of_instance(drop_fn, ty::List::empty()),
drop_fn,
),
};
// We generate a null check for the drop_fn. This saves a bunch of relocations being
// generated for no-op drops.
if maybe_null {
let is_not_null = bx.append_sibling_block("is_not_null");
let llty = bx.fn_ptr_backend_type(fn_abi);
let null = bx.const_null(llty);
let non_null =
bx.icmp(base::bin_op_to_icmp_predicate(mir::BinOp::Ne, false), drop_fn, null);
bx.cond_br(non_null, is_not_null, helper.llbb_with_cleanup(self, target));
bx.switch_to_block(is_not_null);
self.set_debug_loc(bx, *source_info);
}
helper.do_call(
self,
bx,
fn_abi,
drop_fn,
args,
Some((ReturnDest::Nothing, target)),
unwind,
&[],
Some(drop_instance),
!maybe_null && 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.sess().overflow_checks() && 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);
}
// Because we're branching to a panic block (either a `#[cold]` one
// or an inlined abort), there's no need to `expect` it.
// 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 { len, 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 { required, 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])
}
AssertKind::NullPointerDereference => {
// It's `fn panic_null_pointer_dereference()`,
// `#[track_caller]` adds an implicit argument.
(LangItem::PanicNullPointerDereference, vec![location])
}
_ => {
// It's `pub fn panic_...()` and `#[track_caller]` adds an implicit argument.
(msg.panic_function(), vec![location])
}
};
let (fn_abi, llfn, instance) = 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, &[], Some(instance), 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, instance) = 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,
&[],
Some(instance),
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: 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.
if let Some(requirement) = ValidityRequirement::from_intrinsic(intrinsic.name) {
let ty = instance.unwrap().args.type_at(0);
let do_panic = !bx
.tcx()
.check_validity_requirement((requirement, bx.typing_env().as_query_input(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.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, instance) =
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,
&[],
Some(instance),
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(),
bx.typing_env(),
def_id,
args,
fn_span,
)),
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::InstanceKind::DropGlue(_, None) | ty::InstanceKind::AsyncDropGlueCtorShim(_, 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();
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),
};
// 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;
let instance = match def {
Some(ty::InstanceKind::Intrinsic(def_id)) => {
let intrinsic = bx.tcx().intrinsic(def_id).unwrap();
if let Some(merging_succ) = self.codegen_panic_intrinsic(
&helper,
bx,
intrinsic,
instance,
source_info,
target,
unwind,
mergeable_succ,
) {
return merging_succ;
}
let mut llargs = Vec::with_capacity(1);
let ret_dest = self.make_return_dest(
bx,
destination,
&fn_abi.ret,
&mut llargs,
Some(intrinsic),
);
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.val.llval,
ReturnDest::DirectOperand(_) => {
bug!("Cannot use direct operand with an intrinsic call")
}
};
let args: Vec<_> =
args.iter().map(|arg| self.codegen_operand(bx, &arg.node)).collect();
if matches!(intrinsic, ty::IntrinsicDef { name: sym::caller_location, .. }) {
let location = self
.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
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());
return helper.funclet_br(self, bx, target.unwrap(), mergeable_succ);
}
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.val.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)
}
}
}
_ => instance,
};
let mut llargs = Vec::with_capacity(arg_count);
// We still need to call `make_return_dest` even if there's no `target`, since
// `fn_abi.ret` could be `PassMode::Indirect`, even if it is uninhabited,
// and `make_return_dest` adds the return-place indirect pointer to `llargs`.
let return_dest = self.make_return_dest(bx, destination, &fn_abi.ret, &mut llargs, None);
let destination = target.map(|target| (return_dest, target));
// Split the rust-call tupled arguments off.
let (first_args, untuple) = if abi == ExternAbi::RustCall
&& let Some((tup, args)) = args.split_last()
{
(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::InstanceKind::Virtual(_, idx))) = (i, def) {
match op.val {
Pair(data_ptr, meta) => {
// In the case of Rc<Self>, we need to explicitly pass a
// *mut RcInner<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 RcInner<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_raw_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(self, 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;
}
Ref(PlaceValue { llval: data_ptr, llextra: Some(meta), .. }) => {
// by-value dynamic dispatch
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
bx,
meta,
op.layout.ty,
fn_abi,
));
llargs.push(data_ptr);
continue;
}
Immediate(_) => {
// See comment above explaining why we peel these newtypes
while !op.layout.ty.is_raw_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(self, bx, idx);
}
// Make sure that we've actually unwrapped the rcvr down
// to a pointer or ref to `dyn* Trait`.
if !op.layout.ty.builtin_deref(true).unwrap().is_dyn_star() {
span_bug!(span, "can't codegen a virtual call on {:#?}", op);
}
let place = op.deref(bx.cx());
let data_place = place.project_field(bx, 0);
let meta_place = place.project_field(bx, 1);
let meta = bx.load_operand(meta_place);
llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
bx,
meta.immediate(),
op.layout.ty,
fn_abi,
));
llargs.push(data_place.val.llval);
continue;
}
_ => {
span_bug!(span, "can't codegen a virtual call on {:#?}", op);
}
}
}
// The callee needs to own the argument memory if we pass it
// by-ref, so make a local copy of non-immediate constants.
match (&arg.node, op.val) {
(&mir::Operand::Copy(_), Ref(PlaceValue { llextra: None, .. }))
| (&mir::Operand::Constant(_), Ref(PlaceValue { llextra: None, .. })) => {
let tmp = PlaceRef::alloca(bx, op.layout);
bx.lifetime_start(tmp.val.llval, tmp.layout.size);
op.val.store(bx, tmp);
op.val = Ref(tmp.val);
copied_constant_arguments.push(tmp);
}
_ => {}
}
self.codegen_argument(bx, op, &mut llargs, &fn_abi.args[i]);
}
let num_untupled = untuple.map(|tup| {
self.codegen_arguments_untupled(
bx,
&tup.node,
&mut llargs,
&fn_abi.args[first_args.len()..],
)
});
let needs_location =
instance.is_some_and(|i| i.def.requires_caller_location(self.cx.tcx()));
if needs_location {
let mir_args = if let Some(num_untupled) = num_untupled {
first_args.len() + num_untupled
} else {
args.len()
};
assert_eq!(
fn_abi.args.len(),
mir_args + 1,
"#[track_caller] fn's must have 1 more argument in their ABI than in their MIR: {instance:?} {fn_span:?} {fn_abi:?}",
);
let location =
self.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
debug!(
"codegen_call_terminator({:?}): location={:?} (fn_span {:?})",
terminator, location, fn_span
);
let last_arg = fn_abi.args.last().unwrap();
self.codegen_argument(bx, location, &mut llargs, last_arg);
}
let fn_ptr = match (instance, llfn) {
(Some(instance), None) => bx.get_fn_addr(instance),
(_, Some(llfn)) => llfn,
_ => span_bug!(span, "no instance or llfn for call"),
};
helper.do_call(
self,
bx,
fn_abi,
fn_ptr,
&llargs,
destination,
unwind,
&copied_constant_arguments,
instance,
mergeable_succ,
)
}
fn codegen_asm_terminator(
&mut self,
helper: TerminatorCodegenHelper<'tcx>,
bx: &mut Bx,
asm_macro: InlineAsmMacro,
terminator: &mir::Terminator<'tcx>,
template: &[ast::InlineAsmTemplatePiece],
operands: &[mir::InlineAsmOperand<'tcx>],
options: ast::InlineAsmOptions,
line_spans: &[Span],
targets: &[mir::BasicBlock],
unwind: mir::UnwindAction,
instance: Instance<'_>,
mergeable_succ: bool,
) -> MergingSucc {
let span = terminator.source_info.span;
let operands: Vec<_> = operands
.iter()
.map(|op| match *op {
mir::InlineAsmOperand::In { reg, ref value } => {
let value = self.codegen_operand(bx, value);
InlineAsmOperandRef::In { reg, value }
}
mir::InlineAsmOperand::Out { reg, late, ref place } => {
let place = place.map(|place| self.codegen_place(bx, place.as_ref()));
InlineAsmOperandRef::Out { reg, late, place }
}
mir::InlineAsmOperand::InOut { reg, late, ref in_value, ref out_place } => {
let in_value = self.codegen_operand(bx, in_value);
let out_place =
out_place.map(|out_place| self.codegen_place(bx, out_place.as_ref()));
InlineAsmOperandRef::InOut { reg, late, in_value, out_place }
}
mir::InlineAsmOperand::Const { ref value } => {
let const_value = self.eval_mir_constant(value);
let string = common::asm_const_to_str(
bx.tcx(),
span,
const_value,
bx.layout_of(value.ty()),
);
InlineAsmOperandRef::Const { string }
}
mir::InlineAsmOperand::SymFn { ref value } => {
let const_ = self.monomorphize(value.const_);
if let ty::FnDef(def_id, args) = *const_.ty().kind() {
let instance = ty::Instance::resolve_for_fn_ptr(
bx.tcx(),
bx.typing_env(),
def_id,
args,
)
.unwrap();
InlineAsmOperandRef::SymFn { instance }
} else {
span_bug!(span, "invalid type for asm sym (fn)");
}
}
mir::InlineAsmOperand::SymStatic { def_id } => {
InlineAsmOperandRef::SymStatic { def_id }
}
mir::InlineAsmOperand::Label { target_index } => {
InlineAsmOperandRef::Label { label: self.llbb(targets[target_index]) }
}
})
.collect();
helper.do_inlineasm(
self,
bx,
template,
&operands,
options,
line_spans,
if asm_macro.diverges(options) { None } else { targets.get(0).copied() },
unwind,
instance,
mergeable_succ,
)
}
pub(crate) fn codegen_block(&mut self, mut bb: mir::BasicBlock) {
let llbb = match self.try_llbb(bb) {
Some(llbb) => llbb,
None => return,
};
let bx = &mut Bx::build(self.cx, llbb);
let mir = self.mir;
// MIR basic blocks stop at any function call. This may not be the case
// for the backend's basic blocks, in which case we might be able to
// combine multiple MIR basic blocks into a single backend basic block.
loop {
let data = &mir[bb];
debug!("codegen_block({:?}={:?})", bb, data);
for statement in &data.statements {
self.codegen_statement(bx, statement);
}
let merging_succ = self.codegen_terminator(bx, bb, data.terminator());
if let MergingSucc::False = merging_succ {
break;
}
// We are merging the successor into the produced backend basic
// block. Record that the successor should be skipped when it is
// reached.
//
// Note: we must not have already generated code for the successor.
// This is implicitly ensured by the reverse postorder traversal,
// and the assertion explicitly guarantees that.
let mut successors = data.terminator().successors();
let succ = successors.next().unwrap();
assert!(matches!(self.cached_llbbs[succ], CachedLlbb::None));
self.cached_llbbs[succ] = CachedLlbb::Skip;
bb = succ;
}
}
pub(crate) fn codegen_block_as_unreachable(&mut self, bb: mir::BasicBlock) {
let llbb = match self.try_llbb(bb) {
Some(llbb) => llbb,
None => return,
};
let bx = &mut Bx::build(self.cx, llbb);
debug!("codegen_block_as_unreachable({:?})", bb);
bx.unreachable();
}
fn codegen_terminator(
&mut self,
bx: &mut Bx,
bb: mir::BasicBlock,
terminator: &'tcx mir::Terminator<'tcx>,
) -> MergingSucc {
debug!("codegen_terminator: {:?}", terminator);
let helper = TerminatorCodegenHelper { bb, terminator };
let mergeable_succ = || {
// Note: any call to `switch_to_block` will invalidate a `true` value
// of `mergeable_succ`.
let mut successors = terminator.successors();
if let Some(succ) = successors.next()
&& successors.next().is_none()
&& let &[succ_pred] = self.mir.basic_blocks.predecessors()[succ].as_slice()
{
// bb has a single successor, and bb is its only predecessor. This
// makes it a candidate for merging.
assert_eq!(succ_pred, bb);
true
} else {
false
}
};
self.set_debug_loc(bx, terminator.source_info);
match terminator.kind {
mir::TerminatorKind::UnwindResume => {
self.codegen_resume_terminator(helper, bx);
MergingSucc::False
}
mir::TerminatorKind::UnwindTerminate(reason) => {
self.codegen_terminate_terminator(helper, bx, terminator, reason);
MergingSucc::False
}
mir::TerminatorKind::Goto { target } => {
helper.funclet_br(self, bx, target, mergeable_succ())
}
mir::TerminatorKind::SwitchInt { ref discr, ref targets } => {
self.codegen_switchint_terminator(helper, bx, discr, targets);
MergingSucc::False
}
mir::TerminatorKind::Return => {
self.codegen_return_terminator(bx);
MergingSucc::False
}
mir::TerminatorKind::Unreachable => {
bx.unreachable();
MergingSucc::False
}
mir::TerminatorKind::Drop { place, target, unwind, replace: _ } => self
.codegen_drop_terminator(
helper,
bx,
&terminator.source_info,
place,
target,
unwind,
mergeable_succ(),
),
mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, unwind } => self
.codegen_assert_terminator(
helper,
bx,
terminator,
cond,
expected,
msg,
target,
unwind,
mergeable_succ(),
),
mir::TerminatorKind::Call {
ref func,
ref args,
destination,
target,
unwind,
call_source: _,
fn_span,
} => self.codegen_call_terminator(
helper,
bx,
terminator,
func,
args,
destination,
target,
unwind,
fn_span,
mergeable_succ(),
),
mir::TerminatorKind::TailCall { ref func, ref args, fn_span } => {
self.codegen_tail_call_terminator(bx, func, args, fn_span);
MergingSucc::False
}
mir::TerminatorKind::CoroutineDrop | mir::TerminatorKind::Yield { .. } => {
bug!("coroutine ops in codegen")
}
mir::TerminatorKind::FalseEdge { .. } | mir::TerminatorKind::FalseUnwind { .. } => {
bug!("borrowck false edges in codegen")
}
mir::TerminatorKind::InlineAsm {
asm_macro,
template,
ref operands,
options,
line_spans,
ref targets,
unwind,
} => self.codegen_asm_terminator(
helper,
bx,
asm_macro,
terminator,
template,
operands,
options,
line_spans,
targets,
unwind,
self.instance,
mergeable_succ(),
),
}
}
fn codegen_argument(
&mut self,
bx: &mut Bx,
op: OperandRef<'tcx, Bx::Value>,
llargs: &mut Vec<Bx::Value>,
arg: &ArgAbi<'tcx, Ty<'tcx>>,
) {
match arg.mode {
PassMode::Ignore => return,
PassMode::Cast { pad_i32: true, .. } => {
// Fill padding with undef value, where applicable.
llargs.push(bx.const_undef(bx.reg_backend_type(&Reg::i32())));
}
PassMode::Pair(..) => match op.val {
Pair(a, b) => {
llargs.push(a);
llargs.push(b);
return;
}
_ => bug!("codegen_argument: {:?} invalid for pair argument", op),
},
PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => match op.val {
Ref(PlaceValue { llval: a, llextra: Some(b), .. }) => {
llargs.push(a);
llargs.push(b);
return;
}
_ => bug!("codegen_argument: {:?} invalid for unsized indirect argument", op),
},
_ => {}
}
// Force by-ref if we have to load through a cast pointer.
let (mut llval, align, by_ref) = match op.val {
Immediate(_) | Pair(..) => match arg.mode {
PassMode::Indirect { attrs, .. } => {
// Indirect argument may have higher alignment requirements than the type's
// alignment. This can happen, e.g. when passing types with <4 byte alignment
// on the stack on x86.
let required_align = match attrs.pointee_align {
Some(pointee_align) => cmp::max(pointee_align, arg.layout.align.abi),
None => arg.layout.align.abi,
};
let scratch = PlaceValue::alloca(bx, arg.layout.size, required_align);
op.val.store(bx, scratch.with_type(arg.layout));
(scratch.llval, scratch.align, true)
}
PassMode::Cast { .. } => {
let scratch = PlaceRef::alloca(bx, arg.layout);
op.val.store(bx, scratch);
(scratch.val.llval, scratch.val.align, true)
}
_ => (op.immediate_or_packed_pair(bx), arg.layout.align.abi, false),
},
Ref(op_place_val) => match arg.mode {
PassMode::Indirect { attrs, .. } => {
let required_align = match attrs.pointee_align {
Some(pointee_align) => cmp::max(pointee_align, arg.layout.align.abi),
None => arg.layout.align.abi,
};
if op_place_val.align < required_align {
// For `foo(packed.large_field)`, and types with <4 byte alignment on x86,
// alignment requirements may be higher than the type's alignment, so copy
// to a higher-aligned alloca.
let scratch = PlaceValue::alloca(bx, arg.layout.size, required_align);
bx.typed_place_copy(scratch, op_place_val, op.layout);
(scratch.llval, scratch.align, true)
} else {
(op_place_val.llval, op_place_val.align, true)
}
}
_ => (op_place_val.llval, op_place_val.align, true),
},
ZeroSized => match arg.mode {
PassMode::Indirect { on_stack, .. } => {
if on_stack {
// It doesn't seem like any target can have `byval` ZSTs, so this assert
// is here to replace a would-be untested codepath.
bug!("ZST {op:?} passed on stack with abi {arg:?}");
}
// Though `extern "Rust"` doesn't pass ZSTs, some ABIs pass
// a pointer for `repr(C)` structs even when empty, so get
// one from an `alloca` (which can be left uninitialized).
let scratch = PlaceRef::alloca(bx, arg.layout);
(scratch.val.llval, scratch.val.align, true)
}
_ => bug!("ZST {op:?} wasn't ignored, but was passed with abi {arg:?}"),
},
};
if by_ref && !arg.is_indirect() {
// Have to load the argument, maybe while casting it.
if let PassMode::Cast { cast, pad_i32: _ } = &arg.mode {
// The ABI mandates that the value is passed as a different struct representation.
// Spill and reload it from the stack to convert from the Rust representation to
// the ABI representation.
let scratch_size = cast.size(bx);
let scratch_align = cast.align(bx);
// Note that the ABI type may be either larger or smaller than the Rust type,
// due to the presence or absence of trailing padding. For example:
// - On some ABIs, the Rust layout { f64, f32, <f32 padding> } may omit padding
// when passed by value, making it smaller.
// - On some ABIs, the Rust layout { u16, u16, u16 } may be padded up to 8 bytes
// when passed by value, making it larger.
let copy_bytes = cmp::min(cast.unaligned_size(bx).bytes(), arg.layout.size.bytes());
// Allocate some scratch space...
let llscratch = bx.alloca(scratch_size, scratch_align);
bx.lifetime_start(llscratch, scratch_size);
// ...memcpy the value...
bx.memcpy(
llscratch,
scratch_align,
llval,
align,
bx.const_usize(copy_bytes),
MemFlags::empty(),
);
// ...and then load it with the ABI type.
let cast_ty = bx.cast_backend_type(cast);
llval = bx.load(cast_ty, llscratch, scratch_align);
bx.lifetime_end(llscratch, scratch_size);
} else {
// We can't use `PlaceRef::load` here because the argument
// may have a type we don't treat as immediate, but the ABI
// used for this call is passing it by-value. In that case,
// the load would just produce `OperandValue::Ref` instead
// of the `OperandValue::Immediate` we need for the call.
llval = bx.load(bx.backend_type(arg.layout), llval, align);
if let BackendRepr::Scalar(scalar) = arg.layout.backend_repr {
if scalar.is_bool() {
bx.range_metadata(llval, WrappingRange { start: 0, end: 1 });
}
// We store bools as `i8` so we need to truncate to `i1`.
llval = bx.to_immediate_scalar(llval, scalar);
}
}
}
llargs.push(llval);
}
fn codegen_arguments_untupled(
&mut self,
bx: &mut Bx,
operand: &mir::Operand<'tcx>,
llargs: &mut Vec<Bx::Value>,
args: &[ArgAbi<'tcx, Ty<'tcx>>],
) -> usize {
let tuple = self.codegen_operand(bx, operand);
// Handle both by-ref and immediate tuples.
if let Ref(place_val) = tuple.val {
if place_val.llextra.is_some() {
bug!("closure arguments must be sized");
}
let tuple_ptr = place_val.with_type(tuple.layout);
for i in 0..tuple.layout.fields.count() {
let field_ptr = tuple_ptr.project_field(bx, i);
let field = bx.load_operand(field_ptr);
self.codegen_argument(bx, field, llargs, &args[i]);
}
} else {
// If the tuple is immediate, the elements are as well.
for i in 0..tuple.layout.fields.count() {
let op = tuple.extract_field(self, bx, i);
self.codegen_argument(bx, op, llargs, &args[i]);
}
}
tuple.layout.fields.count()
}
fn get_caller_location(
&mut self,
bx: &mut Bx,
source_info: mir::SourceInfo,
) -> OperandRef<'tcx, Bx::Value> {
self.mir.caller_location_span(source_info, self.caller_location, bx.tcx(), |span: Span| {
let const_loc = bx.tcx().span_as_caller_location(span);
OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty())
})
}
fn get_personality_slot(&mut self, bx: &mut Bx) -> PlaceRef<'tcx, Bx::Value> {
let cx = bx.cx();
if let Some(slot) = self.personality_slot {
slot
} else {
let layout = cx.layout_of(Ty::new_tup(
cx.tcx(),
&[Ty::new_mut_ptr(cx.tcx(), cx.tcx().types.u8), cx.tcx().types.i32],
));
let slot = PlaceRef::alloca(bx, layout);
self.personality_slot = Some(slot);
slot
}
}
/// Returns the landing/cleanup pad wrapper around the given basic block.
// FIXME(eddyb) rename this to `eh_pad_for`.
fn landing_pad_for(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
if let Some(landing_pad) = self.landing_pads[bb] {
return landing_pad;
}
let landing_pad = self.landing_pad_for_uncached(bb);
self.landing_pads[bb] = Some(landing_pad);
landing_pad
}
// FIXME(eddyb) rename this to `eh_pad_for_uncached`.
fn landing_pad_for_uncached(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
let llbb = self.llbb(bb);
if base::wants_new_eh_instructions(self.cx.sess()) {
let cleanup_bb = Bx::append_block(self.cx, self.llfn, &format!("funclet_{bb:?}"));
let mut cleanup_bx = Bx::build(self.cx, cleanup_bb);
let funclet = cleanup_bx.cleanup_pad(None, &[]);
cleanup_bx.br(llbb);
self.funclets[bb] = Some(funclet);
cleanup_bb
} else {
let cleanup_llbb = Bx::append_block(self.cx, self.llfn, "cleanup");
let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb);
let llpersonality = self.cx.eh_personality();
let (exn0, exn1) = cleanup_bx.cleanup_landing_pad(llpersonality);
let slot = self.get_personality_slot(&mut cleanup_bx);
slot.storage_live(&mut cleanup_bx);
Pair(exn0, exn1).store(&mut cleanup_bx, slot);
cleanup_bx.br(llbb);
cleanup_llbb
}
}
fn unreachable_block(&mut self) -> Bx::BasicBlock {
self.unreachable_block.unwrap_or_else(|| {
let llbb = Bx::append_block(self.cx, self.llfn, "unreachable");
let mut bx = Bx::build(self.cx, llbb);
bx.unreachable();
self.unreachable_block = Some(llbb);
llbb
})
}
fn terminate_block(&mut self, reason: UnwindTerminateReason) -> Bx::BasicBlock {
if let Some((cached_bb, cached_reason)) = self.terminate_block
&& reason == cached_reason
{
return cached_bb;
}
let funclet;
let llbb;
let mut bx;
if base::wants_new_eh_instructions(self.cx.sess()) {
// This is a basic block that we're aborting the program for,
// notably in an `extern` function. These basic blocks are inserted
// so that we assert that `extern` functions do indeed not panic,
// and if they do we abort the process.
//
// On MSVC these are tricky though (where we're doing funclets). If
// we were to do a cleanuppad (like below) the normal functions like
// `longjmp` would trigger the abort logic, terminating the
// program. Instead we insert the equivalent of `catch(...)` for C++
// which magically doesn't trigger when `longjmp` files over this
// frame.
//
// Lots more discussion can be found on #48251 but this codegen is
// modeled after clang's for:
//
// try {
// foo();
// } catch (...) {
// bar();
// }
//
// which creates an IR snippet like
//
// cs_terminate:
// %cs = catchswitch within none [%cp_terminate] unwind to caller
// cp_terminate:
// %cp = catchpad within %cs [null, i32 64, null]
// ...
llbb = Bx::append_block(self.cx, self.llfn, "cs_terminate");
let cp_llbb = Bx::append_block(self.cx, self.llfn, "cp_terminate");
let mut cs_bx = Bx::build(self.cx, llbb);
let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);
bx = Bx::build(self.cx, cp_llbb);
let null =
bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
// The `null` in first argument here is actually a RTTI type
// descriptor for the C++ personality function, but `catch (...)`
// has no type so it's null.
let args = if base::wants_msvc_seh(self.cx.sess()) {
// This bitmask is a single `HT_IsStdDotDot` flag, which
// represents that this is a C++-style `catch (...)` block that
// only captures programmatic exceptions, not all SEH
// exceptions. The second `null` points to a non-existent
// `alloca` instruction, which an LLVM pass would inline into
// the initial SEH frame allocation.
let adjectives = bx.const_i32(0x40);
&[null, adjectives, null] as &[_]
} else {
// Specifying more arguments than necessary usually doesn't
// hurt, but the `WasmEHPrepare` LLVM pass does not recognize
// anything other than a single `null` as a `catch (...)` block,
// leading to problems down the line during instruction
// selection.
&[null] as &[_]
};
funclet = Some(bx.catch_pad(cs, args));
} else {
llbb = Bx::append_block(self.cx, self.llfn, "terminate");
bx = Bx::build(self.cx, llbb);
let llpersonality = self.cx.eh_personality();
bx.filter_landing_pad(llpersonality);
funclet = None;
}
self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));
let (fn_abi, fn_ptr, instance) = common::build_langcall(&bx, None, reason.lang_item());
if is_call_from_compiler_builtins_to_upstream_monomorphization(bx.tcx(), instance) {
bx.abort();
} else {
let fn_ty = bx.fn_decl_backend_type(fn_abi);
let llret = bx.call(fn_ty, None, Some(fn_abi), fn_ptr, &[], funclet.as_ref(), None);
bx.apply_attrs_to_cleanup_callsite(llret);
}
bx.unreachable();
self.terminate_block = Some((llbb, reason));
llbb
}
/// Get the backend `BasicBlock` for a MIR `BasicBlock`, either already
/// cached in `self.cached_llbbs`, or created on demand (and cached).
// FIXME(eddyb) rename `llbb` and other `ll`-prefixed things to use a
// more backend-agnostic prefix such as `cg` (i.e. this would be `cgbb`).
pub fn llbb(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
self.try_llbb(bb).unwrap()
}
/// Like `llbb`, but may fail if the basic block should be skipped.
pub(crate) fn try_llbb(&mut self, bb: mir::BasicBlock) -> Option<Bx::BasicBlock> {
match self.cached_llbbs[bb] {
CachedLlbb::None => {
let llbb = Bx::append_block(self.cx, self.llfn, &format!("{bb:?}"));
self.cached_llbbs[bb] = CachedLlbb::Some(llbb);
Some(llbb)
}
CachedLlbb::Some(llbb) => Some(llbb),
CachedLlbb::Skip => None,
}
}
fn make_return_dest(
&mut self,
bx: &mut Bx,
dest: mir::Place<'tcx>,
fn_ret: &ArgAbi<'tcx, Ty<'tcx>>,
llargs: &mut Vec<Bx::Value>,
intrinsic: Option<ty::IntrinsicDef>,
) -> ReturnDest<'tcx, Bx::Value> {
// If the return is ignored, we can just return a do-nothing `ReturnDest`.
if fn_ret.is_ignore() {
return ReturnDest::Nothing;
}
let dest = if let Some(index) = dest.as_local() {
match self.locals[index] {
LocalRef::Place(dest) => dest,
LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
LocalRef::PendingOperand => {
// Handle temporary places, specifically `Operand` ones, as
// they don't have `alloca`s.
return if fn_ret.is_indirect() {
// Odd, but possible, case, we have an operand temporary,
// but the calling convention has an indirect return.
let tmp = PlaceRef::alloca(bx, fn_ret.layout);
tmp.storage_live(bx);
llargs.push(tmp.val.llval);
ReturnDest::IndirectOperand(tmp, index)
} else if intrinsic.is_some() {
// Currently, intrinsics always need a location to store
// the result, so we create a temporary `alloca` for the
// result.
let tmp = PlaceRef::alloca(bx, fn_ret.layout);
tmp.storage_live(bx);
ReturnDest::IndirectOperand(tmp, index)
} else {
ReturnDest::DirectOperand(index)
};
}
LocalRef::Operand(_) => {
bug!("place local already assigned to");
}
}
} else {
self.codegen_place(bx, mir::PlaceRef { local: dest.local, projection: dest.projection })
};
if fn_ret.is_indirect() {
if dest.val.align < dest.layout.align.abi {
// Currently, MIR code generation does not create calls
// that store directly to fields of packed structs (in
// fact, the calls it creates write only to temps).
//
// If someone changes that, please update this code path
// to create a temporary.
span_bug!(self.mir.span, "can't directly store to unaligned value");
}
llargs.push(dest.val.llval);
ReturnDest::Nothing
} else {
ReturnDest::Store(dest)
}
}
// Stores the return value of a function call into it's final location.
fn store_return(
&mut self,
bx: &mut Bx,
dest: ReturnDest<'tcx, Bx::Value>,
ret_abi: &ArgAbi<'tcx, Ty<'tcx>>,
llval: Bx::Value,
) {
use self::ReturnDest::*;
match dest {
Nothing => (),
Store(dst) => bx.store_arg(ret_abi, llval, dst),
IndirectOperand(tmp, index) => {
let op = bx.load_operand(tmp);
tmp.storage_dead(bx);
self.overwrite_local(index, LocalRef::Operand(op));
self.debug_introduce_local(bx, index);
}
DirectOperand(index) => {
// If there is a cast, we have to store and reload.
let op = if let PassMode::Cast { .. } = ret_abi.mode {
let tmp = PlaceRef::alloca(bx, ret_abi.layout);
tmp.storage_live(bx);
bx.store_arg(ret_abi, llval, tmp);
let op = bx.load_operand(tmp);
tmp.storage_dead(bx);
op
} else {
OperandRef::from_immediate_or_packed_pair(bx, llval, ret_abi.layout)
};
self.overwrite_local(index, LocalRef::Operand(op));
self.debug_introduce_local(bx, index);
}
}
}
}
enum ReturnDest<'tcx, V> {
/// Do nothing; the return value is indirect or ignored.
Nothing,
/// Store the return value to the pointer.
Store(PlaceRef<'tcx, V>),
/// Store an indirect return value to an operand local place.
IndirectOperand(PlaceRef<'tcx, V>, mir::Local),
/// Store a direct return value to an operand local place.
DirectOperand(mir::Local),
}