use super::operand::OperandRef; use super::operand::OperandValue::{Immediate, Pair, Ref}; use super::place::PlaceRef; use super::{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_index::vec::Idx; use rustc_middle::mir::{self, AssertKind, SwitchTargets}; use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf}; use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths}; use rustc_middle::ty::{self, Instance, Ty, TypeVisitable}; use rustc_span::source_map::Span; use rustc_span::{sym, Symbol}; use rustc_symbol_mangling::typeid::typeid_for_fnabi; use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode, Reg}; use rustc_target::abi::{self, HasDataLayout, WrappingRange}; use rustc_target::spec::abi::Abi; /// 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>, funclet_bb: Option, } 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 funclet_bb = self.funclet_bb?; if base::wants_msvc_seh(fx.cx.tcx().sess) { // 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"), ) } else { None } } /// Get a basic block (creating it if necessary), possibly with a landing /// pad next to it. fn llbb_with_landing_pad>( &self, fx: &mut FunctionCx<'a, 'tcx, Bx>, target: mir::BasicBlock, ) -> (Bx::BasicBlock, bool) { let span = self.terminator.source_info.span; let lltarget = fx.llbb(target); let target_funclet = fx.cleanup_kinds[target].funclet_bb(target); match (self.funclet_bb, target_funclet) { (None, None) => (lltarget, false), // jump *into* cleanup - need a landing pad if GNU, cleanup pad if MSVC (None, Some(_)) => (fx.landing_pad_for(target), false), (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", self.terminator), (Some(f), Some(t_f)) => { if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) { (lltarget, false) } else { (fx.landing_pad_for(target), true) } } } } /// Get a basic block (creating it if necessary), possibly with cleanup /// stuff in it or next to it. fn llbb_with_cleanup>( &self, fx: &mut FunctionCx<'a, 'tcx, Bx>, target: mir::BasicBlock, ) -> Bx::BasicBlock { let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target); if is_cleanupret { // MSVC cross-funclet jump - need a trampoline debug_assert!(base::wants_msvc_seh(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 funclet_br>( &self, fx: &mut FunctionCx<'a, 'tcx, Bx>, bx: &mut Bx, target: mir::BasicBlock, ) { let (lltarget, is_cleanupret) = self.llbb_with_landing_pad(fx, target); if is_cleanupret { // MSVC micro-optimization: generate a `ret` rather than a jump // to a trampoline. debug_assert!(base::wants_msvc_seh(fx.cx.tcx().sess)); bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget)); } else { bx.br(lltarget); } } /// Call `fn_ptr` of `fn_abi` with the arguments `llargs`, the optional /// return destination `destination` and the cleanup function `cleanup`. fn do_call>( &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)>, cleanup: Option, copied_constant_arguments: &[PlaceRef<'tcx, ::Value>], ) { // 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 unwind_block = if let Some(cleanup) = cleanup.filter(|_| fn_abi.can_unwind) { Some(self.llbb_with_cleanup(fx, cleanup)) } else if fx.mir[self.bb].is_cleanup && fn_abi.can_unwind && !base::wants_msvc_seh(fx.cx.tcx().sess) { // Exception must not propagate out of the execution of a cleanup (doing so // can cause undefined behaviour). We insert a double unwind guard for // functions that can potentially unwind to protect against this. // // This is not necessary for SEH which does not use successive unwinding // like Itanium EH. EH frames in SEH are different from normal function // frames and SEH will abort automatically if an exception tries to // propagate out from cleanup. Some(fx.double_unwind_guard()) } else { None }; 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, Some(&fn_abi), fn_ptr, &llargs, ret_llbb, unwind_block, self.funclet(fx), ); if fx.mir[self.bb].is_cleanup { bx.do_not_inline(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); } } else { let llret = bx.call(fn_ty, Some(&fn_abi), fn_ptr, &llargs, self.funclet(fx)); if fx.mir[self.bb].is_cleanup { // Cleanup is always the cold path. Don't inline // drop glue. Also, when there is a deeply-nested // struct, there are "symmetry" issues that cause // exponential inlining - see issue #41696. bx.do_not_inline(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); } else { bx.unreachable(); } } } /// Generates inline assembly with optional `destination` and `cleanup`. fn do_inlineasm>( &self, fx: &mut FunctionCx<'a, 'tcx, Bx>, bx: &mut Bx, template: &[InlineAsmTemplatePiece], operands: &[InlineAsmOperandRef<'tcx, Bx>], options: InlineAsmOptions, line_spans: &[Span], destination: Option, cleanup: Option, instance: Instance<'_>, ) { if let Some(cleanup) = cleanup { 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, self.llbb_with_cleanup(fx, cleanup), self.funclet(fx))), ); } else { bx.codegen_inline_asm(template, &operands, options, line_spans, instance, None); if let Some(target) = destination { self.funclet_br(fx, bx, target); } else { bx.unreachable(); } } } } /// 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>, mut bx: Bx) { if let Some(funclet) = helper.funclet(self) { bx.cleanup_ret(funclet, None); } else { let slot = self.get_personality_slot(&mut bx); let lp0 = slot.project_field(&mut bx, 0); let lp0 = bx.load_operand(lp0).immediate(); let lp1 = slot.project_field(&mut bx, 1); let lp1 = bx.load_operand(lp1).immediate(); slot.storage_dead(&mut bx); let mut lp = bx.const_undef(self.landing_pad_type()); lp = bx.insert_value(lp, lp0, 0); lp = bx.insert_value(lp, lp1, 1); bx.resume(lp); } } fn codegen_switchint_terminator( &mut self, helper: TerminatorCodegenHelper<'tcx>, mut bx: Bx, discr: &mir::Operand<'tcx>, switch_ty: Ty<'tcx>, targets: &SwitchTargets, ) { let discr = self.codegen_operand(&mut bx, &discr); // `switch_ty` is redundant, sanity-check that. assert_eq!(discr.layout.ty, switch_ty); 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.immediate(), llfalse, lltrue), 1 => bx.cond_br(discr.immediate(), 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.immediate(), llval); bx.cond_br(cmp, lltrue, llfalse); } } else { bx.switch( discr.immediate(), 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, mut bx: 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::new(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(&mut 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(&mut bx) } } PassMode::Cast(cast_ty, _) => { let op = match self.locals[mir::RETURN_PLACE] { LocalRef::Operand(Some(op)) => op, LocalRef::Operand(None) => 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(&mut bx, self.fn_abi.ret.layout); op.val.store(&mut bx, scratch); scratch.llval } Ref(llval, _, align) => { assert_eq!(align, op.layout.align.abi, "return place is unaligned!"); llval } }; let ty = bx.cast_backend_type(cast_ty); let addr = bx.pointercast(llslot, bx.type_ptr_to(ty)); bx.load(ty, addr, 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>, mut bx: Bx, location: mir::Place<'tcx>, target: mir::BasicBlock, unwind: Option, ) { 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. helper.funclet_br(self, &mut bx, target); return; } let place = self.codegen_place(&mut 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 ( *mut T, Vtable ) // args[0] args[1] // // args = ( Data, Vtable ) // | // v // /-------\ // | ... | // \-------/ // let virtual_drop = Instance { def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0), substs: drop_fn.substs, }; 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(&mut 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, Vtable) // // 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), substs: drop_fn.substs, }; 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 data = args[0]; let data_ty = bx.cx().backend_type(place.layout); let vtable_ptr = bx.gep(data_ty, data, &[bx.cx().const_i32(0), bx.cx().const_i32(1)]); let vtable = bx.load(bx.type_i8p(), vtable_ptr, abi::Align::ONE); // Truncate vtable off of args list args = &args[..1]; debug!("args' = {:?}", args); ( meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE) .get_fn(&mut bx, vtable, 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, &mut bx, fn_abi, drop_fn, args, Some((ReturnDest::Nothing, target)), unwind, &[], ); } fn codegen_assert_terminator( &mut self, helper: TerminatorCodegenHelper<'tcx>, mut bx: Bx, terminator: &mir::Terminator<'tcx>, cond: &mir::Operand<'tcx>, expected: bool, msg: &mir::AssertMessage<'tcx>, target: mir::BasicBlock, cleanup: Option, ) { let span = terminator.source_info.span; let cond = self.codegen_operand(&mut 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. // NOTE: Unlike binops, negation doesn't have its own // checked operation, just a comparison with the minimum // value, so we have to check for the assert message. if !bx.check_overflow() { if let AssertKind::OverflowNeg(_) = *msg { const_cond = Some(expected); } } // Don't codegen the panic block if success if known. if const_cond == Some(expected) { helper.funclet_br(self, &mut bx, target); return; } // 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(&mut bx, terminator.source_info); // Get the location information. let location = self.get_caller_location(&mut 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(&mut bx, len).immediate(); let index = self.codegen_operand(&mut 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]) } _ => { 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. helper.do_call(self, &mut bx, fn_abi, llfn, &args, None, cleanup, &[]); } fn codegen_abort_terminator( &mut self, helper: TerminatorCodegenHelper<'tcx>, mut bx: Bx, terminator: &mir::Terminator<'tcx>, ) { let span = terminator.source_info.span; self.set_debug_loc(&mut bx, terminator.source_info); // Obtain the panic entry point. let (fn_abi, llfn) = common::build_langcall(&bx, Some(span), LangItem::PanicNoUnwind); // Codegen the actual panic invoke/call. helper.do_call(self, &mut bx, fn_abi, llfn, &[], None, None, &[]); } /// Returns `true` 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, instance: Option>, source_info: mir::SourceInfo, target: Option, cleanup: Option, ) -> bool { // 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. #[derive(Debug, PartialEq)] enum AssertIntrinsic { Inhabited, ZeroValid, UninitValid, } let panic_intrinsic = intrinsic.and_then(|i| match i { sym::assert_inhabited => Some(AssertIntrinsic::Inhabited), sym::assert_zero_valid => Some(AssertIntrinsic::ZeroValid), sym::assert_uninit_valid => Some(AssertIntrinsic::UninitValid), _ => None, }); if let Some(intrinsic) = panic_intrinsic { use AssertIntrinsic::*; let ty = instance.unwrap().substs.type_at(0); let layout = bx.layout_of(ty); let do_panic = match intrinsic { Inhabited => layout.abi.is_uninhabited(), ZeroValid => !bx.tcx().permits_zero_init(layout), UninitValid => !bx.tcx().permits_uninit_init(layout), }; 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 intrinsic == ZeroValid { format!("attempted to zero-initialize type `{}`, which is invalid", ty) } else { format!( "attempted to leave type `{}` uninitialized, which is invalid", ty ) } }) }); let msg = bx.const_str(&msg_str); let location = self.get_caller_location(bx, source_info).immediate(); // Obtain the panic entry point. let (fn_abi, llfn) = common::build_langcall(bx, Some(source_info.span), LangItem::Panic); // Codegen the actual panic invoke/call. helper.do_call( self, bx, fn_abi, llfn, &[msg.0, msg.1, location], target.as_ref().map(|bb| (ReturnDest::Nothing, *bb)), cleanup, &[], ); } else { // a NOP let target = target.unwrap(); helper.funclet_br(self, bx, target) } true } else { false } } fn codegen_call_terminator( &mut self, helper: TerminatorCodegenHelper<'tcx>, mut bx: Bx, terminator: &mir::Terminator<'tcx>, func: &mir::Operand<'tcx>, args: &[mir::Operand<'tcx>], destination: mir::Place<'tcx>, target: Option, cleanup: Option, fn_span: Span, ) { 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(&mut bx, func); let (instance, mut llfn) = match *callee.layout.ty.kind() { ty::FnDef(def_id, substs) => ( Some( ty::Instance::resolve(bx.tcx(), ty::ParamEnv::reveal_all(), def_id, substs) .unwrap() .unwrap() .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(); helper.funclet_br(self, &mut bx, target); return; } // 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().item_name(def_id)), _ => None, }; let extra_args = &args[sig.inputs().skip_binder().len()..]; let extra_args = bx.tcx().mk_type_list(extra_args.iter().map(|op_arg| { let op_ty = op_arg.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 intrinsic == Some(sym::transmute) { if let Some(target) = target { self.codegen_transmute(&mut bx, &args[0], destination); helper.funclet_br(self, &mut bx, target); } else { // If we are trying to transmute to an uninhabited type, // it is likely there is no allotted destination. In fact, // transmuting to an uninhabited type is UB, which means // we can do what we like. Here, we declare that transmuting // into an uninhabited type is impossible, so anything following // it must be unreachable. assert_eq!(fn_abi.ret.layout.abi, abi::Abi::Uninhabited); bx.unreachable(); } return; } if self.codegen_panic_intrinsic( &helper, &mut bx, intrinsic, instance, source_info, target, cleanup, ) { return; } // 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 mut llargs = Vec::with_capacity(arg_count); // Prepare the return value destination let ret_dest = if target.is_some() { let is_intrinsic = intrinsic.is_some(); self.make_return_dest(&mut bx, destination, &fn_abi.ret, &mut llargs, is_intrinsic) } else { ReturnDest::Nothing }; if intrinsic == Some(sym::caller_location) { if let Some(target) = target { let location = self .get_caller_location(&mut bx, mir::SourceInfo { span: fn_span, ..source_info }); if let ReturnDest::IndirectOperand(tmp, _) = ret_dest { location.val.store(&mut bx, tmp); } self.store_return(&mut bx, ret_dest, &fn_abi.ret, location.immediate()); helper.funclet_br(self, &mut bx, target); } return; } match intrinsic { None | Some(sym::drop_in_place) => {} Some(sym::copy_nonoverlapping) => unreachable!(), Some(intrinsic) => { let dest = match ret_dest { _ if fn_abi.ret.is_indirect() => llargs[0], ReturnDest::Nothing => { bx.const_undef(bx.type_ptr_to(bx.arg_memory_ty(&fn_abi.ret))) } 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 const-qualification, which also // promotes any complex rvalues to constants. if i == 2 && intrinsic.as_str().starts_with("simd_shuffle") { if let mir::Operand::Constant(constant) = arg { let c = self.eval_mir_constant(constant); let (llval, ty) = self.simd_shuffle_indices( &bx, constant.span, self.monomorphize(constant.ty()), c, ); return OperandRef { val: Immediate(llval), layout: bx.layout_of(ty), }; } else { span_bug!(span, "shuffle indices must be constant"); } } self.codegen_operand(&mut bx, arg) }) .collect(); Self::codegen_intrinsic_call( &mut bx, *instance.as_ref().unwrap(), &fn_abi, &args, dest, span, ); if let ReturnDest::IndirectOperand(dst, _) = ret_dest { self.store_return(&mut bx, ret_dest, &fn_abi.ret, dst.llval); } if let Some(target) = target { helper.funclet_br(self, &mut bx, target); } else { bx.unreachable(); } return; } } // 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(&mut bx, arg); if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) { match op.val { Pair(data_ptr, meta) => { // In the case of Rc, we need to explicitly pass a // *mut RcBox 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`, we just keep unwrapping newtypes until // we get a value of a built-in pointer type 'descend_newtypes: while !op.layout.ty.is_unsafe_ptr() && !op.layout.ty.is_region_ptr() { for i in 0..op.layout.fields.count() { let field = op.extract_field(&mut bx, i); if !field.layout.is_zst() { // we found the one non-zero-sized field that is allowed // now find *its* non-zero-sized field, or stop if it's a // pointer op = field; continue 'descend_newtypes; } } span_bug!(span, "receiver has no non-zero-sized fields {:?}", op); } // 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( &mut bx, meta, op.layout.ty, &fn_abi, )); llargs.push(data_ptr); continue 'make_args; } Ref(data_ptr, Some(meta), _) => { // by-value dynamic dispatch llfn = Some(meth::VirtualIndex::from_index(idx).get_fn( &mut bx, meta, op.layout.ty, &fn_abi, )); llargs.push(data_ptr); continue; } Immediate(_) => { let ty::Ref(_, ty, _) = op.layout.ty.kind() else { span_bug!(span, "can't codegen a virtual call on {:#?}", op); }; if !ty.is_dyn_star() { span_bug!(span, "can't codegen a virtual call on {:#?}", op); } // FIXME(dyn-star): Make sure this is done on a &dyn* receiver let place = op.deref(bx.cx()); let data_ptr = place.project_field(&mut bx, 0); let meta_ptr = place.project_field(&mut bx, 1); let meta = bx.load_operand(meta_ptr); llfn = Some(meth::VirtualIndex::from_index(idx).get_fn( &mut bx, meta.immediate(), op.layout.ty, &fn_abi, )); llargs.push(data_ptr.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, op.val) { (&mir::Operand::Copy(_), Ref(_, None, _)) | (&mir::Operand::Constant(_), Ref(_, None, _)) => { let tmp = PlaceRef::alloca(&mut bx, op.layout); bx.lifetime_start(tmp.llval, tmp.layout.size); op.val.store(&mut bx, tmp); op.val = Ref(tmp.llval, None, tmp.align); copied_constant_arguments.push(tmp); } _ => {} } self.codegen_argument(&mut bx, op, &mut llargs, &fn_abi.args[i]); } let num_untupled = untuple.map(|tup| { self.codegen_arguments_untupled( &mut bx, tup, &mut llargs, &fn_abi.args[first_args.len()..], ) }); let needs_location = instance.map_or(false, |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(&mut 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(&mut bx, location, &mut llargs, last_arg); } let (is_indirect_call, fn_ptr) = match (llfn, instance) { (Some(llfn), _) => (true, llfn), (None, Some(instance)) => (false, bx.get_fn_addr(instance)), _ => span_bug!(span, "no llfn for call"), }; // For backends that support CFI using type membership (i.e., testing whether a given // pointer is associated with a type identifier). if bx.tcx().sess.is_sanitizer_cfi_enabled() && is_indirect_call { // Emit type metadata and checks. // FIXME(rcvalle): Add support for generalized identifiers. // FIXME(rcvalle): Create distinct unnamed MDNodes for internal identifiers. let typeid = typeid_for_fnabi(bx.tcx(), fn_abi); let typeid_metadata = self.cx.typeid_metadata(typeid); // Test whether the function pointer is associated with the type identifier. let cond = bx.type_test(fn_ptr, typeid_metadata); let bb_pass = bx.append_sibling_block("type_test.pass"); let bb_fail = bx.append_sibling_block("type_test.fail"); bx.cond_br(cond, bb_pass, bb_fail); bx.switch_to_block(bb_pass); helper.do_call( self, &mut bx, fn_abi, fn_ptr, &llargs, target.as_ref().map(|&target| (ret_dest, target)), cleanup, &copied_constant_arguments, ); bx.switch_to_block(bb_fail); bx.abort(); bx.unreachable(); return; } helper.do_call( self, &mut bx, fn_abi, fn_ptr, &llargs, target.as_ref().map(|&target| (ret_dest, target)), cleanup, &copied_constant_arguments, ); } fn codegen_asm_terminator( &mut self, helper: TerminatorCodegenHelper<'tcx>, mut bx: Bx, terminator: &mir::Terminator<'tcx>, template: &[ast::InlineAsmTemplatePiece], operands: &[mir::InlineAsmOperand<'tcx>], options: ast::InlineAsmOptions, line_spans: &[Span], destination: Option, cleanup: Option, instance: Instance<'_>, ) { 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(&mut bx, value); InlineAsmOperandRef::In { reg, value } } mir::InlineAsmOperand::Out { reg, late, ref place } => { let place = place.map(|place| self.codegen_place(&mut 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(&mut bx, in_value); let out_place = out_place.map(|out_place| self.codegen_place(&mut 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) .unwrap_or_else(|_| span_bug!(span, "asm const cannot be resolved")); 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 literal = self.monomorphize(value.literal); if let ty::FnDef(def_id, substs) = *literal.ty().kind() { let instance = ty::Instance::resolve_for_fn_ptr( bx.tcx(), ty::ParamEnv::reveal_all(), def_id, substs, ) .unwrap(); InlineAsmOperandRef::SymFn { instance } } else { span_bug!(span, "invalid type for asm sym (fn)"); } } mir::InlineAsmOperand::SymStatic { def_id } => { InlineAsmOperandRef::SymStatic { def_id } } }) .collect(); helper.do_inlineasm( self, &mut bx, template, &operands, options, line_spans, destination, cleanup, instance, ); } } impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> { pub fn codegen_block(&mut self, bb: mir::BasicBlock) { let llbb = self.llbb(bb); let mut bx = Bx::build(self.cx, llbb); let mir = self.mir; let data = &mir[bb]; debug!("codegen_block({:?}={:?})", bb, data); for statement in &data.statements { bx = self.codegen_statement(bx, statement); } self.codegen_terminator(bx, bb, data.terminator()); } fn codegen_terminator( &mut self, mut bx: Bx, bb: mir::BasicBlock, terminator: &'tcx mir::Terminator<'tcx>, ) { debug!("codegen_terminator: {:?}", terminator); // Create the cleanup bundle, if needed. let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb); let helper = TerminatorCodegenHelper { bb, terminator, funclet_bb }; self.set_debug_loc(&mut bx, terminator.source_info); match terminator.kind { mir::TerminatorKind::Resume => self.codegen_resume_terminator(helper, bx), mir::TerminatorKind::Abort => { self.codegen_abort_terminator(helper, bx, terminator); } mir::TerminatorKind::Goto { target } => { helper.funclet_br(self, &mut bx, target); } mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref targets } => { self.codegen_switchint_terminator(helper, bx, discr, switch_ty, targets); } mir::TerminatorKind::Return => { self.codegen_return_terminator(bx); } mir::TerminatorKind::Unreachable => { bx.unreachable(); } mir::TerminatorKind::Drop { place, target, unwind } => { self.codegen_drop_terminator(helper, bx, place, target, unwind); } mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => { self.codegen_assert_terminator( helper, bx, terminator, cond, expected, msg, target, cleanup, ); } mir::TerminatorKind::DropAndReplace { .. } => { bug!("undesugared DropAndReplace in codegen: {:?}", terminator); } mir::TerminatorKind::Call { ref func, ref args, destination, target, cleanup, from_hir_call: _, fn_span, } => { self.codegen_call_terminator( helper, bx, terminator, func, args, destination, target, cleanup, fn_span, ); } mir::TerminatorKind::GeneratorDrop | mir::TerminatorKind::Yield { .. } => { bug!("generator ops in codegen") } mir::TerminatorKind::FalseEdge { .. } | mir::TerminatorKind::FalseUnwind { .. } => { bug!("borrowck false edges in codegen") } mir::TerminatorKind::InlineAsm { template, ref operands, options, line_spans, destination, cleanup, } => { self.codegen_asm_terminator( helper, bx, terminator, template, operands, options, line_spans, destination, cleanup, self.instance, ); } } } fn codegen_argument( &mut self, bx: &mut Bx, op: OperandRef<'tcx, Bx::Value>, llargs: &mut Vec, arg: &ArgAbi<'tcx, Ty<'tcx>>, ) { match arg.mode { PassMode::Ignore => return, PassMode::Cast(_, 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: _, extra_attrs: Some(_), on_stack: _ } => match op.val { Ref(a, 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 { .. } | PassMode::Cast(..) => { let scratch = PlaceRef::alloca(bx, arg.layout); op.val.store(bx, scratch); (scratch.llval, scratch.align, true) } _ => (op.immediate_or_packed_pair(bx), arg.layout.align.abi, false), }, Ref(llval, _, align) => { if arg.is_indirect() && align < arg.layout.align.abi { // `foo(packed.large_field)`. We can't pass the (unaligned) field directly. I // think that ATM (Rust 1.16) we only pass temporaries, but we shouldn't // have scary latent bugs around. let scratch = PlaceRef::alloca(bx, arg.layout); base::memcpy_ty( bx, scratch.llval, scratch.align, llval, align, op.layout, MemFlags::empty(), ); (scratch.llval, scratch.align, true) } else { (llval, align, true) } } }; if by_ref && !arg.is_indirect() { // Have to load the argument, maybe while casting it. if let PassMode::Cast(ty, _) = &arg.mode { let llty = bx.cast_backend_type(ty); let addr = bx.pointercast(llval, bx.type_ptr_to(llty)); llval = bx.load(llty, addr, align.min(arg.layout.align.abi)); } 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 abi::Abi::Scalar(scalar) = arg.layout.abi { 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(llval, arg.layout); } } llargs.push(llval); } fn codegen_arguments_untupled( &mut self, bx: &mut Bx, operand: &mir::Operand<'tcx>, llargs: &mut Vec, args: &[ArgAbi<'tcx, Ty<'tcx>>], ) -> usize { let tuple = self.codegen_operand(bx, operand); // Handle both by-ref and immediate tuples. if let Ref(llval, None, align) = tuple.val { let tuple_ptr = PlaceRef::new_sized_aligned(llval, tuple.layout, align); 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 let Ref(_, Some(_), _) = tuple.val { bug!("closure arguments must be sized") } else { // If the tuple is immediate, the elements are as well. for i in 0..tuple.layout.fields.count() { let op = tuple.extract_field(bx, i); self.codegen_argument(bx, op, llargs, &args[i]); } } tuple.layout.fields.count() } fn get_caller_location( &mut self, bx: &mut Bx, mut source_info: mir::SourceInfo, ) -> OperandRef<'tcx, Bx::Value> { let tcx = bx.tcx(); let mut span_to_caller_location = |span: Span| { let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span); let caller = tcx.sess.source_map().lookup_char_pos(topmost.lo()); let const_loc = tcx.const_caller_location(( Symbol::intern(&caller.file.name.prefer_remapped().to_string_lossy()), caller.line as u32, caller.col_display as u32 + 1, )); OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty()) }; // Walk up the `SourceScope`s, in case some of them are from MIR inlining. // If so, the starting `source_info.span` is in the innermost inlined // function, and will be replaced with outer callsite spans as long // as the inlined functions were `#[track_caller]`. loop { let scope_data = &self.mir.source_scopes[source_info.scope]; if let Some((callee, callsite_span)) = scope_data.inlined { // Stop inside the most nested non-`#[track_caller]` function, // before ever reaching its caller (which is irrelevant). if !callee.def.requires_caller_location(tcx) { return span_to_caller_location(source_info.span); } source_info.span = callsite_span; } // Skip past all of the parents with `inlined: None`. match scope_data.inlined_parent_scope { Some(parent) => source_info.scope = parent, None => break, } } // No inlined `SourceScope`s, or all of them were `#[track_caller]`. self.caller_location.unwrap_or_else(|| span_to_caller_location(source_info.span)) } 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( cx.tcx().intern_tup(&[cx.tcx().mk_mut_ptr(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_msvc_seh(self.cx.sess()) { let funclet; let ret_llbb; match self.mir[bb].terminator.as_ref().map(|t| &t.kind) { // 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(); // } Some(&mir::TerminatorKind::Abort) => { let cs_llbb = Bx::append_block(self.cx, self.llfn, &format!("cs_funclet{:?}", bb)); let cp_llbb = Bx::append_block(self.cx, self.llfn, &format!("cp_funclet{:?}", bb)); ret_llbb = cs_llbb; let mut cs_bx = Bx::build(self.cx, cs_llbb); let cs = cs_bx.catch_switch(None, None, &[cp_llbb]); // The "null" here is actually a RTTI type descriptor for the // C++ personality function, but `catch (...)` has no type so // it's null. The 64 here is actually a bitfield which // represents that this is a catch-all block. let mut cp_bx = Bx::build(self.cx, cp_llbb); let null = cp_bx.const_null( cp_bx.type_i8p_ext(cp_bx.cx().data_layout().instruction_address_space), ); let sixty_four = cp_bx.const_i32(64); funclet = cp_bx.catch_pad(cs, &[null, sixty_four, null]); cp_bx.br(llbb); } _ => { let cleanup_llbb = Bx::append_block(self.cx, self.llfn, &format!("funclet_{:?}", bb)); ret_llbb = cleanup_llbb; let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb); funclet = cleanup_bx.cleanup_pad(None, &[]); cleanup_bx.br(llbb); } } self.funclets[bb] = Some(funclet); ret_llbb } 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 llretty = self.landing_pad_type(); let lp = cleanup_bx.cleanup_landing_pad(llretty, llpersonality); let slot = self.get_personality_slot(&mut cleanup_bx); slot.storage_live(&mut cleanup_bx); Pair(cleanup_bx.extract_value(lp, 0), cleanup_bx.extract_value(lp, 1)) .store(&mut cleanup_bx, slot); cleanup_bx.br(llbb); cleanup_llbb } } fn landing_pad_type(&self) -> Bx::Type { let cx = self.cx; cx.type_struct(&[cx.type_i8p(), cx.type_i32()], false) } 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 double_unwind_guard(&mut self) -> Bx::BasicBlock { self.double_unwind_guard.unwrap_or_else(|| { assert!(!base::wants_msvc_seh(self.cx.sess())); let llbb = Bx::append_block(self.cx, self.llfn, "abort"); let mut bx = Bx::build(self.cx, llbb); self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span)); let llpersonality = self.cx.eh_personality(); let llretty = self.landing_pad_type(); bx.cleanup_landing_pad(llretty, llpersonality); let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, LangItem::PanicNoUnwind); let fn_ty = bx.fn_decl_backend_type(&fn_abi); let llret = bx.call(fn_ty, Some(&fn_abi), fn_ptr, &[], None); bx.do_not_inline(llret); bx.unreachable(); self.double_unwind_guard = Some(llbb); 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.cached_llbbs[bb].unwrap_or_else(|| { // FIXME(eddyb) only name the block if `fewer_names` is `false`. let llbb = Bx::append_block(self.cx, self.llfn, &format!("{:?}", bb)); self.cached_llbbs[bb] = Some(llbb); llbb }) } fn make_return_dest( &mut self, bx: &mut Bx, dest: mir::Place<'tcx>, fn_ret: &ArgAbi<'tcx, Ty<'tcx>>, llargs: &mut Vec, is_intrinsic: bool, ) -> 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::Operand(None) => { // 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.llval); ReturnDest::IndirectOperand(tmp, index) } else if is_intrinsic { // 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(Some(_)) => { 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.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.llval); ReturnDest::Nothing } else { ReturnDest::Store(dest) } } fn codegen_transmute(&mut self, bx: &mut Bx, src: &mir::Operand<'tcx>, dst: mir::Place<'tcx>) { if let Some(index) = dst.as_local() { match self.locals[index] { LocalRef::Place(place) => self.codegen_transmute_into(bx, src, place), LocalRef::UnsizedPlace(_) => bug!("transmute must not involve unsized locals"), LocalRef::Operand(None) => { let dst_layout = bx.layout_of(self.monomorphized_place_ty(dst.as_ref())); assert!(!dst_layout.ty.has_erasable_regions()); let place = PlaceRef::alloca(bx, dst_layout); place.storage_live(bx); self.codegen_transmute_into(bx, src, place); let op = bx.load_operand(place); place.storage_dead(bx); self.locals[index] = LocalRef::Operand(Some(op)); self.debug_introduce_local(bx, index); } LocalRef::Operand(Some(op)) => { assert!(op.layout.is_zst(), "assigning to initialized SSAtemp"); } } } else { let dst = self.codegen_place(bx, dst.as_ref()); self.codegen_transmute_into(bx, src, dst); } } fn codegen_transmute_into( &mut self, bx: &mut Bx, src: &mir::Operand<'tcx>, dst: PlaceRef<'tcx, Bx::Value>, ) { let src = self.codegen_operand(bx, src); // Special-case transmutes between scalars as simple bitcasts. match (src.layout.abi, dst.layout.abi) { (abi::Abi::Scalar(src_scalar), abi::Abi::Scalar(dst_scalar)) => { // HACK(eddyb) LLVM doesn't like `bitcast`s between pointers and non-pointers. if (src_scalar.primitive() == abi::Pointer) == (dst_scalar.primitive() == abi::Pointer) { assert_eq!(src.layout.size, dst.layout.size); // NOTE(eddyb) the `from_immediate` and `to_immediate_scalar` // conversions allow handling `bool`s the same as `u8`s. let src = bx.from_immediate(src.immediate()); let src_as_dst = bx.bitcast(src, bx.backend_type(dst.layout)); Immediate(bx.to_immediate_scalar(src_as_dst, dst_scalar)).store(bx, dst); return; } } _ => {} } let llty = bx.backend_type(src.layout); let cast_ptr = bx.pointercast(dst.llval, bx.type_ptr_to(llty)); let align = src.layout.align.abi.min(dst.align); src.val.store(bx, PlaceRef::new_sized_aligned(cast_ptr, src.layout, align)); } // 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.locals[index] = LocalRef::Operand(Some(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.locals[index] = LocalRef::Operand(Some(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), }