// Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. use llvm::{self, ValueRef, BasicBlockRef}; use rustc::middle::lang_items; use rustc::ty::{self, Ty, TypeFoldable}; use rustc::ty::layout::{self, LayoutOf}; use rustc::mir; use rustc::mir::interpret::EvalErrorKind; use abi::{Abi, ArgType, ArgTypeExt, FnType, FnTypeExt, LlvmType, PassMode}; use base; use callee; use builder::{Builder, MemFlags}; use common::{self, C_bool, C_str_slice, C_struct, C_u32, C_uint_big, C_undef}; use consts; use meth; use monomorphize; use type_of::LayoutLlvmExt; use type_::Type; use syntax::symbol::Symbol; use syntax_pos::Pos; use super::{FunctionCx, LocalRef}; use super::place::PlaceRef; use super::operand::OperandRef; use super::operand::OperandValue::{Pair, Ref, Immediate}; impl<'a, 'tcx> FunctionCx<'a, 'tcx> { pub fn codegen_block(&mut self, bb: mir::BasicBlock) { let mut bx = self.build_block(bb); let data = &self.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: Builder<'a, 'tcx>, bb: mir::BasicBlock, terminator: &mir::Terminator<'tcx>) { debug!("codegen_terminator: {:?}", terminator); // Create the cleanup bundle, if needed. let tcx = bx.tcx(); let span = terminator.source_info.span; let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb); let funclet = funclet_bb.and_then(|funclet_bb| self.funclets[funclet_bb].as_ref()); let cleanup_pad = funclet.map(|lp| lp.cleanuppad()); let cleanup_bundle = funclet.map(|l| l.bundle()); let lltarget = |this: &mut Self, target: mir::BasicBlock| { let lltarget = this.blocks[target]; let target_funclet = this.cleanup_kinds[target].funclet_bb(target); match (funclet_bb, target_funclet) { (None, None) => (lltarget, false), (Some(f), Some(t_f)) if f == t_f || !base::wants_msvc_seh(tcx.sess) => (lltarget, false), (None, Some(_)) => { // jump *into* cleanup - need a landing pad if GNU (this.landing_pad_to(target), false) } (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", terminator), (Some(_), Some(_)) => { (this.landing_pad_to(target), true) } } }; let llblock = |this: &mut Self, target: mir::BasicBlock| { let (lltarget, is_cleanupret) = lltarget(this, target); if is_cleanupret { // MSVC cross-funclet jump - need a trampoline debug!("llblock: creating cleanup trampoline for {:?}", target); let name = &format!("{:?}_cleanup_trampoline_{:?}", bb, target); let trampoline = this.new_block(name); trampoline.cleanup_ret(cleanup_pad.unwrap(), Some(lltarget)); trampoline.llbb() } else { lltarget } }; let funclet_br = |this: &mut Self, bx: Builder, target: mir::BasicBlock| { let (lltarget, is_cleanupret) = lltarget(this, target); if is_cleanupret { // micro-optimization: generate a `ret` rather than a jump // to a trampoline. bx.cleanup_ret(cleanup_pad.unwrap(), Some(lltarget)); } else { bx.br(lltarget); } }; let do_call = | this: &mut Self, bx: Builder<'a, 'tcx>, fn_ty: FnType<'tcx, Ty<'tcx>>, fn_ptr: ValueRef, llargs: &[ValueRef], destination: Option<(ReturnDest<'tcx>, mir::BasicBlock)>, cleanup: Option | { if let Some(cleanup) = cleanup { let ret_bx = if let Some((_, target)) = destination { this.blocks[target] } else { this.unreachable_block() }; let invokeret = bx.invoke(fn_ptr, &llargs, ret_bx, llblock(this, cleanup), cleanup_bundle); fn_ty.apply_attrs_callsite(&bx, invokeret); if let Some((ret_dest, target)) = destination { let ret_bx = this.build_block(target); this.set_debug_loc(&ret_bx, terminator.source_info); this.store_return(&ret_bx, ret_dest, &fn_ty.ret, invokeret); } } else { let llret = bx.call(fn_ptr, &llargs, cleanup_bundle); fn_ty.apply_attrs_callsite(&bx, llret); if this.mir[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. llvm::Attribute::NoInline.apply_callsite(llvm::AttributePlace::Function, llret); } if let Some((ret_dest, target)) = destination { this.store_return(&bx, ret_dest, &fn_ty.ret, llret); funclet_br(this, bx, target); } else { bx.unreachable(); } } }; self.set_debug_loc(&bx, terminator.source_info); match terminator.kind { mir::TerminatorKind::Resume => { if let Some(cleanup_pad) = cleanup_pad { bx.cleanup_ret(cleanup_pad, None); } else { let slot = self.get_personality_slot(&bx); let lp0 = slot.project_field(&bx, 0).load(&bx).immediate(); let lp1 = slot.project_field(&bx, 1).load(&bx).immediate(); slot.storage_dead(&bx); if !bx.sess().target.target.options.custom_unwind_resume { let mut lp = C_undef(self.landing_pad_type()); lp = bx.insert_value(lp, lp0, 0); lp = bx.insert_value(lp, lp1, 1); bx.resume(lp); } else { bx.call(bx.cx.eh_unwind_resume(), &[lp0], cleanup_bundle); bx.unreachable(); } } } mir::TerminatorKind::Abort => { // Call core::intrinsics::abort() let fnname = bx.cx.get_intrinsic(&("llvm.trap")); bx.call(fnname, &[], None); bx.unreachable(); } mir::TerminatorKind::Goto { target } => { funclet_br(self, bx, target); } mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref values, ref targets } => { let discr = self.codegen_operand(&bx, discr); if switch_ty == bx.tcx().types.bool { let lltrue = llblock(self, targets[0]); let llfalse = llblock(self, targets[1]); if let [0] = values[..] { bx.cond_br(discr.immediate(), llfalse, lltrue); } else { assert_eq!(&values[..], &[1]); bx.cond_br(discr.immediate(), lltrue, llfalse); } } else { let (otherwise, targets) = targets.split_last().unwrap(); let switch = bx.switch(discr.immediate(), llblock(self, *otherwise), values.len()); let switch_llty = bx.cx.layout_of(switch_ty).immediate_llvm_type(bx.cx); for (&value, target) in values.iter().zip(targets) { let llval = C_uint_big(switch_llty, value); let llbb = llblock(self, *target); bx.add_case(switch, llval, llbb) } } } mir::TerminatorKind::Return => { let llval = match self.fn_ty.ret.mode { PassMode::Ignore | PassMode::Indirect(_) => { bx.ret_void(); return; } PassMode::Direct(_) | PassMode::Pair(..) => { let op = self.codegen_consume(&bx, &mir::Place::Local(mir::RETURN_PLACE)); if let Ref(llval, align) = op.val { bx.load(llval, align) } else { op.immediate_or_packed_pair(&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, cg_place.align), layout: cg_place.layout } } }; let llslot = match op.val { Immediate(_) | Pair(..) => { let scratch = PlaceRef::alloca(&bx, self.fn_ty.ret.layout, "ret"); op.val.store(&bx, scratch); scratch.llval } Ref(llval, align) => { assert_eq!(align.abi(), op.layout.align.abi(), "return place is unaligned!"); llval } }; bx.load( bx.pointercast(llslot, cast_ty.llvm_type(bx.cx).ptr_to()), self.fn_ty.ret.layout.align) } }; bx.ret(llval); } mir::TerminatorKind::Unreachable => { bx.unreachable(); } mir::TerminatorKind::Drop { ref location, target, unwind } => { let ty = location.ty(self.mir, bx.tcx()).to_ty(bx.tcx()); let ty = self.monomorphize(&ty); let drop_fn = monomorphize::resolve_drop_in_place(bx.cx.tcx, ty); if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def { // we don't actually need to drop anything. funclet_br(self, bx, target); return } let place = self.codegen_place(&bx, location); let mut args: &[_] = &[place.llval, place.llextra]; args = &args[..1 + place.has_extra() as usize]; let (drop_fn, fn_ty) = match ty.sty { ty::TyDynamic(..) => { let fn_ty = drop_fn.ty(bx.cx.tcx); let sig = common::ty_fn_sig(bx.cx, fn_ty); let sig = bx.tcx().normalize_erasing_late_bound_regions( ty::ParamEnv::reveal_all(), &sig, ); let fn_ty = FnType::new_vtable(bx.cx, sig, &[]); args = &args[..1]; (meth::DESTRUCTOR.get_fn(&bx, place.llextra, &fn_ty), fn_ty) } _ => { (callee::get_fn(bx.cx, drop_fn), FnType::of_instance(bx.cx, &drop_fn)) } }; do_call(self, bx, fn_ty, drop_fn, args, Some((ReturnDest::Nothing, target)), unwind); } mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => { let cond = self.codegen_operand(&bx, cond).immediate(); let mut const_cond = common::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.cx.check_overflow { if let mir::interpret::EvalErrorKind::OverflowNeg = *msg { const_cond = Some(expected); } } // Don't codegen the panic block if success if known. if const_cond == Some(expected) { funclet_br(self, bx, target); return; } // Pass the condition through llvm.expect for branch hinting. let expect = bx.cx.get_intrinsic(&"llvm.expect.i1"); let cond = bx.call(expect, &[cond, C_bool(bx.cx, expected)], None); // Create the failure block and the conditional branch to it. let lltarget = llblock(self, target); let panic_block = self.new_block("panic"); if expected { bx.cond_br(cond, lltarget, panic_block.llbb()); } else { bx.cond_br(cond, panic_block.llbb(), lltarget); } // After this point, bx is the block for the call to panic. bx = panic_block; self.set_debug_loc(&bx, terminator.source_info); // Get the location information. let loc = bx.sess().codemap().lookup_char_pos(span.lo()); let filename = Symbol::intern(&loc.file.name.to_string()).as_str(); let filename = C_str_slice(bx.cx, filename); let line = C_u32(bx.cx, loc.line as u32); let col = C_u32(bx.cx, loc.col.to_usize() as u32 + 1); let align = tcx.data_layout.aggregate_align .max(tcx.data_layout.i32_align) .max(tcx.data_layout.pointer_align); // Put together the arguments to the panic entry point. let (lang_item, args) = match *msg { EvalErrorKind::BoundsCheck { ref len, ref index } => { let len = self.codegen_operand(&mut bx, len).immediate(); let index = self.codegen_operand(&mut bx, index).immediate(); let file_line_col = C_struct(bx.cx, &[filename, line, col], false); let file_line_col = consts::addr_of(bx.cx, file_line_col, align, "panic_bounds_check_loc"); (lang_items::PanicBoundsCheckFnLangItem, vec![file_line_col, index, len]) } _ => { let str = msg.description(); let msg_str = Symbol::intern(str).as_str(); let msg_str = C_str_slice(bx.cx, msg_str); let msg_file_line_col = C_struct(bx.cx, &[msg_str, filename, line, col], false); let msg_file_line_col = consts::addr_of(bx.cx, msg_file_line_col, align, "panic_loc"); (lang_items::PanicFnLangItem, vec![msg_file_line_col]) } }; // Obtain the panic entry point. let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item); let instance = ty::Instance::mono(bx.tcx(), def_id); let fn_ty = FnType::of_instance(bx.cx, &instance); let llfn = callee::get_fn(bx.cx, instance); // Codegen the actual panic invoke/call. do_call(self, bx, fn_ty, llfn, &args, None, cleanup); } mir::TerminatorKind::DropAndReplace { .. } => { bug!("undesugared DropAndReplace in codegen: {:?}", terminator); } mir::TerminatorKind::Call { ref func, ref args, ref destination, cleanup } => { // 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.sty { ty::TyFnDef(def_id, substs) => { (Some(ty::Instance::resolve(bx.cx.tcx, ty::ParamEnv::reveal_all(), def_id, substs).unwrap()), None) } ty::TyFnPtr(_) => { (None, Some(callee.immediate())) } _ => bug!("{} is not callable", callee.layout.ty) }; let def = instance.map(|i| i.def); let sig = callee.layout.ty.fn_sig(bx.tcx()); let sig = bx.tcx().normalize_erasing_late_bound_regions( ty::ParamEnv::reveal_all(), &sig, ); 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).as_str()), _ => None }; let intrinsic = intrinsic.as_ref().map(|s| &s[..]); if intrinsic == Some("transmute") { let &(ref dest, target) = destination.as_ref().unwrap(); self.codegen_transmute(&bx, &args[0], dest); funclet_br(self, bx, target); return; } let extra_args = &args[sig.inputs().len()..]; let extra_args = extra_args.iter().map(|op_arg| { let op_ty = op_arg.ty(self.mir, bx.tcx()); self.monomorphize(&op_ty) }).collect::>(); let fn_ty = match def { Some(ty::InstanceDef::Virtual(..)) => { FnType::new_vtable(bx.cx, sig, &extra_args) } Some(ty::InstanceDef::DropGlue(_, None)) => { // empty drop glue - a nop. let &(_, target) = destination.as_ref().unwrap(); funclet_br(self, bx, target); return; } _ => FnType::new(bx.cx, sig, &extra_args) }; // The arguments we'll be passing. Plus one to account for outptr, if used. let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize; let mut llargs = Vec::with_capacity(arg_count); // Prepare the return value destination let ret_dest = if let Some((ref dest, _)) = *destination { let is_intrinsic = intrinsic.is_some(); self.make_return_dest(&bx, dest, &fn_ty.ret, &mut llargs, is_intrinsic) } else { ReturnDest::Nothing }; if intrinsic.is_some() && intrinsic != Some("drop_in_place") { use intrinsic::codegen_intrinsic_call; let dest = match ret_dest { _ if fn_ty.ret.is_indirect() => llargs[0], ReturnDest::Nothing => { C_undef(fn_ty.ret.memory_ty(bx.cx).ptr_to()) } 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.unwrap().starts_with("simd_shuffle") { match *arg { mir::Operand::Copy(_) | mir::Operand::Move(_) => { span_bug!(span, "shuffle indices must be constant"); } mir::Operand::Constant(ref constant) => { let (llval, ty) = self.simd_shuffle_indices( &bx, constant, ); return OperandRef { val: Immediate(llval), layout: bx.cx.layout_of(ty) }; } } } self.codegen_operand(&bx, arg) }).collect(); let callee_ty = instance.as_ref().unwrap().ty(bx.cx.tcx); codegen_intrinsic_call(&bx, callee_ty, &fn_ty, &args, dest, terminator.source_info.span); if let ReturnDest::IndirectOperand(dst, _) = ret_dest { self.store_return(&bx, ret_dest, &fn_ty.ret, dst.llval); } if let Some((_, target)) = *destination { funclet_br(self, 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) }; for (i, arg) in first_args.iter().enumerate() { let mut op = self.codegen_operand(&bx, arg); if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) { if let Pair(data_ptr, meta) = op.val { llfn = Some(meth::VirtualIndex::from_index(idx) .get_fn(&bx, meta, &fn_ty)); llargs.push(data_ptr); continue; } } // 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(..)) | (&mir::Operand::Constant(_), Ref(..)) => { let tmp = PlaceRef::alloca(&bx, op.layout, "const"); op.val.store(&bx, tmp); op.val = Ref(tmp.llval, tmp.align); } _ => {} } self.codegen_argument(&bx, op, &mut llargs, &fn_ty.args[i]); } if let Some(tup) = untuple { self.codegen_arguments_untupled(&bx, tup, &mut llargs, &fn_ty.args[first_args.len()..]) } let fn_ptr = match (llfn, instance) { (Some(llfn), _) => llfn, (None, Some(instance)) => callee::get_fn(bx.cx, instance), _ => span_bug!(span, "no llfn for call"), }; do_call(self, bx, fn_ty, fn_ptr, &llargs, destination.as_ref().map(|&(_, target)| (ret_dest, target)), cleanup); } mir::TerminatorKind::GeneratorDrop | mir::TerminatorKind::Yield { .. } => bug!("generator ops in codegen"), mir::TerminatorKind::FalseEdges { .. } | mir::TerminatorKind::FalseUnwind { .. } => bug!("borrowck false edges in codegen"), } } fn codegen_argument(&mut self, bx: &Builder<'a, 'tcx>, op: OperandRef<'tcx>, llargs: &mut Vec, arg: &ArgType<'tcx, Ty<'tcx>>) { // Fill padding with undef value, where applicable. if let Some(ty) = arg.pad { llargs.push(C_undef(ty.llvm_type(bx.cx))); } if arg.is_ignore() { return; } if let PassMode::Pair(..) = arg.mode { match op.val { Pair(a, b) => { llargs.push(a); llargs.push(b); return; } _ => bug!("codegen_argument: {:?} invalid for pair arugment", 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, "arg"); op.val.store(bx, scratch); (scratch.llval, scratch.align, true) } _ => { (op.immediate_or_packed_pair(bx), arg.layout.align, false) } } } Ref(llval, align) => { if arg.is_indirect() && align.abi() < 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, "arg"); base::memcpy_ty(bx, scratch.llval, llval, op.layout, align, 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 { llval = bx.load(bx.pointercast(llval, ty.llvm_type(bx.cx).ptr_to()), align.min(arg.layout.align)); } 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(llval, align); if let layout::Abi::Scalar(ref scalar) = arg.layout.abi { if scalar.is_bool() { bx.range_metadata(llval, 0..2); } } // We store bools as i8 so we need to truncate to i1. llval = base::to_immediate(bx, llval, arg.layout); } } llargs.push(llval); } fn codegen_arguments_untupled(&mut self, bx: &Builder<'a, 'tcx>, operand: &mir::Operand<'tcx>, llargs: &mut Vec, args: &[ArgType<'tcx, Ty<'tcx>>]) { let tuple = self.codegen_operand(bx, operand); // Handle both by-ref and immediate tuples. if let Ref(llval, align) = tuple.val { let tuple_ptr = PlaceRef::new_sized(llval, tuple.layout, align); for i in 0..tuple.layout.fields.count() { let field_ptr = tuple_ptr.project_field(bx, i); self.codegen_argument(bx, field_ptr.load(bx), 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(bx, i); self.codegen_argument(bx, op, llargs, &args[i]); } } } fn get_personality_slot(&mut self, bx: &Builder<'a, 'tcx>) -> PlaceRef<'tcx> { 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, "personalityslot"); self.personality_slot = Some(slot); slot } } /// Return the landingpad wrapper around the given basic block /// /// No-op in MSVC SEH scheme. fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> BasicBlockRef { if let Some(block) = self.landing_pads[target_bb] { return block; } let block = self.blocks[target_bb]; let landing_pad = self.landing_pad_uncached(block); self.landing_pads[target_bb] = Some(landing_pad); landing_pad } fn landing_pad_uncached(&mut self, target_bb: BasicBlockRef) -> BasicBlockRef { if base::wants_msvc_seh(self.cx.sess()) { span_bug!(self.mir.span, "landing pad was not inserted?") } let bx = self.new_block("cleanup"); let llpersonality = self.cx.eh_personality(); let llretty = self.landing_pad_type(); let lp = bx.landing_pad(llretty, llpersonality, 1); bx.set_cleanup(lp); let slot = self.get_personality_slot(&bx); slot.storage_live(&bx); Pair(bx.extract_value(lp, 0), bx.extract_value(lp, 1)).store(&bx, slot); bx.br(target_bb); bx.llbb() } fn landing_pad_type(&self) -> Type { let cx = self.cx; Type::struct_(cx, &[Type::i8p(cx), Type::i32(cx)], false) } fn unreachable_block(&mut self) -> BasicBlockRef { self.unreachable_block.unwrap_or_else(|| { let bl = self.new_block("unreachable"); bl.unreachable(); self.unreachable_block = Some(bl.llbb()); bl.llbb() }) } pub fn new_block(&self, name: &str) -> Builder<'a, 'tcx> { Builder::new_block(self.cx, self.llfn, name) } pub fn build_block(&self, bb: mir::BasicBlock) -> Builder<'a, 'tcx> { let bx = Builder::with_cx(self.cx); bx.position_at_end(self.blocks[bb]); bx } fn make_return_dest(&mut self, bx: &Builder<'a, 'tcx>, dest: &mir::Place<'tcx>, fn_ret: &ArgType<'tcx, Ty<'tcx>>, llargs: &mut Vec, is_intrinsic: bool) -> ReturnDest<'tcx> { // 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 mir::Place::Local(index) = *dest { match self.locals[index] { LocalRef::Place(dest) => dest, LocalRef::Operand(None) => { // Handle temporary places, specifically Operand ones, as // they don't have allocas 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_ret"); 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_ret"); 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, dest) }; if fn_ret.is_indirect() { if dest.align.abi() < 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: &Builder<'a, 'tcx>, src: &mir::Operand<'tcx>, dst: &mir::Place<'tcx>) { if let mir::Place::Local(index) = *dst { match self.locals[index] { LocalRef::Place(place) => self.codegen_transmute_into(bx, src, place), LocalRef::Operand(None) => { let dst_layout = bx.cx.layout_of(self.monomorphized_place_ty(dst)); assert!(!dst_layout.ty.has_erasable_regions()); let place = PlaceRef::alloca(bx, dst_layout, "transmute_temp"); place.storage_live(bx); self.codegen_transmute_into(bx, src, place); let op = place.load(bx); place.storage_dead(bx); self.locals[index] = LocalRef::Operand(Some(op)); } LocalRef::Operand(Some(op)) => { assert!(op.layout.is_zst(), "assigning to initialized SSAtemp"); } } } else { let dst = self.codegen_place(bx, dst); self.codegen_transmute_into(bx, src, dst); } } fn codegen_transmute_into(&mut self, bx: &Builder<'a, 'tcx>, src: &mir::Operand<'tcx>, dst: PlaceRef<'tcx>) { let src = self.codegen_operand(bx, src); let llty = src.layout.llvm_type(bx.cx); let cast_ptr = bx.pointercast(dst.llval, llty.ptr_to()); let align = src.layout.align.min(dst.layout.align); src.val.store(bx, PlaceRef::new_sized(cast_ptr, src.layout, align)); } // Stores the return value of a function call into it's final location. fn store_return(&mut self, bx: &Builder<'a, 'tcx>, dest: ReturnDest<'tcx>, ret_ty: &ArgType<'tcx, Ty<'tcx>>, llval: ValueRef) { use self::ReturnDest::*; match dest { Nothing => (), Store(dst) => ret_ty.store(bx, llval, dst), IndirectOperand(tmp, index) => { let op = tmp.load(bx); tmp.storage_dead(bx); self.locals[index] = LocalRef::Operand(Some(op)); } DirectOperand(index) => { // If there is a cast, we have to store and reload. let op = if let PassMode::Cast(_) = ret_ty.mode { let tmp = PlaceRef::alloca(bx, ret_ty.layout, "tmp_ret"); tmp.storage_live(bx); ret_ty.store(bx, llval, tmp); let op = tmp.load(bx); tmp.storage_dead(bx); op } else { OperandRef::from_immediate_or_packed_pair(bx, llval, ret_ty.layout) }; self.locals[index] = LocalRef::Operand(Some(op)); } } } } enum ReturnDest<'tcx> { // Do nothing, the return value is indirect or ignored Nothing, // Store the return value to the pointer Store(PlaceRef<'tcx>), // Stores an indirect return value to an operand local place IndirectOperand(PlaceRef<'tcx>, mir::Local), // Stores a direct return value to an operand local place DirectOperand(mir::Local) }