/
block.rs
1025 lines (928 loc) · 45.5 KB
/
block.rs
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// 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 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
use llvm::{self, BasicBlock};
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 value::Value;
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 FunctionCx<'a, 'll, '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, 'll, '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<'_, 'll, '_>, 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, 'll, 'tcx>,
fn_ty: FnType<'tcx, Ty<'tcx>>,
fn_ptr: &'ll Value,
llargs: &[&'ll Value],
destination: Option<(ReturnDest<'ll, 'tcx>, mir::BasicBlock)>,
cleanup: Option<mir::BasicBlock>
| {
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 targets.len() == 2 {
// If there are two targets, emit br instead of switch
let lltrue = llblock(self, targets[0]);
let llfalse = llblock(self, targets[1]);
if switch_ty == bx.tcx().types.bool {
// Don't generate trivial icmps when switching on bool
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 switch_llty = bx.cx.layout_of(switch_ty).immediate_llvm_type(bx.cx);
let llval = C_uint_big(switch_llty, values[0]);
let cmp = bx.icmp(llvm::IntEQ, discr.immediate(), llval);
bx.cond_br(cmp, 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, None, cg_place.align),
layout: cg_place.layout
}
}
LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
};
let llslot = match op.val {
Immediate(_) | Pair(..) => {
let scratch = PlaceRef::alloca(&bx, self.fn_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 (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_ty) = match ty.sty {
ty::Dynamic(..) => {
let sig = drop_fn.fn_sig(bx.cx.tcx);
let sig = bx.tcx().normalize_erasing_late_bound_regions(
ty::ParamEnv::reveal_all(),
&sig,
);
let fn_ty = FnType::new_vtable(bx.cx, sig, &[]);
let vtable = args[1];
args = &args[..1];
(meth::DESTRUCTOR.get_fn(&bx, vtable, &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().source_map().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,
Some("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,
Some("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,
from_hir_call: _
} => {
// 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::FnDef(def_id, substs) => {
(Some(ty::Instance::resolve(bx.cx.tcx,
ty::ParamEnv::reveal_all(),
def_id,
substs).unwrap()),
None)
}
ty::FnPtr(_) => {
(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") {
if let Some(destination_ref) = destination.as_ref() {
let &(ref dest, target) = destination_ref;
self.codegen_transmute(&bx, &args[0], dest);
funclet_br(self, 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!(bx.cx.layout_of(sig.output()).abi, layout::Abi::Uninhabited);
bx.unreachable();
}
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::<Vec<_>>();
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)
};
// emit a panic instead of instantiating an uninhabited type
if (intrinsic == Some("init") || intrinsic == Some("uninit")) &&
fn_ty.ret.layout.abi.is_uninhabited()
{
let loc = bx.sess().source_map().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);
let str = format!(
"Attempted to instantiate uninhabited type {} using mem::{}",
sig.output(),
if intrinsic == Some("init") { "zeroed" } else { "uninitialized" }
);
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,
Some("panic_loc"));
// Obtain the panic entry point.
let def_id =
common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem);
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,
&[msg_file_line_col],
destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)),
cleanup,
);
return;
}
// 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 {
// The shuffle array argument is usually not an explicit constant,
// but specified directly in the code. This means it gets promoted
// and we can then extract the value by evaluating the promoted.
mir::Operand::Copy(mir::Place::Promoted(box(index, ty))) |
mir::Operand::Move(mir::Place::Promoted(box(index, ty))) => {
let param_env = ty::ParamEnv::reveal_all();
let cid = mir::interpret::GlobalId {
instance: self.instance,
promoted: Some(index),
};
let c = bx.tcx().const_eval(param_env.and(cid));
let (llval, ty) = self.simd_shuffle_indices(
&bx,
terminator.source_info.span,
ty,
c,
);
return OperandRef {
val: Immediate(llval),
layout: bx.cx.layout_of(ty),
};
},
mir::Operand::Copy(_) |
mir::Operand::Move(_) => {
span_bug!(span, "shuffle indices must be constant");
}
mir::Operand::Constant(ref constant) => {
let c = self.eval_mir_constant(&bx, constant);
let (llval, ty) = self.simd_shuffle_indices(
&bx,
constant.span,
constant.ty,
c,
);
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;
} else if let Ref(data_ptr, Some(meta), _) = op.val {
// by-value dynamic dispatch
llfn = Some(meth::VirtualIndex::from_index(idx)
.get_fn(&bx, meta, &fn_ty));
llargs.push(data_ptr);
continue;
} else {
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(&bx, op.layout, "const");
op.val.store(&bx, tmp);
op.val = Ref(tmp.llval, None, 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, 'll, 'tcx>,
op: OperandRef<'ll, 'tcx>,
llargs: &mut Vec<&'ll Value>,
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 argument", op)
}
} else if arg.is_unsized_indirect() {
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, "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, 'll, 'tcx>,
operand: &mir::Operand<'tcx>,
llargs: &mut Vec<&'ll Value>,
args: &[ArgType<'tcx, Ty<'tcx>>]) {
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(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 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]);
}
}
}
fn get_personality_slot(&mut self, bx: &Builder<'a, 'll, 'tcx>) -> PlaceRef<'ll, '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) -> &'ll BasicBlock {
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: &'ll BasicBlock) -> &'ll BasicBlock {
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) -> &'ll Type {
let cx = self.cx;
Type::struct_(cx, &[Type::i8p(cx), Type::i32(cx)], false)
}
fn unreachable_block(&mut self) -> &'ll BasicBlock {
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, 'll, 'tcx> {
Builder::new_block(self.cx, self.llfn, name)
}
pub fn build_block(&self, bb: mir::BasicBlock) -> Builder<'a, 'll, '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, 'll, 'tcx>,
dest: &mir::Place<'tcx>, fn_ret: &ArgType<'tcx, Ty<'tcx>>,
llargs: &mut Vec<&'ll Value>, is_intrinsic: bool)
-> ReturnDest<'ll, '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::UnsizedPlace(_) => bug!("return type must be sized"),
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, 'll, '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::UnsizedPlace(_) => bug!("transmute must not involve unsized locals"),
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, 'll, 'tcx>,
src: &mir::Operand<'tcx>,
dst: PlaceRef<'ll, '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, 'll, 'tcx>,
dest: ReturnDest<'ll, 'tcx>,
ret_ty: &ArgType<'tcx, Ty<'tcx>>,
llval: &'ll Value) {
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 {