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intrinsic.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.
#![allow(non_upper_case_globals)]
use intrinsics::{self, Intrinsic};
use llvm;
use llvm::{ValueRef};
use abi::{Abi, FnType, PassMode};
use mir::place::PlaceRef;
use mir::operand::{OperandRef, OperandValue};
use base::*;
use common::*;
use declare;
use glue;
use type_::Type;
use type_of::LayoutLlvmExt;
use rustc::ty::{self, Ty};
use rustc::ty::layout::{HasDataLayout, LayoutOf};
use rustc::hir;
use syntax::ast;
use syntax::symbol::Symbol;
use builder::Builder;
use rustc::session::Session;
use syntax_pos::Span;
use std::cmp::Ordering;
use std::iter;
fn get_simple_intrinsic(cx: &CodegenCx, name: &str) -> Option<ValueRef> {
let llvm_name = match name {
"sqrtf32" => "llvm.sqrt.f32",
"sqrtf64" => "llvm.sqrt.f64",
"powif32" => "llvm.powi.f32",
"powif64" => "llvm.powi.f64",
"sinf32" => "llvm.sin.f32",
"sinf64" => "llvm.sin.f64",
"cosf32" => "llvm.cos.f32",
"cosf64" => "llvm.cos.f64",
"powf32" => "llvm.pow.f32",
"powf64" => "llvm.pow.f64",
"expf32" => "llvm.exp.f32",
"expf64" => "llvm.exp.f64",
"exp2f32" => "llvm.exp2.f32",
"exp2f64" => "llvm.exp2.f64",
"logf32" => "llvm.log.f32",
"logf64" => "llvm.log.f64",
"log10f32" => "llvm.log10.f32",
"log10f64" => "llvm.log10.f64",
"log2f32" => "llvm.log2.f32",
"log2f64" => "llvm.log2.f64",
"fmaf32" => "llvm.fma.f32",
"fmaf64" => "llvm.fma.f64",
"fabsf32" => "llvm.fabs.f32",
"fabsf64" => "llvm.fabs.f64",
"copysignf32" => "llvm.copysign.f32",
"copysignf64" => "llvm.copysign.f64",
"floorf32" => "llvm.floor.f32",
"floorf64" => "llvm.floor.f64",
"ceilf32" => "llvm.ceil.f32",
"ceilf64" => "llvm.ceil.f64",
"truncf32" => "llvm.trunc.f32",
"truncf64" => "llvm.trunc.f64",
"rintf32" => "llvm.rint.f32",
"rintf64" => "llvm.rint.f64",
"nearbyintf32" => "llvm.nearbyint.f32",
"nearbyintf64" => "llvm.nearbyint.f64",
"roundf32" => "llvm.round.f32",
"roundf64" => "llvm.round.f64",
"assume" => "llvm.assume",
"abort" => "llvm.trap",
_ => return None
};
Some(cx.get_intrinsic(&llvm_name))
}
/// Remember to add all intrinsics here, in librustc_typeck/check/mod.rs,
/// and in libcore/intrinsics.rs; if you need access to any llvm intrinsics,
/// add them to librustc_trans/trans/context.rs
pub fn trans_intrinsic_call<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
callee_ty: Ty<'tcx>,
fn_ty: &FnType<'tcx>,
args: &[OperandRef<'tcx>],
llresult: ValueRef,
span: Span) {
let cx = bx.cx;
let tcx = cx.tcx;
let (def_id, substs) = match callee_ty.sty {
ty::TyFnDef(def_id, substs) => (def_id, substs),
_ => bug!("expected fn item type, found {}", callee_ty)
};
let sig = callee_ty.fn_sig(tcx);
let sig = tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig);
let arg_tys = sig.inputs();
let ret_ty = sig.output();
let name = &*tcx.item_name(def_id);
let llret_ty = cx.layout_of(ret_ty).llvm_type(cx);
let result = PlaceRef::new_sized(llresult, fn_ty.ret.layout, fn_ty.ret.layout.align);
let simple = get_simple_intrinsic(cx, name);
let llval = match name {
_ if simple.is_some() => {
bx.call(simple.unwrap(),
&args.iter().map(|arg| arg.immediate()).collect::<Vec<_>>(),
None)
}
"unreachable" => {
return;
},
"likely" => {
let expect = cx.get_intrinsic(&("llvm.expect.i1"));
bx.call(expect, &[args[0].immediate(), C_bool(cx, true)], None)
}
"unlikely" => {
let expect = cx.get_intrinsic(&("llvm.expect.i1"));
bx.call(expect, &[args[0].immediate(), C_bool(cx, false)], None)
}
"try" => {
try_intrinsic(bx, cx,
args[0].immediate(),
args[1].immediate(),
args[2].immediate(),
llresult);
return;
}
"breakpoint" => {
let llfn = cx.get_intrinsic(&("llvm.debugtrap"));
bx.call(llfn, &[], None)
}
"size_of" => {
let tp_ty = substs.type_at(0);
C_usize(cx, cx.size_of(tp_ty).bytes())
}
"size_of_val" => {
let tp_ty = substs.type_at(0);
if let OperandValue::Pair(_, meta) = args[0].val {
let (llsize, _) =
glue::size_and_align_of_dst(bx, tp_ty, meta);
llsize
} else {
C_usize(cx, cx.size_of(tp_ty).bytes())
}
}
"min_align_of" => {
let tp_ty = substs.type_at(0);
C_usize(cx, cx.align_of(tp_ty).abi())
}
"min_align_of_val" => {
let tp_ty = substs.type_at(0);
if let OperandValue::Pair(_, meta) = args[0].val {
let (_, llalign) =
glue::size_and_align_of_dst(bx, tp_ty, meta);
llalign
} else {
C_usize(cx, cx.align_of(tp_ty).abi())
}
}
"pref_align_of" => {
let tp_ty = substs.type_at(0);
C_usize(cx, cx.align_of(tp_ty).pref())
}
"type_name" => {
let tp_ty = substs.type_at(0);
let ty_name = Symbol::intern(&tp_ty.to_string()).as_str();
C_str_slice(cx, ty_name)
}
"type_id" => {
C_u64(cx, cx.tcx.type_id_hash(substs.type_at(0)))
}
"init" => {
let ty = substs.type_at(0);
if !cx.layout_of(ty).is_zst() {
// Just zero out the stack slot.
// If we store a zero constant, LLVM will drown in vreg allocation for large data
// structures, and the generated code will be awful. (A telltale sign of this is
// large quantities of `mov [byte ptr foo],0` in the generated code.)
memset_intrinsic(bx, false, ty, llresult, C_u8(cx, 0), C_usize(cx, 1));
}
return;
}
// Effectively no-ops
"uninit" => {
return;
}
"needs_drop" => {
let tp_ty = substs.type_at(0);
C_bool(cx, bx.cx.type_needs_drop(tp_ty))
}
"offset" => {
let ptr = args[0].immediate();
let offset = args[1].immediate();
bx.inbounds_gep(ptr, &[offset])
}
"arith_offset" => {
let ptr = args[0].immediate();
let offset = args[1].immediate();
bx.gep(ptr, &[offset])
}
"copy_nonoverlapping" => {
copy_intrinsic(bx, false, false, substs.type_at(0),
args[1].immediate(), args[0].immediate(), args[2].immediate())
}
"copy" => {
copy_intrinsic(bx, true, false, substs.type_at(0),
args[1].immediate(), args[0].immediate(), args[2].immediate())
}
"write_bytes" => {
memset_intrinsic(bx, false, substs.type_at(0),
args[0].immediate(), args[1].immediate(), args[2].immediate())
}
"volatile_copy_nonoverlapping_memory" => {
copy_intrinsic(bx, false, true, substs.type_at(0),
args[0].immediate(), args[1].immediate(), args[2].immediate())
}
"volatile_copy_memory" => {
copy_intrinsic(bx, true, true, substs.type_at(0),
args[0].immediate(), args[1].immediate(), args[2].immediate())
}
"volatile_set_memory" => {
memset_intrinsic(bx, true, substs.type_at(0),
args[0].immediate(), args[1].immediate(), args[2].immediate())
}
"volatile_load" => {
let tp_ty = substs.type_at(0);
let mut ptr = args[0].immediate();
if let PassMode::Cast(ty) = fn_ty.ret.mode {
ptr = bx.pointercast(ptr, ty.llvm_type(cx).ptr_to());
}
let load = bx.volatile_load(ptr);
unsafe {
llvm::LLVMSetAlignment(load, cx.align_of(tp_ty).abi() as u32);
}
to_immediate(bx, load, cx.layout_of(tp_ty))
},
"volatile_store" => {
let tp_ty = substs.type_at(0);
let dst = args[0].deref(bx.cx);
if let OperandValue::Pair(a, b) = args[1].val {
bx.volatile_store(a, dst.project_field(bx, 0).llval);
bx.volatile_store(b, dst.project_field(bx, 1).llval);
} else {
let val = if let OperandValue::Ref(ptr, align) = args[1].val {
bx.load(ptr, align)
} else {
if dst.layout.is_zst() {
return;
}
from_immediate(bx, args[1].immediate())
};
let ptr = bx.pointercast(dst.llval, val_ty(val).ptr_to());
let store = bx.volatile_store(val, ptr);
unsafe {
llvm::LLVMSetAlignment(store, cx.align_of(tp_ty).abi() as u32);
}
}
return;
},
"prefetch_read_data" | "prefetch_write_data" |
"prefetch_read_instruction" | "prefetch_write_instruction" => {
let expect = cx.get_intrinsic(&("llvm.prefetch"));
let (rw, cache_type) = match name {
"prefetch_read_data" => (0, 1),
"prefetch_write_data" => (1, 1),
"prefetch_read_instruction" => (0, 0),
"prefetch_write_instruction" => (1, 0),
_ => bug!()
};
bx.call(expect, &[
args[0].immediate(),
C_i32(cx, rw),
args[1].immediate(),
C_i32(cx, cache_type)
], None)
},
"ctlz" | "ctlz_nonzero" | "cttz" | "cttz_nonzero" | "ctpop" | "bswap" |
"bitreverse" | "add_with_overflow" | "sub_with_overflow" |
"mul_with_overflow" | "overflowing_add" | "overflowing_sub" | "overflowing_mul" |
"unchecked_div" | "unchecked_rem" | "unchecked_shl" | "unchecked_shr" | "exact_div" => {
let ty = arg_tys[0];
match int_type_width_signed(ty, cx) {
Some((width, signed)) =>
match name {
"ctlz" | "cttz" => {
let y = C_bool(bx.cx, false);
let llfn = cx.get_intrinsic(&format!("llvm.{}.i{}", name, width));
bx.call(llfn, &[args[0].immediate(), y], None)
}
"ctlz_nonzero" | "cttz_nonzero" => {
let y = C_bool(bx.cx, true);
let llvm_name = &format!("llvm.{}.i{}", &name[..4], width);
let llfn = cx.get_intrinsic(llvm_name);
bx.call(llfn, &[args[0].immediate(), y], None)
}
"ctpop" => bx.call(cx.get_intrinsic(&format!("llvm.ctpop.i{}", width)),
&[args[0].immediate()], None),
"bswap" => {
if width == 8 {
args[0].immediate() // byte swap a u8/i8 is just a no-op
} else {
bx.call(cx.get_intrinsic(&format!("llvm.bswap.i{}", width)),
&[args[0].immediate()], None)
}
}
"bitreverse" => {
bx.call(cx.get_intrinsic(&format!("llvm.bitreverse.i{}", width)),
&[args[0].immediate()], None)
}
"add_with_overflow" | "sub_with_overflow" | "mul_with_overflow" => {
let intrinsic = format!("llvm.{}{}.with.overflow.i{}",
if signed { 's' } else { 'u' },
&name[..3], width);
let llfn = bx.cx.get_intrinsic(&intrinsic);
// Convert `i1` to a `bool`, and write it to the out parameter
let pair = bx.call(llfn, &[
args[0].immediate(),
args[1].immediate()
], None);
let val = bx.extract_value(pair, 0);
let overflow = bx.zext(bx.extract_value(pair, 1), Type::bool(cx));
let dest = result.project_field(bx, 0);
bx.store(val, dest.llval, dest.align);
let dest = result.project_field(bx, 1);
bx.store(overflow, dest.llval, dest.align);
return;
},
"overflowing_add" => bx.add(args[0].immediate(), args[1].immediate()),
"overflowing_sub" => bx.sub(args[0].immediate(), args[1].immediate()),
"overflowing_mul" => bx.mul(args[0].immediate(), args[1].immediate()),
"exact_div" =>
if signed {
bx.exactsdiv(args[0].immediate(), args[1].immediate())
} else {
bx.exactudiv(args[0].immediate(), args[1].immediate())
},
"unchecked_div" =>
if signed {
bx.sdiv(args[0].immediate(), args[1].immediate())
} else {
bx.udiv(args[0].immediate(), args[1].immediate())
},
"unchecked_rem" =>
if signed {
bx.srem(args[0].immediate(), args[1].immediate())
} else {
bx.urem(args[0].immediate(), args[1].immediate())
},
"unchecked_shl" => bx.shl(args[0].immediate(), args[1].immediate()),
"unchecked_shr" =>
if signed {
bx.ashr(args[0].immediate(), args[1].immediate())
} else {
bx.lshr(args[0].immediate(), args[1].immediate())
},
_ => bug!(),
},
None => {
span_invalid_monomorphization_error(
tcx.sess, span,
&format!("invalid monomorphization of `{}` intrinsic: \
expected basic integer type, found `{}`", name, ty));
return;
}
}
},
"fadd_fast" | "fsub_fast" | "fmul_fast" | "fdiv_fast" | "frem_fast" => {
let sty = &arg_tys[0].sty;
match float_type_width(sty) {
Some(_width) =>
match name {
"fadd_fast" => bx.fadd_fast(args[0].immediate(), args[1].immediate()),
"fsub_fast" => bx.fsub_fast(args[0].immediate(), args[1].immediate()),
"fmul_fast" => bx.fmul_fast(args[0].immediate(), args[1].immediate()),
"fdiv_fast" => bx.fdiv_fast(args[0].immediate(), args[1].immediate()),
"frem_fast" => bx.frem_fast(args[0].immediate(), args[1].immediate()),
_ => bug!(),
},
None => {
span_invalid_monomorphization_error(
tcx.sess, span,
&format!("invalid monomorphization of `{}` intrinsic: \
expected basic float type, found `{}`", name, sty));
return;
}
}
},
"discriminant_value" => {
args[0].deref(bx.cx).trans_get_discr(bx, ret_ty)
}
"align_offset" => {
// `ptr as usize`
let ptr_val = bx.ptrtoint(args[0].immediate(), bx.cx.isize_ty);
// `ptr_val % align`
let align = args[1].immediate();
let offset = bx.urem(ptr_val, align);
let zero = C_null(bx.cx.isize_ty);
// `offset == 0`
let is_zero = bx.icmp(llvm::IntPredicate::IntEQ, offset, zero);
// `if offset == 0 { 0 } else { align - offset }`
bx.select(is_zero, zero, bx.sub(align, offset))
}
name if name.starts_with("simd_") => {
match generic_simd_intrinsic(bx, name,
callee_ty,
args,
ret_ty, llret_ty,
span) {
Ok(llval) => llval,
Err(()) => return
}
}
// This requires that atomic intrinsics follow a specific naming pattern:
// "atomic_<operation>[_<ordering>]", and no ordering means SeqCst
name if name.starts_with("atomic_") => {
use llvm::AtomicOrdering::*;
let split: Vec<&str> = name.split('_').collect();
let is_cxchg = split[1] == "cxchg" || split[1] == "cxchgweak";
let (order, failorder) = match split.len() {
2 => (SequentiallyConsistent, SequentiallyConsistent),
3 => match split[2] {
"unordered" => (Unordered, Unordered),
"relaxed" => (Monotonic, Monotonic),
"acq" => (Acquire, Acquire),
"rel" => (Release, Monotonic),
"acqrel" => (AcquireRelease, Acquire),
"failrelaxed" if is_cxchg =>
(SequentiallyConsistent, Monotonic),
"failacq" if is_cxchg =>
(SequentiallyConsistent, Acquire),
_ => cx.sess().fatal("unknown ordering in atomic intrinsic")
},
4 => match (split[2], split[3]) {
("acq", "failrelaxed") if is_cxchg =>
(Acquire, Monotonic),
("acqrel", "failrelaxed") if is_cxchg =>
(AcquireRelease, Monotonic),
_ => cx.sess().fatal("unknown ordering in atomic intrinsic")
},
_ => cx.sess().fatal("Atomic intrinsic not in correct format"),
};
let invalid_monomorphization = |ty| {
span_invalid_monomorphization_error(tcx.sess, span,
&format!("invalid monomorphization of `{}` intrinsic: \
expected basic integer type, found `{}`", name, ty));
};
match split[1] {
"cxchg" | "cxchgweak" => {
let ty = substs.type_at(0);
if int_type_width_signed(ty, cx).is_some() {
let weak = if split[1] == "cxchgweak" { llvm::True } else { llvm::False };
let pair = bx.atomic_cmpxchg(
args[0].immediate(),
args[1].immediate(),
args[2].immediate(),
order,
failorder,
weak);
let val = bx.extract_value(pair, 0);
let success = bx.zext(bx.extract_value(pair, 1), Type::bool(bx.cx));
let dest = result.project_field(bx, 0);
bx.store(val, dest.llval, dest.align);
let dest = result.project_field(bx, 1);
bx.store(success, dest.llval, dest.align);
return;
} else {
return invalid_monomorphization(ty);
}
}
"load" => {
let ty = substs.type_at(0);
if int_type_width_signed(ty, cx).is_some() {
let align = cx.align_of(ty);
bx.atomic_load(args[0].immediate(), order, align)
} else {
return invalid_monomorphization(ty);
}
}
"store" => {
let ty = substs.type_at(0);
if int_type_width_signed(ty, cx).is_some() {
let align = cx.align_of(ty);
bx.atomic_store(args[1].immediate(), args[0].immediate(), order, align);
return;
} else {
return invalid_monomorphization(ty);
}
}
"fence" => {
bx.atomic_fence(order, llvm::SynchronizationScope::CrossThread);
return;
}
"singlethreadfence" => {
bx.atomic_fence(order, llvm::SynchronizationScope::SingleThread);
return;
}
// These are all AtomicRMW ops
op => {
let atom_op = match op {
"xchg" => llvm::AtomicXchg,
"xadd" => llvm::AtomicAdd,
"xsub" => llvm::AtomicSub,
"and" => llvm::AtomicAnd,
"nand" => llvm::AtomicNand,
"or" => llvm::AtomicOr,
"xor" => llvm::AtomicXor,
"max" => llvm::AtomicMax,
"min" => llvm::AtomicMin,
"umax" => llvm::AtomicUMax,
"umin" => llvm::AtomicUMin,
_ => cx.sess().fatal("unknown atomic operation")
};
let ty = substs.type_at(0);
if int_type_width_signed(ty, cx).is_some() {
bx.atomic_rmw(atom_op, args[0].immediate(), args[1].immediate(), order)
} else {
return invalid_monomorphization(ty);
}
}
}
}
"nontemporal_store" => {
let tp_ty = substs.type_at(0);
let dst = args[0].deref(bx.cx);
let val = if let OperandValue::Ref(ptr, align) = args[1].val {
bx.load(ptr, align)
} else {
from_immediate(bx, args[1].immediate())
};
let ptr = bx.pointercast(dst.llval, val_ty(val).ptr_to());
let store = bx.nontemporal_store(val, ptr);
unsafe {
llvm::LLVMSetAlignment(store, cx.align_of(tp_ty).abi() as u32);
}
return
}
_ => {
let intr = match Intrinsic::find(&name) {
Some(intr) => intr,
None => bug!("unknown intrinsic '{}'", name),
};
fn one<T>(x: Vec<T>) -> T {
assert_eq!(x.len(), 1);
x.into_iter().next().unwrap()
}
fn ty_to_type(cx: &CodegenCx, t: &intrinsics::Type) -> Vec<Type> {
use intrinsics::Type::*;
match *t {
Void => vec![Type::void(cx)],
Integer(_signed, _width, llvm_width) => {
vec![Type::ix(cx, llvm_width as u64)]
}
Float(x) => {
match x {
32 => vec![Type::f32(cx)],
64 => vec![Type::f64(cx)],
_ => bug!()
}
}
Pointer(ref t, ref llvm_elem, _const) => {
let t = llvm_elem.as_ref().unwrap_or(t);
let elem = one(ty_to_type(cx, t));
vec![elem.ptr_to()]
}
Vector(ref t, ref llvm_elem, length) => {
let t = llvm_elem.as_ref().unwrap_or(t);
let elem = one(ty_to_type(cx, t));
vec![Type::vector(&elem, length as u64)]
}
Aggregate(false, ref contents) => {
let elems = contents.iter()
.map(|t| one(ty_to_type(cx, t)))
.collect::<Vec<_>>();
vec![Type::struct_(cx, &elems, false)]
}
Aggregate(true, ref contents) => {
contents.iter()
.flat_map(|t| ty_to_type(cx, t))
.collect()
}
}
}
// This allows an argument list like `foo, (bar, baz),
// qux` to be converted into `foo, bar, baz, qux`, integer
// arguments to be truncated as needed and pointers to be
// cast.
fn modify_as_needed<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
t: &intrinsics::Type,
arg: &OperandRef<'tcx>)
-> Vec<ValueRef>
{
match *t {
intrinsics::Type::Aggregate(true, ref contents) => {
// We found a tuple that needs squishing! So
// run over the tuple and load each field.
//
// This assumes the type is "simple", i.e. no
// destructors, and the contents are SIMD
// etc.
assert!(!bx.cx.type_needs_drop(arg.layout.ty));
let (ptr, align) = match arg.val {
OperandValue::Ref(ptr, align) => (ptr, align),
_ => bug!()
};
let arg = PlaceRef::new_sized(ptr, arg.layout, align);
(0..contents.len()).map(|i| {
arg.project_field(bx, i).load(bx).immediate()
}).collect()
}
intrinsics::Type::Pointer(_, Some(ref llvm_elem), _) => {
let llvm_elem = one(ty_to_type(bx.cx, llvm_elem));
vec![bx.pointercast(arg.immediate(), llvm_elem.ptr_to())]
}
intrinsics::Type::Vector(_, Some(ref llvm_elem), length) => {
let llvm_elem = one(ty_to_type(bx.cx, llvm_elem));
vec![bx.bitcast(arg.immediate(), Type::vector(&llvm_elem, length as u64))]
}
intrinsics::Type::Integer(_, width, llvm_width) if width != llvm_width => {
// the LLVM intrinsic uses a smaller integer
// size than the C intrinsic's signature, so
// we have to trim it down here.
vec![bx.trunc(arg.immediate(), Type::ix(bx.cx, llvm_width as u64))]
}
_ => vec![arg.immediate()],
}
}
let inputs = intr.inputs.iter()
.flat_map(|t| ty_to_type(cx, t))
.collect::<Vec<_>>();
let outputs = one(ty_to_type(cx, &intr.output));
let llargs: Vec<_> = intr.inputs.iter().zip(args).flat_map(|(t, arg)| {
modify_as_needed(bx, t, arg)
}).collect();
assert_eq!(inputs.len(), llargs.len());
let val = match intr.definition {
intrinsics::IntrinsicDef::Named(name) => {
let f = declare::declare_cfn(cx,
name,
Type::func(&inputs, &outputs));
bx.call(f, &llargs, None)
}
};
match *intr.output {
intrinsics::Type::Aggregate(flatten, ref elems) => {
// the output is a tuple so we need to munge it properly
assert!(!flatten);
for i in 0..elems.len() {
let dest = result.project_field(bx, i);
let val = bx.extract_value(val, i as u64);
bx.store(val, dest.llval, dest.align);
}
return;
}
_ => val,
}
}
};
if !fn_ty.ret.is_ignore() {
if let PassMode::Cast(ty) = fn_ty.ret.mode {
let ptr = bx.pointercast(result.llval, ty.llvm_type(cx).ptr_to());
bx.store(llval, ptr, result.align);
} else {
OperandRef::from_immediate_or_packed_pair(bx, llval, result.layout)
.val.store(bx, result);
}
}
}
fn copy_intrinsic<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
allow_overlap: bool,
volatile: bool,
ty: Ty<'tcx>,
dst: ValueRef,
src: ValueRef,
count: ValueRef)
-> ValueRef {
let cx = bx.cx;
let (size, align) = cx.size_and_align_of(ty);
let size = C_usize(cx, size.bytes());
let align = C_i32(cx, align.abi() as i32);
let operation = if allow_overlap {
"memmove"
} else {
"memcpy"
};
let name = format!("llvm.{}.p0i8.p0i8.i{}", operation,
cx.data_layout().pointer_size.bits());
let dst_ptr = bx.pointercast(dst, Type::i8p(cx));
let src_ptr = bx.pointercast(src, Type::i8p(cx));
let llfn = cx.get_intrinsic(&name);
bx.call(llfn,
&[dst_ptr,
src_ptr,
bx.mul(size, count),
align,
C_bool(cx, volatile)],
None)
}
fn memset_intrinsic<'a, 'tcx>(
bx: &Builder<'a, 'tcx>,
volatile: bool,
ty: Ty<'tcx>,
dst: ValueRef,
val: ValueRef,
count: ValueRef
) -> ValueRef {
let cx = bx.cx;
let (size, align) = cx.size_and_align_of(ty);
let size = C_usize(cx, size.bytes());
let align = C_i32(cx, align.abi() as i32);
let dst = bx.pointercast(dst, Type::i8p(cx));
call_memset(bx, dst, val, bx.mul(size, count), align, volatile)
}
fn try_intrinsic<'a, 'tcx>(
bx: &Builder<'a, 'tcx>,
cx: &CodegenCx,
func: ValueRef,
data: ValueRef,
local_ptr: ValueRef,
dest: ValueRef,
) {
if bx.sess().no_landing_pads() {
bx.call(func, &[data], None);
let ptr_align = bx.tcx().data_layout.pointer_align;
bx.store(C_null(Type::i8p(&bx.cx)), dest, ptr_align);
} else if wants_msvc_seh(bx.sess()) {
trans_msvc_try(bx, cx, func, data, local_ptr, dest);
} else {
trans_gnu_try(bx, cx, func, data, local_ptr, dest);
}
}
// MSVC's definition of the `rust_try` function.
//
// This implementation uses the new exception handling instructions in LLVM
// which have support in LLVM for SEH on MSVC targets. Although these
// instructions are meant to work for all targets, as of the time of this
// writing, however, LLVM does not recommend the usage of these new instructions
// as the old ones are still more optimized.
fn trans_msvc_try<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
cx: &CodegenCx,
func: ValueRef,
data: ValueRef,
local_ptr: ValueRef,
dest: ValueRef) {
let llfn = get_rust_try_fn(cx, &mut |bx| {
let cx = bx.cx;
bx.set_personality_fn(bx.cx.eh_personality());
let normal = bx.build_sibling_block("normal");
let catchswitch = bx.build_sibling_block("catchswitch");
let catchpad = bx.build_sibling_block("catchpad");
let caught = bx.build_sibling_block("caught");
let func = llvm::get_param(bx.llfn(), 0);
let data = llvm::get_param(bx.llfn(), 1);
let local_ptr = llvm::get_param(bx.llfn(), 2);
// We're generating an IR snippet that looks like:
//
// declare i32 @rust_try(%func, %data, %ptr) {
// %slot = alloca i64*
// invoke %func(%data) to label %normal unwind label %catchswitch
//
// normal:
// ret i32 0
//
// catchswitch:
// %cs = catchswitch within none [%catchpad] unwind to caller
//
// catchpad:
// %tok = catchpad within %cs [%type_descriptor, 0, %slot]
// %ptr[0] = %slot[0]
// %ptr[1] = %slot[1]
// catchret from %tok to label %caught
//
// caught:
// ret i32 1
// }
//
// This structure follows the basic usage of throw/try/catch in LLVM.
// For example, compile this C++ snippet to see what LLVM generates:
//
// #include <stdint.h>
//
// int bar(void (*foo)(void), uint64_t *ret) {
// try {
// foo();
// return 0;
// } catch(uint64_t a[2]) {
// ret[0] = a[0];
// ret[1] = a[1];
// return 1;
// }
// }
//
// More information can be found in libstd's seh.rs implementation.
let i64p = Type::i64(cx).ptr_to();
let ptr_align = bx.tcx().data_layout.pointer_align;
let slot = bx.alloca(i64p, "slot", ptr_align);
bx.invoke(func, &[data], normal.llbb(), catchswitch.llbb(),
None);
normal.ret(C_i32(cx, 0));
let cs = catchswitch.catch_switch(None, None, 1);
catchswitch.add_handler(cs, catchpad.llbb());
let tcx = cx.tcx;
let tydesc = match tcx.lang_items().msvc_try_filter() {
Some(did) => ::consts::get_static(cx, did),
None => bug!("msvc_try_filter not defined"),
};
let tok = catchpad.catch_pad(cs, &[tydesc, C_i32(cx, 0), slot]);
let addr = catchpad.load(slot, ptr_align);
let i64_align = bx.tcx().data_layout.i64_align;
let arg1 = catchpad.load(addr, i64_align);
let val1 = C_i32(cx, 1);
let arg2 = catchpad.load(catchpad.inbounds_gep(addr, &[val1]), i64_align);
let local_ptr = catchpad.bitcast(local_ptr, i64p);
catchpad.store(arg1, local_ptr, i64_align);
catchpad.store(arg2, catchpad.inbounds_gep(local_ptr, &[val1]), i64_align);
catchpad.catch_ret(tok, caught.llbb());
caught.ret(C_i32(cx, 1));
});
// Note that no invoke is used here because by definition this function
// can't panic (that's what it's catching).
let ret = bx.call(llfn, &[func, data, local_ptr], None);
let i32_align = bx.tcx().data_layout.i32_align;
bx.store(ret, dest, i32_align);
}
// Definition of the standard "try" function for Rust using the GNU-like model
// of exceptions (e.g. the normal semantics of LLVM's landingpad and invoke
// instructions).
//
// This translation is a little surprising because we always call a shim
// function instead of inlining the call to `invoke` manually here. This is done
// because in LLVM we're only allowed to have one personality per function
// definition. The call to the `try` intrinsic is being inlined into the
// function calling it, and that function may already have other personality
// functions in play. By calling a shim we're guaranteed that our shim will have
// the right personality function.
fn trans_gnu_try<'a, 'tcx>(bx: &Builder<'a, 'tcx>,
cx: &CodegenCx,
func: ValueRef,
data: ValueRef,
local_ptr: ValueRef,
dest: ValueRef) {
let llfn = get_rust_try_fn(cx, &mut |bx| {
let cx = bx.cx;
// Translates the shims described above:
//
// bx:
// invoke %func(%args...) normal %normal unwind %catch
//
// normal:
// ret 0
//
// catch:
// (ptr, _) = landingpad
// store ptr, %local_ptr
// ret 1
//
// Note that the `local_ptr` data passed into the `try` intrinsic is
// expected to be `*mut *mut u8` for this to actually work, but that's
// managed by the standard library.
let then = bx.build_sibling_block("then");
let catch = bx.build_sibling_block("catch");
let func = llvm::get_param(bx.llfn(), 0);
let data = llvm::get_param(bx.llfn(), 1);
let local_ptr = llvm::get_param(bx.llfn(), 2);
bx.invoke(func, &[data], then.llbb(), catch.llbb(), None);
then.ret(C_i32(cx, 0));
// Type indicator for the exception being thrown.
//
// The first value in this tuple is a pointer to the exception object
// being thrown. The second value is a "selector" indicating which of
// the landing pad clauses the exception's type had been matched to.
// rust_try ignores the selector.
let lpad_ty = Type::struct_(cx, &[Type::i8p(cx), Type::i32(cx)],
false);
let vals = catch.landing_pad(lpad_ty, bx.cx.eh_personality(), 1);
catch.add_clause(vals, C_null(Type::i8p(cx)));
let ptr = catch.extract_value(vals, 0);
let ptr_align = bx.tcx().data_layout.pointer_align;
catch.store(ptr, catch.bitcast(local_ptr, Type::i8p(cx).ptr_to()), ptr_align);
catch.ret(C_i32(cx, 1));
});
// Note that no invoke is used here because by definition this function
// can't panic (that's what it's catching).
let ret = bx.call(llfn, &[func, data, local_ptr], None);
let i32_align = bx.tcx().data_layout.i32_align;
bx.store(ret, dest, i32_align);
}
// Helper function to give a Block to a closure to translate a shim function.
// This is currently primarily used for the `try` intrinsic functions above.
fn gen_fn<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
name: &str,
inputs: Vec<Ty<'tcx>>,
output: Ty<'tcx>,
trans: &mut for<'b> FnMut(Builder<'b, 'tcx>))
-> ValueRef {
let rust_fn_ty = cx.tcx.mk_fn_ptr(ty::Binder(cx.tcx.mk_fn_sig(
inputs.into_iter(),
output,
false,
hir::Unsafety::Unsafe,
Abi::Rust
)));
let llfn = declare::define_internal_fn(cx, name, rust_fn_ty);
let bx = Builder::new_block(cx, llfn, "entry-block");
trans(bx);
llfn
}
// Helper function used to get a handle to the `__rust_try` function used to
// catch exceptions.
//
// This function is only generated once and is then cached.
fn get_rust_try_fn<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
trans: &mut for<'b> FnMut(Builder<'b, 'tcx>))
-> ValueRef {
if let Some(llfn) = cx.rust_try_fn.get() {
return llfn;
}
// Define the type up front for the signature of the rust_try function.
let tcx = cx.tcx;
let i8p = tcx.mk_mut_ptr(tcx.types.i8);
let fn_ty = tcx.mk_fn_ptr(ty::Binder(tcx.mk_fn_sig(
iter::once(i8p),
tcx.mk_nil(),
false,
hir::Unsafety::Unsafe,
Abi::Rust
)));
let output = tcx.types.i32;
let rust_try = gen_fn(cx, "__rust_try", vec![fn_ty, i8p, i8p], output, trans);
cx.rust_try_fn.set(Some(rust_try));
return rust_try
}