// Copyright 2012-2016 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, AttributePlace}; use base; use builder::{Builder, MemFlags}; use common::{ty_fn_sig, C_usize}; use context::CodegenCx; use mir::place::PlaceRef; use mir::operand::OperandValue; use type_::Type; use type_of::{LayoutLlvmExt, PointerKind}; use value::Value; use rustc_target::abi::{LayoutOf, Size, TyLayout}; use rustc::ty::{self, Ty}; use rustc::ty::layout; use libc::c_uint; pub use rustc_target::spec::abi::Abi; pub use rustc::ty::layout::{FAT_PTR_ADDR, FAT_PTR_EXTRA}; pub use rustc_target::abi::call::*; macro_rules! for_each_kind { ($flags: ident, $f: ident, $($kind: ident),+) => ({ $(if $flags.contains(ArgAttribute::$kind) { $f(llvm::Attribute::$kind) })+ }) } trait ArgAttributeExt { fn for_each_kind(&self, f: F) where F: FnMut(llvm::Attribute); } impl ArgAttributeExt for ArgAttribute { fn for_each_kind(&self, mut f: F) where F: FnMut(llvm::Attribute) { for_each_kind!(self, f, ByVal, NoAlias, NoCapture, NonNull, ReadOnly, SExt, StructRet, ZExt, InReg) } } pub trait ArgAttributesExt { fn apply_llfn(&self, idx: AttributePlace, llfn: &Value); fn apply_callsite(&self, idx: AttributePlace, callsite: &Value); } impl ArgAttributesExt for ArgAttributes { fn apply_llfn(&self, idx: AttributePlace, llfn: &Value) { let mut regular = self.regular; unsafe { let deref = self.pointee_size.bytes(); if deref != 0 { if regular.contains(ArgAttribute::NonNull) { llvm::LLVMRustAddDereferenceableAttr(llfn, idx.as_uint(), deref); } else { llvm::LLVMRustAddDereferenceableOrNullAttr(llfn, idx.as_uint(), deref); } regular -= ArgAttribute::NonNull; } if let Some(align) = self.pointee_align { llvm::LLVMRustAddAlignmentAttr(llfn, idx.as_uint(), align.abi() as u32); } regular.for_each_kind(|attr| attr.apply_llfn(idx, llfn)); } } fn apply_callsite(&self, idx: AttributePlace, callsite: &Value) { let mut regular = self.regular; unsafe { let deref = self.pointee_size.bytes(); if deref != 0 { if regular.contains(ArgAttribute::NonNull) { llvm::LLVMRustAddDereferenceableCallSiteAttr(callsite, idx.as_uint(), deref); } else { llvm::LLVMRustAddDereferenceableOrNullCallSiteAttr(callsite, idx.as_uint(), deref); } regular -= ArgAttribute::NonNull; } if let Some(align) = self.pointee_align { llvm::LLVMRustAddAlignmentCallSiteAttr(callsite, idx.as_uint(), align.abi() as u32); } regular.for_each_kind(|attr| attr.apply_callsite(idx, callsite)); } } } pub trait LlvmType { fn llvm_type(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type; } impl LlvmType for Reg { fn llvm_type(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type { match self.kind { RegKind::Integer => Type::ix(cx, self.size.bits()), RegKind::Float => { match self.size.bits() { 32 => Type::f32(cx), 64 => Type::f64(cx), _ => bug!("unsupported float: {:?}", self) } } RegKind::Vector => { Type::vector(Type::i8(cx), self.size.bytes()) } } } } impl LlvmType for CastTarget { fn llvm_type(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type { let rest_ll_unit = self.rest.unit.llvm_type(cx); let (rest_count, rem_bytes) = if self.rest.unit.size.bytes() == 0 { (0, 0) } else { (self.rest.total.bytes() / self.rest.unit.size.bytes(), self.rest.total.bytes() % self.rest.unit.size.bytes()) }; if self.prefix.iter().all(|x| x.is_none()) { // Simplify to a single unit when there is no prefix and size <= unit size if self.rest.total <= self.rest.unit.size { return rest_ll_unit; } // Simplify to array when all chunks are the same size and type if rem_bytes == 0 { return Type::array(rest_ll_unit, rest_count); } } // Create list of fields in the main structure let mut args: Vec<_> = self.prefix.iter().flat_map(|option_kind| option_kind.map( |kind| Reg { kind: kind, size: self.prefix_chunk }.llvm_type(cx))) .chain((0..rest_count).map(|_| rest_ll_unit)) .collect(); // Append final integer if rem_bytes != 0 { // Only integers can be really split further. assert_eq!(self.rest.unit.kind, RegKind::Integer); args.push(Type::ix(cx, rem_bytes * 8)); } Type::struct_(cx, &args, false) } } pub trait ArgTypeExt<'ll, 'tcx> { fn memory_ty(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type; fn store(&self, bx: &Builder<'_, 'll, 'tcx>, val: &'ll Value, dst: PlaceRef<'ll, 'tcx>); fn store_fn_arg(&self, bx: &Builder<'_, 'll, 'tcx>, idx: &mut usize, dst: PlaceRef<'ll, 'tcx>); } impl ArgTypeExt<'ll, 'tcx> for ArgType<'tcx, Ty<'tcx>> { /// Get the LLVM type for a place of the original Rust type of /// this argument/return, i.e. the result of `type_of::type_of`. fn memory_ty(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type { self.layout.llvm_type(cx) } /// Store a direct/indirect value described by this ArgType into a /// place for the original Rust type of this argument/return. /// Can be used for both storing formal arguments into Rust variables /// or results of call/invoke instructions into their destinations. fn store(&self, bx: &Builder<'_, 'll, 'tcx>, val: &'ll Value, dst: PlaceRef<'ll, 'tcx>) { if self.is_ignore() { return; } let cx = bx.cx; if self.is_indirect() { OperandValue::Ref(val, self.layout.align).store(bx, dst) } else if let PassMode::Cast(cast) = self.mode { // FIXME(eddyb): Figure out when the simpler Store is safe, clang // uses it for i16 -> {i8, i8}, but not for i24 -> {i8, i8, i8}. let can_store_through_cast_ptr = false; if can_store_through_cast_ptr { let cast_dst = bx.pointercast(dst.llval, cast.llvm_type(cx).ptr_to()); bx.store(val, cast_dst, self.layout.align); } else { // The actual return type is a struct, but the ABI // adaptation code has cast it into some scalar type. The // code that follows is the only reliable way I have // found to do a transform like i64 -> {i32,i32}. // Basically we dump the data onto the stack then memcpy it. // // Other approaches I tried: // - Casting rust ret pointer to the foreign type and using Store // is (a) unsafe if size of foreign type > size of rust type and // (b) runs afoul of strict aliasing rules, yielding invalid // assembly under -O (specifically, the store gets removed). // - Truncating foreign type to correct integral type and then // bitcasting to the struct type yields invalid cast errors. // We instead thus allocate some scratch space... let scratch_size = cast.size(cx); let scratch_align = cast.align(cx); let llscratch = bx.alloca(cast.llvm_type(cx), "abi_cast", scratch_align); bx.lifetime_start(llscratch, scratch_size); // ...where we first store the value... bx.store(val, llscratch, scratch_align); // ...and then memcpy it to the intended destination. base::call_memcpy(bx, bx.pointercast(dst.llval, Type::i8p(cx)), bx.pointercast(llscratch, Type::i8p(cx)), C_usize(cx, self.layout.size.bytes()), self.layout.align.min(scratch_align), MemFlags::empty()); bx.lifetime_end(llscratch, scratch_size); } } else { OperandValue::Immediate(val).store(bx, dst); } } fn store_fn_arg(&self, bx: &Builder<'a, 'll, 'tcx>, idx: &mut usize, dst: PlaceRef<'ll, 'tcx>) { let mut next = || { let val = llvm::get_param(bx.llfn(), *idx as c_uint); *idx += 1; val }; match self.mode { PassMode::Ignore => {}, PassMode::Pair(..) => { OperandValue::Pair(next(), next()).store(bx, dst); } PassMode::Direct(_) | PassMode::Indirect(_) | PassMode::Cast(_) => { self.store(bx, next(), dst); } } } } pub trait FnTypeExt<'tcx> { fn of_instance(cx: &CodegenCx<'ll, 'tcx>, instance: &ty::Instance<'tcx>) -> Self; fn new(cx: &CodegenCx<'ll, 'tcx>, sig: ty::FnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self; fn new_vtable(cx: &CodegenCx<'ll, 'tcx>, sig: ty::FnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self; fn new_internal( cx: &CodegenCx<'ll, 'tcx>, sig: ty::FnSig<'tcx>, extra_args: &[Ty<'tcx>], mk_arg_type: impl Fn(Ty<'tcx>, Option) -> ArgType<'tcx, Ty<'tcx>>, ) -> Self; fn adjust_for_abi(&mut self, cx: &CodegenCx<'ll, 'tcx>, abi: Abi); fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type; fn llvm_cconv(&self) -> llvm::CallConv; fn apply_attrs_llfn(&self, llfn: &'ll Value); fn apply_attrs_callsite(&self, bx: &Builder<'a, 'll, 'tcx>, callsite: &'ll Value); } impl<'tcx> FnTypeExt<'tcx> for FnType<'tcx, Ty<'tcx>> { fn of_instance(cx: &CodegenCx<'ll, 'tcx>, instance: &ty::Instance<'tcx>) -> Self { let fn_ty = instance.ty(cx.tcx); let sig = ty_fn_sig(cx, fn_ty); let sig = cx.tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig); FnType::new(cx, sig, &[]) } fn new(cx: &CodegenCx<'ll, 'tcx>, sig: ty::FnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self { FnType::new_internal(cx, sig, extra_args, |ty, _| { ArgType::new(cx.layout_of(ty)) }) } fn new_vtable(cx: &CodegenCx<'ll, 'tcx>, sig: ty::FnSig<'tcx>, extra_args: &[Ty<'tcx>]) -> Self { FnType::new_internal(cx, sig, extra_args, |ty, arg_idx| { let mut layout = cx.layout_of(ty); // Don't pass the vtable, it's not an argument of the virtual fn. // Instead, pass just the (thin pointer) first field of `*dyn Trait`. if arg_idx == Some(0) { // FIXME(eddyb) `layout.field(cx, 0)` is not enough because e.g. // `Box` has a few newtype wrappers around the raw // pointer, so we'd have to "dig down" to find `*dyn Trait`. let pointee = layout.ty.builtin_deref(true) .unwrap_or_else(|| { bug!("FnType::new_vtable: non-pointer self {:?}", layout) }).ty; let fat_ptr_ty = cx.tcx.mk_mut_ptr(pointee); layout = cx.layout_of(fat_ptr_ty).field(cx, 0); } ArgType::new(layout) }) } fn new_internal( cx: &CodegenCx<'ll, 'tcx>, sig: ty::FnSig<'tcx>, extra_args: &[Ty<'tcx>], mk_arg_type: impl Fn(Ty<'tcx>, Option) -> ArgType<'tcx, Ty<'tcx>>, ) -> Self { debug!("FnType::new_internal({:?}, {:?})", sig, extra_args); use self::Abi::*; let conv = match cx.sess().target.target.adjust_abi(sig.abi) { RustIntrinsic | PlatformIntrinsic | Rust | RustCall => Conv::C, // It's the ABI's job to select this, not us. System => bug!("system abi should be selected elsewhere"), Stdcall => Conv::X86Stdcall, Fastcall => Conv::X86Fastcall, Vectorcall => Conv::X86VectorCall, Thiscall => Conv::X86ThisCall, C => Conv::C, Unadjusted => Conv::C, Win64 => Conv::X86_64Win64, SysV64 => Conv::X86_64SysV, Aapcs => Conv::ArmAapcs, PtxKernel => Conv::PtxKernel, Msp430Interrupt => Conv::Msp430Intr, X86Interrupt => Conv::X86Intr, AmdGpuKernel => Conv::AmdGpuKernel, // These API constants ought to be more specific... Cdecl => Conv::C, }; let mut inputs = sig.inputs(); let extra_args = if sig.abi == RustCall { assert!(!sig.variadic && extra_args.is_empty()); match sig.inputs().last().unwrap().sty { ty::TyTuple(ref tupled_arguments) => { inputs = &sig.inputs()[0..sig.inputs().len() - 1]; tupled_arguments } _ => { bug!("argument to function with \"rust-call\" ABI \ is not a tuple"); } } } else { assert!(sig.variadic || extra_args.is_empty()); extra_args }; let target = &cx.sess().target.target; let win_x64_gnu = target.target_os == "windows" && target.arch == "x86_64" && target.target_env == "gnu"; let linux_s390x = target.target_os == "linux" && target.arch == "s390x" && target.target_env == "gnu"; let rust_abi = match sig.abi { RustIntrinsic | PlatformIntrinsic | Rust | RustCall => true, _ => false }; // Handle safe Rust thin and fat pointers. let adjust_for_rust_scalar = |attrs: &mut ArgAttributes, scalar: &layout::Scalar, layout: TyLayout<'tcx, Ty<'tcx>>, offset: Size, is_return: bool| { // Booleans are always an i1 that needs to be zero-extended. if scalar.is_bool() { attrs.set(ArgAttribute::ZExt); return; } // Only pointer types handled below. if scalar.value != layout::Pointer { return; } if scalar.valid_range.start() < scalar.valid_range.end() { if *scalar.valid_range.start() > 0 { attrs.set(ArgAttribute::NonNull); } } if let Some(pointee) = layout.pointee_info_at(cx, offset) { if let Some(kind) = pointee.safe { attrs.pointee_size = pointee.size; attrs.pointee_align = Some(pointee.align); // HACK(eddyb) LLVM inserts `llvm.assume` calls when inlining functions // with align attributes, and those calls later block optimizations. if !is_return && !cx.tcx.sess.opts.debugging_opts.arg_align_attributes { attrs.pointee_align = None; } // `Box` pointer parameters never alias because ownership is transferred // `&mut` pointer parameters never alias other parameters, // or mutable global data // // `&T` where `T` contains no `UnsafeCell` is immutable, // and can be marked as both `readonly` and `noalias`, as // LLVM's definition of `noalias` is based solely on memory // dependencies rather than pointer equality let no_alias = match kind { PointerKind::Shared => false, PointerKind::UniqueOwned => true, PointerKind::Frozen | PointerKind::UniqueBorrowed => !is_return }; if no_alias { attrs.set(ArgAttribute::NoAlias); } if kind == PointerKind::Frozen && !is_return { attrs.set(ArgAttribute::ReadOnly); } } } }; let arg_of = |ty: Ty<'tcx>, arg_idx: Option| { let is_return = arg_idx.is_none(); let mut arg = mk_arg_type(ty, arg_idx); if arg.layout.is_zst() { // For some forsaken reason, x86_64-pc-windows-gnu // doesn't ignore zero-sized struct arguments. // The same is true for s390x-unknown-linux-gnu. if is_return || rust_abi || (!win_x64_gnu && !linux_s390x) { arg.mode = PassMode::Ignore; } } // FIXME(eddyb) other ABIs don't have logic for scalar pairs. if !is_return && rust_abi { if let layout::Abi::ScalarPair(ref a, ref b) = arg.layout.abi { let mut a_attrs = ArgAttributes::new(); let mut b_attrs = ArgAttributes::new(); adjust_for_rust_scalar(&mut a_attrs, a, arg.layout, Size::ZERO, false); adjust_for_rust_scalar(&mut b_attrs, b, arg.layout, a.value.size(cx).abi_align(b.value.align(cx)), false); arg.mode = PassMode::Pair(a_attrs, b_attrs); return arg; } } if let layout::Abi::Scalar(ref scalar) = arg.layout.abi { if let PassMode::Direct(ref mut attrs) = arg.mode { adjust_for_rust_scalar(attrs, scalar, arg.layout, Size::ZERO, is_return); } } arg }; let mut fn_ty = FnType { ret: arg_of(sig.output(), None), args: inputs.iter().chain(extra_args).enumerate().map(|(i, ty)| { arg_of(ty, Some(i)) }).collect(), variadic: sig.variadic, conv, }; fn_ty.adjust_for_abi(cx, sig.abi); fn_ty } fn adjust_for_abi(&mut self, cx: &CodegenCx<'ll, 'tcx>, abi: Abi) { if abi == Abi::Unadjusted { return } if abi == Abi::Rust || abi == Abi::RustCall || abi == Abi::RustIntrinsic || abi == Abi::PlatformIntrinsic { let fixup = |arg: &mut ArgType<'tcx, Ty<'tcx>>| { if arg.is_ignore() { return; } match arg.layout.abi { layout::Abi::Aggregate { .. } => {} // This is a fun case! The gist of what this is doing is // that we want callers and callees to always agree on the // ABI of how they pass SIMD arguments. If we were to *not* // make these arguments indirect then they'd be immediates // in LLVM, which means that they'd used whatever the // appropriate ABI is for the callee and the caller. That // means, for example, if the caller doesn't have AVX // enabled but the callee does, then passing an AVX argument // across this boundary would cause corrupt data to show up. // // This problem is fixed by unconditionally passing SIMD // arguments through memory between callers and callees // which should get them all to agree on ABI regardless of // target feature sets. Some more information about this // issue can be found in #44367. // // Note that the platform intrinsic ABI is exempt here as // that's how we connect up to LLVM and it's unstable // anyway, we control all calls to it in libstd. layout::Abi::Vector { .. } if abi != Abi::PlatformIntrinsic => { arg.make_indirect(); return } _ => return } let size = arg.layout.size; if size > layout::Pointer.size(cx) { arg.make_indirect(); } else { // We want to pass small aggregates as immediates, but using // a LLVM aggregate type for this leads to bad optimizations, // so we pick an appropriately sized integer type instead. arg.cast_to(Reg { kind: RegKind::Integer, size }); } }; fixup(&mut self.ret); for arg in &mut self.args { fixup(arg); } if let PassMode::Indirect(ref mut attrs) = self.ret.mode { attrs.set(ArgAttribute::StructRet); } return; } if let Err(msg) = self.adjust_for_cabi(cx, abi) { cx.sess().fatal(&msg); } } fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type { let args_capacity: usize = self.args.iter().map(|arg| if arg.pad.is_some() { 1 } else { 0 } + if let PassMode::Pair(_, _) = arg.mode { 2 } else { 1 } ).sum(); let mut llargument_tys = Vec::with_capacity( if let PassMode::Indirect(_) = self.ret.mode { 1 } else { 0 } + args_capacity ); let llreturn_ty = match self.ret.mode { PassMode::Ignore => Type::void(cx), PassMode::Direct(_) | PassMode::Pair(..) => { self.ret.layout.immediate_llvm_type(cx) } PassMode::Cast(cast) => cast.llvm_type(cx), PassMode::Indirect(_) => { llargument_tys.push(self.ret.memory_ty(cx).ptr_to()); Type::void(cx) } }; for arg in &self.args { // add padding if let Some(ty) = arg.pad { llargument_tys.push(ty.llvm_type(cx)); } let llarg_ty = match arg.mode { PassMode::Ignore => continue, PassMode::Direct(_) => arg.layout.immediate_llvm_type(cx), PassMode::Pair(..) => { llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 0, true)); llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 1, true)); continue; } PassMode::Cast(cast) => cast.llvm_type(cx), PassMode::Indirect(_) => arg.memory_ty(cx).ptr_to(), }; llargument_tys.push(llarg_ty); } if self.variadic { Type::variadic_func(&llargument_tys, llreturn_ty) } else { Type::func(&llargument_tys, llreturn_ty) } } fn llvm_cconv(&self) -> llvm::CallConv { match self.conv { Conv::C => llvm::CCallConv, Conv::AmdGpuKernel => llvm::AmdGpuKernel, Conv::ArmAapcs => llvm::ArmAapcsCallConv, Conv::Msp430Intr => llvm::Msp430Intr, Conv::PtxKernel => llvm::PtxKernel, Conv::X86Fastcall => llvm::X86FastcallCallConv, Conv::X86Intr => llvm::X86_Intr, Conv::X86Stdcall => llvm::X86StdcallCallConv, Conv::X86ThisCall => llvm::X86_ThisCall, Conv::X86VectorCall => llvm::X86_VectorCall, Conv::X86_64SysV => llvm::X86_64_SysV, Conv::X86_64Win64 => llvm::X86_64_Win64, } } fn apply_attrs_llfn(&self, llfn: &'ll Value) { let mut i = 0; let mut apply = |attrs: &ArgAttributes| { attrs.apply_llfn(llvm::AttributePlace::Argument(i), llfn); i += 1; }; match self.ret.mode { PassMode::Direct(ref attrs) => { attrs.apply_llfn(llvm::AttributePlace::ReturnValue, llfn); } PassMode::Indirect(ref attrs) => apply(attrs), _ => {} } for arg in &self.args { if arg.pad.is_some() { apply(&ArgAttributes::new()); } match arg.mode { PassMode::Ignore => {} PassMode::Direct(ref attrs) | PassMode::Indirect(ref attrs) => apply(attrs), PassMode::Pair(ref a, ref b) => { apply(a); apply(b); } PassMode::Cast(_) => apply(&ArgAttributes::new()), } } } fn apply_attrs_callsite(&self, bx: &Builder<'a, 'll, 'tcx>, callsite: &'ll Value) { let mut i = 0; let mut apply = |attrs: &ArgAttributes| { attrs.apply_callsite(llvm::AttributePlace::Argument(i), callsite); i += 1; }; match self.ret.mode { PassMode::Direct(ref attrs) => { attrs.apply_callsite(llvm::AttributePlace::ReturnValue, callsite); } PassMode::Indirect(ref attrs) => apply(attrs), _ => {} } if let layout::Abi::Scalar(ref scalar) = self.ret.layout.abi { // If the value is a boolean, the range is 0..2 and that ultimately // become 0..0 when the type becomes i1, which would be rejected // by the LLVM verifier. match scalar.value { layout::Int(..) if !scalar.is_bool() => { let range = scalar.valid_range_exclusive(bx.cx); if range.start != range.end { bx.range_metadata(callsite, range); } } _ => {} } } for arg in &self.args { if arg.pad.is_some() { apply(&ArgAttributes::new()); } match arg.mode { PassMode::Ignore => {} PassMode::Direct(ref attrs) | PassMode::Indirect(ref attrs) => apply(attrs), PassMode::Pair(ref a, ref b) => { apply(a); apply(b); } PassMode::Cast(_) => apply(&ArgAttributes::new()), } } let cconv = self.llvm_cconv(); if cconv != llvm::CCallConv { llvm::SetInstructionCallConv(callsite, cconv); } } }