2 use crate::builder::Builder;
3 use crate::context::CodegenCx;
4 use crate::llvm::{self, Attribute, AttributePlace};
5 use crate::type_::Type;
6 use crate::type_of::LayoutLlvmExt;
7 use crate::value::Value;
9 use rustc_codegen_ssa::mir::operand::OperandValue;
10 use rustc_codegen_ssa::mir::place::PlaceRef;
11 use rustc_codegen_ssa::traits::*;
12 use rustc_codegen_ssa::MemFlags;
13 use rustc_middle::bug;
14 use rustc_middle::ty::layout::LayoutOf;
15 pub use rustc_middle::ty::layout::{FAT_PTR_ADDR, FAT_PTR_EXTRA};
16 use rustc_middle::ty::Ty;
17 use rustc_session::config;
18 use rustc_target::abi::call::ArgAbi;
19 pub use rustc_target::abi::call::*;
20 use rustc_target::abi::{self, HasDataLayout, Int};
21 pub use rustc_target::spec::abi::Abi;
24 use smallvec::SmallVec;
26 pub trait ArgAttributesExt {
27 fn apply_attrs_to_llfn(&self, idx: AttributePlace, cx: &CodegenCx<'_, '_>, llfn: &Value);
28 fn apply_attrs_to_callsite(
31 cx: &CodegenCx<'_, '_>,
36 fn should_use_mutable_noalias(cx: &CodegenCx<'_, '_>) -> bool {
37 // LLVM prior to version 12 had known miscompiles in the presence of
38 // noalias attributes (see #54878), but we don't support earlier
39 // versions at all anymore. We now enable mutable noalias by default.
40 cx.tcx.sess.opts.unstable_opts.mutable_noalias.unwrap_or(true)
43 const ABI_AFFECTING_ATTRIBUTES: [(ArgAttribute, llvm::AttributeKind); 1] =
44 [(ArgAttribute::InReg, llvm::AttributeKind::InReg)];
46 const OPTIMIZATION_ATTRIBUTES: [(ArgAttribute, llvm::AttributeKind); 5] = [
47 (ArgAttribute::NoAlias, llvm::AttributeKind::NoAlias),
48 (ArgAttribute::NoCapture, llvm::AttributeKind::NoCapture),
49 (ArgAttribute::NonNull, llvm::AttributeKind::NonNull),
50 (ArgAttribute::ReadOnly, llvm::AttributeKind::ReadOnly),
51 (ArgAttribute::NoUndef, llvm::AttributeKind::NoUndef),
54 fn get_attrs<'ll>(this: &ArgAttributes, cx: &CodegenCx<'ll, '_>) -> SmallVec<[&'ll Attribute; 8]> {
55 let mut regular = this.regular;
57 let mut attrs = SmallVec::new();
59 // ABI-affecting attributes must always be applied
60 for (attr, llattr) in ABI_AFFECTING_ATTRIBUTES {
61 if regular.contains(attr) {
62 attrs.push(llattr.create_attr(cx.llcx));
65 if let Some(align) = this.pointee_align {
66 attrs.push(llvm::CreateAlignmentAttr(cx.llcx, align.bytes()));
69 ArgExtension::None => {}
70 ArgExtension::Zext => attrs.push(llvm::AttributeKind::ZExt.create_attr(cx.llcx)),
71 ArgExtension::Sext => attrs.push(llvm::AttributeKind::SExt.create_attr(cx.llcx)),
74 // Only apply remaining attributes when optimizing
75 if cx.sess().opts.optimize != config::OptLevel::No {
76 let deref = this.pointee_size.bytes();
78 if regular.contains(ArgAttribute::NonNull) {
79 attrs.push(llvm::CreateDereferenceableAttr(cx.llcx, deref));
81 attrs.push(llvm::CreateDereferenceableOrNullAttr(cx.llcx, deref));
83 regular -= ArgAttribute::NonNull;
85 for (attr, llattr) in OPTIMIZATION_ATTRIBUTES {
86 if regular.contains(attr) {
87 attrs.push(llattr.create_attr(cx.llcx));
90 if regular.contains(ArgAttribute::NoAliasMutRef) && should_use_mutable_noalias(cx) {
91 attrs.push(llvm::AttributeKind::NoAlias.create_attr(cx.llcx));
98 impl ArgAttributesExt for ArgAttributes {
99 fn apply_attrs_to_llfn(&self, idx: AttributePlace, cx: &CodegenCx<'_, '_>, llfn: &Value) {
100 let attrs = get_attrs(self, cx);
101 attributes::apply_to_llfn(llfn, idx, &attrs);
104 fn apply_attrs_to_callsite(
107 cx: &CodegenCx<'_, '_>,
110 let attrs = get_attrs(self, cx);
111 attributes::apply_to_callsite(callsite, idx, &attrs);
116 fn llvm_type<'ll>(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type;
119 impl LlvmType for Reg {
120 fn llvm_type<'ll>(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type {
122 RegKind::Integer => cx.type_ix(self.size.bits()),
123 RegKind::Float => match self.size.bits() {
126 _ => bug!("unsupported float: {:?}", self),
128 RegKind::Vector => cx.type_vector(cx.type_i8(), self.size.bytes()),
133 impl LlvmType for CastTarget {
134 fn llvm_type<'ll>(&self, cx: &CodegenCx<'ll, '_>) -> &'ll Type {
135 let rest_ll_unit = self.rest.unit.llvm_type(cx);
136 let (rest_count, rem_bytes) = if self.rest.unit.size.bytes() == 0 {
140 self.rest.total.bytes() / self.rest.unit.size.bytes(),
141 self.rest.total.bytes() % self.rest.unit.size.bytes(),
145 if self.prefix.iter().all(|x| x.is_none()) {
146 // Simplify to a single unit when there is no prefix and size <= unit size
147 if self.rest.total <= self.rest.unit.size {
151 // Simplify to array when all chunks are the same size and type
153 return cx.type_array(rest_ll_unit, rest_count);
157 // Create list of fields in the main structure
158 let mut args: Vec<_> = self
161 .flat_map(|option_reg| option_reg.map(|reg| reg.llvm_type(cx)))
162 .chain((0..rest_count).map(|_| rest_ll_unit))
165 // Append final integer
167 // Only integers can be really split further.
168 assert_eq!(self.rest.unit.kind, RegKind::Integer);
169 args.push(cx.type_ix(rem_bytes * 8));
172 cx.type_struct(&args, false)
176 pub trait ArgAbiExt<'ll, 'tcx> {
177 fn memory_ty(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
180 bx: &mut Builder<'_, 'll, 'tcx>,
182 dst: PlaceRef<'tcx, &'ll Value>,
186 bx: &mut Builder<'_, 'll, 'tcx>,
188 dst: PlaceRef<'tcx, &'ll Value>,
192 impl<'ll, 'tcx> ArgAbiExt<'ll, 'tcx> for ArgAbi<'tcx, Ty<'tcx>> {
193 /// Gets the LLVM type for a place of the original Rust type of
194 /// this argument/return, i.e., the result of `type_of::type_of`.
195 fn memory_ty(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
196 self.layout.llvm_type(cx)
199 /// Stores a direct/indirect value described by this ArgAbi into a
200 /// place for the original Rust type of this argument/return.
201 /// Can be used for both storing formal arguments into Rust variables
202 /// or results of call/invoke instructions into their destinations.
205 bx: &mut Builder<'_, 'll, 'tcx>,
207 dst: PlaceRef<'tcx, &'ll Value>,
209 if self.is_ignore() {
212 if self.is_sized_indirect() {
213 OperandValue::Ref(val, None, self.layout.align.abi).store(bx, dst)
214 } else if self.is_unsized_indirect() {
215 bug!("unsized `ArgAbi` must be handled through `store_fn_arg`");
216 } else if let PassMode::Cast(cast, _) = &self.mode {
217 // FIXME(eddyb): Figure out when the simpler Store is safe, clang
218 // uses it for i16 -> {i8, i8}, but not for i24 -> {i8, i8, i8}.
219 let can_store_through_cast_ptr = false;
220 if can_store_through_cast_ptr {
221 let cast_ptr_llty = bx.type_ptr_to(cast.llvm_type(bx));
222 let cast_dst = bx.pointercast(dst.llval, cast_ptr_llty);
223 bx.store(val, cast_dst, self.layout.align.abi);
225 // The actual return type is a struct, but the ABI
226 // adaptation code has cast it into some scalar type. The
227 // code that follows is the only reliable way I have
228 // found to do a transform like i64 -> {i32,i32}.
229 // Basically we dump the data onto the stack then memcpy it.
231 // Other approaches I tried:
232 // - Casting rust ret pointer to the foreign type and using Store
233 // is (a) unsafe if size of foreign type > size of rust type and
234 // (b) runs afoul of strict aliasing rules, yielding invalid
235 // assembly under -O (specifically, the store gets removed).
236 // - Truncating foreign type to correct integral type and then
237 // bitcasting to the struct type yields invalid cast errors.
239 // We instead thus allocate some scratch space...
240 let scratch_size = cast.size(bx);
241 let scratch_align = cast.align(bx);
242 let llscratch = bx.alloca(cast.llvm_type(bx), scratch_align);
243 bx.lifetime_start(llscratch, scratch_size);
245 // ... where we first store the value...
246 bx.store(val, llscratch, scratch_align);
248 // ... and then memcpy it to the intended destination.
251 self.layout.align.abi,
254 bx.const_usize(self.layout.size.bytes()),
258 bx.lifetime_end(llscratch, scratch_size);
261 OperandValue::Immediate(val).store(bx, dst);
267 bx: &mut Builder<'_, 'll, 'tcx>,
269 dst: PlaceRef<'tcx, &'ll Value>,
272 let val = llvm::get_param(bx.llfn(), *idx as c_uint);
277 PassMode::Ignore => {}
278 PassMode::Pair(..) => {
279 OperandValue::Pair(next(), next()).store(bx, dst);
281 PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
282 OperandValue::Ref(next(), Some(next()), self.layout.align.abi).store(bx, dst);
285 | PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ }
286 | PassMode::Cast(..) => {
287 let next_arg = next();
288 self.store(bx, next_arg, dst);
294 impl<'ll, 'tcx> ArgAbiMethods<'tcx> for Builder<'_, 'll, 'tcx> {
297 arg_abi: &ArgAbi<'tcx, Ty<'tcx>>,
299 dst: PlaceRef<'tcx, Self::Value>,
301 arg_abi.store_fn_arg(self, idx, dst)
305 arg_abi: &ArgAbi<'tcx, Ty<'tcx>>,
307 dst: PlaceRef<'tcx, &'ll Value>,
309 arg_abi.store(self, val, dst)
311 fn arg_memory_ty(&self, arg_abi: &ArgAbi<'tcx, Ty<'tcx>>) -> &'ll Type {
312 arg_abi.memory_ty(self)
316 pub trait FnAbiLlvmExt<'ll, 'tcx> {
317 fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
318 fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type;
319 fn llvm_cconv(&self) -> llvm::CallConv;
320 fn apply_attrs_llfn(&self, cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value);
321 fn apply_attrs_callsite(&self, bx: &mut Builder<'_, 'll, 'tcx>, callsite: &'ll Value);
324 impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
325 fn llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
326 // Ignore "extra" args from the call site for C variadic functions.
327 // Only the "fixed" args are part of the LLVM function signature.
329 if self.c_variadic { &self.args[..self.fixed_count as usize] } else { &self.args };
331 // This capacity calculation is approximate.
332 let mut llargument_tys = Vec::with_capacity(
333 self.args.len() + if let PassMode::Indirect { .. } = self.ret.mode { 1 } else { 0 },
336 let llreturn_ty = match &self.ret.mode {
337 PassMode::Ignore => cx.type_void(),
338 PassMode::Direct(_) | PassMode::Pair(..) => self.ret.layout.immediate_llvm_type(cx),
339 PassMode::Cast(cast, _) => cast.llvm_type(cx),
340 PassMode::Indirect { .. } => {
341 llargument_tys.push(cx.type_ptr_to(self.ret.memory_ty(cx)));
347 let llarg_ty = match &arg.mode {
348 PassMode::Ignore => continue,
349 PassMode::Direct(_) => arg.layout.immediate_llvm_type(cx),
350 PassMode::Pair(..) => {
351 llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 0, true));
352 llargument_tys.push(arg.layout.scalar_pair_element_llvm_type(cx, 1, true));
355 PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => {
356 let ptr_ty = cx.tcx.mk_mut_ptr(arg.layout.ty);
357 let ptr_layout = cx.layout_of(ptr_ty);
358 llargument_tys.push(ptr_layout.scalar_pair_element_llvm_type(cx, 0, true));
359 llargument_tys.push(ptr_layout.scalar_pair_element_llvm_type(cx, 1, true));
362 PassMode::Cast(cast, pad_i32) => {
365 llargument_tys.push(Reg::i32().llvm_type(cx));
369 PassMode::Indirect { attrs: _, extra_attrs: None, on_stack: _ } => {
370 cx.type_ptr_to(arg.memory_ty(cx))
373 llargument_tys.push(llarg_ty);
377 cx.type_variadic_func(&llargument_tys, llreturn_ty)
379 cx.type_func(&llargument_tys, llreturn_ty)
383 fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
385 llvm::LLVMPointerType(
387 cx.data_layout().instruction_address_space.0 as c_uint,
392 fn llvm_cconv(&self) -> llvm::CallConv {
394 Conv::C | Conv::Rust | Conv::CCmseNonSecureCall => llvm::CCallConv,
395 Conv::RustCold => llvm::ColdCallConv,
396 Conv::AmdGpuKernel => llvm::AmdGpuKernel,
397 Conv::AvrInterrupt => llvm::AvrInterrupt,
398 Conv::AvrNonBlockingInterrupt => llvm::AvrNonBlockingInterrupt,
399 Conv::ArmAapcs => llvm::ArmAapcsCallConv,
400 Conv::Msp430Intr => llvm::Msp430Intr,
401 Conv::PtxKernel => llvm::PtxKernel,
402 Conv::X86Fastcall => llvm::X86FastcallCallConv,
403 Conv::X86Intr => llvm::X86_Intr,
404 Conv::X86Stdcall => llvm::X86StdcallCallConv,
405 Conv::X86ThisCall => llvm::X86_ThisCall,
406 Conv::X86VectorCall => llvm::X86_VectorCall,
407 Conv::X86_64SysV => llvm::X86_64_SysV,
408 Conv::X86_64Win64 => llvm::X86_64_Win64,
412 fn apply_attrs_llfn(&self, cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value) {
413 let mut func_attrs = SmallVec::<[_; 2]>::new();
414 if self.ret.layout.abi.is_uninhabited() {
415 func_attrs.push(llvm::AttributeKind::NoReturn.create_attr(cx.llcx));
417 if !self.can_unwind {
418 func_attrs.push(llvm::AttributeKind::NoUnwind.create_attr(cx.llcx));
420 attributes::apply_to_llfn(llfn, llvm::AttributePlace::Function, &{ func_attrs });
423 let mut apply = |attrs: &ArgAttributes| {
424 attrs.apply_attrs_to_llfn(llvm::AttributePlace::Argument(i), cx, llfn);
428 match &self.ret.mode {
429 PassMode::Direct(attrs) => {
430 attrs.apply_attrs_to_llfn(llvm::AttributePlace::ReturnValue, cx, llfn);
432 PassMode::Indirect { attrs, extra_attrs: _, on_stack } => {
434 let i = apply(attrs);
435 let sret = llvm::CreateStructRetAttr(cx.llcx, self.ret.layout.llvm_type(cx));
436 attributes::apply_to_llfn(llfn, llvm::AttributePlace::Argument(i), &[sret]);
438 PassMode::Cast(cast, _) => {
439 cast.attrs.apply_attrs_to_llfn(llvm::AttributePlace::ReturnValue, cx, llfn);
443 for arg in self.args.iter() {
445 PassMode::Ignore => {}
446 PassMode::Indirect { attrs, extra_attrs: None, on_stack: true } => {
447 let i = apply(attrs);
448 let byval = llvm::CreateByValAttr(cx.llcx, arg.layout.llvm_type(cx));
449 attributes::apply_to_llfn(llfn, llvm::AttributePlace::Argument(i), &[byval]);
451 PassMode::Direct(attrs)
452 | PassMode::Indirect { attrs, extra_attrs: None, on_stack: false } => {
455 PassMode::Indirect { attrs, extra_attrs: Some(extra_attrs), on_stack } => {
460 PassMode::Pair(a, b) => {
464 PassMode::Cast(cast, pad_i32) => {
466 apply(&ArgAttributes::new());
474 fn apply_attrs_callsite(&self, bx: &mut Builder<'_, 'll, 'tcx>, callsite: &'ll Value) {
475 let mut func_attrs = SmallVec::<[_; 2]>::new();
476 if self.ret.layout.abi.is_uninhabited() {
477 func_attrs.push(llvm::AttributeKind::NoReturn.create_attr(bx.cx.llcx));
479 if !self.can_unwind {
480 func_attrs.push(llvm::AttributeKind::NoUnwind.create_attr(bx.cx.llcx));
482 attributes::apply_to_callsite(callsite, llvm::AttributePlace::Function, &{ func_attrs });
485 let mut apply = |cx: &CodegenCx<'_, '_>, attrs: &ArgAttributes| {
486 attrs.apply_attrs_to_callsite(llvm::AttributePlace::Argument(i), cx, callsite);
490 match &self.ret.mode {
491 PassMode::Direct(attrs) => {
492 attrs.apply_attrs_to_callsite(llvm::AttributePlace::ReturnValue, bx.cx, callsite);
494 PassMode::Indirect { attrs, extra_attrs: _, on_stack } => {
496 let i = apply(bx.cx, attrs);
497 let sret = llvm::CreateStructRetAttr(bx.cx.llcx, self.ret.layout.llvm_type(bx));
498 attributes::apply_to_callsite(callsite, llvm::AttributePlace::Argument(i), &[sret]);
500 PassMode::Cast(cast, _) => {
501 cast.attrs.apply_attrs_to_callsite(
502 llvm::AttributePlace::ReturnValue,
509 if let abi::Abi::Scalar(scalar) = self.ret.layout.abi {
510 // If the value is a boolean, the range is 0..2 and that ultimately
511 // become 0..0 when the type becomes i1, which would be rejected
512 // by the LLVM verifier.
513 if let Int(..) = scalar.primitive() {
514 if !scalar.is_bool() && !scalar.is_always_valid(bx) {
515 bx.range_metadata(callsite, scalar.valid_range(bx));
519 for arg in self.args.iter() {
521 PassMode::Ignore => {}
522 PassMode::Indirect { attrs, extra_attrs: None, on_stack: true } => {
523 let i = apply(bx.cx, attrs);
524 let byval = llvm::CreateByValAttr(bx.cx.llcx, arg.layout.llvm_type(bx));
525 attributes::apply_to_callsite(
527 llvm::AttributePlace::Argument(i),
531 PassMode::Direct(attrs)
532 | PassMode::Indirect { attrs, extra_attrs: None, on_stack: false } => {
535 PassMode::Indirect { attrs, extra_attrs: Some(extra_attrs), on_stack: _ } => {
537 apply(bx.cx, extra_attrs);
539 PassMode::Pair(a, b) => {
543 PassMode::Cast(cast, pad_i32) => {
545 apply(bx.cx, &ArgAttributes::new());
547 apply(bx.cx, &cast.attrs);
552 let cconv = self.llvm_cconv();
553 if cconv != llvm::CCallConv {
554 llvm::SetInstructionCallConv(callsite, cconv);
557 if self.conv == Conv::CCmseNonSecureCall {
558 // This will probably get ignored on all targets but those supporting the TrustZone-M
559 // extension (thumbv8m targets).
560 let cmse_nonsecure_call = llvm::CreateAttrString(bx.cx.llcx, "cmse_nonsecure_call");
561 attributes::apply_to_callsite(
563 llvm::AttributePlace::Function,
564 &[cmse_nonsecure_call],
568 // Some intrinsics require that an elementtype attribute (with the pointee type of a
569 // pointer argument) is added to the callsite.
570 let element_type_index = unsafe { llvm::LLVMRustGetElementTypeArgIndex(callsite) };
571 if element_type_index >= 0 {
572 let arg_ty = self.args[element_type_index as usize].layout.ty;
573 let pointee_ty = arg_ty.builtin_deref(true).expect("Must be pointer argument").ty;
574 let element_type_attr = unsafe {
575 llvm::LLVMRustCreateElementTypeAttr(bx.llcx, bx.layout_of(pointee_ty).llvm_type(bx))
577 attributes::apply_to_callsite(
579 llvm::AttributePlace::Argument(element_type_index as u32),
580 &[element_type_attr],
586 impl<'tcx> AbiBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
587 fn apply_attrs_callsite(&mut self, fn_abi: &FnAbi<'tcx, Ty<'tcx>>, callsite: Self::Value) {
588 fn_abi.apply_attrs_callsite(self, callsite)
591 fn get_param(&mut self, index: usize) -> Self::Value {
592 llvm::get_param(self.llfn(), index as c_uint)