rustc_codegen_ssa/traits/
builder.rs

1use std::assert_matches;
2use std::ops::Deref;
3
4use rustc_abi::{Align, Scalar, Size, WrappingRange};
5use rustc_ast::expand::typetree::{FncTree, TypeTree};
6use rustc_hir::attrs::AttributeKind;
7use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs;
8use rustc_middle::mir;
9use rustc_middle::ty::layout::{FnAbiOf, LayoutOf, TyAndLayout};
10use rustc_middle::ty::typetree::typetree_from_ty;
11use rustc_middle::ty::{AtomicOrdering, Instance, Ty};
12use rustc_session::config::OptLevel;
13use rustc_span::Span;
14use rustc_target::callconv::FnAbi;
15
16use super::abi::AbiBuilderMethods;
17use super::asm::AsmBuilderMethods;
18use super::consts::ConstCodegenMethods;
19use super::coverageinfo::CoverageInfoBuilderMethods;
20use super::debuginfo::DebugInfoBuilderMethods;
21use super::intrinsic::IntrinsicCallBuilderMethods;
22use super::misc::MiscCodegenMethods;
23use super::type_::{ArgAbiBuilderMethods, BaseTypeCodegenMethods, LayoutTypeCodegenMethods};
24use super::{CodegenMethods, StaticBuilderMethods};
25use crate::MemFlags;
26use crate::common::{AtomicRmwBinOp, IntPredicate, RealPredicate, SynchronizationScope, TypeKind};
27use crate::mir::operand::{OperandRef, OperandValue};
28use crate::mir::place::{PlaceRef, PlaceValue};
29
30#[derive(#[automatically_derived]
impl ::core::marker::Copy for OverflowOp { }Copy, #[automatically_derived]
impl ::core::clone::Clone for OverflowOp {
    #[inline]
    fn clone(&self) -> OverflowOp { *self }
}Clone, #[automatically_derived]
impl ::core::fmt::Debug for OverflowOp {
    #[inline]
    fn fmt(&self, f: &mut ::core::fmt::Formatter) -> ::core::fmt::Result {
        ::core::fmt::Formatter::write_str(f,
            match self {
                OverflowOp::Add => "Add",
                OverflowOp::Sub => "Sub",
                OverflowOp::Mul => "Mul",
            })
    }
}Debug, #[automatically_derived]
impl ::core::cmp::PartialEq for OverflowOp {
    #[inline]
    fn eq(&self, other: &OverflowOp) -> bool {
        let __self_discr = ::core::intrinsics::discriminant_value(self);
        let __arg1_discr = ::core::intrinsics::discriminant_value(other);
        __self_discr == __arg1_discr
    }
}PartialEq, #[automatically_derived]
impl ::core::cmp::Eq for OverflowOp {
    #[inline]
    #[doc(hidden)]
    #[coverage(off)]
    fn assert_fields_are_eq(&self) {}
}Eq)]
31pub enum OverflowOp {
32    Add,
33    Sub,
34    Mul,
35}
36
37pub trait BuilderMethods<'a, 'tcx>:
38    Sized
39    + LayoutOf<'tcx, LayoutOfResult = TyAndLayout<'tcx>>
40    + FnAbiOf<'tcx, FnAbiOfResult = &'tcx FnAbi<'tcx, Ty<'tcx>>>
41    + Deref<Target = Self::CodegenCx>
42    + CoverageInfoBuilderMethods<'tcx>
43    + DebugInfoBuilderMethods<'tcx>
44    + ArgAbiBuilderMethods<'tcx>
45    + AbiBuilderMethods
46    + IntrinsicCallBuilderMethods<'tcx>
47    + AsmBuilderMethods<'tcx>
48    + StaticBuilderMethods
49{
50    // `BackendTypes` is a supertrait of both `CodegenMethods` and
51    // `BuilderMethods`. This bound ensures all impls agree on the associated
52    // types within.
53    type CodegenCx: CodegenMethods<
54            'tcx,
55            Value = Self::Value,
56            Function = Self::Function,
57            BasicBlock = Self::BasicBlock,
58            Type = Self::Type,
59            FunctionSignature = Self::FunctionSignature,
60            Funclet = Self::Funclet,
61            DIScope = Self::DIScope,
62            DILocation = Self::DILocation,
63            DIVariable = Self::DIVariable,
64        >;
65
66    fn build(cx: &'a Self::CodegenCx, llbb: Self::BasicBlock) -> Self;
67
68    fn cx(&self) -> &Self::CodegenCx;
69    fn llbb(&self) -> Self::BasicBlock;
70
71    fn set_span(&mut self, span: Span);
72
73    // FIXME(eddyb) replace uses of this with `append_sibling_block`.
74    fn append_block(cx: &'a Self::CodegenCx, llfn: Self::Function, name: &str) -> Self::BasicBlock;
75
76    fn append_sibling_block(&mut self, name: &str) -> Self::BasicBlock;
77
78    fn switch_to_block(&mut self, llbb: Self::BasicBlock);
79
80    fn ret_void(&mut self);
81    fn ret(&mut self, v: Self::Value);
82    fn br(&mut self, dest: Self::BasicBlock);
83    fn br_with_attrs(&mut self, dest: Self::BasicBlock, _attributes: &[AttributeKind]) {
84        self.br(dest)
85    }
86    fn cond_br(
87        &mut self,
88        cond: Self::Value,
89        then_llbb: Self::BasicBlock,
90        else_llbb: Self::BasicBlock,
91    );
92
93    // Conditional with expectation.
94    //
95    // This function is opt-in for back ends.
96    //
97    // The default implementation calls `self.expect()` before emitting the branch
98    // by calling `self.cond_br()`
99    fn cond_br_with_expect(
100        &mut self,
101        mut cond: Self::Value,
102        then_llbb: Self::BasicBlock,
103        else_llbb: Self::BasicBlock,
104        expect: Option<bool>,
105    ) {
106        if let Some(expect) = expect {
107            cond = self.expect(cond, expect);
108        }
109        self.cond_br(cond, then_llbb, else_llbb)
110    }
111
112    fn switch(
113        &mut self,
114        v: Self::Value,
115        else_llbb: Self::BasicBlock,
116        cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock)>,
117    );
118
119    // This is like `switch()`, but every case has a bool flag indicating whether it's cold.
120    //
121    // Default implementation throws away the cold flags and calls `switch()`.
122    fn switch_with_weights(
123        &mut self,
124        v: Self::Value,
125        else_llbb: Self::BasicBlock,
126        _else_is_cold: bool,
127        cases: impl ExactSizeIterator<Item = (u128, Self::BasicBlock, bool)>,
128    ) {
129        self.switch(v, else_llbb, cases.map(|(val, bb, _)| (val, bb)))
130    }
131
132    fn invoke(
133        &mut self,
134        llty: Self::FunctionSignature,
135        fn_attrs: Option<&CodegenFnAttrs>,
136        fn_abi: Option<&FnAbi<'tcx, Ty<'tcx>>>,
137        llfn: Self::Value,
138        args: &[Self::Value],
139        then: Self::BasicBlock,
140        catch: Self::BasicBlock,
141        funclet: Option<&Self::Funclet>,
142        instance: Option<Instance<'tcx>>,
143    ) -> Self::Value;
144    fn unreachable(&mut self);
145
146    /// Like [`Self::unreachable`], but for use in the middle of a basic block.
147    fn unreachable_nonterminator(&mut self) {
148        // This is the preferred LLVM incantation for this per
149        // https://llvm.org/docs/Frontend/PerformanceTips.html#other-things-to-consider
150        // Other backends may override if they have a better way.
151        let const_true = self.cx().const_bool(true);
152        let poison_ptr = self.const_poison(self.cx().type_ptr());
153        self.store(const_true, poison_ptr, Align::ONE);
154    }
155
156    fn add(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
157    fn fadd(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
158    fn fadd_fast(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
159    fn fadd_algebraic(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
160    fn sub(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
161    fn fsub(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
162    fn fsub_fast(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
163    fn fsub_algebraic(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
164    fn mul(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
165    fn fmul(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
166    fn fmul_fast(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
167    fn fmul_algebraic(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
168    fn udiv(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
169    fn exactudiv(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
170    fn sdiv(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
171    fn exactsdiv(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
172    fn fdiv(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
173    fn fdiv_fast(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
174    fn fdiv_algebraic(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
175    fn urem(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
176    fn srem(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
177    fn frem(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
178    fn frem_fast(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
179    fn frem_algebraic(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
180    /// Generate a left-shift. Both operands must have the same size. The right operand must be
181    /// interpreted as unsigned and can be assumed to be less than the size of the left operand.
182    fn shl(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
183    /// Generate a logical right-shift. Both operands must have the same size. The right operand
184    /// must be interpreted as unsigned and can be assumed to be less than the size of the left
185    /// operand.
186    fn lshr(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
187    /// Generate an arithmetic right-shift. Both operands must have the same size. The right operand
188    /// must be interpreted as unsigned and can be assumed to be less than the size of the left
189    /// operand.
190    fn ashr(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
191    fn unchecked_sadd(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
192        self.add(lhs, rhs)
193    }
194    fn unchecked_uadd(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
195        self.add(lhs, rhs)
196    }
197    fn unchecked_suadd(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
198        self.unchecked_sadd(lhs, rhs)
199    }
200    fn unchecked_ssub(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
201        self.sub(lhs, rhs)
202    }
203    fn unchecked_usub(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
204        self.sub(lhs, rhs)
205    }
206    fn unchecked_susub(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
207        self.unchecked_ssub(lhs, rhs)
208    }
209    fn unchecked_smul(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
210        self.mul(lhs, rhs)
211    }
212    fn unchecked_umul(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
213        self.mul(lhs, rhs)
214    }
215    fn unchecked_sumul(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
216        // Which to default to is a fairly arbitrary choice,
217        // but this is what slice layout was using before.
218        self.unchecked_smul(lhs, rhs)
219    }
220    fn and(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
221    fn or(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
222    /// Defaults to [`Self::or`], but guarantees `(lhs & rhs) == 0` so some backends
223    /// can emit something more helpful for optimizations.
224    fn or_disjoint(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value {
225        self.or(lhs, rhs)
226    }
227    fn xor(&mut self, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
228    fn neg(&mut self, v: Self::Value) -> Self::Value;
229    fn fneg(&mut self, v: Self::Value) -> Self::Value;
230    fn not(&mut self, v: Self::Value) -> Self::Value;
231
232    fn checked_binop(
233        &mut self,
234        oop: OverflowOp,
235        ty: Ty<'tcx>,
236        lhs: Self::Value,
237        rhs: Self::Value,
238    ) -> (Self::Value, Self::Value);
239
240    fn from_immediate(&mut self, val: Self::Value) -> Self::Value;
241    fn to_immediate_scalar(&mut self, val: Self::Value, scalar: Scalar) -> Self::Value;
242
243    fn alloca(&mut self, size: Size, align: Align) -> Self::Value;
244    fn alloca_with_ty(&mut self, layout: TyAndLayout<'tcx>) -> Self::Value;
245
246    fn load(&mut self, ty: Self::Type, ptr: Self::Value, align: Align) -> Self::Value;
247    fn volatile_load(&mut self, ty: Self::Type, ptr: Self::Value, align: Align) -> Self::Value;
248    fn atomic_load(
249        &mut self,
250        ty: Self::Type,
251        ptr: Self::Value,
252        order: AtomicOrdering,
253        size: Size,
254    ) -> Self::Value;
255    fn load_from_place(&mut self, ty: Self::Type, place: PlaceValue<Self::Value>) -> Self::Value {
256        {
    match (&place.llextra, &None) {
        (left_val, right_val) => {
            if !(*left_val == *right_val) {
                let kind = ::core::panicking::AssertKind::Eq;
                ::core::panicking::assert_failed(kind, &*left_val,
                    &*right_val, ::core::option::Option::None);
            }
        }
    }
};assert_eq!(place.llextra, None);
257        self.load(ty, place.llval, place.align)
258    }
259    fn load_operand(&mut self, place: PlaceRef<'tcx, Self::Value>)
260    -> OperandRef<'tcx, Self::Value>;
261
262    /// Called for Rvalue::Repeat when the elem is neither a ZST nor optimizable using memset.
263    fn write_operand_repeatedly(
264        &mut self,
265        elem: OperandRef<'tcx, Self::Value>,
266        count: u64,
267        dest: PlaceRef<'tcx, Self::Value>,
268    );
269
270    /// Emits an `assume` that the integer value `imm` of type `ty` is contained in `range`.
271    ///
272    /// This *always* emits the assumption, so you probably want to check the
273    /// optimization level and `Scalar::is_always_valid` before calling it.
274    fn assume_integer_range(&mut self, imm: Self::Value, ty: Self::Type, range: WrappingRange) {
275        let WrappingRange { start, end } = range;
276
277        // Perhaps one day we'll be able to use assume operand bundles for this,
278        // but for now this encoding with a single icmp+assume is best per
279        // <https://github.com/llvm/llvm-project/issues/123278#issuecomment-2597440158>
280        let shifted = if start == 0 {
281            imm
282        } else {
283            let low = self.const_uint_big(ty, start);
284            self.sub(imm, low)
285        };
286        let width = self.const_uint_big(ty, u128::wrapping_sub(end, start));
287        let cmp = self.icmp(IntPredicate::IntULE, shifted, width);
288        self.assume(cmp);
289    }
290
291    /// Emits an `assume` that the `val` of pointer type is non-null.
292    ///
293    /// You may want to check the optimization level before bothering calling this.
294    fn assume_nonnull(&mut self, val: Self::Value) {
295        // Arguably in LLVM it'd be better to emit an assume operand bundle instead
296        // <https://llvm.org/docs/LangRef.html#assume-operand-bundles>
297        // but this works fine for all backends.
298
299        let null = self.const_null(self.type_ptr());
300        let is_null = self.icmp(IntPredicate::IntNE, val, null);
301        self.assume(is_null);
302    }
303
304    fn range_metadata(&mut self, load: Self::Value, range: WrappingRange);
305    fn nonnull_metadata(&mut self, load: Self::Value);
306
307    fn store(&mut self, val: Self::Value, ptr: Self::Value, align: Align) -> Self::Value;
308    fn store_to_place(&mut self, val: Self::Value, place: PlaceValue<Self::Value>) -> Self::Value {
309        {
    match (&place.llextra, &None) {
        (left_val, right_val) => {
            if !(*left_val == *right_val) {
                let kind = ::core::panicking::AssertKind::Eq;
                ::core::panicking::assert_failed(kind, &*left_val,
                    &*right_val, ::core::option::Option::None);
            }
        }
    }
};assert_eq!(place.llextra, None);
310        self.store(val, place.llval, place.align)
311    }
312    fn store_with_flags(
313        &mut self,
314        val: Self::Value,
315        ptr: Self::Value,
316        align: Align,
317        flags: MemFlags,
318    ) -> Self::Value;
319    fn store_to_place_with_flags(
320        &mut self,
321        val: Self::Value,
322        place: PlaceValue<Self::Value>,
323        flags: MemFlags,
324    ) -> Self::Value {
325        {
    match (&place.llextra, &None) {
        (left_val, right_val) => {
            if !(*left_val == *right_val) {
                let kind = ::core::panicking::AssertKind::Eq;
                ::core::panicking::assert_failed(kind, &*left_val,
                    &*right_val, ::core::option::Option::None);
            }
        }
    }
};assert_eq!(place.llextra, None);
326        self.store_with_flags(val, place.llval, place.align, flags)
327    }
328    fn atomic_store(
329        &mut self,
330        val: Self::Value,
331        ptr: Self::Value,
332        order: AtomicOrdering,
333        size: Size,
334    );
335
336    fn gep(&mut self, ty: Self::Type, ptr: Self::Value, indices: &[Self::Value]) -> Self::Value;
337    fn inbounds_gep(
338        &mut self,
339        ty: Self::Type,
340        ptr: Self::Value,
341        indices: &[Self::Value],
342    ) -> Self::Value;
343    fn inbounds_nuw_gep(
344        &mut self,
345        ty: Self::Type,
346        ptr: Self::Value,
347        indices: &[Self::Value],
348    ) -> Self::Value {
349        self.inbounds_gep(ty, ptr, indices)
350    }
351    fn ptradd(&mut self, ptr: Self::Value, offset: Self::Value) -> Self::Value {
352        self.gep(self.cx().type_i8(), ptr, &[offset])
353    }
354    fn inbounds_ptradd(&mut self, ptr: Self::Value, offset: Self::Value) -> Self::Value {
355        self.inbounds_gep(self.cx().type_i8(), ptr, &[offset])
356    }
357
358    fn trunc(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
359    /// Produces the same value as [`Self::trunc`] (and defaults to that),
360    /// but is UB unless the *zero*-extending the result can reproduce `val`.
361    fn unchecked_utrunc(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value {
362        self.trunc(val, dest_ty)
363    }
364    /// Produces the same value as [`Self::trunc`] (and defaults to that),
365    /// but is UB unless the *sign*-extending the result can reproduce `val`.
366    fn unchecked_strunc(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value {
367        self.trunc(val, dest_ty)
368    }
369
370    fn sext(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
371    fn fptoui_sat(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
372    fn fptosi_sat(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
373    fn fptoui(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
374    fn fptosi(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
375    fn uitofp(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
376    fn sitofp(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
377    fn fptrunc(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
378    fn fpext(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
379    fn ptrtoint(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
380    fn inttoptr(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
381    fn bitcast(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
382    fn intcast(&mut self, val: Self::Value, dest_ty: Self::Type, is_signed: bool) -> Self::Value;
383    fn pointercast(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
384
385    fn cast_float_to_int(
386        &mut self,
387        signed: bool,
388        x: Self::Value,
389        dest_ty: Self::Type,
390    ) -> Self::Value {
391        let in_ty = self.cx().val_ty(x);
392        let (float_ty, int_ty) = if self.cx().type_kind(dest_ty) == TypeKind::Vector
393            && self.cx().type_kind(in_ty) == TypeKind::Vector
394        {
395            (self.cx().element_type(in_ty), self.cx().element_type(dest_ty))
396        } else {
397            (in_ty, dest_ty)
398        };
399        {
    match self.cx().type_kind(float_ty) {
        TypeKind::Half | TypeKind::Float | TypeKind::Double | TypeKind::FP128
            => {}
        ref left_val => {
            ::core::panicking::assert_matches_failed(left_val,
                "TypeKind::Half | TypeKind::Float | TypeKind::Double | TypeKind::FP128",
                ::core::option::Option::None);
        }
    }
};assert_matches!(
400            self.cx().type_kind(float_ty),
401            TypeKind::Half | TypeKind::Float | TypeKind::Double | TypeKind::FP128
402        );
403        {
    match (&self.cx().type_kind(int_ty), &TypeKind::Integer) {
        (left_val, right_val) => {
            if !(*left_val == *right_val) {
                let kind = ::core::panicking::AssertKind::Eq;
                ::core::panicking::assert_failed(kind, &*left_val,
                    &*right_val, ::core::option::Option::None);
            }
        }
    }
};assert_eq!(self.cx().type_kind(int_ty), TypeKind::Integer);
404
405        if let Some(false) = self.cx().sess().opts.unstable_opts.saturating_float_casts {
406            return if signed { self.fptosi(x, dest_ty) } else { self.fptoui(x, dest_ty) };
407        }
408
409        if signed { self.fptosi_sat(x, dest_ty) } else { self.fptoui_sat(x, dest_ty) }
410    }
411
412    fn icmp(&mut self, op: IntPredicate, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
413    fn fcmp(&mut self, op: RealPredicate, lhs: Self::Value, rhs: Self::Value) -> Self::Value;
414
415    /// Returns `-1` if `lhs < rhs`, `0` if `lhs == rhs`, and `1` if `lhs > rhs`.
416    fn three_way_compare(
417        &mut self,
418        ty: Ty<'tcx>,
419        lhs: Self::Value,
420        rhs: Self::Value,
421    ) -> Self::Value {
422        // FIXME: This implementation was designed around LLVM's ability to optimize, but `cg_llvm`
423        // overrides this to just use `@llvm.scmp`/`ucmp` since LLVM 20. This default impl should be
424        // reevaluated with respect to the remaining backends like cg_gcc, whether they might use
425        // specialized implementations as well, or continue to use a generic implementation here.
426        use std::cmp::Ordering;
427        let pred = |op| crate::base::bin_op_to_icmp_predicate(op, ty.is_signed());
428        if self.cx().sess().opts.optimize == OptLevel::No {
429            // This actually generates tighter assembly, and is a classic trick:
430            // <https://graphics.stanford.edu/~seander/bithacks.html#CopyIntegerSign>.
431            // However, as of 2023-11 it optimized worse in LLVM in things like derived
432            // `PartialOrd`, so we were only using it in debug. Since LLVM now uses its own
433            // intrinsics, it may be be worth trying it in optimized builds for other backends.
434            let is_gt = self.icmp(pred(mir::BinOp::Gt), lhs, rhs);
435            let gtext = self.zext(is_gt, self.type_i8());
436            let is_lt = self.icmp(pred(mir::BinOp::Lt), lhs, rhs);
437            let ltext = self.zext(is_lt, self.type_i8());
438            self.unchecked_ssub(gtext, ltext)
439        } else {
440            // These operations were better optimized by LLVM, before `@llvm.scmp`/`ucmp` in 20.
441            // See <https://github.com/rust-lang/rust/pull/63767>.
442            let is_lt = self.icmp(pred(mir::BinOp::Lt), lhs, rhs);
443            let is_ne = self.icmp(pred(mir::BinOp::Ne), lhs, rhs);
444            let ge = self.select(
445                is_ne,
446                self.cx().const_i8(Ordering::Greater as i8),
447                self.cx().const_i8(Ordering::Equal as i8),
448            );
449            self.select(is_lt, self.cx().const_i8(Ordering::Less as i8), ge)
450        }
451    }
452
453    fn memcpy(
454        &mut self,
455        dst: Self::Value,
456        dst_align: Align,
457        src: Self::Value,
458        src_align: Align,
459        size: Self::Value,
460        flags: MemFlags,
461        tt: Option<FncTree>,
462    );
463    fn memmove(
464        &mut self,
465        dst: Self::Value,
466        dst_align: Align,
467        src: Self::Value,
468        src_align: Align,
469        size: Self::Value,
470        flags: MemFlags,
471    );
472    fn memset(
473        &mut self,
474        ptr: Self::Value,
475        fill_byte: Self::Value,
476        size: Self::Value,
477        align: Align,
478        flags: MemFlags,
479    );
480
481    // Produce a value from calling the `vscale` intrinsic (containing the `vscale` multiplier that
482    // a scalable vector's element size and count can be multiplied by to get the real size of the
483    // vector)
484    fn vscale(&mut self, ty: Self::Type) -> Self::Value;
485
486    /// *Typed* copy for non-overlapping places.
487    ///
488    /// Has a default implementation in terms of `memcpy`, but specific backends
489    /// can override to do something smarter if possible.
490    ///
491    /// (For example, typed load-stores with alias metadata.)
492    fn typed_place_copy(
493        &mut self,
494        dst: PlaceValue<Self::Value>,
495        src: PlaceValue<Self::Value>,
496        layout: TyAndLayout<'tcx>,
497    ) {
498        self.typed_place_copy_with_flags(dst, src, layout, MemFlags::empty());
499    }
500
501    fn typed_place_copy_with_flags(
502        &mut self,
503        dst: PlaceValue<Self::Value>,
504        src: PlaceValue<Self::Value>,
505        layout: TyAndLayout<'tcx>,
506        flags: MemFlags,
507    ) {
508        if !layout.is_sized() {
    {
        ::core::panicking::panic_fmt(format_args!("cannot typed-copy an unsigned type"));
    }
};assert!(layout.is_sized(), "cannot typed-copy an unsigned type");
509        if !src.llextra.is_none() {
    {
        ::core::panicking::panic_fmt(format_args!("cannot directly copy from unsized values"));
    }
};assert!(src.llextra.is_none(), "cannot directly copy from unsized values");
510        if !dst.llextra.is_none() {
    {
        ::core::panicking::panic_fmt(format_args!("cannot directly copy into unsized values"));
    }
};assert!(dst.llextra.is_none(), "cannot directly copy into unsized values");
511        if flags.contains(MemFlags::NONTEMPORAL) {
512            // HACK(nox): This is inefficient but there is no nontemporal memcpy.
513            let ty = self.backend_type(layout);
514            let val = self.load_from_place(ty, src);
515            self.store_to_place_with_flags(val, dst, flags);
516        } else if self.sess().opts.optimize == OptLevel::No
517            && layout.backend_repr.is_scalar_or_simd()
518        {
519            // If we're not optimizing, the aliasing information from `memcpy`
520            // isn't useful, so just load-store the value for smaller code.
521            let temp = self.load_operand(src.with_type(layout));
522            temp.val.store_with_flags(self, dst.with_type(layout), flags);
523        } else if !layout.is_zst() {
524            let tt = typetree_from_ty(self.tcx(), layout.ty);
525            // We seem to pass all values to memcpy with one more indirection.
526            let tt = tt.add_indirection();
527            let fnc_tree = FncTree { args: ::alloc::boxed::box_assume_init_into_vec_unsafe(::alloc::intrinsics::write_box_via_move(::alloc::boxed::Box::new_uninit(),
        [tt.clone(), tt]))vec![tt.clone(), tt], ret: TypeTree::new() };
528            let bytes = self.const_usize(layout.size.bytes());
529            let bytes = if layout.peel_transparent_wrappers(self).ty.is_scalable_vector() {
530                let vscale = self.vscale(self.type_i64());
531                self.mul(vscale, bytes)
532            } else {
533                bytes
534            };
535            self.memcpy(dst.llval, dst.align, src.llval, src.align, bytes, flags, Some(fnc_tree));
536        }
537    }
538
539    /// *Typed* swap for non-overlapping places.
540    ///
541    /// Avoids `alloca`s for Immediates and ScalarPairs.
542    ///
543    /// FIXME: Maybe do something smarter for Ref types too?
544    /// For now, the `typed_swap_nonoverlapping` intrinsic just doesn't call this for those
545    /// cases (in non-debug), preferring the fallback body instead.
546    fn typed_place_swap(
547        &mut self,
548        left: PlaceValue<Self::Value>,
549        right: PlaceValue<Self::Value>,
550        layout: TyAndLayout<'tcx>,
551    ) {
552        let mut temp = self.load_operand(left.with_type(layout));
553        if let OperandValue::Ref(..) = temp.val {
554            // The SSA value isn't stand-alone, so we need to copy it elsewhere
555            let alloca = PlaceRef::alloca(self, layout);
556            self.typed_place_copy(alloca.val, left, layout);
557            temp = self.load_operand(alloca);
558        }
559        self.typed_place_copy(left, right, layout);
560        temp.val.store(self, right.with_type(layout));
561    }
562
563    fn select(
564        &mut self,
565        cond: Self::Value,
566        then_val: Self::Value,
567        else_val: Self::Value,
568    ) -> Self::Value;
569
570    fn va_arg(&mut self, list: Self::Value, ty: Self::Type) -> Self::Value;
571    fn extract_element(&mut self, vec: Self::Value, idx: Self::Value) -> Self::Value;
572    fn vector_splat(&mut self, num_elts: usize, elt: Self::Value) -> Self::Value;
573    fn extract_value(&mut self, agg_val: Self::Value, idx: u64) -> Self::Value;
574    fn insert_value(&mut self, agg_val: Self::Value, elt: Self::Value, idx: u64) -> Self::Value;
575
576    fn set_personality_fn(&mut self, personality: Self::Function);
577
578    // These are used by everyone except msvc and wasm EH
579    fn cleanup_landing_pad(&mut self, pers_fn: Self::Function) -> (Self::Value, Self::Value);
580    fn filter_landing_pad(&mut self, pers_fn: Self::Function);
581    fn resume(&mut self, exn0: Self::Value, exn1: Self::Value);
582
583    // These are used by msvc and wasm EH
584    fn cleanup_pad(&mut self, parent: Option<Self::Value>, args: &[Self::Value]) -> Self::Funclet;
585    fn cleanup_ret(&mut self, funclet: &Self::Funclet, unwind: Option<Self::BasicBlock>);
586    fn catch_pad(&mut self, parent: Self::Value, args: &[Self::Value]) -> Self::Funclet;
587    fn catch_switch(
588        &mut self,
589        parent: Option<Self::Value>,
590        unwind: Option<Self::BasicBlock>,
591        handlers: &[Self::BasicBlock],
592    ) -> Self::Value;
593    fn get_funclet_cleanuppad(&self, funclet: &Self::Funclet) -> Self::Value;
594
595    fn atomic_cmpxchg(
596        &mut self,
597        dst: Self::Value,
598        cmp: Self::Value,
599        src: Self::Value,
600        order: AtomicOrdering,
601        failure_order: AtomicOrdering,
602        weak: bool,
603    ) -> (Self::Value, Self::Value);
604    /// `ret_ptr` indicates whether the return type (which is also the type `dst` points to)
605    /// is a pointer or the same type as `src`.
606    fn atomic_rmw(
607        &mut self,
608        op: AtomicRmwBinOp,
609        dst: Self::Value,
610        src: Self::Value,
611        order: AtomicOrdering,
612        ret_ptr: bool,
613    ) -> Self::Value;
614    fn atomic_fence(&mut self, order: AtomicOrdering, scope: SynchronizationScope);
615    fn set_invariant_load(&mut self, load: Self::Value);
616
617    /// Called for `StorageLive`
618    fn lifetime_start(&mut self, ptr: Self::Value, size: Size);
619
620    /// Called for `StorageDead`
621    fn lifetime_end(&mut self, ptr: Self::Value, size: Size);
622
623    /// "Finally codegen the call"
624    ///
625    /// ## Arguments
626    ///
627    /// `caller_attrs` are the attributes of the surrounding caller; they have nothing to do with
628    /// the callee.
629    ///
630    /// The `caller_attrs`, `fn_abi`, and `callee_instance` arguments are Options because they are
631    /// advisory. They relate to optional codegen enhancements like LLVM CFI, and do not affect ABI
632    /// per se. Any ABI-related transformations should be handled by different, earlier stages of
633    /// codegen. For instance, in the caller of `BuilderMethods::call`.
634    ///
635    /// This means that a codegen backend which disregards `fn_attrs`, `fn_abi`, and `instance`
636    /// should still do correct codegen, and code should not be miscompiled if they are omitted.
637    /// It is not a miscompilation in this sense if it fails to run under CFI, other sanitizers, or
638    /// in the context of other compiler-enhanced security features.
639    ///
640    /// The typical case that they are None is during the codegen of intrinsics and lang-items,
641    /// as those are "fake functions" with only a trivial ABI if any, et cetera.
642    ///
643    /// ## Return
644    ///
645    /// Must return the value the function will return so it can be written to the destination,
646    /// assuming the function does not explicitly pass the destination as a pointer in `args`.
647    fn call(
648        &mut self,
649        llty: Self::FunctionSignature,
650        caller_attrs: Option<&CodegenFnAttrs>,
651        fn_abi: Option<&FnAbi<'tcx, Ty<'tcx>>>,
652        fn_val: Self::Value,
653        args: &[Self::Value],
654        funclet: Option<&Self::Funclet>,
655        callee_instance: Option<Instance<'tcx>>,
656    ) -> Self::Value;
657
658    fn tail_call(
659        &mut self,
660        llty: Self::FunctionSignature,
661        caller_attrs: Option<&CodegenFnAttrs>,
662        fn_abi: &FnAbi<'tcx, Ty<'tcx>>,
663        llfn: Self::Value,
664        args: &[Self::Value],
665        funclet: Option<&Self::Funclet>,
666        callee_instance: Option<Instance<'tcx>>,
667    );
668
669    fn zext(&mut self, val: Self::Value, dest_ty: Self::Type) -> Self::Value;
670
671    fn apply_attrs_to_cleanup_callsite(&mut self, llret: Self::Value);
672}
rustc_codegen_ssa/traits/builder.rs

rustc_codegen_ssa/traits/
builder.rs
