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reitermarkusreitermarkus
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Replace hints with optimized code generation.
1 parent ed49f86 commit 3905371

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2 files changed

+83
-75
lines changed

2 files changed

+83
-75
lines changed

‎compiler/rustc_codegen_ssa/src/mir/rvalue.rs‎

Lines changed: 80 additions & 57 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,6 @@ use crate::MemFlags;
99

1010
use rustc_hir as hir;
1111
use rustc_middle::mir;
12-
use rustc_middle::ty::cast::{CastTy, IntTy};
1312
use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, TyAndLayout};
1413
use rustc_middle::ty::{self, adjustment::PointerCoercion, Instance, Ty, TyCtxt};
1514
use rustc_middle::{bug, span_bug};
@@ -239,21 +238,21 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
239238
}
240239
}
241240
OperandValue::Immediate(imm) => {
242-
let OperandValueKind::Immediate(in_scalar) = operand_kind else {
241+
let OperandValueKind::Immediate(from_scalar) = operand_kind else {
243242
bug!("Found {operand_kind:?} for operand {operand:?}");
244243
};
245-
if let OperandValueKind::Immediate(out_scalar) = cast_kind
246-
&& in_scalar.size(self.cx) == out_scalar.size(self.cx)
244+
if let OperandValueKind::Immediate(to_scalar) = cast_kind
245+
&& from_scalar.size(self.cx) == to_scalar.size(self.cx)
247246
{
248-
let operand_bty = bx.backend_type(operand.layout);
249-
let cast_bty = bx.backend_type(cast);
247+
let from_backend_ty = bx.backend_type(operand.layout);
248+
let to_backend_ty = bx.backend_type(cast);
250249
Some(OperandValue::Immediate(self.transmute_immediate(
251250
bx,
252251
imm,
253-
in_scalar,
254-
operand_bty,
255-
out_scalar,
256-
cast_bty,
252+
from_scalar,
253+
from_backend_ty,
254+
to_scalar,
255+
to_backend_ty,
257256
)))
258257
} else {
259258
None
@@ -282,6 +281,59 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
282281
}
283282
}
284283

284+
/// Cast one of the immediates from an [`OperandValue::Immediate`]
285+
/// or an [`OperandValue::Pair`] to an immediate of the target type.
286+
fn cast_immediate(
287+
&self,
288+
bx: &mut Bx,
289+
mut imm: Bx::Value,
290+
from_scalar: abi::Scalar,
291+
from_backend_ty: Bx::Type,
292+
to_scalar: abi::Scalar,
293+
to_backend_ty: Bx::Type,
294+
) -> Option<Bx::Value> {
295+
use abi::Primitive::*;
296+
297+
// When scalars are passed by value, there's no metadata recording their
298+
// valid ranges. For example, `char`s are passed as just `i32`, with no
299+
// way for LLVM to know that they're 0x10FFFF at most. Thus we assume
300+
// the range of the input value too, not just the output range.
301+
self.assume_scalar_range(bx, imm, from_scalar, from_backend_ty);
302+
303+
imm = match (from_scalar.primitive(), to_scalar.primitive()) {
304+
(Int(_, is_signed), Int(..)) => bx.intcast(imm, to_backend_ty, is_signed),
305+
(Float(_), Float(_)) => {
306+
let srcsz = bx.cx().float_width(from_backend_ty);
307+
let dstsz = bx.cx().float_width(to_backend_ty);
308+
if dstsz > srcsz {
309+
bx.fpext(imm, to_backend_ty)
310+
} else if srcsz > dstsz {
311+
bx.fptrunc(imm, to_backend_ty)
312+
} else {
313+
imm
314+
}
315+
}
316+
(Int(_, is_signed), Float(_)) => {
317+
if is_signed {
318+
bx.sitofp(imm, to_backend_ty)
319+
} else {
320+
bx.uitofp(imm, to_backend_ty)
321+
}
322+
}
323+
(Pointer(..), Pointer(..)) => bx.pointercast(imm, to_backend_ty),
324+
(Int(_, is_signed), Pointer(..)) => {
325+
let usize_imm = bx.intcast(imm, bx.cx().type_isize(), is_signed);
326+
bx.inttoptr(usize_imm, to_backend_ty)
327+
}
328+
(Float(_), Int(_, is_signed)) => {
329+
bx.cast_float_to_int(is_signed, imm, to_backend_ty)
330+
}
331+
_ => return None,
332+
};
333+
self.assume_scalar_range(bx, imm, to_scalar, to_backend_ty);
334+
Some(imm)
335+
}
336+
285337
/// Transmutes one of the immediates from an [`OperandValue::Immediate`]
286338
/// or an [`OperandValue::Pair`] to an immediate of the target type.
287339
///
@@ -508,62 +560,33 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
508560
| mir::CastKind::IntToFloat
509561
| mir::CastKind::PtrToPtr
510562
| mir::CastKind::FnPtrToPtr
511-
512563
// Since int2ptr can have arbitrary integer types as input (so we have to do
513564
// sign extension and all that), it is currently best handled in the same code
514565
// path as the other integer-to-X casts.
515566
| mir::CastKind::PointerWithExposedProvenance => {
567+
let imm = operand.immediate();
568+
let operand_kind = self.value_kind(operand.layout);
569+
let OperandValueKind::Immediate(from_scalar) = operand_kind else {
570+
bug!("Found {operand_kind:?} for operand {operand:?}");
571+
};
572+
let from_backend_ty = bx.cx().immediate_backend_type(operand.layout);
573+
516574
assert!(bx.cx().is_backend_immediate(cast));
517-
let ll_t_out = bx.cx().immediate_backend_type(cast);
575+
let to_backend_ty = bx.cx().immediate_backend_type(cast);
518576
if operand.layout.abi.is_uninhabited() {
519-
let val = OperandValue::Immediate(bx.cx().const_poison(ll_t_out));
577+
let val = OperandValue::Immediate(bx.cx().const_poison(to_backend_ty));
520578
return OperandRef { val, layout: cast };
521579
}
522-
let r_t_in =
523-
CastTy::from_ty(operand.layout.ty).expect("bad input type for cast");
524-
let r_t_out = CastTy::from_ty(cast.ty).expect("bad output type for cast");
525-
let ll_t_in = bx.cx().immediate_backend_type(operand.layout);
526-
let llval = operand.immediate();
527-
528-
let newval = match (r_t_in, r_t_out) {
529-
(CastTy::Int(i), CastTy::Int(_)) => {
530-
bx.intcast(llval, ll_t_out, i.is_signed())
531-
}
532-
(CastTy::Float, CastTy::Float) => {
533-
let srcsz = bx.cx().float_width(ll_t_in);
534-
let dstsz = bx.cx().float_width(ll_t_out);
535-
if dstsz > srcsz {
536-
bx.fpext(llval, ll_t_out)
537-
} else if srcsz > dstsz {
538-
bx.fptrunc(llval, ll_t_out)
539-
} else {
540-
llval
541-
}
542-
}
543-
(CastTy::Int(i), CastTy::Float) => {
544-
if i.is_signed() {
545-
bx.sitofp(llval, ll_t_out)
546-
} else {
547-
bx.uitofp(llval, ll_t_out)
548-
}
549-
}
550-
(CastTy::Ptr(_) | CastTy::FnPtr, CastTy::Ptr(_)) => {
551-
bx.pointercast(llval, ll_t_out)
552-
}
553-
(CastTy::Int(i), CastTy::Ptr(_)) => {
554-
let usize_llval =
555-
bx.intcast(llval, bx.cx().type_isize(), i.is_signed());
556-
bx.inttoptr(usize_llval, ll_t_out)
557-
}
558-
(CastTy::Float, CastTy::Int(IntTy::I)) => {
559-
bx.cast_float_to_int(true, llval, ll_t_out)
560-
}
561-
(CastTy::Float, CastTy::Int(_)) => {
562-
bx.cast_float_to_int(false, llval, ll_t_out)
563-
}
564-
_ => bug!("unsupported cast: {:?} to {:?}", operand.layout.ty, cast.ty),
580+
let cast_kind = self.value_kind(cast);
581+
let OperandValueKind::Immediate(to_scalar) = cast_kind else {
582+
bug!("Found {cast_kind:?} for operand {cast:?}");
565583
};
566-
OperandValue::Immediate(newval)
584+
585+
self.cast_immediate(bx, imm, from_scalar, from_backend_ty, to_scalar, to_backend_ty)
586+
.map(OperandValue::Immediate)
587+
.unwrap_or_else(|| {
588+
bug!("Unsupported cast of {operand:?} to {cast:?}");
589+
})
567590
}
568591
mir::CastKind::Transmute => {
569592
self.codegen_transmute_operand(bx, operand, cast).unwrap_or_else(|| {

‎library/core/src/char/convert.rs‎

Lines changed: 3 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -48,12 +48,7 @@ impl From<char> for u32 {
4848
/// ```
4949
#[inline]
5050
fn from(c: char) -> Self {
51-
let c = c as Self;
52-
53-
// SAFETY: `char::MAX` is the highest valid Unicode code point.
54-
unsafe { core::hint::assert_unchecked(c <= char::MAX as Self) };
55-
56-
c
51+
c as Self
5752
}
5853
}
5954

@@ -74,12 +69,7 @@ impl From<char> for u64 {
7469
fn from(c: char) -> Self {
7570
// The char is casted to the value of the code point, then zero-extended to 64 bit.
7671
// See [https://doc.rust-lang.org/reference/expressions/operator-expr.html#semantics]
77-
let c = c as Self;
78-
79-
// SAFETY: `char::MAX` is the highest valid Unicode code point.
80-
unsafe { core::hint::assert_unchecked(c <= char::MAX as Self) };
81-
82-
c
72+
c as Self
8373
}
8474
}
8575

@@ -100,12 +90,7 @@ impl From<char> for u128 {
10090
fn from(c: char) -> Self {
10191
// The char is casted to the value of the code point, then zero-extended to 128 bit.
10292
// See [https://doc.rust-lang.org/reference/expressions/operator-expr.html#semantics]
103-
let c = c as Self;
104-
105-
// SAFETY: `char::MAX` is the highest valid Unicode code point.
106-
unsafe { core::hint::assert_unchecked(c <= char::MAX as Self) };
107-
108-
c
93+
c as Self
10994
}
11095
}
11196

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