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Auto merge of #17942 - HKalbasi:fp-const-eval, r=HKalbasi

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Implement floating point casts in const eval

fix #17926
This commit is contained in:
bors 2024-08-22 16:02:50 +00:00
commit 0fe4653871
2 changed files with 102 additions and 3 deletions
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11
crates/hir-ty/src/consteval/tests.rs
View file

@ -247,6 +247,17 @@ fn casts() {
check_number(r#"const GOAL: i32 = -12i8 as i32"#, -12);
}
#[test]
fn floating_point_casts() {
check_number(r#"const GOAL: usize = 12i32 as f32 as usize"#, 12);
check_number(r#"const GOAL: i8 = -12i32 as f64 as i8"#, -12);
check_number(r#"const GOAL: i32 = (-1ui8 as f32 + 2u64 as f32) as i32"#, 1);
check_number(r#"const GOAL: i8 = (0./0.) as i8"#, 0);
check_number(r#"const GOAL: i8 = (1./0.) as i8"#, 127);
check_number(r#"const GOAL: i8 = (-1./0.) as i8"#, -128);
check_number(r#"const GOAL: i64 = 1e18f64 as f32 as i64"#, 999999984306749440);
}
#[test]
fn raw_pointer_equality() {
check_number(

94
crates/hir-ty/src/mir/eval.rs
View file

@ -1518,9 +1518,97 @@ impl Evaluator<'_> {
self.size_of_sized(target_ty, locals, "destination of int to int cast")?;
Owned(current[0..dest_size].to_vec())
}
CastKind::FloatToInt => not_supported!("float to int cast"),
CastKind::FloatToFloat => not_supported!("float to float cast"),
CastKind::IntToFloat => not_supported!("float to int cast"),
CastKind::FloatToInt => {
let ty = self.operand_ty(operand, locals)?;
let TyKind::Scalar(chalk_ir::Scalar::Float(ty)) = ty.kind(Interner) else {
not_supported!("invalid float to int cast");
};
let value = self.eval_operand(operand, locals)?.get(self)?;
let value = match ty {
chalk_ir::FloatTy::F32 => {
let value = value.try_into().unwrap();
f32::from_le_bytes(value) as f64
}
chalk_ir::FloatTy::F64 => {
let value = value.try_into().unwrap();
f64::from_le_bytes(value)
}
chalk_ir::FloatTy::F16 | chalk_ir::FloatTy::F128 => {
not_supported!("unstable floating point type f16 and f128");
}
};
let is_signed = matches!(
target_ty.kind(Interner),
TyKind::Scalar(chalk_ir::Scalar::Int(_))
);
let dest_size =
self.size_of_sized(target_ty, locals, "destination of float to int cast")?;
let dest_bits = dest_size * 8;
let (max, min) = if dest_bits == 128 {
(i128::MAX, i128::MIN)
} else if is_signed {
let max = 1i128 << (dest_bits - 1);
(max - 1, -max)
} else {
(1i128 << dest_bits, 0)
};
let value = (value as i128).min(max).max(min);
let result = value.to_le_bytes();
Owned(result[0..dest_size].to_vec())
}
CastKind::FloatToFloat => {
let ty = self.operand_ty(operand, locals)?;
let TyKind::Scalar(chalk_ir::Scalar::Float(ty)) = ty.kind(Interner) else {
not_supported!("invalid float to int cast");
};
let value = self.eval_operand(operand, locals)?.get(self)?;
let value = match ty {
chalk_ir::FloatTy::F32 => {
let value = value.try_into().unwrap();
f32::from_le_bytes(value) as f64
}
chalk_ir::FloatTy::F64 => {
let value = value.try_into().unwrap();
f64::from_le_bytes(value)
}
chalk_ir::FloatTy::F16 | chalk_ir::FloatTy::F128 => {
not_supported!("unstable floating point type f16 and f128");
}
};
let TyKind::Scalar(chalk_ir::Scalar::Float(target_ty)) =
target_ty.kind(Interner)
else {
not_supported!("invalid float to float cast");
};
match target_ty {
chalk_ir::FloatTy::F32 => Owned((value as f32).to_le_bytes().to_vec()),
chalk_ir::FloatTy::F64 => Owned((value as f64).to_le_bytes().to_vec()),
chalk_ir::FloatTy::F16 | chalk_ir::FloatTy::F128 => {
not_supported!("unstable floating point type f16 and f128");
}
}
}
CastKind::IntToFloat => {
let current_ty = self.operand_ty(operand, locals)?;
let is_signed = matches!(
current_ty.kind(Interner),
TyKind::Scalar(chalk_ir::Scalar::Int(_))
);
let value = pad16(self.eval_operand(operand, locals)?.get(self)?, is_signed);
let value = i128::from_le_bytes(value);
let TyKind::Scalar(chalk_ir::Scalar::Float(target_ty)) =
target_ty.kind(Interner)
else {
not_supported!("invalid int to float cast");
};
match target_ty {
chalk_ir::FloatTy::F32 => Owned((value as f32).to_le_bytes().to_vec()),
chalk_ir::FloatTy::F64 => Owned((value as f64).to_le_bytes().to_vec()),
chalk_ir::FloatTy::F16 | chalk_ir::FloatTy::F128 => {
not_supported!("unstable floating point type f16 and f128");
}
}
}
CastKind::FnPtrToPtr => not_supported!("fn ptr to ptr cast"),
},
})