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rustc: give Layout::CEnum a discriminant field like Layout::General.

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This commit is contained in:
Eduard-Mihai Burtescu 2017-09-16 16:40:29 +03:00
parent d318b9c27b
commit 658ebfc788
2 changed files with 55 additions and 55 deletions
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5
src/librustc/ty/layout.rs
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@ -1203,8 +1203,7 @@ impl<'a, 'tcx> Layout {
let success = |layout| {
let layout = tcx.intern_layout(layout);
let fields = match *layout {
Scalar(_) |
CEnum { .. } => {
Scalar(_) => {
FieldPlacement::union(0)
}
@ -1241,6 +1240,7 @@ impl<'a, 'tcx> Layout {
FieldPlacement::union(def.struct_variant().fields.len())
}
CEnum { .. } |
General { .. } => FieldPlacement::union(1),
NullablePointer { ref discr_offset, .. } => {
@ -2356,6 +2356,7 @@ impl<'a, 'tcx> FullLayout<'tcx> {
match self.variant_index {
None => match *self.layout {
// Discriminant field for enums (where applicable).
CEnum { discr, .. } |
General { discr, .. } |
NullablePointer { discr, .. } => {
return [discr.to_ty(tcx)][i];

105
src/librustc_trans/mir/lvalue.rs
View file

@ -235,7 +235,6 @@ impl<'a, 'tcx> LvalueRef<'tcx> {
// Discriminant field of enums.
match *l {
layout::General { .. } |
layout::NullablePointer { .. } if l.variant_index.is_none() => {
let ty = ccx.llvm_type_of(field.ty);
let size = field.size(ccx).bytes();
@ -350,60 +349,66 @@ impl<'a, 'tcx> LvalueRef<'tcx> {
}
}
/// Helper for cases where the discriminant is simply loaded.
fn load_discr(self, bcx: &Builder, discr: layout::Primitive, min: u64, max: u64) -> ValueRef {
if let layout::Int(ity, _) = discr {
let bits = ity.size().bits();
assert!(bits <= 64);
let bits = bits as usize;
let mask = !0u64 >> (64 - bits);
// For a (max) discr of -1, max will be `-1 as usize`, which overflows.
// However, that is fine here (it would still represent the full range),
if max.wrapping_add(1) & mask == min & mask {
// i.e., if the range is everything. The lo==hi case would be
// rejected by the LLVM verifier (it would mean either an
// empty set, which is impossible, or the entire range of the
// type, which is pointless).
} else {
// llvm::ConstantRange can deal with ranges that wrap around,
// so an overflow on (max + 1) is fine.
return bcx.load_range_assert(self.llval, min, max.wrapping_add(1),
/* signed: */ llvm::True,
self.alignment.non_abi());
}
}
bcx.load(self.llval, self.alignment.non_abi())
}
/// Obtain the actual discriminant of a value.
pub fn trans_get_discr(self, bcx: &Builder<'a, 'tcx>, cast_to: Ty<'tcx>) -> ValueRef {
let l = bcx.ccx.layout_of(self.ty.to_ty(bcx.tcx()));
let cast_to = bcx.ccx.immediate_llvm_type_of(cast_to);
let (val, discr) = match *l {
match *l {
layout::Univariant { .. } |
layout::UntaggedUnion { .. } => return C_uint(cast_to, 0),
layout::CEnum { discr, min, max, .. } => {
(self.load_discr(bcx, discr, min, max), discr)
_ => {}
}
layout::General { discr, ref variants, .. } => {
let ptr = self.project_field(bcx, 0);
(ptr.load_discr(bcx, discr, 0, variants.len() as u64 - 1), discr)
}
layout::NullablePointer { nndiscr, .. } => {
let ptr = self.project_field(bcx, 0);
let lldiscr = bcx.load(ptr.llval, ptr.alignment.non_abi());
let cmp = if nndiscr == 0 { llvm::IntEQ } else { llvm::IntNE };
(bcx.icmp(cmp, lldiscr, C_null(bcx.ccx.llvm_type_of(ptr.ty.to_ty(bcx.tcx())))),
layout::Int(layout::I1, false))
},
_ => bug!("{} is not an enum", l.ty)
let discr = self.project_field(bcx, 0);
let discr_layout = bcx.ccx.layout_of(discr.ty.to_ty(bcx.tcx()));
let discr_scalar = match discr_layout.abi {
layout::Abi::Scalar(discr) => discr,
_ => bug!("discriminant not scalar: {:#?}", discr_layout)
};
let signed = match discr {
let (min, max) = match *l {
layout::CEnum { min, max, .. } => (min, max),
layout::General { ref variants, .. } => (0, variants.len() as u64 - 1),
_ => (0, u64::max_value()),
};
let max_next = max.wrapping_add(1);
let bits = discr_scalar.size(bcx.ccx).bits();
assert!(bits <= 64);
let mask = !0u64 >> (64 - bits);
let lldiscr = match discr_scalar {
// For a (max) discr of -1, max will be `-1 as usize`, which overflows.
// However, that is fine here (it would still represent the full range),
layout::Int(..) if max_next & mask != min & mask => {
// llvm::ConstantRange can deal with ranges that wrap around,
// so an overflow on (max + 1) is fine.
bcx.load_range_assert(discr.llval, min, max_next,
/* signed: */ llvm::True,
discr.alignment.non_abi())
}
_ => {
// i.e., if the range is everything. The lo==hi case would be
// rejected by the LLVM verifier (it would mean either an
// empty set, which is impossible, or the entire range of the
// type, which is pointless).
bcx.load(discr.llval, discr.alignment.non_abi())
}
};
match *l {
layout::CEnum { .. } |
layout::General { .. } => {
let signed = match discr_scalar {
layout::Int(_, signed) => signed,
_ => false
};
bcx.intcast(val, cast_to, signed)
bcx.intcast(lldiscr, cast_to, signed)
}
layout::NullablePointer { nndiscr, .. } => {
let cmp = if nndiscr == 0 { llvm::IntEQ } else { llvm::IntNE };
let zero = C_null(bcx.ccx.llvm_type_of(discr_layout.ty));
bcx.intcast(bcx.icmp(cmp, lldiscr, zero), cast_to, false)
}
_ => bug!("{} is not an enum", l.ty)
}
}
/// Set the discriminant for a new value of the given case of the given
@ -414,20 +419,12 @@ impl<'a, 'tcx> LvalueRef<'tcx> {
.discriminant_for_variant(bcx.tcx(), variant_index)
.to_u128_unchecked() as u64;
match *l {
layout::CEnum { .. } => {
bcx.store(C_int(bcx.ccx.llvm_type_of(self.ty.to_ty(bcx.tcx())), to as i64),
self.llval, self.alignment.non_abi());
}
layout::CEnum { .. } |
layout::General { .. } => {
let ptr = self.project_field(bcx, 0);
bcx.store(C_int(bcx.ccx.llvm_type_of(ptr.ty.to_ty(bcx.tcx())), to as i64),
ptr.llval, ptr.alignment.non_abi());
}
layout::Univariant { .. }
| layout::UntaggedUnion { .. }
| layout::Vector { .. } => {
assert_eq!(to, 0);
}
layout::NullablePointer { nndiscr, .. } => {
if to != nndiscr {
let use_memset = match l.abi {
@ -451,7 +448,9 @@ impl<'a, 'tcx> LvalueRef<'tcx> {
}
}
}
_ => bug!("Cannot handle {} represented as {:#?}", l.ty, l)
_ => {
assert_eq!(to, 0);
}
}
}