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Simplify type_is_immediate and type_is_fat_ptr #38854

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Merged
merged 4 commits into from
Jan 14, 2017
Merged

Simplify type_is_immediate and type_is_fat_ptr #38854

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7461038
Make type_is_immediate not depend on LLVM.
Mark-Simulacrum Jan 5, 2017
08290b2
Make type_is_fat_ptr not depend on LLVM.
Mark-Simulacrum Jan 5, 2017
e393046
Simplify code since CEnum is always immediate now.
Mark-Simulacrum Jan 5, 2017
43cf5b9
Avoid using load/stores on first class aggregates
dotdash Jan 7, 2017
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45 changes: 19 additions & 26 deletions src/librustc_trans/common.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -45,37 +45,30 @@ use rustc_i128::u128;
pub use context::{CrateContext, SharedCrateContext};

pub fn type_is_fat_ptr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
match ty.sty {
ty::TyRawPtr(ty::TypeAndMut{ty, ..}) |
ty::TyRef(_, ty::TypeAndMut{ty, ..}) |
ty::TyBox(ty) => {
!ccx.shared().type_is_sized(ty)
}
_ => {
false
}
if let Layout::FatPointer { .. } = *ccx.layout_of(ty) {
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Check that this does not regress rustc performance - this fn is called quite often.

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The layouts are cached and sometime during compilation the layout of any type will be requested anyway, so it seems fine to me?

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I can do some benchmarking with regards to this, but it does feel needless because they are cached.

true
} else {
false
}
}

pub fn type_is_immediate<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, ty: Ty<'tcx>) -> bool {
use machine::llsize_of_alloc;
use type_of::sizing_type_of;

let simple = ty.is_scalar() ||
ty.is_unique() || ty.is_region_ptr() ||
ty.is_simd();
if simple && !type_is_fat_ptr(ccx, ty) {
return true;
}
if !ccx.shared().type_is_sized(ty) {
return false;
}
match ty.sty {
ty::TyAdt(..) | ty::TyTuple(..) | ty::TyArray(..) | ty::TyClosure(..) => {
let llty = sizing_type_of(ccx, ty);
llsize_of_alloc(ccx, llty) <= llsize_of_alloc(ccx, ccx.int_type())
let layout = ccx.layout_of(ty);
match *layout {
Layout::CEnum { .. } |
Layout::Scalar { .. } |
Layout::Vector { .. } => true,

Layout::FatPointer { .. } => false,

Layout::Array { .. } |
Layout::Univariant { .. } |
Layout::General { .. } |
Layout::UntaggedUnion { .. } |
Layout::RawNullablePointer { .. } |
Layout::StructWrappedNullablePointer { .. } => {
!layout.is_unsized() && layout.size(&ccx.tcx().data_layout).bytes() == 0
}
_ => type_is_zero_size(ccx, ty)
}
}

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29 changes: 8 additions & 21 deletions src/librustc_trans/mir/rvalue.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -260,37 +260,24 @@ impl<'a, 'tcx> MirContext<'a, 'tcx> {
let r_t_out = CastTy::from_ty(cast_ty).expect("bad output type for cast");
let ll_t_in = type_of::immediate_type_of(bcx.ccx, operand.ty);
let ll_t_out = type_of::immediate_type_of(bcx.ccx, cast_ty);
let (llval, signed) = if let CastTy::Int(IntTy::CEnum) = r_t_in {
let l = bcx.ccx.layout_of(operand.ty);
let discr = match operand.val {
OperandValue::Immediate(llval) => llval,
OperandValue::Ref(llptr) => {
adt::trans_get_discr(&bcx, operand.ty, llptr, None, true)
}
OperandValue::Pair(..) => bug!("Unexpected Pair operand")
};
let (signed, min, max) = match l {
&Layout::CEnum { signed, min, max, .. } => {
(signed, min, max)
}
_ => bug!("CEnum {:?} is not an enum", operand)
};

let llval = operand.immediate();
let l = bcx.ccx.layout_of(operand.ty);
let signed = if let Layout::CEnum { signed, min, max, .. } = *l {
if max > min {
// We want `table[e as usize]` to not
// have bound checks, and this is the most
// convenient place to put the `assume`.

base::call_assume(&bcx, bcx.icmp(
llvm::IntULE,
discr,
C_integral(common::val_ty(discr), max, false)
))
llval,
C_integral(common::val_ty(llval), max, false)
));
}

(discr, signed)
signed
} else {
(operand.immediate(), operand.ty.is_signed())
operand.ty.is_signed()
};

let newval = match (r_t_in, r_t_out) {
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