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make various intrinsics work in const contexts #50579

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make various intrinsics work in const contexts #50579

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775683f
make various intrinsics work in const contexts
Gankra May 9, 2018
8dc0567
change test to use still-non-const intrinsic
Gankra May 9, 2018
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324 changes: 322 additions & 2 deletions src/librustc_mir/interpret/const_eval.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ use rustc::ty::subst::Subst;
use syntax::ast::Mutability;
use syntax::codemap::Span;

use rustc::mir::interpret::{EvalResult, EvalError, EvalErrorKind, GlobalId, Value, MemoryPointer, Pointer, PrimVal, AllocId};
use rustc::mir::interpret::{EvalResult, EvalError, EvalErrorKind, GlobalId, Value, MemoryPointer, Pointer, PrimVal, PrimValKind, AllocId};
use super::{Place, EvalContext, StackPopCleanup, ValTy, PlaceExtra, Memory};

use std::fmt;
Expand Down Expand Up @@ -256,7 +256,7 @@ impl<'mir, 'tcx> super::Machine<'mir, 'tcx> for CompileTimeEvaluator {
fn call_intrinsic<'a>(
ecx: &mut EvalContext<'a, 'mir, 'tcx, Self>,
instance: ty::Instance<'tcx>,
_args: &[ValTy<'tcx>],
args: &[ValTy<'tcx>],
dest: Place,
dest_layout: layout::TyLayout<'tcx>,
target: mir::BasicBlock,
Expand All @@ -265,6 +265,280 @@ impl<'mir, 'tcx> super::Machine<'mir, 'tcx> for CompileTimeEvaluator {

let intrinsic_name = &ecx.tcx.item_name(instance.def_id()).as_str()[..];
match intrinsic_name {
"add_with_overflow" => {
ecx.intrinsic_with_overflow(
mir::BinOp::Add,
args[0],
args[1],
dest,
dest_layout.ty,
)?
}

"sub_with_overflow" => {
ecx.intrinsic_with_overflow(
mir::BinOp::Sub,
args[0],
args[1],
dest,
dest_layout.ty,
)?
}

"mul_with_overflow" => {
ecx.intrinsic_with_overflow(
mir::BinOp::Mul,
args[0],
args[1],
dest,
dest_layout.ty,
)?
}

"overflowing_sub" => {
ecx.intrinsic_overflowing(
mir::BinOp::Sub,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"overflowing_mul" => {
ecx.intrinsic_overflowing(
mir::BinOp::Mul,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"overflowing_add" => {
ecx.intrinsic_overflowing(
mir::BinOp::Add,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"powf32" => {
let f = ecx.value_to_primval(args[0])?.to_bytes()?;
let f = f32::from_bits(f as u32);
let f2 = ecx.value_to_primval(args[1])?.to_bytes()?;
let f2 = f32::from_bits(f2 as u32);
ecx.write_primval(
dest,
PrimVal::Bytes(f.powf(f2).to_bits() as u128),
dest_layout.ty,
)?;
}

"powf64" => {
let f = ecx.value_to_primval(args[0])?.to_bytes()?;
let f = f64::from_bits(f as u64);
let f2 = ecx.value_to_primval(args[1])?.to_bytes()?;
let f2 = f64::from_bits(f2 as u64);
ecx.write_primval(
dest,
PrimVal::Bytes(f.powf(f2).to_bits() as u128),
dest_layout.ty,
)?;
}

"fmaf32" => {
let a = ecx.value_to_primval(args[0])?.to_bytes()?;
let a = f32::from_bits(a as u32);
let b = ecx.value_to_primval(args[1])?.to_bytes()?;
let b = f32::from_bits(b as u32);
let c = ecx.value_to_primval(args[2])?.to_bytes()?;
let c = f32::from_bits(c as u32);
ecx.write_primval(
dest,
PrimVal::Bytes((a * b + c).to_bits() as u128),
dest_layout.ty,
)?;
}

"fmaf64" => {
let a = ecx.value_to_primval(args[0])?.to_bytes()?;
let a = f64::from_bits(a as u64);
let b = ecx.value_to_primval(args[1])?.to_bytes()?;
let b = f64::from_bits(b as u64);
let c = ecx.value_to_primval(args[2])?.to_bytes()?;
let c = f64::from_bits(c as u64);
ecx.write_primval(
dest,
PrimVal::Bytes((a * b + c).to_bits() as u128),
dest_layout.ty,
)?;
}

"powif32" => {
let f = ecx.value_to_primval(args[0])?.to_bytes()?;
let f = f32::from_bits(f as u32);
let i = ecx.value_to_primval(args[1])?.to_i128()?;
ecx.write_primval(
dest,
PrimVal::Bytes(f.powi(i as i32).to_bits() as u128),
dest_layout.ty,
)?;
}

"powif64" => {
let f = ecx.value_to_primval(args[0])?.to_bytes()?;
let f = f64::from_bits(f as u64);
let i = ecx.value_to_primval(args[1])?.to_i128()?;
ecx.write_primval(
dest,
PrimVal::Bytes(f.powi(i as i32).to_bits() as u128),
dest_layout.ty,
)?;
}

"unchecked_shl" => {
let bits = dest_layout.size.bytes() as u128 * 8;
let rhs = ecx.value_to_primval(args[1])?
.to_bytes()?;
if rhs >= bits {
return err!(Intrinsic(
format!("Overflowing shift by {} in unchecked_shl", rhs),
));
}
ecx.intrinsic_overflowing(
mir::BinOp::Shl,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"unchecked_shr" => {
let bits = dest_layout.size.bytes() as u128 * 8;
let rhs = ecx.value_to_primval(args[1])?
.to_bytes()?;
if rhs >= bits {
return err!(Intrinsic(
format!("Overflowing shift by {} in unchecked_shr", rhs),
));
}
ecx.intrinsic_overflowing(
mir::BinOp::Shr,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"unchecked_div" => {
let rhs = ecx.value_to_primval(args[1])?
.to_bytes()?;
if rhs == 0 {
return err!(Intrinsic(format!("Division by 0 in unchecked_div")));
}
ecx.intrinsic_overflowing(
mir::BinOp::Div,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"unchecked_rem" => {
let rhs = ecx.value_to_primval(args[1])?
.to_bytes()?;
if rhs == 0 {
return err!(Intrinsic(format!("Division by 0 in unchecked_rem")));
}
ecx.intrinsic_overflowing(
mir::BinOp::Rem,
args[0],
args[1],
dest,
dest_layout.ty,
)?;
}

"ctpop" | "cttz" | "cttz_nonzero" | "ctlz" | "ctlz_nonzero" | "bswap" => {
let ty = substs.type_at(0);
let num = ecx.value_to_primval(args[0])?.to_bytes()?;
let kind = ecx.ty_to_primval_kind(ty)?;
let num = if intrinsic_name.ends_with("_nonzero") {
if num == 0 {
return err!(Intrinsic(format!("{} called on 0", intrinsic_name)));
}
numeric_intrinsic(intrinsic_name.trim_right_matches("_nonzero"), num, kind)?
} else {
numeric_intrinsic(intrinsic_name, num, kind)?
};
ecx.write_primval(dest, num, ty)?;
}

"sinf32" | "fabsf32" | "cosf32" | "sqrtf32" | "expf32" | "exp2f32" | "logf32" |
"log10f32" | "log2f32" | "floorf32" | "ceilf32" | "truncf32" => {
let f = ecx.value_to_primval(args[0])?.to_bytes()?;
let f = f32::from_bits(f as u32);
let f = match intrinsic_name {
"sinf32" => f.sin(),
"fabsf32" => f.abs(),
"cosf32" => f.cos(),
"sqrtf32" => f.sqrt(),
"expf32" => f.exp(),
"exp2f32" => f.exp2(),
"logf32" => f.ln(),
"log10f32" => f.log10(),
"log2f32" => f.log2(),
"floorf32" => f.floor(),
"ceilf32" => f.ceil(),
"truncf32" => f.trunc(),
_ => bug!(),
};
ecx.write_primval(dest, PrimVal::Bytes(f.to_bits() as u128), dest_layout.ty)?;
}

"sinf64" | "fabsf64" | "cosf64" | "sqrtf64" | "expf64" | "exp2f64" | "logf64" |
"log10f64" | "log2f64" | "floorf64" | "ceilf64" | "truncf64" => {
let f = ecx.value_to_primval(args[0])?.to_bytes()?;
let f = f64::from_bits(f as u64);
let f = match intrinsic_name {
"sinf64" => f.sin(),
"fabsf64" => f.abs(),
"cosf64" => f.cos(),
"sqrtf64" => f.sqrt(),
"expf64" => f.exp(),
"exp2f64" => f.exp2(),
"logf64" => f.ln(),
"log10f64" => f.log10(),
"log2f64" => f.log2(),
"floorf64" => f.floor(),
"ceilf64" => f.ceil(),
"truncf64" => f.trunc(),
_ => bug!(),
};
ecx.write_primval(dest, PrimVal::Bytes(f.to_bits() as u128), dest_layout.ty)?;
}

"assume" => {
let cond = ecx.value_to_primval(args[0])?.to_bool()?;
if !cond {
return err!(AssumptionNotHeld);
}
}

"likely" | "unlikely" | "forget" => {}

"align_offset" => {
// FIXME: return a real value in case the target allocation has an
// alignment bigger than the one requested
ecx.write_primval(dest, PrimVal::Bytes(u128::max_value()), dest_layout.ty)?;
},

"min_align_of" => {
let elem_ty = substs.type_at(0);
let elem_align = ecx.layout_of(elem_ty)?.align.abi();
Expand All @@ -278,6 +552,14 @@ impl<'mir, 'tcx> super::Machine<'mir, 'tcx> for CompileTimeEvaluator {
ecx.write_primval(dest, PrimVal::from_u128(size), dest_layout.ty)?;
}

"transmute" => {
let src_ty = substs.type_at(0);
let _src_align = ecx.layout_of(src_ty)?.align;
let ptr = ecx.force_allocation(dest)?.to_ptr()?;
let dest_align = ecx.layout_of(substs.type_at(1))?.align;
ecx.write_value_to_ptr(args[0].value, ptr.into(), dest_align, src_ty).unwrap();
}

"type_id" => {
let ty = substs.type_at(0);
let type_id = ecx.tcx.type_id_hash(ty) as u128;
Expand Down Expand Up @@ -351,6 +633,44 @@ impl<'mir, 'tcx> super::Machine<'mir, 'tcx> for CompileTimeEvaluator {
}
}


fn numeric_intrinsic<'tcx>(
name: &str,
bytes: u128,
kind: PrimValKind,
) -> EvalResult<'tcx, PrimVal> {
macro_rules! integer_intrinsic {
($method:ident) => ({
use rustc::mir::interpret::PrimValKind::*;
let result_bytes = match kind {
I8 => (bytes as i8).$method() as u128,
U8 => (bytes as u8).$method() as u128,
I16 => (bytes as i16).$method() as u128,
U16 => (bytes as u16).$method() as u128,
I32 => (bytes as i32).$method() as u128,
U32 => (bytes as u32).$method() as u128,
I64 => (bytes as i64).$method() as u128,
U64 => (bytes as u64).$method() as u128,
I128 => (bytes as i128).$method() as u128,
U128 => bytes.$method() as u128,
_ => bug!("invalid `{}` argument: {:?}", name, bytes),
};

PrimVal::Bytes(result_bytes)
});
}

let result_val = match name {
"bswap" => integer_intrinsic!(swap_bytes),
"ctlz" => integer_intrinsic!(leading_zeros),
"ctpop" => integer_intrinsic!(count_ones),
"cttz" => integer_intrinsic!(trailing_zeros),
_ => bug!("not a numeric intrinsic: {}", name),
};

Ok(result_val)
}

pub fn const_val_field<'a, 'tcx>(
tcx: TyCtxt<'a, 'tcx, 'tcx>,
param_env: ty::ParamEnv<'tcx>,
Expand Down
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