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cleanup overflow binop code #28

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merged 19 commits into from
Jun 20, 2016
Merged

cleanup overflow binop code #28

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58b4fac
implement overflowing ops
oli-obk Jun 17, 2016
3ba4f6d
remove code repetition and fix overflowing intrinsics
oli-obk Jun 17, 2016
6376ef4
run the *compiled* run-pass tests on the host machine
oli-obk Jun 17, 2016
4f48bef
cfail test for std::env::args()
oli-obk Jun 17, 2016
e3a2bf8
clippy
oli-obk Jun 17, 2016
00eb198
implement fn -> unsafe fn pointer casts
oli-obk Jun 17, 2016
874d683
improve method names and add documentation
oli-obk Jun 20, 2016
d977642
compiletest 2.0 uses json errors and doesn't depend on the output for…
oli-obk Jun 20, 2016
e90ee16
fix comparing of function pointers
oli-obk Jun 20, 2016
a1082b9
Merge remote-tracking branch 'origin/master' into oflo
oli-obk Jun 20, 2016
ed4af21
fix master
oli-obk Jun 20, 2016
b9ac85d
rustc does overflow checking for us, don't duplicate it.
oli-obk Jun 20, 2016
68469be
rename function cache member
oli-obk Jun 20, 2016
0821a15
no need for EvalContext::eval_binop
oli-obk Jun 20, 2016
3e3aeab
implement bit masks as the compiler would translate them
oli-obk Jun 20, 2016
a088f10
add a comment explaining the magic numbers
oli-obk Jun 20, 2016
001ae69
remove the bad rhs value error and panic instead. the typechecker pre…
oli-obk Jun 20, 2016
c7039db
simplify the masked rhs computation
oli-obk Jun 20, 2016
65de5dd
simplify even more
oli-obk Jun 20, 2016
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2 changes: 1 addition & 1 deletion src/error.rs
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Expand Up @@ -69,7 +69,7 @@ impl<'tcx> Error for EvalError<'tcx> {
EvalError::Math(..) =>
"mathematical operation failed",
EvalError::InvalidBitShiftRhs(..) =>
"bit shift rhs negative or not an int",
"bit shift rhs not an int",
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We shouldn't have EvalError variants for things the type checker should catch. If a primitive bit shift RHS isn't an integer, we can just panic.

}
}

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27 changes: 19 additions & 8 deletions src/primval.rs
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Expand Up @@ -69,15 +69,26 @@ pub fn binary_op<'tcx>(bin_op: mir::BinOp, left: PrimVal, right: PrimVal) -> Eva
match bin_op {
// can have rhs with a different numeric type
Shl | Shr => {
let mask_bits = match left {
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@oli-obk Can you add a comment explaining the masking? It's a bit non-obvious.

@eddyb Is there a source in rustc or the docs we can refer to for this?

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https://github.com/rust-lang/rust/blob/5522e678bcefe14cc2ab3d0ab329b7059ce52b36/src/librustc_trans/common.rs#L1295-L1315

I8(_) => 3,
I16(_) => 4,
I32(_) => 5,
I64(_) => 6,
U8(_) => 3,
U16(_) => 4,
U32(_) => 5,
U64(_) => 6,
_ => unreachable!(),
};
let r = match right {
I8(i) if i >= 0 => i as u32,
I16(i) if i >= 0 => i as u32,
I32(i) if i >= 0 => i as u32,
I64(i) if i >= 0 && i as i32 as i64 == i => i as u32,
U8(i) => i as u32,
U16(i) => i as u32,
U32(i) => i,
U64(i) if i as u32 as u64 == i => i as u32,
I8(i) => (i & ((1 << mask_bits) - 1)) as u32,
I16(i) => (i & ((1 << mask_bits) - 1)) as u32,
I32(i) => (i & ((1 << mask_bits) - 1)) as u32,
I64(i) => (i & ((1 << mask_bits) - 1)) as u32,
U8(i) => (i & ((1 << mask_bits) - 1)) as u32,
U16(i) => (i & ((1 << mask_bits) - 1)) as u32,
U32(i) => (i & ((1 << mask_bits) - 1)) as u32,
U64(i) => (i & ((1 << mask_bits) - 1)) as u32,
_ => return Err(EvalError::InvalidBitShiftRhs(right)),
};
macro_rules! shift {
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