nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2024-11-22 14:55:26 +00:00
Code Issues Packages Projects Releases Wiki Activity

Follow target ABI sign-/zero-extension rules for enum types

Browse Source 
While attempting to port Rust to s390x, I ran into an ABI violation
(that caused rust_eh_personality to be miscompiled, breaking unwinding).
The problem is that this function returns an enum type, which is
supposed to be sign-extended according to the s390x ABI.  However,
common code would ignore target sign-/zero-extension rules for any
types that do not satisfy is_integral(), which includes enums.

For the general case of Rust enum types, which map to structure types
with a discriminant, that seems correct.  However, in the special case
of simple enums that map directly to C enum types (i.e. LLVM integers),
this is incorrect; we must follow the target extension rules for those.

Signed-off-by: Ulrich Weigand <ulrich.weigand@de.ibm.com>
This commit is contained in:
Ulrich Weigand 2016-09-07 17:09:24 +02:00
parent 2819eca69c
commit 8760a5e3cc
1 changed files with 9 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
src/librustc_trans/abi.rs
View File

@ -26,6 +26,7 @@ use cabi_asmjs;
use machine::{llalign_of_min, llsize_of, llsize_of_real, llsize_of_store};
use type_::Type;
use type_of;
use adt;
use rustc::hir;
use rustc::ty::{self, Ty};
@ -317,6 +318,14 @@ impl FnType {
if ty.is_integral() {
arg.signedness = Some(ty.is_signed());
}
// Rust enum types that map onto C enums (LLVM integers) also
// need to follow the target ABI zero-/sign-extension rules.
if let ty::TyEnum(..) = ty.sty {
if arg.ty.kind() == llvm::Integer {
let repr = adt::represent_type(ccx, ty);
arg.signedness = Some(adt::is_discr_signed(&repr));
}
}
if llsize_of_real(ccx, arg.ty) == 0 {
// For some forsaken reason, x86_64-pc-windows-gnu
// doesn't ignore zero-sized struct arguments.