Follow target ABI sign-/zero-extension rules for enum types#36321
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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>
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@rust-highfive didn't assign a reviewer. Could we get someone familiar with the backend (@eddyb? 😄) to review this PR? |
| 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)); |
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This should pattern-match on ccx.layout_of(ty) (see librustc/ty/layout.rs) instead of checking the LLVM type and then asking adt (which is being phased out by #36151) for more information.
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r? @eddyb |
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@bors r+ Thanks! |
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📌 Commit ce3cecf has been approved by |
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⌛ Testing commit ce3cecf with merge 9d76bed... |
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💔 Test failed - auto-win-gnu-32-opt-rustbuild |
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@bors retry |
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Sep 9, 2016
Follow target ABI sign-/zero-extension rules for enum types 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>
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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