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Fix invalid bitcast taking bool out of a union represented as a scalar #56097

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Merged
merged 2 commits into from
Nov 23, 2018
Merged

Fix invalid bitcast taking bool out of a union represented as a scalar #56097

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86d4135
Fix invalid bitcast taking bool out of a union represented as a scalar
ogoffart Nov 20, 2018
4c21f66
Add comments and rename a local variable
ogoffart Nov 20, 2018
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17 changes: 14 additions & 3 deletions src/librustc_codegen_ssa/mir/operand.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -244,13 +244,24 @@ impl<'a, 'tcx: 'a, V: CodegenObject> OperandRef<'tcx, V> {
};

// HACK(eddyb) have to bitcast pointers until LLVM removes pointee types.
// Bools in union fields needs to be truncated.
let to_immediate_or_cast = |bx: &mut Bx, val, ty| {
if ty == bx.cx().type_i1() {
bx.trunc(val, ty)
} else {
bx.bitcast(val, ty)
}
};

match val {
OperandValue::Immediate(ref mut llval) => {
*llval = bx.bitcast(*llval, bx.cx().immediate_backend_type(field));
*llval = to_immediate_or_cast(bx, *llval, bx.cx().immediate_backend_type(field));
}
OperandValue::Pair(ref mut a, ref mut b) => {
*a = bx.bitcast(*a, bx.cx().scalar_pair_element_backend_type(field, 0, true));
*b = bx.bitcast(*b, bx.cx().scalar_pair_element_backend_type(field, 1, true));
*a = to_immediate_or_cast(bx, *a, bx.cx()
.scalar_pair_element_backend_type(field, 0, true));
*b = to_immediate_or_cast(bx, *b, bx.cx()
.scalar_pair_element_backend_type(field, 1, true));
}
OperandValue::Ref(..) => bug!()
}
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6 changes: 6 additions & 0 deletions src/test/codegen/union-abi.rs
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Expand Up @@ -78,3 +78,9 @@ pub union CUnionU128{a:u128}
#[no_mangle]
pub fn test_CUnionU128(_: CUnionU128) { loop {} }

pub union UnionBool { b:bool }
// CHECK: define zeroext i1 @test_UnionBool(i8 %b)
#[no_mangle]
pub fn test_UnionBool(b: UnionBool) -> bool { unsafe { b.b } }
// CHECK: %0 = trunc i8 %b to i1