forked from OSchip/llvm-project
7dd7ccd224
Currently, code generation was creating weak symbols for derived type descriptor global it could not find in the current compilation unit. The rational is that: - the derived type descriptors of external module derived types are generated in the compilation unit that compiled the module so that the type descriptor address is uniquely associated with the type. - some types do not have derived type descriptors: the builtin derived types used to create derived type descriptors. The runtime knows about them and does not need them to accomplish the feat of describing themselves. Hence, all unresolved derived type descriptors in codegen cannot be assumed to be resolved at link time. However, this caused immense debugging pain when, for some reasons, derived type descriptor that should be generated were not. This caused random runtime failures instead of a much cleaner link time failure. Improve this situation by allowing codegen to detect the builtin derived types that have no derived type descriptors and requiring the other unresolved derived type descriptor to be resolved at link time. Also make derived type descriptor constant data since this was a TODO and makes the situation even cleaner. This requiring telling lowering which compiler created symbols can be placed in read only memory. I considered using PARAMETER, but I have mixed feeling using it since that would cause the initializer expressions of derived type descriptor to be invalid from a Fortran point of view since pointer targets cannot be parameters. I do not want to start misusing Fortran attributes, even if I think it is quite unlikely semantics would currently complain. I also do not want to rely on the fact that all object symbols with the CompilerCreated flags are currently constant data. This could easily change in the future and cause runtime bugs if lowering rely on this while the assumption is not loud and clear in semantics. Instead, add a ReadOnly symbol flag to tell lowering that a compiler generated symbol can be placed in read only memory. Differential Revision: https://reviews.llvm.org/D119555 |
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| .. | ||
| Driver | ||
| Evaluate | ||
| Examples | ||
| Fir | ||
| Frontend | ||
| Lower | ||
| NonGtestUnit | ||
| Parser | ||
| Preprocessing | ||
| Runtime | ||
| Semantics | ||
| Unit | ||
| CMakeLists.txt | ||
| lit.cfg.py | ||
| lit.site.cfg.py.in | ||