50fcab2984
Implement the tls_value for s390 in the ELF general-dynamic mode. Notable differences to the x86_64 implementation are: - We use a __tls_get_offset libcall instead of __tls_get_addr. - The current thread pointer (stored in a pair of access registers) needs to be added to the result of __tls_get_offset. - __tls_get_offset has a variant ABI that requires the address of the GOT (global offset table) is passed in %r12. This means we need a new libcall entries for __tls_get_offset. In addition, we also need a way to access _GLOBAL_OFFSET_TABLE_. The latter is a "magic" symbol with a well-known name defined by the ABI and recognized by the linker. This patch introduces a new ExternalName::KnownSymbol variant to support such names (originally due to @afonso360). We also need to emit a relocation on a symbol placed in a constant pool, as well as an extra relocation on the call to __tls_get_offset required for TLS linker optimization. Needed by the cg_clif frontend.
This crate contains the core Cranelift code generator. It translates code from an intermediate representation into executable machine code.