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[SystemZ] Support all TLS access models - CodeGen part

Description

[SystemZ] Support all TLS access models - CodeGen part

The current SystemZ back-end only supports the local-exec TLS access model.
This patch adds all required CodeGen support for the other TLS models, which
means in particular:

  • Expand initial-exec TLS accesses by loading TLS offsets from the GOT using @indntpoff relocations.
  • Expand general-dynamic and local-dynamic accesses by generating the appropriate calls to __tls_get_offset. Note that this routine has a non-standard ABI and requires loading the GOT pointer into %r12, so the patch also adds support for the GLOBAL_OFFSET_TABLE ISD node.
  • Add a new platform-specific optimization pass to remove redundant __tls_get_offset calls in the local-dynamic model (modeled after the corresponding X86 pass).
  • Add test cases verifying all access models and optimizations.

Details

Committed
uweigandFeb 18 2015, 1:13 AM
Parents
rL229653: Testing commit access
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