[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.

llvm-svn: 229654

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
index 9b8dc43..73198b1 100644
--- a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
@@ -61,6 +61,10 @@ void SystemZPassConfig::addIRPasses() {
 
 bool SystemZPassConfig::addInstSelector() {
   addPass(createSystemZISelDag(getSystemZTargetMachine(), getOptLevel()));
+
+ if (getOptLevel() != CodeGenOpt::None)
+    addPass(createSystemZLDCleanupPass(getSystemZTargetMachine()));
+
   return false;
 }