This patch introduces initial-exec model support for thread-local storage

on 64-bit PowerPC ELF.

The patch includes code to handle external assembly and MC output with the
integrated assembler.  It intentionally does not support the "old" JIT.

For the initial-exec TLS model, the ABI requires the following to calculate
the address of external thread-local variable x:

 Code sequence            Relocation                  Symbol
  ld 9,x@got@tprel(2)      R_PPC64_GOT_TPREL16_DS      x
  add 9,9,x@tls            R_PPC64_TLS                 x

The register 9 is arbitrary here.  The linker will replace x@got@tprel
with the offset relative to the thread pointer to the generated GOT
entry for symbol x.  It will replace x@tls with the thread-pointer
register (13).

The two test cases verify correct assembly output and relocation output
as just described.

PowerPC-specific selection node variants are added for the two
instructions above:  LD_GOT_TPREL and ADD_TLS.  These are inserted
when an initial-exec global variable is encountered by
PPCTargetLowering::LowerGlobalTLSAddress(), and later lowered to
machine instructions LDgotTPREL and ADD8TLS.  LDgotTPREL is a pseudo
that uses the same LDrs support added for medium code model's LDtocL,
with a different relocation type.

The rest of the processing is straightforward.

llvm-svn: 169281

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
index 997465e97f6..462d7072b56 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCELFObjectWriter.cpp
@@ -119,8 +119,14 @@ unsigned PPCELFObjectWriter::getRelocTypeInner(const MCValue &Target,
       case MCSymbolRefExpr::VK_PPC_TOC16_LO:
         Type = ELF::R_PPC64_TOC16_LO_DS;
         break;
+      case MCSymbolRefExpr::VK_PPC_GOT_TPREL16_DS:
+        Type = ELF::R_PPC64_GOT_TPREL16_DS;
+        break;
       }
       break;
+    case PPC::fixup_ppc_tlsreg:
+      Type = ELF::R_PPC64_TLS;
+      break;
     case FK_Data_8:
       switch (Modifier) {
       default: llvm_unreachable("Unsupported Modifier");