ARM: support tlscall relocations

This adds support for TLS CALL relocations.  TLS CALL relocations are used to
indicate to the linker to generate appropriate entries to resolve TLS references
via an appropriate function invocation (e.g. __tls_get_addr(PLT)).

In order to accomodate the linker relaxation of the TLS access model for the
references (GD/LD -> IE, IE -> LE), the relocation addend must be incomplete.
This requires that the partial inplace value is also incomplete (i.e. 0).  We
simply avoid the offset value calculation at the time of the fixup adjustment in
the ARM assembler backend.

llvm-svn: 200446

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
index 305c7587cb1..7db700472cb 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMAsmBackend.cpp
@@ -380,6 +380,9 @@ static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
   case ARM::fixup_arm_blx:
     // These values don't encode the low two bits since they're always zero.
     // Offset by 8 just as above.
+    if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
+      if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
+        return 0;
     return 0xffffff & ((Value - 8) >> 2);
   case ARM::fixup_t2_uncondbranch: {
     Value = Value - 4;
@@ -461,6 +464,9 @@ static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value,
     // Note that the halfwords are stored high first, low second; so we need
     // to transpose the fixup value here to map properly.
     uint32_t offset = (Value - 2) >> 2;
+    if (const MCSymbolRefExpr *SRE = dyn_cast<MCSymbolRefExpr>(Fixup.getValue()))
+      if (SRE->getKind() == MCSymbolRefExpr::VK_ARM_TLSCALL)
+        offset = 0;
     uint32_t signBit = (offset & 0x400000) >> 22;
     uint32_t I1Bit = (offset & 0x200000) >> 21;
     uint32_t J1Bit = (I1Bit ^ 0x1) ^ signBit;