[RISCV] Support assembling %tls_{ie,gd}_pcrel_hi modifiers

This patch adds support for parsing and assembling the %tls_ie_pcrel_hi
and %tls_gd_pcrel_hi modifiers.

Differential Revision: https://reviews.llvm.org/D55342

llvm-svn: 358994
diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
index f1248e5..32e9f4e 100644
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVMCCodeEmitter.cpp
@@ -307,6 +307,12 @@
       FixupKind = RISCV::fixup_riscv_tprel_hi20;
       RelaxCandidate = true;
       break;
+    case RISCVMCExpr::VK_RISCV_TLS_GOT_HI:
+      FixupKind = RISCV::fixup_riscv_tls_got_hi20;
+      break;
+    case RISCVMCExpr::VK_RISCV_TLS_GD_HI:
+      FixupKind = RISCV::fixup_riscv_tls_gd_hi20;
+      break;
     case RISCVMCExpr::VK_RISCV_CALL:
       FixupKind = RISCV::fixup_riscv_call;
       RelaxCandidate = true;