[mips] Add '-mrelax-pic-calls', '-mno-relax-pic-calls'

These two options enable/disable emission of R_{MICRO}MIPS_JALR fixups along
with PIC calls. The linker may then try to turn PIC calls into direct jumps.
By default, these fixups do get emitted by the backend, use
'-mno-relax-pic-calls' to omit them.

Differential revision: https://reviews.llvm.org/D56878

llvm-svn: 351579

1 files changed, 8 insertions, 0 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 75f16898dfa..589f53b1192 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1716,6 +1716,14 @@ void Clang::AddMIPSTargetArgs(const ArgList &Args,
     } else
       D.Diag(diag::warn_target_unsupported_compact_branches) << CPUName;
   }
+
+  if (Arg *A = Args.getLastArg(options::OPT_mrelax_pic_calls,
+                               options::OPT_mno_relax_pic_calls)) {
+    if (A->getOption().matches(options::OPT_mno_relax_pic_calls)) {
+      CmdArgs.push_back("-mllvm");
+      CmdArgs.push_back("-mips-jalr-reloc=0");
+    }
+  }
 }
 
 void Clang::AddPPCTargetArgs(const ArgList &Args,