[libunwind][MIPS]: Add support for unwinding in O32 and N64 processes.

This supports the soft-float ABI only and has been tested with both clang
and gcc on FreeBSD.

Reviewed By: sdardis, compnerd

Differential Revision: https://reviews.llvm.org/D38110

llvm-svn: 320528
Cr-Mirrored-From: sso://chromium.googlesource.com/_direct/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: dfbbbdf8cd42b10969f96d4f65ae32012eff035b
diff --git a/src/libunwind.cpp b/src/libunwind.cpp
index 1039a3b..0b7fb40 100644
--- a/src/libunwind.cpp
+++ b/src/libunwind.cpp
@@ -59,8 +59,12 @@
 # define REGISTER_KIND Registers_arm
 #elif defined(__or1k__)
 # define REGISTER_KIND Registers_or1k
+#elif defined(__mips__) && defined(_ABIO32) && defined(__mips_soft_float)
+# define REGISTER_KIND Registers_mips_o32
+#elif defined(__mips__) && defined(_ABI64) && defined(__mips_soft_float)
+# define REGISTER_KIND Registers_mips_n64
 #elif defined(__mips__)
-# warning The MIPS architecture is not supported.
+# warning The MIPS architecture is not supported with this ABI and environment!
 #else
 # error Architecture not supported
 #endif