[llvm-exegesis] Change how the native architecture is determined

Currently the llvm-exegesis native architecture is determined by comparing the
llvm native architecture with X86, so to add a new target would mean adding a
new check. Change this to building up a list of the targets llvm-exegesis
supports then using that, as this means that when adding a new target you just
add the target to the list of supported targets.

Differential Revision: https://reviews.llvm.org/D48778

llvm-svn: 336105
diff --git a/llvm/tools/llvm-exegesis/CMakeLists.txt b/llvm/tools/llvm-exegesis/CMakeLists.txt
index 01a795b..65b1ada 100644
--- a/llvm/tools/llvm-exegesis/CMakeLists.txt
+++ b/llvm/tools/llvm-exegesis/CMakeLists.txt
@@ -11,8 +11,8 @@
 add_subdirectory(lib)
 
 # Link the native exegesis target if compiled and on the right host.
-if ((LLVM_TARGETS_TO_BUILD MATCHES "X86") AND ("${LLVM_NATIVE_ARCH}" STREQUAL "X86"))
-  set(LLVM_EXEGESIS_NATIVE_ARCH "X86")
+if ((LLVM_TARGETS_TO_BUILD MATCHES "${LLVM_NATIVE_ARCH}") AND (LLVM_EXEGESIS_TARGETS MATCHES "${LLVM_NATIVE_ARCH}"))
+  set(LLVM_EXEGESIS_NATIVE_ARCH "${LLVM_NATIVE_ARCH}")
 endif()
 
 if (LLVM_EXEGESIS_NATIVE_ARCH)
diff --git a/llvm/tools/llvm-exegesis/lib/CMakeLists.txt b/llvm/tools/llvm-exegesis/lib/CMakeLists.txt
index 02eeb75..3c69dea7 100644
--- a/llvm/tools/llvm-exegesis/lib/CMakeLists.txt
+++ b/llvm/tools/llvm-exegesis/lib/CMakeLists.txt
@@ -1,5 +1,6 @@
 if (LLVM_TARGETS_TO_BUILD MATCHES "X86")
   add_subdirectory(X86)
+  set(LLVM_EXEGESIS_TARGETS "${LLVM_EXEGESIS_TARGETS} X86" PARENT_SCOPE)
 endif()
 
 add_library(LLVMExegesis