enable cross compilation with cmake

This patch allows us to use cmake to specify a cross compiler: target different
than host. In particular, it moves LLVM_DEFAULT_TARGET_TRIPLE and TARGET_TRIPLE
variables from cmake/config-ix.cmake to the toplevel CMakeLists.txt to make them
available at configure time.

Here is the command line that I have used to test my patches to create a Hexagon
cross compiler hosted on x86:

$ cmake -G Ninja -D LLVM_TARGETS_TO_BUILD:STRING=Hexagon -D TARGET_TRIPLE:STRING=hexagon-unknown-linux-gnu -D LLVM_DEFAULT_TARGET_TRIPLE:STRING=hexagon-unknown-linux-gnu -D LLVM_TARGET_ARCH:STRING=hexagon-unknown-linux-gnu ..
$ ninja check

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162219 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/CMakeLists.txt b/CMakeLists.txt
index fbf8e2bb90e5d8cb6e045aea8030fde8d1eda42f..df781f52cdd289ae41b9390ae1babf04e940cb80 100644 (file)
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -249,6 +249,14 @@ option(LLVM_INCLUDE_TESTS "Generate build targets for the LLVM unit tests." ON)
 # BEFORE this include, otherwise options will not be correctly set on
 # first cmake run
 include(config-ix)
+
+# By default, we target the host, but this can be overridden at CMake
+# invocation time.
+set(LLVM_DEFAULT_TARGET_TRIPLE "${LLVM_HOST_TRIPLE}" CACHE STRING
+  "Default target for which LLVM will generate code." )
+set(TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}" CACHE STRING
+  "Default target for which LLVM will generate code." )
+
 include(HandleLLVMOptions)
 
 # Verify that we can find a Python interpreter,

diff --git a/cmake/config-ix.cmake b/cmake/config-ix.cmake
index 1e72258d448a68992abb134c9878a6bd54d4bc44..94cc5551c8ddae882fb52399eb6b29c6912c02c2 100755 (executable)
--- a/cmake/config-ix.cmake
+++ b/cmake/config-ix.cmake
@@ -294,9 +294,7 @@ get_host_triple(LLVM_HOST_TRIPLE)
 
 # By default, we target the host, but this can be overridden at CMake
 # invocation time.
-set(LLVM_DEFAULT_TARGET_TRIPLE "${LLVM_HOST_TRIPLE}")
 set(LLVM_HOSTTRIPLE "${LLVM_HOST_TRIPLE}")
-set(TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
 
 # Determine the native architecture.
 string(TOLOWER "${LLVM_TARGET_ARCH}" LLVM_NATIVE_ARCH)