Initial configure support for using Clang as the LLVM capable compiler.

Comes in two parts:
 1. Use --with-clang=path/to/clang/compiler to select an installed clang, or
    --with-built-clang to have the makefiles use the clang which will be built
    as the LLVM capable compiler. If neither is given, --with-built-clang will
    be used if the Clang sources are checked out into the standard location
    (tools/clang).

 2. Use --with-llvmcc={llvm-gcc,clang,none} to specify which LLVM capable
    compiler to use. If not given, then llvm-gcc will be used if available,
    otherwise Clang.

Makefile support still to come.

Eric, Doug, Chris, seem reasonable?

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96934 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 73 insertions, 0 deletions

diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 762c41e1cc..9e8cdfc226 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -612,6 +612,56 @@ if test -n "$LLVMGXX" && test -z "$LLVMGCC"; then
    AC_MSG_ERROR([Invalid llvm-gcc. Use --with-llvmgcc when --with-llvmgxx is used]);
 fi
 
+dnl Allow a specific Clang compiler to be used with this LLVM config.
+AC_ARG_WITH(clang,
+  AS_HELP_STRING([--with-clang],
+    [Specify location of clang compiler (default is --with-built-clang)]),
+    [],[with_clang=default])
+
+dnl Enable use of the built Clang.
+AC_ARG_WITH(built-clang,
+  AS_HELP_STRING([--with-built-clang],
+    [Use the compiled Clang as the LLVM compiler (default=check)]),
+    [],[with_built_clang=check])
+
+dnl Select the Clang compiler option.
+dnl
+dnl If --with-clang is given, always honor that; otherwise honor
+dnl --with-built-clang, or check if we have the clang sources.
+AC_MSG_CHECKING([clang compiler])
+WITH_CLANGPATH=""
+WITH_BUILT_CLANG=0
+if test "$with_clang" != "default"; then
+   WITH_CLANGPATH="$with_clang"
+   if ! test -x "$WITH_CLANGPATH"; then
+     AC_MSG_ERROR([invalid --with-clang, path does not specify an executable])
+   fi
+elif test "$with_built_clang" = "yes"; then
+   WITH_BUILT_CLANG=1
+elif test "$with_built_clang" = "no"; then
+   WITH_BUILT_CLANG=0
+else
+   if test "$with_built_clang" != "check"; then
+      AC_MSG_ERROR([invalid value for --with-built-clang.])
+   fi
+
+   if test -f ${srcdir}/tools/clang/README.txt; then
+     WITH_BUILT_CLANG=1
+   fi
+fi
+
+if ! test -z "$WITH_CLANGPATH"; then
+   AC_MSG_RESULT([$WITH_CLANGPATH])
+   WITH_CLANGXXPATH=`"$WITH_CLANGPATH" --print-prog-name=clang++`
+elif test "$WITH_BUILT_CLANG" = "1"; then
+   AC_MSG_RESULT([built])
+else
+   AC_MSG_RESULT([none])
+fi
+AC_SUBST(CLANGPATH,$WITH_CLANGPATH)
+AC_SUBST(CLANGXXPATH,$WITH_CLANGXXPATH)
+AC_SUBST(ENABLE_BUILT_CLANG,$WITH_BUILT_CLANG)
+
 dnl Override the option to use for optimized builds.
 AC_ARG_WITH(optimize-option,
   AS_HELP_STRING([--with-optimize-option],
@@ -946,6 +996,29 @@ else
   AC_SUBST(LLVMGXXCOMMAND,$LLVMGXXCOMMAND)
 fi
 
+dnl Select the LLVM capable compiler to use, we default to using llvm-gcc if
+dnl found, otherwise clang if available.
+AC_ARG_WITH(llvmcc,
+  AS_HELP_STRING([--with-llvmcc=<name>],
+    [Choose the LLVM capable compiler to use (llvm-gcc, clang, or none; default=check)]),
+    [],[with_llvmcc=check])
+AC_MSG_CHECKING([LLVM capable compiler])
+if test "$with_llvmcc" != "check"; then
+   if (test "$with_llvmcc" != "llvm-gcc" &&
+       test "$with_llvmcc" != "clang" &&
+       test "$with_llvmcc" != "none"); then
+      AC_MSG_ERROR([invalid value for --with-llvmcc, expected 'llvm-gcc', 'clang', or 'none'.])
+   fi
+   WITH_LLVMCC="$with_llvmcc"
+elif test -n "$LLVMGCC"; then
+   WITH_LLVMCC=llvm-gcc
+elif test -n "$WITH_CLANGPATH" || test "$WITH_BUILT_CLANG" -ne "0"; then
+   WITH_LLVMCC=clang
+else
+   WITH_LLVMCC=none
+fi
+AC_MSG_RESULT([$WITH_LLVMCC])
+AC_SUBST(LLVMCC_OPTION,$WITH_LLVMCC)
 
 AC_MSG_CHECKING([tool compatibility])