Allow bootstrapping llvm-tblgen on macOS and Linux

This is needed in order to build various LLVM binutils (e.g. addr2line)
as well as clang/lld/lldb.

Co-authored-by: Jessica Clarke <jrtc27@FreeBSD.org>
Test Plan:	Compiles on ubuntu 18.04 and macOS 11.4
Reviewed By:	dim
Differential Revision: https://reviews.freebsd.org/D31057

3 files changed, 65 insertions, 8 deletions

diff --git a/lib/clang/include/llvm/Config/config.h b/lib/clang/include/llvm/Config/config.h
index 0cd6dabeab17..35ce8c189d2b 100644
--- a/lib/clang/include/llvm/Config/config.h
+++ b/lib/clang/include/llvm/Config/config.h
@@ -29,7 +29,11 @@
 /* #undef HAVE_CRASHREPORTERCLIENT_H */
 
 /* can use __crashreporter_info__ */
+#if defined(__APPLE__)
+#define HAVE_CRASHREPORTER_INFO 1
+#else
 #define HAVE_CRASHREPORTER_INFO 0
+#endif
 
 /* Define to 1 if you have the declaration of `arc4random', and to 0 if you
    don't. */
@@ -125,28 +129,46 @@
 #define HAVE_PTHREAD_SETNAME_NP 1
 
 /* Define to 1 if you have the <link.h> header file. */
+#if __has_include(<link.h>)
 #define HAVE_LINK_H 1
+#else
+#define HAVE_LINK_H 0
+#endif
 
 /* Define to 1 if you have the `lseek64' function. */
-/* #undef HAVE_LSEEK64 */
+#if defined(__linux__)
+#define HAVE_LSEEK64 1
+#endif
 
 /* Define to 1 if you have the <mach/mach.h> header file. */
-/* #undef HAVE_MACH_MACH_H */
+#if __has_include(<mach/mach.h>)
+#define HAVE_MACH_MACH_H 1
+#endif
 
 /* Define to 1 if you have the `mallctl' function. */
+#if defined(__FreeBSD__)
 #define HAVE_MALLCTL 1
+#endif
 
 /* Define to 1 if you have the `mallinfo' function. */
-/* #undef HAVE_MALLINFO */
+#if defined(__linux__)
+#define HAVE_MALLINFO 1
+#endif
 
 /* Define to 1 if you have the <malloc/malloc.h> header file. */
-/* #undef HAVE_MALLOC_MALLOC_H */
+#if __has_include(<malloc/malloc.h>)
+#define HAVE_MALLOC_MALLOC_H 1
+#endif
 
 /* Define to 1 if you have the `malloc_zone_statistics' function. */
-/* #undef HAVE_MALLOC_ZONE_STATISTICS */
+#if defined(__APPLE__)
+#define HAVE_MALLOC_ZONE_STATISTICS 1
+#endif
 
 /* Define to 1 if you have the `posix_fallocate' function. */
+#if !defined(__APPLE__)
 #define HAVE_POSIX_FALLOCATE 1
+#endif
 
 /* Define to 1 if you have the `posix_spawn' function. */
 #define HAVE_POSIX_SPAWN 1
@@ -209,19 +231,31 @@
 #define HAVE_SYS_TIME_H 1
 
 /* Define to 1 if stat struct has st_mtimespec member .*/
+#if !defined(__linux__)
 #define HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC 1
+#endif
 
 /* Define to 1 if stat struct has st_mtim member. */
+#if !defined(__APPLE__)
 #define HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC 1
+#endif
 
 /* Define to 1 if you have the <sys/types.h> header file. */
 #define HAVE_SYS_TYPES_H 1
 
 /* Define if the setupterm() function is supported this platform. */
+#if defined(__FreeBSD__)
+/*
+ * This is only needed for terminalHasColors(). When disabled LLVM falls back
+ * to checking a list of TERM prefixes which is sufficient for a bootstrap tool.
+ */
 #define LLVM_ENABLE_TERMINFO 1
+#endif
 
 /* Define if the xar_open() function is supported this platform. */
-/* #undef HAVE_LIBXAR */
+#if defined(__APPLE__)
+#define HAVE_LIBXAR
+#endif
 
 /* Define to 1 if you have the <termios.h> header file. */
 #define HAVE_TERMIOS_H 1
@@ -239,7 +273,9 @@
 /* #undef HAVE__CHSIZE_S */
 
 /* Define to 1 if you have the `_Unwind_Backtrace' function. */
-/* #undef HAVE__UNWIND_BACKTRACE */
+#if !defined(__FreeBSD__)
+#define HAVE__UNWIND_BACKTRACE 1
+#endif
 
 /* Have host's __alloca */
 /* #undef HAVE___ALLOCA */
@@ -315,7 +351,11 @@
 /* #undef LLVM_LIBXML2_ENABLED */
 
 /* Define to the extension used for shared libraries, say, ".so". */
+#if defined(__APPLE__)
+#define LTDL_SHLIB_EXT ".dylib"
+#else
 #define LTDL_SHLIB_EXT ".so"
+#endif
 
 /* Define to the address where bug reports for this package should be sent. */
 #define PACKAGE_BUGREPORT "https://bugs.freebsd.org/submit/"
@@ -351,6 +391,10 @@
 /* #undef LLVM_GISEL_COV_PREFIX */
 
 /* Whether Timers signpost passes in Xcode Instruments */
+#if defined(__APPLE__)
+#define LLVM_SUPPORT_XCODE_SIGNPOSTS 1
+#else
 #define LLVM_SUPPORT_XCODE_SIGNPOSTS 0
+#endif
 
 #endif
diff --git a/lib/clang/libllvm/Makefile b/lib/clang/libllvm/Makefile
index 85440f467a18..09d6336c01d9 100644
--- a/lib/clang/libllvm/Makefile
+++ b/lib/clang/libllvm/Makefile
@@ -717,7 +717,8 @@ SRCS_EXL+=	LTO/LTOModule.cpp
 SRCS_EXL+=	LTO/SummaryBasedOptimizations.cpp
 SRCS_EXL+=	LTO/ThinLTOCodeGenerator.cpp
 SRCS_MIN+=	LTO/UpdateCompilerUsed.cpp
-SRCS_MIN+=	LineEditor/LineEditor.cpp
+# Only needed for clangd/clang-query, uncomment once we build those.
+# SRCS_XDW+=	LineEditor/LineEditor.cpp
 SRCS_MIN+=	Linker/IRMover.cpp
 SRCS_MIN+=	Linker/LinkModules.cpp
 SRCS_MIN+=	MC/ConstantPools.cpp
diff --git a/lib/clang/llvm.build.mk b/lib/clang/llvm.build.mk
index b248fb816364..70b39fdc44ca 100644
--- a/lib/clang/llvm.build.mk
+++ b/lib/clang/llvm.build.mk
@@ -100,12 +100,24 @@ CFLAGS+=	-DLLVM_NATIVE_TARGETMC=LLVMInitialize${LLVM_NATIVE_ARCH}TargetMC
 
 CFLAGS+=	-ffunction-sections
 CFLAGS+=	-fdata-sections
+.if ${LINKER_TYPE} == "mac"
+LDFLAGS+=	-Wl,-dead_strip
+.else
 LDFLAGS+=	-Wl,--gc-sections
+.endif
 
 CXXSTD?=	c++14
 CXXFLAGS+=	-fno-exceptions
 CXXFLAGS+=	-fno-rtti
+.if ${.MAKE.OS} == "FreeBSD" || !defined(BOOTSTRAPPING)
+# Building on macOS/Linux needs the real sysctl() not the bootstrap tools stub.
+CFLAGS+=	-DBOOTSTRAPPING_WANT_NATIVE_SYSCTL
+.else
 CXXFLAGS.clang+= -stdlib=libc++
+.endif
+.if defined(BOOTSTRAPPING) && ${.MAKE.OS} == "Linux"
+LIBADD+=	dl
+.endif
 
 .if ${MACHINE_ARCH:Mmips64}
 STATIC_CFLAGS+= -mxgot