MFC LLD changes and enable LLD as /usr/bin/ld on arm64 by default

MFC r316629: do not require binutils port when using lld as ld

r279908 added logic to Makefile.inc1 to automatically set
CROSS_BINUTILS_PREFIX for architectures not supported by the in-tree
binutils: arm64 when first introduced, and later riscv64 as well.

LLVM's LLD linker is now included in the base system, and is enabled by
default for arm64 and capable of linking world and kernel. Thus, avoid
automatically setting CROSS_BINUTILS_PREFIX and requiring the binutils
port if WITH_LLD_IS_LD is true.

--

MFC r317608: revert r313473 (Disable LLD_IS_LD option combinations that fail)

r316647 corrected the build of tblgen and libllvm as dependencies for
LLD so undo the temporary seat-belt.

We still want to extend the build infrastructure to automatically detect
the case where the host LLD can be used instead of building a bootstrap
LLD, and likely extend libllvmminimal to meet LLD's needs for cases
where the build includes LLD but not Clang.

--

MFC r316684: Make WITHOUT_TOOLCHAIN imply WITHOUT_LLD.

LLD is a toolchain component.

--

MFC r316647: Introduce LLD_BOOTSTRAP to control lld as bootstrap linker

Add WITH_LLD_BOOTSTRAP and WITHOUT_LLD_BOOTSTRAP knobs, similar to the
Clang bootstrap knobs.

Reviewed by:	andrew
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D10793

5 files changed, 28 insertions, 20 deletions

diff --git a/Makefile.inc1 b/Makefile.inc1
index 1473be5..4995c24 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -195,10 +195,11 @@ CROSS_BINUTILS_PREFIX?=${CROSS_TOOLCHAIN_PREFIX}
 .endif
 # If we do not have a bootstrap binutils (because the in-tree one does not
 # support the target architecture), provide a default cross-binutils prefix.
-# This allows aarch64 builds, for example, to automatically use the
-# aarch64-binutils port or package.
+# This allows riscv64 builds, for example, to automatically use the
+# riscv64-binutils port or package.
 .if !make(showconfig)
 .if !empty(BROKEN_OPTIONS:MBINUTILS_BOOTSTRAP) && \
+    ${MK_LLD_BOOTSTRAP} == "no" && \
     !defined(CROSS_BINUTILS_PREFIX)
 CROSS_BINUTILS_PREFIX=/usr/local/${TARGET_ARCH}-freebsd/bin/
 .if !exists(${CROSS_BINUTILS_PREFIX})
@@ -1666,9 +1667,10 @@ ${_bt}-usr.bin/yacc: ${_bt}-lib/liby
 _gensnmptree=	usr.sbin/bsnmpd/gensnmptree
 .endif
 
-# We need to build tblgen when we're building clang either as
-# the bootstrap compiler, or as the part of the normal build.
-.if ${MK_CLANG_BOOTSTRAP} != "no" || ${MK_CLANG} != "no"
+# We need to build tblgen when we're building clang or lld, either as
+# bootstrap tools, or as the part of the normal build.
+.if ${MK_CLANG_BOOTSTRAP} != "no" || ${MK_CLANG} != "no" || \
+    ${MK_LLD_BOOTSTRAP} != "no" || ${MK_LLD} != "no"
 _clang_tblgen= \
 	lib/clang/libllvmminimal \
 	usr.bin/clang/llvm-tblgen \
@@ -1832,9 +1834,6 @@ _elftctools=	lib/libelftc \
 # cross-build on a FreeBSD 10 host:
 _elftctools+=	usr.bin/addr2line
 .endif
-.if ${MK_LLD_IS_LD} != "no"
-_lld=		usr.bin/clang/lld
-.endif
 .elif ${TARGET_ARCH} != ${MACHINE_ARCH} && ${MK_ELFTOOLCHAIN_BOOTSTRAP} != "no"
 # If cross-building with an external binutils we still need to build strip for
 # the target (for at least crunchide).
@@ -1845,6 +1844,11 @@ _elftctools=	lib/libelftc \
 
 .if ${MK_CLANG_BOOTSTRAP} != "no"
 _clang=		usr.bin/clang
+.endif
+.if ${MK_LLD_BOOTSTRAP} != "no"
+_lld=		usr.bin/clang/lld
+.endif
+.if ${MK_CLANG_BOOTSTRAP} != "no" || ${MK_LLD_BOOTSTRAP} != "no"
 _clang_libs=	lib/clang
 .endif
 .if ${MK_GCC_BOOTSTRAP} != "no"
diff --git a/UPDATING b/UPDATING
index 60ef4e3..916e3da 100644
--- a/UPDATING
+++ b/UPDATING
@@ -16,6 +16,12 @@ from older versions of FreeBSD, try WITHOUT_CLANG and WITH_GCC to bootstrap to
 the tip of head, and then rebuild without this option. The bootstrap process
 from older version of current across the gcc/clang cutover is a bit fragile.
 
+20170518:
+	arm64 builds now use the base system LLD 4.0.0 linker by default,
+	instead of requiring that the aarch64-binutils port or package be
+	installed. To continue using aarch64-binutils, set
+	CROSS_BINUTILS_PREFIX=/usr/local/aarch64-freebsd/bin .
+
 20170511:
 	The mmcsd.ko module now additionally depends on geom_flashmap.ko.
 	Also, mmc.ko and mmcsd.ko need to be a matching pair built from the
diff --git a/share/mk/src.opts.mk b/share/mk/src.opts.mk
index 9bbbadd..9679722 100644
--- a/share/mk/src.opts.mk
+++ b/share/mk/src.opts.mk
@@ -247,9 +247,9 @@ BROKEN_OPTIONS+=TESTS   # "undefined reference to `_Unwind_Resume'"
 BROKEN_OPTIONS+=CXX     # "libcxxrt.so: undefined reference to `_Unwind_Resume_or_Rethrow'"
 .endif
 .if ${__T} == "aarch64"
-__DEFAULT_YES_OPTIONS+=LLD_IS_LD
+__DEFAULT_YES_OPTIONS+=LLD_BOOTSTRAP LLD_IS_LD
 .else
-__DEFAULT_NO_OPTIONS+=LLD_IS_LD
+__DEFAULT_NO_OPTIONS+=LLD_BOOTSTRAP LLD_IS_LD
 .endif
 .if ${__T} == "aarch64" || ${__T} == "amd64"
 __DEFAULT_YES_OPTIONS+=LLDB
@@ -306,16 +306,6 @@ MK_LDNS_UTILS:=	no
 MK_UNBOUND:= no
 .endif
 
-.if ${MK_LLD} == "no"
-MK_LLD_IS_LD:=	no
-.endif
-
-# LLD requires LLVM libraries, and we do not yet compare in-tree and host LLD
-# versions to avoid building it if they are identical.
-.if ${MK_LLD_IS_LD} != "no"
-MK_SYSTEM_COMPILER:=	no
-.endif
-
 .if ${MK_SOURCELESS} == "no"
 MK_SOURCELESS_HOST:=	no
 MK_SOURCELESS_UCODE:= no
@@ -383,6 +373,7 @@ MK_CLANG:=	no
 MK_GCC:=	no
 MK_GDB:=	no
 MK_INCLUDES:=	no
+MK_LLD:=	no
 MK_LLDB:=	no
 .endif
 
diff --git a/tools/build/options/WITHOUT_LLD_BOOTSTRAP b/tools/build/options/WITHOUT_LLD_BOOTSTRAP
new file mode 100644
index 0000000..646edd3
--- /dev/null
+++ b/tools/build/options/WITHOUT_LLD_BOOTSTRAP
@@ -0,0 +1,5 @@
+.\" $FreeBSD$
+Set to not build the LLD linker during the bootstrap phase of
+the build.
+To be able to build the system, either Binutils or LLD bootstrap must be
+enabled unless an alternate linker is provided via XLD.
diff --git a/tools/build/options/WITH_LLD_BOOTSTRAP b/tools/build/options/WITH_LLD_BOOTSTRAP
new file mode 100644
index 0000000..4977b97
--- /dev/null
+++ b/tools/build/options/WITH_LLD_BOOTSTRAP
@@ -0,0 +1,2 @@
+.\" $FreeBSD$
+Set to build the LLD linker during the bootstrap phase of the build.