svn commit: r360391 - in stable/12: gnu/usr.bin/gdb share/mk sys/conf

[Kyle Evans]

Author: kevans
Date: Mon Apr 27 19:49:35 2020
New Revision: 360391
URL: https://svnweb.freebsd.org/changeset/base/360391

Log:
  MFC r359702, r359774: enforce -fno-common for userland/kernel src builds
  
  r359702:
  Add -fno-common to all userland/kernel src builds
  
  -fno-common will become the default in GCC10/LLVM11. Plenty of work has been
  put in to make sure our world builds are no -fno-common clean, so let's slap
  the build with this until it becomes the compiler default to ensure we don't
  regress.
  
  At this time, we will not be enforcing -fno-common on ports builds. I
  suspect most ports will be or quickly become -fno-common clean as they're
  naturally built against compilers that default to it, so this will hopefully
  become a non-issue in due time. The exception to this, which is actually the
  status quo, is that kmods built from ports will continue to build with
  -fno-common.
  
  As of the time of writing, I intend to also make stable/12 -fno-common
  clean. What's been done will be MFC'd to stable/11 if it's easily applicable
  and/or not much work to massage it into being functional, but I anticipate
  adding -fcommon to stable/11 builds to maintain its ability to be built with
  newer compilers for the rest of its lifetime instead of putting in a third
  branch's worth of effort.
  
  r359774:
  userland build: replace -fno-common with ${CFCOMMONFLAG}
  
  This change allows any downstream or otherwise consumer to easily override
  the new -fno-common default on a temporary basis without having to hack into
  src.sys.mk, and also makes it a bit easier to search for these specific
  cases where -fno-common must be overridden with -fcommon or else the build
  will fail.
  
  The gdb build, the only program requiring -fcommon on head/, is switched
  over as an example usage. It will need it on all branches, so this does not
  harm future mergability.

Modified:
  stable/12/gnu/usr.bin/gdb/Makefile.inc
  stable/12/share/mk/src.sys.mk
  stable/12/sys/conf/kern.pre.mk
  stable/12/sys/conf/kmod.mk
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/gnu/usr.bin/gdb/Makefile.inc
==============================================================================
--- stable/12/gnu/usr.bin/gdb/Makefile.inc	Mon Apr 27 19:29:48 2020	(r360390)
+++ stable/12/gnu/usr.bin/gdb/Makefile.inc	Mon Apr 27 19:49:35 2020	(r360391)
@@ -50,7 +50,7 @@ CFLAGS+= -I${SYSROOT:U${DESTDIR}}/${INCLUDEDIR}/edit
 # Some bits here currently rely on some of the linker-merging magic that happens
 # with -fcommon.  While this is the default right now, explicitly set -fcommon
 # so that it continues to build when the default flips.
-CFLAGS+= -fcommon
+CFCOMMONFLAG= -fcommon
 
 GENSRCS+= nm.h tm.h
 

Modified: stable/12/share/mk/src.sys.mk
==============================================================================
--- stable/12/share/mk/src.sys.mk	Mon Apr 27 19:29:48 2020	(r360390)
+++ stable/12/share/mk/src.sys.mk	Mon Apr 27 19:49:35 2020	(r360391)
@@ -34,6 +34,12 @@ __postrcconf_${var}:=	${MK_${var}:U-}${WITHOUT_${var}:
 .endif # SRCCONF
 .endif
 
+# The following should be removed no earlier than LLVM11 being imported into the
+# tree, to ensure we don't regress the build.  LLVM11 and GCC10 will switch the
+# default over to -fno-common, making this redundant.
+CFCOMMONFLAG?=	-fno-common
+CFLAGS+=	${CFCOMMONFLAG}
+
 # tempting, but bsd.compiler.mk causes problems this early
 # probably need to remove dependence on bsd.own.mk 
 #.include "src.opts.mk"

Modified: stable/12/sys/conf/kern.pre.mk
==============================================================================
--- stable/12/sys/conf/kern.pre.mk	Mon Apr 27 19:29:48 2020	(r360390)
+++ stable/12/sys/conf/kern.pre.mk	Mon Apr 27 19:49:35 2020	(r360391)
@@ -86,7 +86,7 @@ CFLAGS_PARAM_LARGE_FUNCTION_GROWTH?=1000
 .if ${MACHINE_CPUARCH} == "mips"
 CFLAGS_ARCH_PARAMS?=--param max-inline-insns-single=1000 -DMACHINE_ARCH='"${MACHINE_ARCH}"'
 .endif
-CFLAGS.gcc+= -fno-common -fms-extensions -finline-limit=${INLINE_LIMIT}
+CFLAGS.gcc+= -fms-extensions -finline-limit=${INLINE_LIMIT}
 CFLAGS.gcc+= --param inline-unit-growth=${CFLAGS_PARAM_INLINE_UNIT_GROWTH}
 CFLAGS.gcc+= --param large-function-growth=${CFLAGS_PARAM_LARGE_FUNCTION_GROWTH}
 CFLAGS.gcc+= -fms-extensions
@@ -98,6 +98,10 @@ WERROR?=	-Wno-error
 .else
 WERROR?=	-Werror
 .endif
+# The following should be removed no earlier than LLVM11 being imported into the
+# tree, to ensure we don't regress the build.  LLVM11 and GCC10 will switch the
+# default over to -fno-common, making this redundant.
+CFLAGS+=	-fno-common
 
 # XXX LOCORE means "don't declare C stuff" not "for locore.s".
 ASM_CFLAGS= -x assembler-with-cpp -DLOCORE ${CFLAGS} ${ASM_CFLAGS.${.IMPSRC:T}} 

Modified: stable/12/sys/conf/kmod.mk
==============================================================================
--- stable/12/sys/conf/kmod.mk	Mon Apr 27 19:29:48 2020	(r360390)
+++ stable/12/sys/conf/kmod.mk	Mon Apr 27 19:49:35 2020	(r360391)
@@ -149,6 +149,13 @@ CFLAGS.gcc+= --param large-function-growth=1000
 
 # Disallow common variables, and if we end up with commons from
 # somewhere unexpected, allocate storage for them in the module itself.
+#
+# -fno-common is the default for src builds, but this should be left in place
+# until at least we catch up to GCC10/LLVM11 or otherwise enable -fno-common
+# in <bsd.sys.mk> instead.  For now, we will have duplicate -fno-common in
+# CFLAGS for in-tree module builds as they will also pick it up from
+# share/mk/src.sys.mk, but the following is important for out-of-tree modules
+# (e.g. ports).
 CFLAGS+=	-fno-common
 LDFLAGS+=	-d -warn-common