[PULL 58/59] build-sys: clean up flags included in the linker command line

[Paolo Bonzini <pbonzini@redhat.com>]

Some of the CFLAGS that are discovered during configure, for example
compiler warnings, are being included on the linker command line because
QEMU_CFLAGS is added to it.  Other flags, such as the -m32, appear twice
because they are included in both QEMU_CFLAGS and LDFLAGS.  All this
leads to confusion with respect to what goes in which Makefile variables
(and we have plenty).

So, introduce QEMU_LDFLAGS for flags discovered by configure, following
the lead of QEMU_CFLAGS, and stop adding to it:

1) options that are already in CFLAGS, for example "-g"

2) duplicate options

At the same time, options that _are_ needed by both compiler and linker
must now be added to both QEMU_CFLAGS and QEMU_LDFLAGS, which is clearer.
This is mostly -fsanitize options.

Meson will not include CFLAGS on the linker command line, do the same in our
build system as well.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 .travis.yml                 |  4 +--
 Makefile                    |  4 +--
 configure                   | 60 ++++++++++++++++++++++-----------------------
 qga/vss-win32/Makefile.objs |  4 +--
 rules.mak                   |  4 +--
 5 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 6c1038a..142d28f 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -179,7 +179,7 @@ matrix:
       compiler: clang
       before_script:
         - mkdir -p ${BUILD_DIR} && cd ${BUILD_DIR}
-        - ${SRC_DIR}/configure ${CONFIG} --extra-cflags="-fsanitize=undefined -Werror" || { cat config.log && exit 1; }
+        - ${SRC_DIR}/configure ${CONFIG} --extra-cflags="-fsanitize=undefined -Werror" --extra-ldflags="-fsanitize=undefined" || { cat config.log && exit 1; }
 
 
     - env:
@@ -327,7 +327,7 @@ matrix:
         - TEST_CMD=""
       before_script:
         - mkdir -p ${BUILD_DIR} && cd ${BUILD_DIR}
-        - ${SRC_DIR}/configure ${CONFIG} --extra-cflags="-g3 -O0 -Wno-error=stringop-truncation -fsanitize=thread -fuse-ld=gold" || { cat config.log && exit 1; }
+        - ${SRC_DIR}/configure ${CONFIG} --extra-cflags="-g3 -O0 -Wno-error=stringop-truncation -fsanitize=thread" --extra-ldflags="-fsanitize=thread -fuse-ld=gold" || { cat config.log && exit 1; }
 
 
     # Run check-tcg against linux-user
diff --git a/Makefile b/Makefile
index 6562b0d..c20c6fe 100644
--- a/Makefile
+++ b/Makefile
@@ -490,7 +490,7 @@ DTC_CPPFLAGS=-I$(BUILD_DIR)/dtc -I$(SRC_PATH)/dtc -I$(SRC_PATH)/dtc/libfdt
 
 .PHONY: dtc/all
 dtc/all: .git-submodule-status dtc/libfdt dtc/tests
-	$(call quiet-command,$(MAKE) $(DTC_MAKE_ARGS) CPPFLAGS="$(DTC_CPPFLAGS)" CFLAGS="$(DTC_CFLAGS)" LDFLAGS="$(LDFLAGS)" ARFLAGS="$(ARFLAGS)" CC="$(CC)" AR="$(AR)" LD="$(LD)" $(SUBDIR_MAKEFLAGS) libfdt/libfdt.a,)
+	$(call quiet-command,$(MAKE) $(DTC_MAKE_ARGS) CPPFLAGS="$(DTC_CPPFLAGS)" CFLAGS="$(DTC_CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)" ARFLAGS="$(ARFLAGS)" CC="$(CC)" AR="$(AR)" LD="$(LD)" $(SUBDIR_MAKEFLAGS) libfdt/libfdt.a,)
 
 dtc/%: .git-submodule-status
 	@mkdir -p $@
@@ -517,7 +517,7 @@ slirp/all: .git-submodule-status
 		BUILD_DIR="$(BUILD_DIR)/slirp" 			\
 		PKG_CONFIG="$(PKG_CONFIG)" 				\
 		CC="$(CC)" AR="$(AR)" 	LD="$(LD)" RANLIB="$(RANLIB)"	\
-		CFLAGS="$(QEMU_CFLAGS) $(CFLAGS)" LDFLAGS="$(LDFLAGS)")
+		CFLAGS="$(QEMU_CFLAGS) $(CFLAGS)" LDFLAGS="$(QEMU_LDFLAGS)")
 
 # Compatibility gunk to keep make working across the rename of targets
 # for recursion, to be removed some time after 4.1.
diff --git a/configure b/configure
index c67a7e7..b308150 100755
--- a/configure
+++ b/configure
@@ -126,7 +126,7 @@ compile_object() {
 compile_prog() {
   local_cflags="$1"
   local_ldflags="$2"
-  do_cc $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC $LDFLAGS $local_ldflags
+  do_cc $QEMU_CFLAGS $local_cflags -o $TMPE $TMPC $QEMU_LDFLAGS $local_ldflags
 }
 
 # symbolically link $1 to $2.  Portable version of "ln -sf".
@@ -526,7 +526,7 @@ for opt do
   ;;
   --extra-cxxflags=*) QEMU_CXXFLAGS="$QEMU_CXXFLAGS $optarg"
   ;;
-  --extra-ldflags=*) LDFLAGS="$LDFLAGS $optarg"
+  --extra-ldflags=*) QEMU_LDFLAGS="$QEMU_LDFLAGS $optarg"
                      EXTRA_LDFLAGS="$optarg"
   ;;
   --enable-debug-info) debug_info="yes"
@@ -599,7 +599,6 @@ QEMU_INCLUDES="-iquote . -iquote \$(SRC_PATH) -iquote \$(SRC_PATH)/accel/tcg -iq
 QEMU_INCLUDES="$QEMU_INCLUDES -iquote \$(SRC_PATH)/disas/libvixl"
 if test "$debug_info" = "yes"; then
     CFLAGS="-g $CFLAGS"
-    LDFLAGS="-g $LDFLAGS"
 fi
 
 # running configure in the source tree?
@@ -845,12 +844,12 @@ Darwin)
   LDFLAGS_SHARED="-bundle -undefined dynamic_lookup"
   if [ "$cpu" = "x86_64" ] ; then
     QEMU_CFLAGS="-arch x86_64 $QEMU_CFLAGS"
-    LDFLAGS="-arch x86_64 $LDFLAGS"
+    QEMU_LDFLAGS="-arch x86_64 $QEMU_LDFLAGS"
   fi
   cocoa="yes"
   audio_drv_list="coreaudio try-sdl"
   audio_possible_drivers="coreaudio sdl"
-  LDFLAGS="-framework CoreFoundation -framework IOKit $LDFLAGS"
+  QEMU_LDFLAGS="-framework CoreFoundation -framework IOKit $QEMU_LDFLAGS"
   libs_softmmu="-F/System/Library/Frameworks -framework Cocoa -framework IOKit $libs_softmmu"
   # Disable attempts to use ObjectiveC features in os/object.h since they
   # won't work when we're compiling with gcc as a C compiler.
@@ -1025,7 +1024,7 @@ for opt do
   ;;
   --static)
     static="yes"
-    LDFLAGS="-static $LDFLAGS"
+    QEMU_LDFLAGS="-static $QEMU_LDFLAGS"
     QEMU_PKG_CONFIG_FLAGS="--static $QEMU_PKG_CONFIG_FLAGS"
   ;;
   --mandir=*) mandir="$optarg"
@@ -1551,42 +1550,42 @@ done
 case "$cpu" in
     ppc)
            CPU_CFLAGS="-m32"
-           LDFLAGS="-m32 $LDFLAGS"
+           QEMU_LDFLAGS="-m32 $QEMU_LDFLAGS"
            ;;
     ppc64)
            CPU_CFLAGS="-m64"
-           LDFLAGS="-m64 $LDFLAGS"
+           QEMU_LDFLAGS="-m64 $QEMU_LDFLAGS"
            ;;
     sparc)
            CPU_CFLAGS="-m32 -mv8plus -mcpu=ultrasparc"
-           LDFLAGS="-m32 -mv8plus $LDFLAGS"
+           QEMU_LDFLAGS="-m32 -mv8plus $QEMU_LDFLAGS"
            ;;
     sparc64)
            CPU_CFLAGS="-m64 -mcpu=ultrasparc"
-           LDFLAGS="-m64 $LDFLAGS"
+           QEMU_LDFLAGS="-m64 $QEMU_LDFLAGS"
            ;;
     s390)
            CPU_CFLAGS="-m31"
-           LDFLAGS="-m31 $LDFLAGS"
+           QEMU_LDFLAGS="-m31 $QEMU_LDFLAGS"
            ;;
     s390x)
            CPU_CFLAGS="-m64"
-           LDFLAGS="-m64 $LDFLAGS"
+           QEMU_LDFLAGS="-m64 $QEMU_LDFLAGS"
            ;;
     i386)
            CPU_CFLAGS="-m32"
-           LDFLAGS="-m32 $LDFLAGS"
+           QEMU_LDFLAGS="-m32 $QEMU_LDFLAGS"
            ;;
     x86_64)
            # ??? Only extremely old AMD cpus do not have cmpxchg16b.
            # If we truly care, we should simply detect this case at
            # runtime and generate the fallback to serial emulation.
            CPU_CFLAGS="-m64 -mcx16"
-           LDFLAGS="-m64 $LDFLAGS"
+           QEMU_LDFLAGS="-m64 $QEMU_LDFLAGS"
            ;;
     x32)
            CPU_CFLAGS="-mx32"
-           LDFLAGS="-mx32 $LDFLAGS"
+           QEMU_LDFLAGS="-mx32 $QEMU_LDFLAGS"
            ;;
     # No special flags required for other host CPUs
 esac
@@ -1967,6 +1966,7 @@ EOF
     if do_cc $QEMU_CFLAGS -Werror $flag -c -o $TMPO $TMPC &&
        compile_prog "-Werror $flag" ""; then
       QEMU_CFLAGS="$QEMU_CFLAGS $flag"
+      QEMU_LDFLAGS="$QEMU_LDFLAGS $flag"
       sp_on=1
       break
     fi
@@ -2051,10 +2051,10 @@ EOF
 
   if compile_prog "-fPIE -DPIE" "-pie"; then
     QEMU_CFLAGS="-fPIE -DPIE $QEMU_CFLAGS"
-    LDFLAGS="-pie $LDFLAGS"
+    QEMU_LDFLAGS="-pie $QEMU_LDFLAGS"
     pie="yes"
     if compile_prog "" "-Wl,-z,relro -Wl,-z,now" ; then
-      LDFLAGS="-Wl,-z,relro -Wl,-z,now $LDFLAGS"
+      QEMU_LDFLAGS="-Wl,-z,relro -Wl,-z,now $QEMU_LDFLAGS"
     fi
   else
     if test "$pie" = "yes"; then
@@ -5837,7 +5837,7 @@ EOF
     hvf='no'
   else
     hvf='yes'
-    LDFLAGS="-framework Hypervisor $LDFLAGS"
+    QEMU_LDFLAGS="-framework Hypervisor $QEMU_LDFLAGS"
   fi
 fi
 
@@ -6071,8 +6071,8 @@ esac
 write_c_skeleton
 
 if test "$gcov" = "yes" ; then
-  CFLAGS="-fprofile-arcs -ftest-coverage -g $CFLAGS"
-  LDFLAGS="-fprofile-arcs -ftest-coverage $LDFLAGS"
+  QEMU_CFLAGS="-fprofile-arcs -ftest-coverage -g $QEMU_CFLAGS"
+  QEMU_LDFLAGS="-fprofile-arcs -ftest-coverage $QEMU_LDFLAGS"
 elif test "$fortify_source" = "yes" ; then
   CFLAGS="-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
 elif test "$debug" = "no"; then
@@ -6080,7 +6080,8 @@ elif test "$debug" = "no"; then
 fi
 
 if test "$have_asan" = "yes"; then
-  CFLAGS="-fsanitize=address $CFLAGS"
+  QEMU_CFLAGS="-fsanitize=address $QEMU_CFLAGS"
+  QEMU_LDFLAGS="-fsanitize=address $QEMU_LDFLAGS"
   if test "$have_asan_iface_h" = "no" ; then
       echo "ASAN build enabled, but ASAN header missing." \
            "Without code annotation, the report may be inferior."
@@ -6090,7 +6091,8 @@ if test "$have_asan" = "yes"; then
   fi
 fi
 if test "$have_ubsan" = "yes"; then
-  CFLAGS="-fsanitize=undefined $CFLAGS"
+  QEMU_CFLAGS="-fsanitize=undefined $QEMU_CFLAGS"
+  QEMU_LDFLAGS="-fsanitize=undefined $QEMU_LDFLAGS"
 fi
 
 ##########################################
@@ -6125,7 +6127,7 @@ fi
 
 if test "$solaris" = "no" ; then
     if $ld --version 2>/dev/null | grep "GNU ld" >/dev/null 2>/dev/null ; then
-        LDFLAGS="-Wl,--warn-common $LDFLAGS"
+        QEMU_LDFLAGS="-Wl,--warn-common $QEMU_LDFLAGS"
     fi
 fi
 
@@ -6140,7 +6142,7 @@ fi
 if test "$mingw32" = "yes" ; then
     for flag in --dynamicbase --no-seh --nxcompat; do
         if ld_has $flag ; then
-            LDFLAGS="-Wl,$flag $LDFLAGS"
+            QEMU_LDFLAGS="-Wl,$flag $QEMU_LDFLAGS"
         fi
     done
 fi
@@ -6375,7 +6377,7 @@ EOF
 
     update_cxxflags
 
-    if do_cxx $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $LDFLAGS; then
+    if do_cxx $QEMU_CXXFLAGS -o $TMPE $TMPCXX $TMPO $QEMU_LDFLAGS; then
         # C++ compiler $cxx works ok with C compiler $cc
         :
     else
@@ -6427,7 +6429,6 @@ echo "Objective-C compiler $objcc"
 echo "ARFLAGS           $ARFLAGS"
 echo "CFLAGS            $CFLAGS"
 echo "QEMU_CFLAGS       $QEMU_CFLAGS"
-echo "LDFLAGS           $LDFLAGS"
 echo "QEMU_LDFLAGS      $QEMU_LDFLAGS"
 echo "make              $make"
 echo "install           $install"
@@ -7479,9 +7480,8 @@ if test "$sparse" = "yes" ; then
   echo "HOST_CC      := REAL_CC=\"\$(HOST_CC)\" cgcc"  >> $config_host_mak
   echo "QEMU_CFLAGS  += -Wbitwise -Wno-transparent-union -Wno-old-initializer -Wno-non-pointer-null" >> $config_host_mak
 fi
-echo "LDFLAGS=$LDFLAGS" >> $config_host_mak
-echo "LDFLAGS_NOPIE=$LDFLAGS_NOPIE" >> $config_host_mak
 echo "QEMU_LDFLAGS=$QEMU_LDFLAGS" >> $config_host_mak
+echo "LDFLAGS_NOPIE=$LDFLAGS_NOPIE" >> $config_host_mak
 echo "LD_REL_FLAGS=$LD_REL_FLAGS" >> $config_host_mak
 echo "LD_I386_EMULATION=$ld_i386_emulation" >> $config_host_mak
 echo "LIBS+=$LIBS" >> $config_host_mak
@@ -7807,7 +7807,7 @@ if test "$target_bsd_user" = "yes" ; then
 fi
 
 
-# generate QEMU_CFLAGS/LDFLAGS for targets
+# generate QEMU_CFLAGS/QEMU_LDFLAGS for targets
 
 cflags=""
 ldflags=""
@@ -7928,7 +7928,7 @@ if test "$TARGET_ARCH" = "s390x" && test "$target_softmmu" = "yes" && \
     fi
 fi
 
-echo "LDFLAGS+=$ldflags" >> $config_target_mak
+echo "QEMU_LDFLAGS+=$ldflags" >> $config_target_mak
 echo "QEMU_CFLAGS+=$cflags" >> $config_target_mak
 
 done # for target in $targets
diff --git a/qga/vss-win32/Makefile.objs b/qga/vss-win32/Makefile.objs
index fd3ba18..c82676a 100644
--- a/qga/vss-win32/Makefile.objs
+++ b/qga/vss-win32/Makefile.objs
@@ -5,9 +5,9 @@ qga-vss-dll-obj-y += requester.o provider.o install.o
 obj-qga-vss-dll-obj-y = $(addprefix $(obj)/, $(qga-vss-dll-obj-y))
 $(obj-qga-vss-dll-obj-y): QEMU_CXXFLAGS := $(filter-out -fstack-protector-all -fstack-protector-strong, $(QEMU_CXXFLAGS)) -Wno-unknown-pragmas -Wno-delete-non-virtual-dtor
 
-$(obj)/qga-vss.dll: LDFLAGS = -shared -Wl,--add-stdcall-alias,--enable-stdcall-fixup -lglib-2.0 -lole32 -loleaut32 -lshlwapi -luuid -lintl -lws2_32 -static
+QGA_VSS_LDFLAGS = -shared -Wl,--add-stdcall-alias,--enable-stdcall-fixup -lglib-2.0 -lole32 -loleaut32 -lshlwapi -luuid -lintl -lws2_32 -static
 $(obj)/qga-vss.dll: $(obj-qga-vss-dll-obj-y) $(SRC_PATH)/$(obj)/qga-vss.def
-	$(call quiet-command,$(CXX) -o $@ $(qga-vss-dll-obj-y) $(SRC_PATH)/qga/vss-win32/qga-vss.def $(CXXFLAGS) $(LDFLAGS),"LINK","$(TARGET_DIR)$@")
+	$(call quiet-command,$(CXX) -o $@ $(qga-vss-dll-obj-y) $(SRC_PATH)/qga/vss-win32/qga-vss.def $(CXXFLAGS) $(QGA_VSS_LDFLAGS),"LINK","$(TARGET_DIR)$@")
 
 
 # rules to build qga-provider.tlb
diff --git a/rules.mak b/rules.mak
index 967295d..c855887 100644
--- a/rules.mak
+++ b/rules.mak
@@ -76,7 +76,7 @@ expand-objs = $(strip $(sort $(filter %.o,$1)) \
 # must link with the C++ compiler, not the plain C compiler.
 LINKPROG = $(or $(CXX),$(CC))
 
-LINK = $(call quiet-command, $(LINKPROG) $(QEMU_LDFLAGS) $(QEMU_CFLAGS) $(CFLAGS) $(LDFLAGS) -o $@ \
+LINK = $(call quiet-command, $(LINKPROG) $(CFLAGS) $(QEMU_LDFLAGS) -o $@ \
        $(call process-archive-undefs, $1) \
        $(version-obj-y) $(call extract-libs,$1) $(LIBS),"LINK","$(TARGET_DIR)$@")
 
@@ -105,7 +105,7 @@ LINK = $(call quiet-command, $(LINKPROG) $(QEMU_LDFLAGS) $(QEMU_CFLAGS) $(CFLAGS
 
 DSO_OBJ_CFLAGS := -fPIC -DBUILD_DSO
 module-common.o: CFLAGS += $(DSO_OBJ_CFLAGS)
-%$(DSOSUF): LDFLAGS += $(LDFLAGS_SHARED)
+%$(DSOSUF): QEMU_LDFLAGS += $(LDFLAGS_SHARED)
 %$(DSOSUF): %.mo
 	$(call LINK,$^)
 	@# Copy to build root so modules can be loaded when program started without install
-- 
1.8.3.1