build-sys: clean up flags included in the linker command line

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.  For now, --extra-cflags has this behavior
(but --extra-cxxflags does not).

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>

5 files changed, 38 insertions, 37 deletions

diff --git a/.travis.yml b/.travis.yml
index 6c1038a0f1..1ae645e9fc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -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="-fuse-ld=gold" || { cat config.log && exit 1; }
 
 
     # Run check-tcg against linux-user
diff --git a/Makefile b/Makefile
index 6562b0dc97..c20c6fe9ac 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 c67a7e73db..f7c4d074be 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 $2.  Portable version of "ln -sf".
@@ -523,10 +523,11 @@ for opt do
   --cpu=*) cpu="$optarg"
   ;;
   --extra-cflags=*) QEMU_CFLAGS="$QEMU_CFLAGS $optarg"
+                    QEMU_LDFLAGS="$QEMU_LDFLAGS $optarg"
   ;;
   --extra-cxxflags=*) QEMU_CXXFLAGS="$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 +600,6 @@ 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 +845,12 @@ 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 +1025,7 @@ 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 +1551,42 @@ 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 +1967,7 @@ 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 +2052,10 @@ 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 +5838,7 @@ EOF
     hvf='no'
   else
     hvf='yes'
-    LDFLAGS="-framework Hypervisor $LDFLAGS"
+    QEMU_LDFLAGS="-framework Hypervisor $QEMU_LDFLAGS"
   fi
 fi
 
@@ -6071,8 +6072,8 @@ 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 +6081,8 @@ 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 +6092,8 @@ 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 +6128,7 @@ 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 +6143,7 @@ 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 +6378,7 @@ 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 +6430,6 @@ 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           $install"
@@ -7479,9 +7481,8 @@ if test "$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" >> $config_host_mak
@@ -7807,7 +7808,7 @@ if test "$target_bsd_user" = "yes" ; then
 fi
 
 
-# generate QEMU_CFLAGS/LDFLAGS for targets
+# generate QEMU_CFLAGS/QEMU_LDFLAGS for targets
 
 cflags=""
 ldflags=""
@@ -7928,7 +7929,7 @@ 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 fd3ba1896b..c82676aeb8 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 967295dd2b..c8558876f3 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