Re: [PATCH] build-sys: clean up flags included in the linker command lin

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Re: [PATCH] build-sys: clean up flags included in the linker command lin

From:	Philippe Mathieu-Daudé
Subject:	Re: [PATCH] build-sys: clean up flags included in the linker command line
Date:	Fri, 24 Jan 2020 10:46:50 +0100
User-agent:	Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2

On 12/11/19 3:46 PM, Paolo Bonzini wrote:

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.


So with this patch we can kill configure:CPU_CFLAGS?

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 <address@hidden>
Signed-off-by: Paolo Bonzini <address@hidden>
---
  .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 d3a12ae..186738d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -193,7 +193,7 @@ 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:

@@ -325,7 +325,7 @@ 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 96e69dd..df92220 100644
--- a/Makefile
+++ b/Makefile
@@ -487,7 +487,7 @@ 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 $@
@@ -514,7 +514,7 @@ slirp/all: .git-submodule-status
                BUILD_DIR="$(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 19b209a..7f96279 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
@@ -5862,7 +5862,7 @@ EOF
      hvf='no'
    else
      hvf='yes'
-    LDFLAGS="-framework Hypervisor $LDFLAGS"
+    QEMU_LDFLAGS="-framework Hypervisor $QEMU_LDFLAGS"
    fi
  fi

@@ -6096,8 +6096,8 @@ 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
@@ -6105,7 +6105,8 @@ 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."
@@ -6115,7 +6116,8 @@ 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

##########################################

@@ -6150,7 +6152,7 @@ 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

@@ -6165,7 +6167,7 @@ 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
@@ -6400,7 +6402,7 @@ 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
@@ -6452,7 +6454,6 @@ 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           $install"
@@ -7519,9 +7520,8 @@ if test "$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" >> $config_host_mak
@@ -7847,7 +7847,7 @@ if test "$target_bsd_user" = "yes" ; then
  fi

-# generate QEMU_CFLAGS/LDFLAGS for targets

+# generate QEMU_CFLAGS/QEMU_LDFLAGS for targets

cflags=""

  ldflags=""
@@ -7968,7 +7968,7 @@ 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) $(CFLAGSDSO_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

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