[Qemu-devel] [PATCH for-4.0 v2 0/7] Assume GCC v4.8 and Clang v3.4 as minimum compiler

[Qemu-devel] [PATCH for-4.0 v2 0/7] Assume GCC v4.8 and Clang v3.4 as minimum compiler

[Thomas Huth]

It's unlikely that any of the developers still uses an older version
than GCC 4.8 or Clang 3.4, since all supported distributions have at
least these versions nowadays, so let's add a proper sanity check for
these versions and get rid of code that is only there for older versions.

Note: I did not remove all "#if QEMU_GNUC_PREREQ(4, <8)" checks yet
since some of them still apply to Clang, which reports itself as
GCC 4.2. We should replace those checks with proper checks for the
Clang version instead, in case newer versions of Clang support the
corresponding feature - but that needs some time-consuming research
first which I'll only start if this patch series gets accepted first.

v2:
 - Don't remove CONFIG_INT128 sections, they are still required for
   32-bit hosts
 - Check for Apple's Xcode version of Clang

Thomas Huth (7):
  configure: Add a test for the minimum compiler version
  configure: Remove obsolete check for Clang < 3.2
  configure: Remove old -fno-gcse workaround for GCC 4.6.x and 4.7.[012]
  tcg/tcg.h: Remove GCC check for tcg_debug_assert() macro
  audio/alsaaudio: Remove compiler check around pragma
  includes: Replace QEMU_GNUC_PREREQ with "__has_builtin ||
    !defined(__clang__)"
  Remove QEMU_ARTIFICIAL macro

 Makefile.target            |  3 ---
 audio/alsaaudio.c          |  2 --
 configure                  | 57 ++++++++++++++++++++--------------------------
 include/qemu/compiler.h    |  8 +------
 include/qemu/host-utils.h  |  4 ++--
 scripts/checkpatch.pl      |  1 -
 scripts/cocci-macro-file.h |  1 -
 tcg/tcg.h                  |  4 +---
 8 files changed, 29 insertions(+), 51 deletions(-)

-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 1/7] configure: Add a test for the minimum compiler version

[Thomas Huth]

So far we only had implicit requirements for the minimum compiler version,
e.g. we require at least GCC 4.1 for the support of atomics. However,
such old compiler versions are not tested anymore by the developers, so
they are not really supported anymore. Since we recently declared explicitly
what platforms we intend to support, we can also get more explicit on the
compiler version now. The supported distributions use the following version
of GCC:

      RHEL-7: 4.8.5
      Debian (Stretch): 6.3.0
      Debian (Jessie): 4.8.4
      OpenBSD (ports): 4.9.4
      FreeBSD (ports): 8.2.0
      OpenSUSE Leap 15: 7.3.1
      Ubuntu (Xenial): 5.3.1
      macOS (Homebrew): 8.2.0

So we can safely assume GCC 4.8 these days. For Clang, the situation is
a little bit more ambiguous, since it is sometimes not available in the
main distros but rather third party repositories. At least Debian Jessie
uses version 3.5, and EPEL7 for RHEL7 uses 3.4, so let's use 3.4 as
minimum Clang version now - we still can adjust this later if necessary.

Unfortunately Apple uses different version numbers for the Clang that is
included in their Xcode suite, so we need to check the version numbers
for Xcode separately. Xcode 5.1 seems to be the first one that has been
shipped with LLVM 3.4, so use this version as the minimum there.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 configure | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/configure b/configure
index 0a3c6a7..7621c00 100755
--- a/configure
+++ b/configure
@@ -1840,6 +1840,31 @@ if test "$bogus_os" = "yes"; then
     error_exit "Unrecognized host OS (uname -s reports '$(uname -s)')"
 fi
 
+# Check whether the compiler matches our minimum requirements:
+cat > $TMPC << EOF
+#if defined(__clang_major__) && defined(__clang_minor__)
+# ifdef __apple_build_version__
+#  if __clang_major__ < 5 || (__clang_major__ == 5 && __clang_minor__ < 1)
+#   error You need at least XCode Clang v5.1 to compile QEMU
+#  endif
+# else
+#  if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 4)
+#   error You need at least Clang v3.4 to compile QEMU
+#  endif
+# endif
+#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
+# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
+#  error You need at least GCC v4.8 to compile QEMU
+# endif
+#else
+# error You either need GCC or Clang to compiler QEMU
+#endif
+int main (void) { return 0; }
+EOF
+if ! compile_prog "" "" ; then
+    error_exit "You need at least GCC v4.8 or Clang v3.4 (or XCode Clang v5.1)"
+fi
+
 gcc_flags="-Wold-style-declaration -Wold-style-definition -Wtype-limits"
 gcc_flags="-Wformat-security -Wformat-y2k -Winit-self -Wignored-qualifiers $gcc_flags"
 gcc_flags="-Wno-missing-include-dirs -Wempty-body -Wnested-externs $gcc_flags"
-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 2/7] configure: Remove obsolete check for Clang < 3.2

[Thomas Huth]

Since we have got a check for Clang >= 3.4 now, we do not need to
check for older Clang versions in the configure test for 128-bit ints
anymore.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 configure | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/configure b/configure
index 7621c00..ca364f6 100755
--- a/configure
+++ b/configure
@@ -5148,11 +5148,6 @@ fi
 
 int128=no
 cat > $TMPC << EOF
-#if defined(__clang_major__) && defined(__clang_minor__)
-# if ((__clang_major__ < 3) || (__clang_major__ == 3) && (__clang_minor__ < 2))
-#  error __int128_t does not work in CLANG before 3.2
-# endif
-#endif
 __int128_t a;
 __uint128_t b;
 int main (void) {
-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 3/7] configure: Remove old -fno-gcse workaround for GCC 4.6.x and 4.7.[012]

[Thomas Huth]

Now that we require at least GCC 4.8, we don't need this als workaround
for 4.6 and 4.7 anymore.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 Makefile.target |  3 ---
 configure       | 27 ---------------------------
 2 files changed, 30 deletions(-)

diff --git a/Makefile.target b/Makefile.target
index 4d56298..44ec4b6 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -158,9 +158,6 @@ GENERATED_FILES += hmp-commands.h hmp-commands-info.h
 
 endif # CONFIG_SOFTMMU
 
-# Workaround for http://gcc.gnu.org/PR55489, see configure.
-%/translate.o: QEMU_CFLAGS += $(TRANSLATE_OPT_CFLAGS)
-
 dummy := $(call unnest-vars,,obj-y)
 all-obj-y := $(obj-y)
 
diff --git a/configure b/configure
index ca364f6..c160b59 100755
--- a/configure
+++ b/configure
@@ -1936,32 +1936,6 @@ else
   QEMU_CFLAGS="$QEMU_CFLAGS -Wno-missing-braces"
 fi
 
-# Workaround for http://gcc.gnu.org/PR55489.  Happens with -fPIE/-fPIC and
-# large functions that use global variables.  The bug is in all releases of
-# GCC, but it became particularly acute in 4.6.x and 4.7.x.  It is fixed in
-# 4.7.3 and 4.8.0.  We should be able to delete this at the end of 2013.
-cat > $TMPC << EOF
-#if __GNUC__ == 4 && (__GNUC_MINOR__ == 6 || (__GNUC_MINOR__ == 7 && __GNUC_PATCHLEVEL__ <= 2))
-int main(void) { return 0; }
-#else
-#error No bug in this compiler.
-#endif
-EOF
-if compile_prog "-Werror -fno-gcse" "" ; then
-  TRANSLATE_OPT_CFLAGS=-fno-gcse
-fi
-
-if test "$static" = "yes" ; then
-  if test "$modules" = "yes" ; then
-    error_exit "static and modules are mutually incompatible"
-  fi
-  if test "$pie" = "yes" ; then
-    error_exit "static and pie are mutually incompatible"
-  else
-    pie="no"
-  fi
-fi
-
 # Unconditional check for compiler __thread support
   cat > $TMPC << EOF
 static __thread int tls_var;
@@ -6983,7 +6957,6 @@ echo "LIBS_QGA+=$libs_qga" >> $config_host_mak
 echo "TASN1_LIBS=$tasn1_libs" >> $config_host_mak
 echo "TASN1_CFLAGS=$tasn1_cflags" >> $config_host_mak
 echo "POD2MAN=$POD2MAN" >> $config_host_mak
-echo "TRANSLATE_OPT_CFLAGS=$TRANSLATE_OPT_CFLAGS" >> $config_host_mak
 if test "$gcov" = "yes" ; then
   echo "CONFIG_GCOV=y" >> $config_host_mak
   echo "GCOV=$gcov_tool" >> $config_host_mak
-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 4/7] tcg/tcg.h: Remove GCC check for tcg_debug_assert() macro

[Thomas Huth]

Both GCC v4.8 and Clang v3.4 support (our minimum versions) support
__builtin_unreachable(), so we can remove the version check here now.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tcg/tcg.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tcg/tcg.h b/tcg/tcg.h
index f4efbaa..f9a56a9 100644
--- a/tcg/tcg.h
+++ b/tcg/tcg.h
@@ -230,11 +230,9 @@ typedef uint64_t tcg_insn_unit;
 
 #if defined CONFIG_DEBUG_TCG || defined QEMU_STATIC_ANALYSIS
 # define tcg_debug_assert(X) do { assert(X); } while (0)
-#elif QEMU_GNUC_PREREQ(4, 5)
+#else
 # define tcg_debug_assert(X) \
     do { if (!(X)) { __builtin_unreachable(); } } while (0)
-#else
-# define tcg_debug_assert(X) do { (void)(X); } while (0)
 #endif
 
 typedef struct TCGRelocation {
-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 5/7] audio/alsaaudio: Remove compiler check around pragma

[Thomas Huth]

Both GCC v4.8 and Clang v3.4 support the -Waddress option, so we do
not need the compiler version check here anymore.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 audio/alsaaudio.c | 2 --
 1 file changed, 2 deletions(-)

diff --git a/audio/alsaaudio.c b/audio/alsaaudio.c
index 362a227..635be73 100644
--- a/audio/alsaaudio.c
+++ b/audio/alsaaudio.c
@@ -28,9 +28,7 @@
 #include "audio.h"
 #include "trace.h"
 
-#if QEMU_GNUC_PREREQ(4, 3)
 #pragma GCC diagnostic ignored "-Waddress"
-#endif
 
 #define AUDIO_CAP "alsa"
 #include "audio_int.h"
-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 6/7] includes: Replace QEMU_GNUC_PREREQ with "__has_builtin || !defined(__clang__)"

[Thomas Huth]

Since we require GCC version 4.8 or newer now, we can be sure that
the builtin functions are always available on GCC. And for Clang,
we can check the availablility with __has_builtin instead.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 include/qemu/compiler.h   | 2 +-
 include/qemu/host-utils.h | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 6b92710..1593bca 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -127,7 +127,7 @@
 #define __has_builtin(x) 0 /* compatibility with non-clang compilers */
 #endif
 
-#if __has_builtin(__builtin_assume_aligned) || QEMU_GNUC_PREREQ(4, 7)
+#if __has_builtin(__builtin_assume_aligned) || !defined(__clang__)
 #define HAS_ASSUME_ALIGNED
 #endif
 
diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h
index 38da849..4cd170e 100644
--- a/include/qemu/host-utils.h
+++ b/include/qemu/host-utils.h
@@ -207,7 +207,7 @@ static inline int cto64(uint64_t val)
  */
 static inline int clrsb32(uint32_t val)
 {
-#if QEMU_GNUC_PREREQ(4, 7)
+#if __has_builtin(__builtin_clrsb) || !defined(__clang__)
     return __builtin_clrsb(val);
 #else
     return clz32(val ^ ((int32_t)val >> 1)) - 1;
@@ -223,7 +223,7 @@ static inline int clrsb32(uint32_t val)
  */
 static inline int clrsb64(uint64_t val)
 {
-#if QEMU_GNUC_PREREQ(4, 7)
+#if __has_builtin(__builtin_clrsbll) || !defined(__clang__)
     return __builtin_clrsbll(val);
 #else
     return clz64(val ^ ((int64_t)val >> 1)) - 1;
-- 
1.8.3.1

[Qemu-devel] [PATCH for-4.0 v2 7/7] Remove QEMU_ARTIFICIAL macro

[Thomas Huth]

The code that used it has already been removed a while ago with commit
dc41aa7d34989b552ef ("tcg: Remove GET_TCGV_* and MAKE_TCGV_*").

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 include/qemu/compiler.h    | 6 ------
 scripts/checkpatch.pl      | 1 -
 scripts/cocci-macro-file.h | 1 -
 3 files changed, 8 deletions(-)

diff --git a/include/qemu/compiler.h b/include/qemu/compiler.h
index 1593bca..261842b 100644
--- a/include/qemu/compiler.h
+++ b/include/qemu/compiler.h
@@ -28,12 +28,6 @@
 
 #define QEMU_SENTINEL __attribute__((sentinel))
 
-#if QEMU_GNUC_PREREQ(4, 3)
-#define QEMU_ARTIFICIAL __attribute__((always_inline, artificial))
-#else
-#define QEMU_ARTIFICIAL
-#endif
-
 #if defined(_WIN32)
 # define QEMU_PACKED __attribute__((gcc_struct, packed))
 #else
diff --git a/scripts/checkpatch.pl b/scripts/checkpatch.pl
index 60f6f89..a892a6c 100755
--- a/scripts/checkpatch.pl
+++ b/scripts/checkpatch.pl
@@ -202,7 +202,6 @@ our $Attribute	= qr{
 			QEMU_NORETURN|
 			QEMU_WARN_UNUSED_RESULT|
 			QEMU_SENTINEL|
-			QEMU_ARTIFICIAL|
 			QEMU_PACKED|
 			GCC_FMT_ATTR
 		  }x;
diff --git a/scripts/cocci-macro-file.h b/scripts/cocci-macro-file.h
index 9f2e72e..7e200a1 100644
--- a/scripts/cocci-macro-file.h
+++ b/scripts/cocci-macro-file.h
@@ -23,7 +23,6 @@
 #define QEMU_NORETURN __attribute__ ((__noreturn__))
 #define QEMU_WARN_UNUSED_RESULT __attribute__((warn_unused_result))
 #define QEMU_SENTINEL __attribute__((sentinel))
-#define QEMU_ARTIFICIAL __attribute__((always_inline, artificial))
 #define QEMU_PACKED __attribute__((gcc_struct, packed))
 
 #define cat(x,y) x ## y
-- 
1.8.3.1

Re: [Qemu-devel] [PATCH for-4.0 v2 1/7] configure: Add a test for the minimum compiler version

[Richard Henderson]

On 12/4/18 9:32 AM, Thomas Huth wrote:
> +# Check whether the compiler matches our minimum requirements:
> +cat > $TMPC << EOF
> +#if defined(__clang_major__) && defined(__clang_minor__)
> +# ifdef __apple_build_version__
> +#  if __clang_major__ < 5 || (__clang_major__ == 5 && __clang_minor__ < 1)
> +#   error You need at least XCode Clang v5.1 to compile QEMU
> +#  endif
> +# else
> +#  if __clang_major__ < 3 || (__clang_major__ == 3 && __clang_minor__ < 4)
> +#   error You need at least Clang v3.4 to compile QEMU
> +#  endif
> +# endif
> +#elif defined(__GNUC__) && defined(__GNUC_MINOR__)
> +# if __GNUC__ < 4 || (__GNUC__ == 4 && __GNUC_MINOR__ < 8)
> +#  error You need at least GCC v4.8 to compile QEMU
> +# endif
> +#else
> +# error You either need GCC or Clang to compiler QEMU
> +#endif
> +int main (void) { return 0; }
> +EOF
> +if ! compile_prog "" "" ; then
> +    error_exit "You need at least GCC v4.8 or Clang v3.4 (or XCode Clang v5.1)"
> +fi

I wonder if we could capture the actual error message that you used during the
test and feed that back to the user.  That said,

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

Re: [Qemu-devel] [PATCH for-4.0 v2 2/7] configure: Remove obsolete check for Clang < 3.2

[Richard Henderson]

On 12/4/18 9:32 AM, Thomas Huth wrote:
> Since we have got a check for Clang >= 3.4 now, we do not need to
> check for older Clang versions in the configure test for 128-bit ints
> anymore.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  configure | 5 -----
>  1 file changed, 5 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

Re: [Qemu-devel] [PATCH for-4.0 v2 5/7] audio/alsaaudio: Remove compiler check around pragma

[Richard Henderson]

On 12/4/18 9:32 AM, Thomas Huth wrote:
> Both GCC v4.8 and Clang v3.4 support the -Waddress option, so we do
> not need the compiler version check here anymore.
> 
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  audio/alsaaudio.c | 2 --
>  1 file changed, 2 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>


r~

Re: [Qemu-devel] [PATCH for-4.0 v2 3/7] configure: Remove old -fno-gcse workaround for GCC 4.6.x and 4.7.[012]

[Thomas Huth]

On 2018-12-04 16:32, Thomas Huth wrote:
> Now that we require at least GCC 4.8, we don't need this als workaround
> for 4.6 and 4.7 anymore.
> 
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Signed-off-by: Thomas Huth <thuth@redhat.com>
> ---
>  Makefile.target |  3 ---
>  configure       | 27 ---------------------------
>  2 files changed, 30 deletions(-)
> 
> diff --git a/Makefile.target b/Makefile.target
> index 4d56298..44ec4b6 100644
> --- a/Makefile.target
> +++ b/Makefile.target
> @@ -158,9 +158,6 @@ GENERATED_FILES += hmp-commands.h hmp-commands-info.h
>  
>  endif # CONFIG_SOFTMMU
>  
> -# Workaround for http://gcc.gnu.org/PR55489, see configure.
> -%/translate.o: QEMU_CFLAGS += $(TRANSLATE_OPT_CFLAGS)
> -
>  dummy := $(call unnest-vars,,obj-y)
>  all-obj-y := $(obj-y)
>  
> diff --git a/configure b/configure
> index ca364f6..c160b59 100755
> --- a/configure
> +++ b/configure
> @@ -1936,32 +1936,6 @@ else
>    QEMU_CFLAGS="$QEMU_CFLAGS -Wno-missing-braces"
>  fi
>  
> -# Workaround for http://gcc.gnu.org/PR55489.  Happens with -fPIE/-fPIC and
> -# large functions that use global variables.  The bug is in all releases of
> -# GCC, but it became particularly acute in 4.6.x and 4.7.x.  It is fixed in
> -# 4.7.3 and 4.8.0.  We should be able to delete this at the end of 2013.
> -cat > $TMPC << EOF
> -#if __GNUC__ == 4 && (__GNUC_MINOR__ == 6 || (__GNUC_MINOR__ == 7 && __GNUC_PATCHLEVEL__ <= 2))
> -int main(void) { return 0; }
> -#else
> -#error No bug in this compiler.
> -#endif
> -EOF
> -if compile_prog "-Werror -fno-gcse" "" ; then
> -  TRANSLATE_OPT_CFLAGS=-fno-gcse
> -fi
> -
> -if test "$static" = "yes" ; then
> -  if test "$modules" = "yes" ; then
> -    error_exit "static and modules are mutually incompatible"
> -  fi
> -  if test "$pie" = "yes" ; then
> -    error_exit "static and pie are mutually incompatible"
> -  else
> -    pie="no"
> -  fi
> -fi

For the records: I just noticed that the last 10 lines do not belong to
the gcse workaround - I'll remove them from the patch again.

 Thomas