[Qemu-devel] [PATCH] Improve gcc 3 checking

[Qemu-devel] [PATCH] Improve gcc 3 checking

[Anthony Liguori]

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In Xen, we use a single top level Makefile to build everything.  This 
means we automatically kick off the configure script.  It would be nice 
if QEMU's configure did a better job of finding existing GCC 3.x 
installs so that the user didn't have to manually specific the location.

The attached patch adds a white list to configure to check for various 
versions of GCC 3.x.  The white list so far covers the various versions 
of GCC in recent versions of OpenSUSE, Fedora, RHEL, and Ubuntu 
(presumably also Debian).

I don't think this patch will impact any of the other platforms but 
getting some testing first on weird platforms (Solaris and Win32 
especially) would be helpful.

Regards,

Anthony Liguori

[-- Attachment #2: qemu-gcc-3x.diff --]
[-- Type: text/x-patch, Size: 2029 bytes --]

diff -r ca36b7b88df2 configure
--- a/configure	Mon Dec 18 18:57:19 2006 -0600
+++ b/configure	Mon Dec 18 20:18:01 2006 -0600
@@ -22,6 +22,7 @@ static="no"
 static="no"
 cross_prefix=""
 cc="gcc"
+gcc3_list="gcc32 gcc33 gcc34 gcc-3.2 gcc-3.3 gcc-3.4"
 host_cc="gcc"
 ar="ar"
 make="make"
@@ -311,6 +312,41 @@ if test "$mingw32" = "yes" ; then
     oss="no"
     if [ "$cpu" = "i386" ] ; then
         kqemu="yes"
+    fi
+fi
+
+# Check for gcc4, error if pre-gcc4 
+if test "$check_gcc" = "yes" ; then
+    cat > $TMPC <<EOF
+#if __GNUC__ < 4
+#error gcc3
+#endif
+int main(){return 0;}
+EOF
+    check_cc() {
+	which "$1" >&/dev/null
+	return $?
+    }
+
+    if check_cc "$cc" ; then
+	echo "WARNING: \"$cc\" looks like gcc 4.x"
+	echo "Looking for gcc 3.x"
+	found_compat_cc="no"
+	for compat_cc in $gcc3_list ; do
+	    if check_cc "$compat_cc" ; then
+		echo "Found \"$compat_cc\""
+		cc="$compat_cc"
+		found_compat_cc="yes"
+		break
+	    fi
+	done
+	if test "$found_compat_cc" = "no" ; then
+	    echo "gcc 3.x not found!"
+	    echo "QEMU is known to have problems when compiled with gcc 4.x"
+	    echo "It is recommended that you use gcc 3.x to build QEMU"
+	    echo "To use this compiler anyway, configure with --disable-gcc-check"
+	    exit 1;
+	fi
     fi
 fi
 
@@ -414,23 +450,6 @@ have_gcc3_options="no"
 have_gcc3_options="no"
 if $cc -fno-reorder-blocks -fno-optimize-sibling-calls -o $TMPO $TMPC 2> /dev/null ; then
    have_gcc3_options="yes"
-fi
-
-# Check for gcc4, error if pre-gcc4 
-if test "$check_gcc" = "yes" ; then
-    cat > $TMPC <<EOF
-#if __GNUC__ < 4
-#error gcc3
-#endif
-int main(){return 0;}
-EOF
-    if $cc -o $TMPO $TMPC 2>/dev/null ; then
-        echo "ERROR: \"$cc\" looks like gcc 4.x"
-        echo "QEMU is known to have problems when compiled with gcc 4.x"
-        echo "It is recommended that you use gcc 3.x to build QEMU"
-        echo "To use this compiler anyway, configure with --disable-gcc-check"
-        exit 1;
-    fi
 fi
 
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Re: [Qemu-devel] [PATCH] Improve gcc 3 checking

[Paul Brook]

On Tuesday 19 December 2006 02:25, Anthony Liguori wrote:
> +gcc3_list="gcc32 gcc33 gcc34 gcc-3.2 gcc-3.3 gcc-3.4"

Shouldn't we be preferring newer compilers?

> +       echo "Looking for gcc 3.x"

We shouldn't do this if if the user explicitly specified a compiler.
Replacing explicit user setting with guesses is bad.

Paul

Re: [Qemu-devel] [PATCH] Improve gcc 3 checking

[Anthony Liguori]

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Paul Brook wrote:
> On Tuesday 19 December 2006 02:25, Anthony Liguori wrote:
>   
>> +gcc3_list="gcc32 gcc33 gcc34 gcc-3.2 gcc-3.3 gcc-3.4"
>>     
>
> Shouldn't we be preferring newer compilers?
>   

Attached patch changes order plus improves the initial GCC 4 check a bit.

>> +       echo "Looking for gcc 3.x"
>>     
>
> We shouldn't do this if if the user explicitly specified a compiler.
> Replacing explicit user setting with guesses is bad.
>   

This stuff kicks in only if the user doesn't specific 
--disable-gcc-check and CC is not GCC 4.

So if the user specific a valid --cc=, then this check won't get triggered.

If they explicitly specific an invalid --cc=, the checks will get 
triggered (but in the past, we would have bailed).

So, if the user wants to explicitly specify a compiler, they can happily 
do that.

Regards,

Anthony Liguori


> Paul
>
>
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
>   


[-- Attachment #2: qemu-gcc-3x.diff --]
[-- Type: text/x-patch, Size: 2047 bytes --]

diff -r f928121a13c1 configure
--- a/configure	Mon Dec 18 20:29:34 2006 -0600
+++ b/configure	Mon Dec 18 20:54:20 2006 -0600
@@ -22,6 +22,7 @@ static="no"
 static="no"
 cross_prefix=""
 cc="gcc"
+gcc3_list="gcc-3.4 gcc34 gcc-3.3 gcc33 gcc-3.2 gcc32"
 host_cc="gcc"
 ar="ar"
 make="make"
@@ -311,6 +312,41 @@ if test "$mingw32" = "yes" ; then
     oss="no"
     if [ "$cpu" = "i386" ] ; then
         kqemu="yes"
+    fi
+fi
+
+# Check for gcc4, error if pre-gcc4 
+if test "$check_gcc" = "yes" ; then
+    cat > $TMPC <<EOF
+#if __GNUC__ < 4
+#error gcc3
+#endif
+int main(){return 0;}
+EOF
+    check_cc() {
+	which "$1" >&/dev/null
+	return $?
+    }
+
+    if "$cc" -o $TMPE $TMPC 2>/dev/null ; then
+	echo "WARNING: \"$cc\" looks like gcc 4.x"
+	echo "Looking for gcc 3.x"
+	found_compat_cc="no"
+	for compat_cc in $gcc3_list ; do
+	    if check_cc "$compat_cc" ; then
+		echo "Found \"$compat_cc\""
+		cc="$compat_cc"
+		found_compat_cc="yes"
+		break
+	    fi
+	done
+	if test "$found_compat_cc" = "no" ; then
+	    echo "gcc 3.x not found!"
+	    echo "QEMU is known to have problems when compiled with gcc 4.x"
+	    echo "It is recommended that you use gcc 3.x to build QEMU"
+	    echo "To use this compiler anyway, configure with --disable-gcc-check"
+	    exit 1;
+	fi
     fi
 fi
 
@@ -414,23 +450,6 @@ have_gcc3_options="no"
 have_gcc3_options="no"
 if $cc -fno-reorder-blocks -fno-optimize-sibling-calls -o $TMPO $TMPC 2> /dev/null ; then
    have_gcc3_options="yes"
-fi
-
-# Check for gcc4, error if pre-gcc4 
-if test "$check_gcc" = "yes" ; then
-    cat > $TMPC <<EOF
-#if __GNUC__ < 4
-#error gcc3
-#endif
-int main(){return 0;}
-EOF
-    if $cc -o $TMPO $TMPC 2>/dev/null ; then
-        echo "ERROR: \"$cc\" looks like gcc 4.x"
-        echo "QEMU is known to have problems when compiled with gcc 4.x"
-        echo "It is recommended that you use gcc 3.x to build QEMU"
-        echo "To use this compiler anyway, configure with --disable-gcc-check"
-        exit 1;
-    fi
 fi
 
 ##########################################

Re: [Qemu-devel] [PATCH] Improve gcc 3 checking

[Paul Brook]

> If they explicitly specific an invalid --cc=, the checks will get
> triggered (but in the past, we would have bailed).

That's what I'm objecting to. If I do:

./configure --cc=gcc4

I expect configure to either use gcc4 or fail with an error. Preferably the 
latter, but I'm open to persuasion.

I don't want configure to decide it knows better and use gcc3 anyway.

Paul

Re: [Qemu-devel] [PATCH] Improve gcc 3 checking

[Anthony Liguori]

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Paul Brook wrote:
>> If they explicitly specific an invalid --cc=, the checks will get
>> triggered (but in the past, we would have bailed).
>>     
>
> That's what I'm objecting to. If I do:
>
> ./configure --cc=gcc4
>
> I expect configure to either use gcc4 or fail with an error. Preferably the 
> latter, but I'm open to persuasion.
>
> I don't want configure to decide it knows better and use gcc3 anyway.
>   

Okay, it now will throw an error if you specify --cc=gcc4.

Regards,

Anthony Liguori

> Paul
>   


[-- Attachment #2: qemu-gcc-3x.diff --]
[-- Type: text/x-patch, Size: 2354 bytes --]

diff -r f928121a13c1 configure
--- a/configure	Mon Dec 18 20:29:34 2006 -0600
+++ b/configure	Mon Dec 18 21:20:36 2006 -0600
@@ -22,6 +22,8 @@ static="no"
 static="no"
 cross_prefix=""
 cc="gcc"
+gcc3_check="yes"
+gcc3_list="gcc-3.4 gcc34 gcc-3.3 gcc33 gcc-3.2 gcc32"
 host_cc="gcc"
 ar="ar"
 make="make"
@@ -178,6 +180,7 @@ for opt do
   --cross-prefix=*) cross_prefix="$optarg"
   ;;
   --cc=*) cc="$optarg"
+  gcc3_check="no"
   ;;
   --host-cc=*) host_cc="$optarg"
   ;;
@@ -311,6 +314,45 @@ if test "$mingw32" = "yes" ; then
     oss="no"
     if [ "$cpu" = "i386" ] ; then
         kqemu="yes"
+    fi
+fi
+
+# Check for gcc4, error if pre-gcc4 
+if test "$check_gcc" = "yes" ; then
+    cat > $TMPC <<EOF
+#if __GNUC__ < 4
+#error gcc3
+#endif
+int main(){return 0;}
+EOF
+    check_cc() {
+	which "$1" >&/dev/null
+	return $?
+    }
+
+    if "$cc" -o $TMPE $TMPC 2>/dev/null ; then
+	echo "WARNING: \"$cc\" looks like gcc 4.x"
+	found_compat_cc="no"
+	if test "$gcc3_check" = "yes" ; then
+	    echo "Looking for gcc 3.x"
+	    for compat_cc in $gcc3_list ; do
+		if check_cc "$compat_cc" ; then
+		    echo "Found \"$compat_cc\""
+		    cc="$compat_cc"
+		    found_compat_cc="yes"
+		    break
+		fi
+	    done
+	    if test "$found_compat_cc" = "no" ; then
+		echo "gcc 3.x not found!"
+	    fi
+	fi
+	if test "$found_compat_cc" = "no" ; then
+	    echo "QEMU is known to have problems when compiled with gcc 4.x"
+	    echo "It is recommended that you use gcc 3.x to build QEMU"
+	    echo "To use this compiler anyway, configure with --disable-gcc-check"
+	    exit 1;
+	fi
     fi
 fi
 
@@ -414,23 +456,6 @@ have_gcc3_options="no"
 have_gcc3_options="no"
 if $cc -fno-reorder-blocks -fno-optimize-sibling-calls -o $TMPO $TMPC 2> /dev/null ; then
    have_gcc3_options="yes"
-fi
-
-# Check for gcc4, error if pre-gcc4 
-if test "$check_gcc" = "yes" ; then
-    cat > $TMPC <<EOF
-#if __GNUC__ < 4
-#error gcc3
-#endif
-int main(){return 0;}
-EOF
-    if $cc -o $TMPO $TMPC 2>/dev/null ; then
-        echo "ERROR: \"$cc\" looks like gcc 4.x"
-        echo "QEMU is known to have problems when compiled with gcc 4.x"
-        echo "It is recommended that you use gcc 3.x to build QEMU"
-        echo "To use this compiler anyway, configure with --disable-gcc-check"
-        exit 1;
-    fi
 fi
 
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