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[Qemu-devel] [PATCH v3 4/4] configure: Add workaround for ccache and cla
From: |
John Snow |
Subject: |
[Qemu-devel] [PATCH v3 4/4] configure: Add workaround for ccache and clang |
Date: |
Thu, 19 Mar 2015 15:01:37 -0400 |
Test if ccache is interfering with our life, and
disable its habit of trying to compile already pre-processed
versions of code if so.
In particular, clang has different semantic warnings based on
if the warning arose from a macro or not. By trying to build
preprocessed versions of code, we get more errors than we should.
ccache allows us to disable this feature, opting instead to
compile the original version instead of its preprocessed version.
This makes ccache much slower for cache misses, but at least it
becomes usable with QEMU/clang.
Thanks to Peter Eisentraut for his writeup on the issue:
http://peter.eisentraut.org/blog/2014/12/01/ccache-and-clang-part-3/
Signed-off-by: John Snow <address@hidden>
---
configure | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/configure b/configure
index fbcbf50..75219a9 100755
--- a/configure
+++ b/configure
@@ -4172,6 +4172,33 @@ if compile_prog "" "" ; then
getauxval=yes
fi
+########################################
+# check if ccache is interfering with
+# semantic analysis of macros
+
+ccache=no
+cat > $TMPC << EOF
+static const int Z = 1;
+#define fn() ({ Z; })
+#define TAUT(X) ((X) == Z)
+#define PAREN(X, Y) (X == Y)
+#define ID(X) (X)
+int main(int argc, char *argv[])
+{
+ int x = 0, y = 0;
+ x = ID(x);
+ x = fn();
+ fn();
+ if (PAREN(x, y)) return 0;
+ if (TAUT(Z)) return 0;
+ return 0;
+}
+EOF
+
+if ! compile_object; then
+ ccache=yes
+fi
+
##########################################
# End of CC checks
# After here, no more $cc or $ld runs
@@ -5462,6 +5489,10 @@ if test "$numa" = "yes"; then
echo "CONFIG_NUMA=y" >> $config_host_mak
fi
+if test "$ccache" = "yes"; then
+ echo "export CCACHE_CPP2=y" >> $config_host_mak
+fi
+
# build tree in object directory in case the source is not in the current
directory
DIRS="tests tests/tcg tests/tcg/cris tests/tcg/lm32 tests/libqos
tests/qapi-schema tests/tcg/xtensa tests/qemu-iotests"
DIRS="$DIRS fsdev"
--
2.1.0
[Qemu-devel] [PATCH v3 3/4] configure: silence glib unknown attribute __alloc_size__, John Snow, 2015/03/19
[Qemu-devel] [PATCH v3 1/4] configure: handle clang -nopie argument warning, John Snow, 2015/03/19