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authorMarc-André Lureau <marcandre.lureau@redhat.com>2018-01-04 17:05:09 +0100
committerPaolo Bonzini <pbonzini@redhat.com>2018-01-12 13:22:02 +0100
commit906548689e37ab6cca1e93b3f8d9327a4e17e8af (patch)
treebb057de9ee3e9f9c21901b6a892ae38256d9faaa /configure
parentde1da442ea38b7f4627072df0cd80f3537cf8390 (diff)
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build-sys: compile with -Og or -O1 when --enable-debug
When --enable-debug is turned on, configure doesn't set -O level, and uses default compiler -O0 level, which is slow. Instead, use -Og if supported by the compiler (optimize debugging experience), or -O1 (keeps code somewhat debuggable and works around compiler bugs). Unfortunately, gcc has many false-positive maybe-uninitialized errors with Og and O1 (f27 gcc 7.2.1 20170915): /home/elmarco/src/qemu/hw/ipmi/isa_ipmi_kcs.c: In function ‘ipmi_kcs_ioport_read’: /home/elmarco/src/qemu/hw/ipmi/isa_ipmi_kcs.c:279:12: error: ‘ret’ may be used uninitialized in this function [-Werror=maybe-uninitialized] return ret; ^~~ cc1: all warnings being treated as errors make: *** [/home/elmarco/src/qemu/rules.mak:66: hw/ipmi/isa_ipmi_kcs.o] Error 1 make: *** Waiting for unfinished jobs.... /home/elmarco/src/qemu/hw/ide/ahci.c: In function ‘ahci_populate_sglist’: /home/elmarco/src/qemu/hw/ide/ahci.c:903:58: error: ‘tbl_entry_size’ may be used uninitialized in this function [-Werror=maybe-uninitialized] if ((off_idx == -1) || (off_pos < 0) || (off_pos > tbl_entry_size)) { ~~~~~~~~~^~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors make: *** [/home/elmarco/src/qemu/rules.mak:66: hw/ide/ahci.o] Error 1 /home/elmarco/src/qemu/hw/display/qxl.c: In function ‘qxl_add_memslot’: /home/elmarco/src/qemu/hw/display/qxl.c:1397:52: error: ‘pci_start’ may be used uninitialized in this function [-Werror=maybe-uninitialized] memslot.virt_end = virt_start + (guest_end - pci_start); ~~~~~~~~~~~~~^~~~~~~~~~~~ /home/elmarco/src/qemu/hw/display/qxl.c:1389:9: error: ‘pci_region’ may be used uninitialized in this function [-Werror=maybe-uninitialized] qxl_set_guest_bug(d, "%s: pci_region = %d", __func__, pci_region); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ cc1: all warnings being treated as errors There seems to be a long list of related bugs in upstream GCC, some of them are being fixed very recently: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639 For now, let's workaround it by using Wno-maybe-uninitialized (gcc-only). Suggested-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20180104160523.22995-5-marcandre.lureau@redhat.com> Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'configure')
-rwxr-xr-xconfigure15
1 files changed, 13 insertions, 2 deletions
diff --git a/configure b/configure
index ac392d2..6f1b7cd 100755
--- a/configure
+++ b/configure
@@ -5194,8 +5194,19 @@ if test "$gcov" = "yes" ; then
LDFLAGS="-fprofile-arcs -ftest-coverage $LDFLAGS"
elif test "$fortify_source" = "yes" ; then
CFLAGS="-O2 -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=2 $CFLAGS"
-elif test "$debug" = "no"; then
- CFLAGS="-O2 $CFLAGS"
+elif test "$debug" = "yes"; then
+ if compile_prog "-Og" ""; then
+ CFLAGS="-Og $CFLAGS"
+ elif compile_prog "-O1" ""; then
+ CFLAGS="-O1 $CFLAGS"
+ fi
+ # Workaround GCC false-positive Wuninitialized bugs with Og or O1:
+ # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=24639
+ if cc_has_warning_flag "-Wno-maybe-uninitialized"; then
+ CFLAGS="-Wno-maybe-uninitialized $CFLAGS"
+ fi
+else
+ CFLAGS="-O2 $CFLAGS"
fi
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