| Message ID | 20110906080245.GA26732@rox.home.comstyle.com |
|---|---|
| State | New |
| Headers | show |
On 6 September 2011 09:02, Brad <brad@comstyle.com> wrote:
> Only build with -g CFLAGS/LDFLAGS if using --enable-debug.
I'm not convinced -- I think we should always build with -g;
it means you can do at least some debugging on an in-tree
build even if it's the optimised version. Debug info should
be stripped at install time, right?
(I don't think this is a particularly out-on-a-limb view;
it's the standard policy for building things in Debian,
for instance.)
-- PMM
On 09/06/11 10:02, Brad wrote: > Only build with -g CFLAGS/LDFLAGS if using --enable-debug. > Add --optflags to allow overriding the default optimization > level added to CFLAGS. > > This is a first draft of coming up with a patch I could potentially > push upstream based on much cruder local patches to do something > similar. I'm trying to eliminate having to patch the configure > script. You don't have to. You can just run 'make CFLAGS="$optflags"' to override the defaults. Nevertheless having optflags would be nice as you don't have to type this for each make run then. I don't think we should mess with the -g flag. It should stay enabled by default, so you can easily get a useful stacktrace out of a core without having to rebuild with debug info first. cheers, Gerd
On 6 September 2011 09:02, Brad <brad@comstyle.com> wrote: > @@ -937,6 +940,7 @@ echo " --cross-prefix=PREFIX use PREFIX for compile tools [$cross_prefix]" > echo " --cc=CC use C compiler CC [$cc]" > echo " --host-cc=CC use C compiler CC [$host_cc] for code run at" > echo " build time" > +echo " --optflags=FLAGS override optimization compiler flags" > echo " --extra-cflags=CFLAGS append extra C compiler flags QEMU_CFLAGS" > echo " --extra-ldflags=LDFLAGS append extra linker flags LDFLAGS" > echo " --make=MAKE use specified make [$make]" No in principle objection to the --optflags bit of the patch, but you should rearrange things so that the help message can include the default optflags, something like: --optflags=FLAGS specify compiler flags for optimization [-O2] (...which might also let you avoid the 'if test -n "$optflags" later.) -- PMM
----- Original message ----- > On 09/06/11 10:02, Brad wrote: > > Only build with -g CFLAGS/LDFLAGS if using --enable-debug. > > Add --optflags to allow overriding the default optimization > > level added to CFLAGS. > > > > This is a first draft of coming up with a patch I could potentially > > push upstream based on much cruder local patches to do something > > similar. I'm trying to eliminate having to patch the configure > > script. > > You don't have to. You can just run 'make CFLAGS="$optflags"' to > override the defaults. Nevertheless having optflags would be nice as > you don't have to type this for each make run then. I do when its unconditionally on the commandline either way. If the configure scipt didnt put it their if CFLAGS wasnt empty it wouldnt be an issue. > I don't think we should mess with the -g flag. It should stay enabled > by default, so you can easily get a useful stacktrace out of a core > without having to rebuild with debug info first. I dont care what the default is as long as I can disable it without patching.
Brad <brad@comstyle.com> wrote: > ----- Original message ----- >> On 09/06/11 10:02, Brad wrote: >> > Only build with -g CFLAGS/LDFLAGS if using --enable-debug. >> > Add --optflags to allow overriding the default optimization >> > level added to CFLAGS. >> > >> > This is a first draft of coming up with a patch I could potentially >> > push upstream based on much cruder local patches to do something >> > similar. I'm trying to eliminate having to patch the configure >> > script. >> >> You don't have to. You can just run 'make CFLAGS="$optflags"' to >> override the defaults. Nevertheless having optflags would be nice as >> you don't have to type this for each make run then. > > I do when its unconditionally on the commandline either way. If the configure scipt didnt put it their if CFLAGS wasnt empty it wouldnt be an issue. $(call quiet-command,$(CC) $(QEMU_INCLUDES) $(QEMU_CFLAGS) $(QEMU_DGFLAGS) $(CFLAGS) -c -o $@ $<," CC $(TARGET_DIR)$@") this is the rule called in rules.make. QEMU don't use CFLAGS internally^W^W^W^W, it is only used for -g -O2, so it should be enough to use make CFLAGS="" or something like that. > >> I don't think we should mess with the -g flag. It should stay enabled >> by default, so you can easily get a useful stacktrace out of a core >> without having to rebuild with debug info first. > > I dont care what the default is as long as I can disable it without patching. What is the reason for that? I guess that compilation speed/memory, but just to be sure. Later, Juan.
On Wed, Sep 7, 2011 at 10:54 AM, Juan Quintela <quintela@redhat.com> wrote: > Brad <brad@comstyle.com> wrote: >> ----- Original message ----- >>> On 09/06/11 10:02, Brad wrote: >>> > Only build with -g CFLAGS/LDFLAGS if using --enable-debug. >>> > Add --optflags to allow overriding the default optimization >>> > level added to CFLAGS. >>> > >>> > This is a first draft of coming up with a patch I could potentially >>> > push upstream based on much cruder local patches to do something >>> > similar. I'm trying to eliminate having to patch the configure >>> > script. >>> >>> You don't have to. You can just run 'make CFLAGS="$optflags"' to >>> override the defaults. Nevertheless having optflags would be nice as >>> you don't have to type this for each make run then. >> >> I do when its unconditionally on the commandline either way. If the configure scipt didnt put it their if CFLAGS wasnt empty it wouldnt be an issue. > > $(call quiet-command,$(CC) $(QEMU_INCLUDES) $(QEMU_CFLAGS) $(QEMU_DGFLAGS) $(CFLAGS) -c -o $@ $<," CC $(TARGET_DIR)$@") > > this is the rule called in rules.make. QEMU don't use CFLAGS > internally^W^W^W^W, it is only used for -g -O2, so it should be enough > to use make CFLAGS="" or something like that. > >> >>> I don't think we should mess with the -g flag. It should stay enabled >>> by default, so you can easily get a useful stacktrace out of a core >>> without having to rebuild with debug info first. >> >> I dont care what the default is as long as I can disable it without patching. > > What is the reason for that? I guess that compilation speed/memory, but > just to be sure. Also disk space. Speed/memory effect seems to be about 3%. Generating sparc64-softmmu/translate.o with -g, time -v output: User time (seconds): 33.00 System time (seconds): 0.95 Percent of CPU this job got: 99% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:34.01 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 1636016 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 240264 Voluntary context switches: 7 Involuntary context switches: 3201 Swaps: 0 File system inputs: 0 File system outputs: 17488 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 $ ls -sh translate.o 2.5M translate.o Without: User time (seconds): 31.55 System time (seconds): 1.10 Percent of CPU this job got: 99% Elapsed (wall clock) time (h:mm:ss or m:ss): 0:32.73 Average shared text size (kbytes): 0 Average unshared data size (kbytes): 0 Average stack size (kbytes): 0 Average total size (kbytes): 0 Maximum resident set size (kbytes): 1619056 Average resident set size (kbytes): 0 Major (requiring I/O) page faults: 0 Minor (reclaiming a frame) page faults: 220316 Voluntary context switches: 7 Involuntary context switches: 3335 Swaps: 0 File system inputs: 0 File system outputs: 4040 Socket messages sent: 0 Socket messages received: 0 Signals delivered: 0 Page size (bytes): 4096 Exit status: 0 $ ls -sh translate.o 768K translate.o
Am 06.09.2011 18:30, schrieb Brad: > ----- Original message ----- >> On 09/06/11 10:02, Brad wrote: >>> Only build with -g CFLAGS/LDFLAGS if using --enable-debug. >>> Add --optflags to allow overriding the default optimization >>> level added to CFLAGS. >>> >>> This is a first draft of coming up with a patch I could potentially >>> push upstream based on much cruder local patches to do something >>> similar. I'm trying to eliminate having to patch the configure >>> script. >> >> You don't have to. You can just run 'make CFLAGS="$optflags"' to >> override the defaults. Nevertheless having optflags would be nice as >> you don't have to type this for each make run then. > > I do when its unconditionally on the commandline either way. If the > configure scipt didnt put it their if CFLAGS wasnt empty it wouldnt be > an issue. > >> I don't think we should mess with the -g flag. It should stay enabled >> by default, so you can easily get a useful stacktrace out of a core >> without having to rebuild with debug info first. > > I dont care what the default is as long as I can disable it without > patching. I'm sorry but I still don't understand why you want this patch. It's already possible to run the compiler with or without -g and with any optimization you want: make CFLAGS="-O1", make CFLAGS=-g (my favourite), make CFLAGS="-O0", ... There must be a really good reason for new options like --optflags. Is this flag some kind of standard which is widely used (like CFLAGS)? If it isn't, users won't know it, so they won't use it, so it is useless. Regards, Stefan Weil
diff --git a/configure b/configure index c3044c7..23a85a7 100755 --- a/configure +++ b/configure @@ -77,6 +77,7 @@ path_of() { # default parameters source_path=`dirname "$0"` cpu="" +optflags="" interp_prefix="/usr/gnemul/qemu-%M" static="no" sparc_cpu="" @@ -195,6 +196,8 @@ for opt do ;; --cpu=*) cpu="$optarg" ;; + --optflags=*) optflags="$optarg" + ;; --extra-cflags=*) QEMU_CFLAGS="$optarg $QEMU_CFLAGS" ;; --extra-ldflags=*) LDFLAGS="$optarg $LDFLAGS" @@ -232,13 +235,11 @@ sdl_config="${SDL_CONFIG-${cross_prefix}sdl-config}" # default flags for all hosts QEMU_CFLAGS="-fno-strict-aliasing $QEMU_CFLAGS" -CFLAGS="-g $CFLAGS" QEMU_CFLAGS="-Wall -Wundef -Wwrite-strings -Wmissing-prototypes $QEMU_CFLAGS" QEMU_CFLAGS="-Wstrict-prototypes -Wredundant-decls $QEMU_CFLAGS" QEMU_CFLAGS="-D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE $QEMU_CFLAGS" QEMU_CFLAGS="-D_FORTIFY_SOURCE=2 $QEMU_CFLAGS" QEMU_INCLUDES="-I. -I\$(SRC_PATH) -I\$(SRC_PATH)/fpu" -LDFLAGS="-g $LDFLAGS" # make source path absolute source_path=`cd "$source_path"; pwd` @@ -518,6 +519,8 @@ for opt do ;; --cc=*) ;; + --optflags=*) + ;; --host-cc=*) host_cc="$optarg" ;; --make=*) make="$optarg" @@ -937,6 +940,7 @@ echo " --cross-prefix=PREFIX use PREFIX for compile tools [$cross_prefix]" echo " --cc=CC use C compiler CC [$cc]" echo " --host-cc=CC use C compiler CC [$host_cc] for code run at" echo " build time" +echo " --optflags=FLAGS override optimization compiler flags" echo " --extra-cflags=CFLAGS append extra C compiler flags QEMU_CFLAGS" echo " --extra-ldflags=LDFLAGS append extra linker flags LDFLAGS" echo " --make=MAKE use specified make [$make]" @@ -2569,8 +2573,15 @@ fi # End of CC checks # After here, no more $cc or $ld runs -if test "$debug" = "no" ; then - CFLAGS="-O2 $CFLAGS" +if test "$debug" = "yes" ; then + CFLAGS="-g $CFLAGS" + LDFLAGS="-g $LDFLAGS" +else + if test -n "$optflags" ; then + CFLAGS="$optflags $CFLAGS" + else + CFLAGS="-O2 $CFLAGS" + fi fi # Consult white-list to determine whether to enable werror