| Message ID | 20191207224953.25944-1-olof@lixom.net (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ALSA: echoaudio: simplify get_audio_levels | expand |
On Sat, 07 Dec 2019 23:49:53 +0100, Olof Johansson wrote: > > The loop optimizer seems to go astray here, and produces some warnings > that don't seem valid. > > Still, the code can be simplified -- just clear the whole array at the > beginning, and fill in whatever values are valid on the platform. > > Warnings before this change (GCC 8.2.0 ARM allmodconfig): > > In file included from ../sound/pci/echoaudio/gina24.c:115: > ../sound/pci/echoaudio/echoaudio.c: In function 'snd_echo_vumeters_get': > ../sound/pci/echoaudio/echoaudio_dsp.c:647:9: warning: iteration 1073741824 invokes undefined behavior [-Waggressive-loop-optimizations] > In file included from ../sound/pci/echoaudio/layla24.c:112: > ../sound/pci/echoaudio/echoaudio.c: In function 'snd_echo_vumeters_get': > ../sound/pci/echoaudio/echoaudio_dsp.c:658:9: warning: iteration 1073741824 invokes undefined behavior [-Waggressive-loop-optimizations] > ../sound/pci/echoaudio/echoaudio_dsp.c:647:9: warning: iteration 1073741824 invokes undefined behavior [-Waggressive-loop-optimizations] > > Signed-off-by: Olof Johansson <olof@lixom.net> Applied now, thanks. Takashi
diff --git a/sound/pci/echoaudio/echoaudio_dsp.c b/sound/pci/echoaudio/echoaudio_dsp.c index 50d4a87a6bb34..f02f5b1568dee 100644 --- a/sound/pci/echoaudio/echoaudio_dsp.c +++ b/sound/pci/echoaudio/echoaudio_dsp.c @@ -635,36 +635,30 @@ This function assumes there are no more than 16 in/out busses or pipes Meters is an array [3][16][2] of long. */ static void get_audio_meters(struct echoaudio *chip, long *meters) { - int i, m, n; + unsigned int i, m, n; - m = 0; - n = 0; - for (i = 0; i < num_busses_out(chip); i++, m++) { + for (i = 0 ; i < 96; i++) + meters[i] = 0; + + for (m = 0, n = 0, i = 0; i < num_busses_out(chip); i++, m++) { meters[n++] = chip->comm_page->vu_meter[m]; meters[n++] = chip->comm_page->peak_meter[m]; } - for (; n < 32; n++) - meters[n] = 0; #ifdef ECHOCARD_ECHO3G m = E3G_MAX_OUTPUTS; /* Skip unused meters */ #endif - for (i = 0; i < num_busses_in(chip); i++, m++) { + for (n = 32, i = 0; i < num_busses_in(chip); i++, m++) { meters[n++] = chip->comm_page->vu_meter[m]; meters[n++] = chip->comm_page->peak_meter[m]; } - for (; n < 64; n++) - meters[n] = 0; - #ifdef ECHOCARD_HAS_VMIXER - for (i = 0; i < num_pipes_out(chip); i++, m++) { + for (n = 64, i = 0; i < num_pipes_out(chip); i++, m++) { meters[n++] = chip->comm_page->vu_meter[m]; meters[n++] = chip->comm_page->peak_meter[m]; } #endif - for (; n < 96; n++) - meters[n] = 0; }
The loop optimizer seems to go astray here, and produces some warnings that don't seem valid. Still, the code can be simplified -- just clear the whole array at the beginning, and fill in whatever values are valid on the platform. Warnings before this change (GCC 8.2.0 ARM allmodconfig): In file included from ../sound/pci/echoaudio/gina24.c:115: ../sound/pci/echoaudio/echoaudio.c: In function 'snd_echo_vumeters_get': ../sound/pci/echoaudio/echoaudio_dsp.c:647:9: warning: iteration 1073741824 invokes undefined behavior [-Waggressive-loop-optimizations] In file included from ../sound/pci/echoaudio/layla24.c:112: ../sound/pci/echoaudio/echoaudio.c: In function 'snd_echo_vumeters_get': ../sound/pci/echoaudio/echoaudio_dsp.c:658:9: warning: iteration 1073741824 invokes undefined behavior [-Waggressive-loop-optimizations] ../sound/pci/echoaudio/echoaudio_dsp.c:647:9: warning: iteration 1073741824 invokes undefined behavior [-Waggressive-loop-optimizations] Signed-off-by: Olof Johansson <olof@lixom.net> --- sound/pci/echoaudio/echoaudio_dsp.c | 20 +++++++------------- 1 file changed, 7 insertions(+), 13 deletions(-)