On 24/05/18 17:46, Gedare Bloom wrote:
On Thu, May 24, 2018 at 9:05 AM, Joel Sherrill <j...@rtems.org> wrote:
On Thu, May 24, 2018, 8:04 AM Gedare Bloom <ged...@rtems.org> wrote:
On Wed, May 23, 2018 at 2:28 AM, Sebastian Huber
<sebastian.hu...@embedded-brains.de> wrote:
On 23/05/18 01:06, Joel Sherrill wrote:
Or we may need to limit ourselves to source line mapping on a per
executable
basis. And generate reports using gcov output if we see methods change
between executables. I have shied away from gcov as the primary format
because I don't see how to do subexpression analysis.
if (a == 0 || b == 1)
That's one line of source but two sub-expressions. Unless it's changed
recently, the debug info is not at a level of granularity to generate
gcov data that can tell we always too the first sub-expression.
I'm not arguing -- just saying that doing the analysis at the asm level
gives us branch information I don't think we get via source line
analysis and gcov.
Is the --all-blocks option of gcov helpful here?
https://gcc.gnu.org/onlinedocs/gcc/Invoking-Gcov.html#Invoking-Gcov
Yes, that seems like it should work to me.
Can you decipher the gcov output to see if it is working?
Not immediately, but maybe you can put together a simple example of a
subexpr that is 'dead code' to test with/without the option.
It seems that gcov already produces sub-expression branch counts without
the -a option:
int ff(int a, int b)
{
if (a != 0 && b != 0) {
return 1;
}
return 0;
}
int ft(int a, int b)
{
if (a != 0 && b != 0) {
return 1;
}
return 0;
}
int tf(int a, int b)
{
if (a != 0 && b != 0) {
return 1;
}
return 0;
}
int tt(int a, int b)
{
if (a != 0 && b != 0) {
return 1;
}
return 0;
}
int main(void)
{
ff(0, 0);
ft(0, 1);
tf(1, 0);
tt(1, 1);
return 0;
}
gcc -fprofile-arcs -ftest-coverage test.c
./a.out
gcov -b -c test.c
File 'test.c'
Lines executed:81.82% of 22
Branches executed:75.00% of 16
Taken at least once:37.50% of 16
Calls executed:100.00% of 4
Creating 'test.c.gcov'
cat test.c.gcov
-: 0:Source:test.c
-: 0:Graph:test.gcno
-: 0:Data:test.gcda
-: 0:Runs:1
-: 0:Programs:1
function ff called 1 returned 100% blocks executed 60%
1: 1:int ff(int a, int b)
-: 2:{
1: 3: if (a != 0 && b != 0) {
branch 0 taken 0 (fallthrough)
branch 1 taken 1
branch 2 never executed
branch 3 never executed
#####: 4: return 1;
-: 5: }
-: 6:
1: 7: return 0;
-: 8:}
-: 9:
function ft called 1 returned 100% blocks executed 60%
1: 10:int ft(int a, int b)
-: 11:{
1: 12: if (a != 0 && b != 0) {
branch 0 taken 0 (fallthrough)
branch 1 taken 1
branch 2 never executed
branch 3 never executed
#####: 13: return 1;
-: 14: }
-: 15:
1: 16: return 0;
-: 17:}
-: 18:
function tf called 1 returned 100% blocks executed 80%
1: 19:int tf(int a, int b)
-: 20:{
1: 21: if (a != 0 && b != 0) {
branch 0 taken 1 (fallthrough)
branch 1 taken 0
branch 2 taken 0 (fallthrough)
branch 3 taken 1
#####: 22: return 1;
-: 23: }
-: 24:
1: 25: return 0;
-: 26:}
-: 27:
function tt called 1 returned 100% blocks executed 80%
1: 28:int tt(int a, int b)
-: 29:{
1: 30: if (a != 0 && b != 0) {
branch 0 taken 1 (fallthrough)
branch 1 taken 0
branch 2 taken 1 (fallthrough)
branch 3 taken 0
1: 31: return 1;
-: 32: }
-: 33:
#####: 34: return 0;
-: 35:}
-: 36:
function main called 1 returned 100% blocks executed 100%
1: 37:int main(void)
-: 38:{
1: 39: ff(0, 0);
call 0 returned 1
1: 40: ft(0, 1);
call 0 returned 1
1: 41: tf(1, 0);
call 0 returned 1
1: 42: tt(1, 1);
call 0 returned 1
1: 43: return 0;
-: 44:}
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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