(0013280)
Bill Hoffman (manager)
2008-09-03 15:00

You could try this:

SET(CMAKE_REQUIRED_LIBRARIES -fprofile-arcs )
CHECK_C_COMPILER_FLAG (-fprofile-arcs FLAG_Gcov1)

(0013292)
Mahendra Ladhe (reporter)
2008-09-04 00:04

Per Bill's suggestion, when I added one more line
SET(CMAKE_REQUIRED_LIBRARIES -fprofile-arcs )
found that gcc is no longer being passed the flag -fprofile-arcs
during compilation, but only during linking so it has no effect.
i.e. after incorporating the suggestion, my CMakeLists.txt's relevant
portion became as below.

#To build the code for use with gcov, call cmake as below
#cmake -DGCOV=1 ..
IF (${GCOV})
    SET(CMAKE_REQUIRED_LIBRARIES -fprofile-arcs )
    CHECK_C_COMPILER_FLAG (-fprofile-arcs FLAG_Gcov1)
    IF (FLAG_Gcov1)
      add_definitions (-fprofile-arcs)
    ELSE (FLAG_Gcov1)
      MESSAGE(FATAL_ERROR "Compiler does not support the -fprofile-arcs flag needed for using gcov")
    ENDIF (FLAG_Gcov1)
    CHECK_C_COMPILER_FLAG (-ftest-coverage FLAG_Gcov2)
    IF (FLAG_Gcov2)
      add_definitions (-ftest-coverage)
    ELSE (FLAG_Gcov2)
      MESSAGE(FATAL_ERROR "Compiler does not support the -ftest-coverage flag needed for using gcov")
    ENDIF (FLAG_Gcov2)
ENDIF (${GCOV})

After this change I'm not getting the error message
"Compiler does not support the -fprofile-arcs flag needed for using gcov"
But the statement add_definitions (-fprofile-arcs) is not taking effect.
During compilation(e.g. gcc -c a.c -o a.o), gcc is not being passed -fprofile-arcs flag. So code does not get compiled for use with GCOV.

One more observation: While the cmake 2.6 documentation for CHECK_C_SOURCE_COMPILES is as follows.
=======================
CHECK_C_SOURCE_COMPILES(SOURCE VAR)

  SOURCE - source code to try to compile
  VAR - variable to store whether the source code compiled

The following variables may be set before calling this macro to modify the way the check is run:

  CMAKE_REQUIRED_LIBRARIES = list of libraries to link
=======================

the documentation for CHECK_C_COMPILER_FLAG macro does not say that
the variable CMAKE_REQUIRED_LIBRARIES may be set before calling this
macro to modify the way the check is run.

(0013384)
Bill Hoffman (manager)
2008-09-09 14:12

I have updated the docs to say this:

CheckCCompilerFlag
       Check whether the C compiler supports a given flag.

       CHECK_C_COMPILER_FLAG(FLAG VARIABLE)

         FLAG - the compiler flag
         VARIABLE - variable to store the result



         This actually calls the check_c_source_compiles macro.
         See help for CheckCSourceCompiles for a listing of variables
         that can modify the build.

       Defined in: C:/hoffman/My Builds/CMake/Modules/CheckCCompilerFlag.cmake

  CheckCSourceCompiles
       macro which checks if the source code compiles

       CHECK_C_SOURCE_COMPILES(SOURCE VAR)

         SOURCE - source code to try to compile
         VAR - variable to store whether the source code compiled



       The following variables may be set before calling this macro to modify
       the way the check is run:

         CMAKE_REQUIRED_FLAGS = string of compile command line flags
         CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar)
         CMAKE_REQUIRED_INCLUDES = list of include directories
         CMAKE_REQUIRED_LIBRARIES = list of libraries to link

       Defined in: C:/hoffman/My Builds/CMake/Modules/CheckCSourceCompiles.cmake

(0013385)
Bill Hoffman (manager)
2008-09-09 14:14

Does the add_definition work without the if?

Also, it might be better to modify CMAKE_CXX_FLAGS instead.

Something like this should work:
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fprofile-arcs")

Make sure this is done BEFORE the target that you want to build with profile information.

(0013406)
Mahendra Ladhe (reporter)
2008-09-11 04:24

Yes, add_definitions work without the if, but only while compiling.
Consider my following simple CMakeLists.txt file

add_definitions (-fprofile-arcs)
add_definitions (-ftest-coverage)
add_executable(sample_test test.c)

When compiling test.c gcc did receive -fprofile-arcs and -ftest-coverage
flags. But when linking it didn't. So linking failed as gcc needs the
two flags again so that it can link gcov library.

Adding following line instead of 2 add_definitions is helping and giving
the desired behaviour.
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fprofile-arcs -ftest-coverage")

Now gcc is being passed these 2 flags while compiling and as well as linking.

Thanks Bill.

But the behaviour of Check_C_Compiler_Flag macro still needs a fix.

(0013411)
Bill Hoffman (manager)
2008-09-11 08:50

I am not sure, you are confusing link flags and compile flags. In this case you want to test a link flag and a compile flag at the same time. They happen to be the same thing. However, many compile flags are not useful or wanted at link time. add_definition is only used at compile time and is really meant for -D stuff.

(0013478)
Mahendra Ladhe (reporter)
2008-09-15 23:10

Yes, -fprofile-arcs and -ftest-coverage are both compile and link flags.
So is there any way to check if such flags(compile+link) are supported by
the compiler?

(0013639)
Bill Hoffman (manager)
2008-10-01 10:17

You could do something like this:

set(CMAKE_C_FLAGS_SAVE "${CMAKE_C_FLAGS}")
set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fprofile-arcs")
CHECK_C_COMPILER_FLAG (-fprofile-arcs FLAG_Gcov1)

But that seems kind of silly. I guess the macro could be augmented to support compile and link flags. Maybe a version that just sets CMAKE_C_FLAGS.

(0028177)
Alex Neundorf (developer)
2012-01-04 16:12

I think I won't work on this.

Alex

(0041446)
Kitware Robot (administrator)
2016-06-10 14:27

Resolving issue as `moved`.

This issue tracker is no longer used. Further discussion of this issue may take place in the current CMake Issues page linked in the banner at the top of this page.

Issue History
Date Modified	Username	Field	Change
2008-09-02 07:21	Mahendra Ladhe	New Issue
2008-09-03 15:00	Bill Hoffman	Note Added: 0013280
2008-09-03 15:00	Bill Hoffman	Status	new => assigned
2008-09-03 15:00	Bill Hoffman	Assigned To	=> Bill Hoffman
2008-09-04 00:04	Mahendra Ladhe	Note Added: 0013292
2008-09-09 14:12	Bill Hoffman	Note Added: 0013384
2008-09-09 14:14	Bill Hoffman	Note Added: 0013385
2008-09-11 04:24	Mahendra Ladhe	Note Added: 0013406
2008-09-11 08:50	Bill Hoffman	Note Added: 0013411
2008-09-15 23:10	Mahendra Ladhe	Note Added: 0013478
2008-10-01 10:17	Bill Hoffman	Note Added: 0013639
2008-10-01 10:18	Bill Hoffman	Assigned To	Bill Hoffman => Alex Neundorf
2010-08-29 10:23	Kovarththanan Rajaratnam	Category	CMake => Modules
2012-01-04 16:12	Alex Neundorf	Note Added: 0028177
2012-01-04 16:12	Alex Neundorf	Assigned To	Alex Neundorf =>
2012-01-04 16:12	Alex Neundorf	Status	assigned => backlog
2016-06-10 14:27	Kitware Robot	Note Added: 0041446
2016-06-10 14:27	Kitware Robot	Status	backlog => resolved
2016-06-10 14:27	Kitware Robot	Resolution	open => moved
2016-06-10 14:27	Kitware Robot	Assigned To	=> Kitware Robot
2016-06-10 14:30	Kitware Robot	Status	resolved => closed

Notes
(0013280) Bill Hoffman (manager) 2008-09-03 15:00	You could try this: SET(CMAKE_REQUIRED_LIBRARIES -fprofile-arcs ) CHECK_C_COMPILER_FLAG (-fprofile-arcs FLAG_Gcov1)

(0013292) Mahendra Ladhe (reporter) 2008-09-04 00:04	Per Bill's suggestion, when I added one more line SET(CMAKE_REQUIRED_LIBRARIES -fprofile-arcs ) found that gcc is no longer being passed the flag -fprofile-arcs during compilation, but only during linking so it has no effect. i.e. after incorporating the suggestion, my CMakeLists.txt's relevant portion became as below. #To build the code for use with gcov, call cmake as below #cmake -DGCOV=1 .. IF (${GCOV}) SET(CMAKE_REQUIRED_LIBRARIES -fprofile-arcs ) CHECK_C_COMPILER_FLAG (-fprofile-arcs FLAG_Gcov1) IF (FLAG_Gcov1) add_definitions (-fprofile-arcs) ELSE (FLAG_Gcov1) MESSAGE(FATAL_ERROR "Compiler does not support the -fprofile-arcs flag needed for using gcov") ENDIF (FLAG_Gcov1) CHECK_C_COMPILER_FLAG (-ftest-coverage FLAG_Gcov2) IF (FLAG_Gcov2) add_definitions (-ftest-coverage) ELSE (FLAG_Gcov2) MESSAGE(FATAL_ERROR "Compiler does not support the -ftest-coverage flag needed for using gcov") ENDIF (FLAG_Gcov2) ENDIF (${GCOV}) After this change I'm not getting the error message "Compiler does not support the -fprofile-arcs flag needed for using gcov" But the statement add_definitions (-fprofile-arcs) is not taking effect. During compilation(e.g. gcc -c a.c -o a.o), gcc is not being passed -fprofile-arcs flag. So code does not get compiled for use with GCOV. One more observation: While the cmake 2.6 documentation for CHECK_C_SOURCE_COMPILES is as follows. ======================= CHECK_C_SOURCE_COMPILES(SOURCE VAR) SOURCE - source code to try to compile VAR - variable to store whether the source code compiled The following variables may be set before calling this macro to modify the way the check is run: CMAKE_REQUIRED_LIBRARIES = list of libraries to link ======================= the documentation for CHECK_C_COMPILER_FLAG macro does not say that the variable CMAKE_REQUIRED_LIBRARIES may be set before calling this macro to modify the way the check is run.

(0013384) Bill Hoffman (manager) 2008-09-09 14:12	I have updated the docs to say this: CheckCCompilerFlag Check whether the C compiler supports a given flag. CHECK_C_COMPILER_FLAG(FLAG VARIABLE) FLAG - the compiler flag VARIABLE - variable to store the result This actually calls the check_c_source_compiles macro. See help for CheckCSourceCompiles for a listing of variables that can modify the build. Defined in: C:/hoffman/My Builds/CMake/Modules/CheckCCompilerFlag.cmake CheckCSourceCompiles macro which checks if the source code compiles CHECK_C_SOURCE_COMPILES(SOURCE VAR) SOURCE - source code to try to compile VAR - variable to store whether the source code compiled The following variables may be set before calling this macro to modify the way the check is run: CMAKE_REQUIRED_FLAGS = string of compile command line flags CMAKE_REQUIRED_DEFINITIONS = list of macros to define (-DFOO=bar) CMAKE_REQUIRED_INCLUDES = list of include directories CMAKE_REQUIRED_LIBRARIES = list of libraries to link Defined in: C:/hoffman/My Builds/CMake/Modules/CheckCSourceCompiles.cmake

(0013385) Bill Hoffman (manager) 2008-09-09 14:14	Does the add_definition work without the if? Also, it might be better to modify CMAKE_CXX_FLAGS instead. Something like this should work: set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fprofile-arcs") Make sure this is done BEFORE the target that you want to build with profile information.

(0013406) Mahendra Ladhe (reporter) 2008-09-11 04:24	Yes, add_definitions work without the if, but only while compiling. Consider my following simple CMakeLists.txt file add_definitions (-fprofile-arcs) add_definitions (-ftest-coverage) add_executable(sample_test test.c) When compiling test.c gcc did receive -fprofile-arcs and -ftest-coverage flags. But when linking it didn't. So linking failed as gcc needs the two flags again so that it can link gcov library. Adding following line instead of 2 add_definitions is helping and giving the desired behaviour. set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fprofile-arcs -ftest-coverage") Now gcc is being passed these 2 flags while compiling and as well as linking. Thanks Bill. But the behaviour of Check_C_Compiler_Flag macro still needs a fix.

(0013411) Bill Hoffman (manager) 2008-09-11 08:50	I am not sure, you are confusing link flags and compile flags. In this case you want to test a link flag and a compile flag at the same time. They happen to be the same thing. However, many compile flags are not useful or wanted at link time. add_definition is only used at compile time and is really meant for -D stuff.

(0013478) Mahendra Ladhe (reporter) 2008-09-15 23:10	Yes, -fprofile-arcs and -ftest-coverage are both compile and link flags. So is there any way to check if such flags(compile+link) are supported by the compiler?

(0013639) Bill Hoffman (manager) 2008-10-01 10:17	You could do something like this: set(CMAKE_C_FLAGS_SAVE "${CMAKE_C_FLAGS}") set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fprofile-arcs") CHECK_C_COMPILER_FLAG (-fprofile-arcs FLAG_Gcov1) But that seems kind of silly. I guess the macro could be augmented to support compile and link flags. Maybe a version that just sets CMAKE_C_FLAGS.

(0028177) Alex Neundorf (developer) 2012-01-04 16:12	I think I won't work on this. Alex

(0041446) Kitware Robot (administrator) 2016-06-10 14:27	Resolving issue as `moved`. This issue tracker is no longer used. Further discussion of this issue may take place in the current CMake Issues page linked in the banner at the top of this page.

Relationships