Re: [PATCH] Modify align-c/align-c++ test case for AIX

[Ulrich Weigand <Ulrich.Weigand@de.ibm.com>]

Aditya Kamath1 <Aditya.Kamath1@ibm.com> wrote:

>So clearly, linker optimises out unused global variables. More about the
>same can be read in the documentation
>{https://www.ibm.com/docs/en/aix/7.1?topic=l-ld-command } 

I see the -Wl,-bnogc option there, this makes sense.

I'm not sure why "-lodm -lcfg" should be necessary as well, this
doesn't really appear related to me.  Can you try without those?


>So I was thinking if we can pass these to our site.exp file if the target is AIX:
>
>set CC_FOR_TARGET "/opt/freeware/bin/gcc"
>set CXX_FOR_TARGET "/opt/freeware/bin/g++"
>set CXXFLAGS_FOR_TARGET "-O0 -w -g -gdwarf -maix64"
>set CFLAGS_FOR_TARGET "-O0 -w -g -gdwarf -maix64"
>
>with the options -Wl,-bnogc  -lodm -lcfg. 
>
>We also use -maix32 for testing in 32 bit mode as well. 
>
>I think this would be a better patch and in AIX we will not be seeing
>so many failures as we see now instead of the initial proposed ifdef patch.
>Only thing is we need to add this in a file which I am not aware of such
>that if the target is AIX we need to add these flags in the site.exp
>file so that while running test cases we get this file to pass these flags
>during the compilation of them. 

If the -bnogc flag is always necessary with the AIX linker, this
should be handled automatically by the test instead of via site.exp.

I'm assuming this is only needed with test files that use global
variables unused in the source code, but used by the debugger.
I think it would be best to explicitly add the flag to those tests
where it is needed.

For example, for the align-c tests, you can change the beginning
of run_alignment_test in gdb.base/align.exp.tcl to something like:

    set flags {debug}
    if { "$lang" == "c++" } {
        lappend flags "additional_flags=-std=c++11"
    }
    if { [istarget *-*-aix*] } {
        # Disable linker garbage collection to avoid optimizing
        # out global variables unused in the test source code.
        lappend flags "ldflags=-Wl,-bnogc"
    }
    standard_testfile $filename
    if {[prepare_for_testing "failed to prepare" "$testfile" $srcfile $flags]} {
        return -1
    }

Bye,
Ulrich