Re: [PATCH 1/2] AArch64 AAPCS: Empty structs have non zero size in C++

[Pedro Alves <palves@redhat.com>]

On 01/16/2019 03:57 PM, Alan Hayward wrote:
> When gdb.base/infcall-nested-structs.c is complied as C++, the structs
> containing empty structs are no longer passed via float arguments.

This reads a bit ambiguously.  Which is it?

#1 - No longer passed by GCC, but GDB still passes.
#2 - No longer passed by GDB, but GCC still passes.

> This is because structs in C++ have a minimum size of 1.  This can then
> cause padding in the struct, which is disallowed for AAPCS.

Does this "disallowed" mean that structs with padding are
not allowed to be passed via float arguments?  Took me a while to
grok that.

It'd be good to clarify the commit log.

> +foreach l $lang {
> +    set dir "$l"
> +    remote_exec build "rm -rf [standard_output_file ${dir}]"
> +    remote_exec build "mkdir -p [standard_output_file ${dir}]"

I think these should be

   remote_exec host

not "build" ?

For remote-host testing, where the compiler and debugger run on the
host machine.

Could you please file a bug for the x86 internal errors, and
kfail the test for x86?

Otherwise looks fine to me.

Thanks,
Pedro Alves

> +}
> +
> +
>  set int_types { tc ts ti tl tll }
>  set float_types { tf td tld }
>  set complex_types { tfc tdc tldc }
> @@ -44,7 +58,7 @@ proc I2A { n } {
>  # types of the struct fields within the source.  Run up to main.
>  # Also updates the global "testfile" to reflect the most recent build.
>  
> -proc start_nested_structs_test { types } {
> +proc start_nested_structs_test { lang types } {
>      global testfile
>      global srcfile
>      global binfile
> @@ -53,9 +67,11 @@ proc start_nested_structs_test { types } {
>      global compile_flags
>  
>      standard_testfile .c
> +    set dir "$lang"
>  
>      # Create the additional flags
>      set flags $compile_flags
> +    lappend flags $lang
>  
>      for {set n 0} {$n<[llength ${types}]} {incr n} {
>  	set m [I2A ${n}]
> @@ -64,7 +80,7 @@ proc start_nested_structs_test { types } {
>  	append testfile "-" "$t"
>      }
>  
> -    set binfile [standard_output_file ${testfile}]
> +    set binfile [standard_output_file ${dir}/${testfile}]
>      if  { [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable "${flags}"] != "" } {
>  	unresolved "failed to compile"
>  	return 0
> @@ -125,48 +141,50 @@ proc run_tests {} {
>  # Set up a test prefix, compile the test binary, run to main, and then
>  # run some tests.
>  
> -proc start_gdb_and_run_tests { types } {
> +proc start_gdb_and_run_tests { lang types } {

>      set prefix "types"
>  
>      foreach t $types {
>  	append prefix "-" "${t}"
>      }
>  
> -    with_test_prefix $prefix {
> -	if { [start_nested_structs_test $types] } {
> -	    run_tests
> +    foreach_with_prefix l $lang {
> +	with_test_prefix $prefix {
> +	    if { [start_nested_structs_test $l $types] } {
> +		run_tests
> +	    }
>  	}
>      }
>  }
>  
>  foreach ta $int_types {
> -    start_gdb_and_run_tests $ta
> +    start_gdb_and_run_tests $lang $ta
>  }
>  
>  if [support_complex_tests] {
>      foreach ta $complex_types {
> -	start_gdb_and_run_tests $ta
> +	start_gdb_and_run_tests $lang $ta
>      }
>  }
>  
>  if ![gdb_skip_float_test] {
>      foreach ta $float_types {
> -	start_gdb_and_run_tests $ta
> +	start_gdb_and_run_tests $lang $ta
>      }
>  
>      foreach ta $int_types {
>  	foreach tb $float_types {
> -	    start_gdb_and_run_tests [list $ta $tb]
> +	    start_gdb_and_run_tests $lang [list $ta $tb]
>  	}
>      }
>  
>      foreach ta $float_types {
>  	foreach tb $int_types {
> -	    start_gdb_and_run_tests [list $ta $tb]
> +	    start_gdb_and_run_tests $lang [list $ta $tb]
>  	}
>  
>  	foreach tb $float_types {
> -	    start_gdb_and_run_tests [list $ta $tb]
> +	    start_gdb_and_run_tests $lang [list $ta $tb]
>  	}
>      }
>  }
>