Re: [PATCH 5/5] gdb: native target invalid architecture detection

[Luis Machado <luis.machado@arm.com>]

On 6/7/22 21:15, Pedro Alves wrote:
> On 2022-06-07 19:42, Pedro Alves wrote:
> 
>>      When we use gcc for arm-linux target, its file name can be different,
>>      arm-linux-gnueabihf-gcc, arm-linux-gnueabi-gcc, or arm-none-linux-gnueabi-gcc,
>>      so I add a variable ARM_CC_FOR_TARGET, so that user can set the name
>>      of gcc for arm-linux target on aarch64, like:
> 
> ...
> 
>> Maybe it would be possible to come up with a way to default ARM_CC_FOR_TARGET to
>> something that works for most people when testing aarch64, somehow.
> 
> Maybe something like this?  Completely untested, other than hacking it such that
> the aarch64 linux path is taken on my x86-64 box, to ensure the tcl at least parses
> as expected.
> 

Thanks for the patch. I think it is fine to have some of these tests run conditionally
based on the presence of an environment variable. What we're really missing is proper
documentation of ARM_CC_FOR_TARGET, explaining what it does, when it should be enabled
and under what conditions.

I wonder if putting that on the GDB manual, under a testing section, would work. The Wiki
has an entry for testing, but I find it a bit chaotic. What do you say?

> I left arm-linux-gnueabihf-gcc last on the theory that binaries produced by
> arm-linux-gnueabi-gcc and arm-none-linux-gnueabi-gcc would run everywhere, but
> arm-linux-gnueabihf-gcc might now.  I am not really sure about that, I may be
> making that up.
> 
> gdb.multi/multi-arch-exec.exp also uses ARM_CC_FOR_TARGET.  If something like
> this works, then we could do the same to that testcase.  Even better if we
> manage to factor this out to a shared procedure used by both testcases.
> 
>  From 56cdd32a54b236d35c433809fcb015f20487dc4b Mon Sep 17 00:00:00 2001
> From: Pedro Alves <pedro@palves.net>
> Date: Tue, 7 Jun 2022 20:11:32 +0100
> Subject: [PATCH] aarch64: gdb.multi/multi-arch.exp: Add fallback if
>   ARM_CC_FOR_TARGET not set
> 
> On Aarch64, you can set ARM_CC_FOR_TARGET to the 32-bit compiler to
> use when testing gdb.multi/multi-arch.exp.  If you set it, then the
> testcase doesn't run.
> 
> I guess that approximately nobody remembers to set ARM_CC_FOR_TARGET.
> 
> This commit adds a fallback.  If ARM_CC_FOR_TARGET is not set, and
> testing for Linux, try arm-linux-gnueabi-gcc,
> arm-none-linux-gnueabi-gcc, arm-linux-gnueabihf-gcc.
> 
> Change-Id: Iefe5865d5fc84b4032eaff7f4c5c61582bf75c39
> ---
>   gdb/testsuite/gdb.multi/multi-arch.exp | 39 ++++++++++++++++++++++----
>   1 file changed, 34 insertions(+), 5 deletions(-)
> 
> diff --git a/gdb/testsuite/gdb.multi/multi-arch.exp b/gdb/testsuite/gdb.multi/multi-arch.exp
> index e5c2d9cc161..a9d442d89ad 100644
> --- a/gdb/testsuite/gdb.multi/multi-arch.exp
> +++ b/gdb/testsuite/gdb.multi/multi-arch.exp
> @@ -61,18 +61,47 @@ set options [list debug]
>   
>   if [istarget "aarch64*-*-*"] {
>       if {[info exists ARM_CC_FOR_TARGET]} {
> -	lappend options "compiler=${ARM_CC_FOR_TARGET}"
> +	set compilers [list ${ARM_CC_FOR_TARGET}]
> +    } elseif [istarget "*-linux*-*"] {
> +	# Try a few common compiler names.
> +	set compilers {
> +	    arm-linux-gnueabi-gcc
> +	    arm-none-linux-gnueabi-gcc
> +	    arm-linux-gnueabihf-gcc
> +	}
>       } else {
> +	set compilers {}
> +    }
> +
> +    set ok 0
> +    foreach compiler $compilers {
> +	set arm_options $options
> +	lappend arm_options "compiler=$compiler"
> +
> +	if {![is_remote host] && [which $compiler] == 0} {
> +	    # Avoid "default_target_compile: Can't find
> +	    # $compiler." warning issued from gdb_compile.
> +	    continue
> +	}
> +
> +	if { [gdb_compile "${srcdir}/${subdir}/${srcfile2}" ${exec2} \
> +		  executable $arm_options] == "" } {
> +	    set ok 1
> +	    break
> +	}
> +    }
> +
> +    if {!$ok} {
>   	unsupported "ARM compiler is not known"
>   	return -1
>       }
>   } else {
>       lappend options "additional_flags=${march2}"
> -}
>   
> -if { [build_executable "failed to prepare" ${exec2} "${srcfile2}" \
> -	 $options]} {
> -    return -1
> +    if { [build_executable "failed to prepare" ${exec2} "${srcfile2}" \
> +	      $options]} {
> +	return -1
> +    }
>   }
>   
>   # Start inferior 1
> 
> base-commit: 0c8cd1de90b97f12b27b40c2922a03a68932eea1