[PATCH][gdb/tdep] Fix PowerPC IEEE 128-bit format arg passing

[Tom de Vries]

On 9/12/22 11:01, Tom de Vries wrote:
> Hi,
> 
> On a powerpc system with gcc 12 built to default to 128-bit IEEE long double,
> I run into:
> ...
> (gdb) print find_max_long_double_real(4, ldc1, ldc2, ldc3, ldc4)^M
> $8 = 0 + 0i^M
> (gdb) FAIL: gdb.base/varargs.exp: print \
>    find_max_long_double_real(4, ldc1, ldc2, ldc3, ldc4)
> ...
> 
> This is due to incorrect handling of the argument in ppc64_sysv_abi_push_param.
> 
> Fix this and similar cases, and expand the test-case to test handling of
> homogeneous aggregates.
> 
> Tested on ppc64le-linux, power 10.
> 
> Co-Authored-By: Ulrich Weigand <uweigand@de.ibm.com>
> Tested-by: Carl Love <cel@us.ibm.com>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29543
> 

Committed.

Thanks,
- Tom

> Any comments?
> 
> Thanks,
> - Tom
> 
> [gdb/tdep] Fix PowerPC IEEE 128-bit format arg passing
> 
> ---
>   gdb/ppc-sysv-tdep.c                | 25 +++++++++++++++++++------
>   gdb/testsuite/gdb.base/varargs.c   | 28 ++++++++++++++++++++++++++++
>   gdb/testsuite/gdb.base/varargs.exp |  2 ++
>   3 files changed, 49 insertions(+), 6 deletions(-)
> 
> diff --git a/gdb/ppc-sysv-tdep.c b/gdb/ppc-sysv-tdep.c
> index 1fe81b95f6c..78bb40e49e4 100644
> --- a/gdb/ppc-sysv-tdep.c
> +++ b/gdb/ppc-sysv-tdep.c
> @@ -1444,7 +1444,7 @@ ppc64_sysv_abi_push_param (struct gdbarch *gdbarch,
>   	  == floatformats_ieee_quad))
>       {
>         /* IEEE FLOAT128, args in vector registers.  */
> -      ppc64_sysv_abi_push_val (gdbarch, val, TYPE_LENGTH (type), 0, argpos);
> +      ppc64_sysv_abi_push_val (gdbarch, val, TYPE_LENGTH (type), 16, argpos);
>         ppc64_sysv_abi_push_vreg (gdbarch, val, argpos);
>       }
>     else if (type->code () == TYPE_CODE_FLT
> @@ -1514,7 +1514,10 @@ ppc64_sysv_abi_push_param (struct gdbarch *gdbarch,
>       }
>     else
>       {
> -      ppc64_sysv_abi_push_val (gdbarch, val, TYPE_LENGTH (type), 0, argpos);
> +      /* Align == 0 is correct for ppc64_sysv_abi_push_freg,
> +	 Align == 16 is correct for ppc64_sysv_abi_push_vreg.
> +	 Default to 0.	*/
> +      int align = 0;
>   
>         /* The ABI (version 1.9) specifies that structs containing a
>   	 single floating-point value, at any level of nesting of
> @@ -1532,7 +1535,10 @@ ppc64_sysv_abi_push_param (struct gdbarch *gdbarch,
>   	    if (TYPE_LENGTH (type) == 16
>   		&& (gdbarch_long_double_format (gdbarch)
>   		    == floatformats_ieee_quad))
> -	      ppc64_sysv_abi_push_vreg (gdbarch, val, argpos);
> +	      {
> +		ppc64_sysv_abi_push_vreg (gdbarch, val, argpos);
> +		align = 16;
> +	      }
>   	    else
>   	      ppc64_sysv_abi_push_freg (gdbarch, type, val, argpos);
>   	  }
> @@ -1556,8 +1562,10 @@ ppc64_sysv_abi_push_param (struct gdbarch *gdbarch,
>   		    && (gdbarch_long_double_format (gdbarch)
>   			== floatformats_ieee_quad))
>                    /* IEEE FLOAT128, args in vector registers.  */
> -                 ppc64_sysv_abi_push_vreg (gdbarch, elval, argpos);
> -
> +		  {
> +		    ppc64_sysv_abi_push_vreg (gdbarch, elval, argpos);
> +		    align = 16;
> +		  }
>   		else if (eltype->code () == TYPE_CODE_FLT
>                             || eltype->code () == TYPE_CODE_DECFLOAT)
>   		    /* IBM long double and all other floats and decfloats, args
> @@ -1567,9 +1575,14 @@ ppc64_sysv_abi_push_param (struct gdbarch *gdbarch,
>   			 && eltype->is_vector ()
>   			 && tdep->vector_abi == POWERPC_VEC_ALTIVEC
>   			 && TYPE_LENGTH (eltype) == 16)
> -		  ppc64_sysv_abi_push_vreg (gdbarch, elval, argpos);
> +		  {
> +		    ppc64_sysv_abi_push_vreg (gdbarch, elval, argpos);
> +		    align = 16;
> +		  }
>   	      }
>   	}
> +
> +      ppc64_sysv_abi_push_val (gdbarch, val, TYPE_LENGTH (type), align, argpos);
>       }
>   }
>   
> diff --git a/gdb/testsuite/gdb.base/varargs.c b/gdb/testsuite/gdb.base/varargs.c
> index cacb29d89e7..fcadcee6fb3 100644
> --- a/gdb/testsuite/gdb.base/varargs.c
> +++ b/gdb/testsuite/gdb.base/varargs.c
> @@ -45,6 +45,16 @@ long double _Complex ldc2 = 2.0L + 2.0Li;
>   long double _Complex ldc3 = 3.0L + 3.0Li;
>   long double _Complex ldc4 = 4.0L + 4.0Li;
>   
> +struct sldc
> +{
> +  long double _Complex ldc;
> +};
> +
> +struct sldc sldc1 = { 1.0L + 1.0Li };
> +struct sldc sldc2 = { 2.0L + 2.0Li };
> +struct sldc sldc3 = { 3.0L + 3.0Li };
> +struct sldc sldc4 = { 4.0L + 4.0Li };
> +
>   #endif
>   
>   int
> @@ -201,4 +211,22 @@ find_max_long_double_real (int num_vals, ...)
>   }
>   
>   
> +long double _Complex
> +find_max_struct_long_double_real (int num_vals, ...)
> +{
> +  long double _Complex max = 0.0L + 0.0iL;
> +  struct sldc x;
> +  va_list argp;
> +  int i;
> +
> +  va_start(argp, num_vals);
> +  for (i = 0; i < num_vals; i++)
> +    {
> +      x = va_arg (argp, struct sldc);
> +      if (creall (max) < creal (x.ldc)) max = x.ldc;
> +    }
> +
> +  return max;
> +}
> +
>   #endif /* TEST_COMPLEX */
> diff --git a/gdb/testsuite/gdb.base/varargs.exp b/gdb/testsuite/gdb.base/varargs.exp
> index 7bd2cb08207..7fa464f09ad 100644
> --- a/gdb/testsuite/gdb.base/varargs.exp
> +++ b/gdb/testsuite/gdb.base/varargs.exp
> @@ -103,4 +103,6 @@ if [support_complex_tests] {
>       set test "print find_max_long_double_real(4, ldc1, ldc2, ldc3, ldc4)"
>       gdb_test $test ".*= 4 \\+ 4i"
>   
> +    set test "print find_max_struct_long_double_real(4, sldc1, sldc2, sldc3, sldc4)"
> +    gdb_test $test ".*= 4 \\+ 4i"
>   }