Re: [PATCHv2 1/2] aarch64: Do not give ABI change diagnostics for _BitInt(N)

["Andre Vieira (lists)" <andre.simoesdiasvieira@arm.com>]

[-- Attachment #1: Type: text/plain, Size: 5372 bytes --]

Hey,

Added the warn_pcs_change_le_gcc14 variable and changed the uses of 
warn_pcs_change to use this new variable.
Also fixed an issue with the loop through TREE_FIELDS to avoid an ICE 
during bootstrap.

OK for trunk?

Bootstrapped and regression tested on aarch64-unknown-linux-gnu.

Kind regards,
Andre

On 28/03/2024 12:54, Richard Sandiford wrote:
> "Andre Vieira (lists)" <andre.simoesdiasvieira@arm.com> writes:
>> This patch makes sure we do not give ABI change diagnostics for the ABI
>> breaks of GCC 9, 13 and 14 for any type involving _BitInt(N), since that
>> type did not exist before this GCC version.
>>
>> ChangeLog:
>>
>> 	* config/aarch64/aarch64.cc (bitint_or_aggr_of_bitint_p): New function.
>> 	(aarch64_layout_arg): Don't emit diagnostics for types involving
>> 	_BitInt(N).
>>
>> diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
>> index 1ea84c8bd7386e399f6ffa3a5e36408cf8831fc6..b68cf3e7cb9a6fa89b4e5826a39ffa11f64ca20a 100644
>> --- a/gcc/config/aarch64/aarch64.cc
>> +++ b/gcc/config/aarch64/aarch64.cc
>> @@ -6744,6 +6744,33 @@ aarch64_function_arg_alignment (machine_mode mode, const_tree type,
>>     return alignment;
>>   }
>>   
>> +/* Return true if TYPE describes a _BitInt(N) or an angreggate that uses the
>> +   _BitInt(N) type.  These include ARRAY_TYPE's with an element that is a
>> +   _BitInt(N) or an aggregate that uses it, and a RECORD_TYPE or a UNION_TYPE
>> +   with a field member that is a _BitInt(N) or an aggregate that uses it.
>> +   Return false otherwise.  */
>> +
>> +static bool
>> +bitint_or_aggr_of_bitint_p (tree type)
>> +{
>> +  if (!type)
>> +    return false;
>> +
>> +  if (TREE_CODE (type) == BITINT_TYPE)
>> +    return true;
>> +
>> +  /* If ARRAY_TYPE, check it's element type.  */
>> +  if (TREE_CODE (type) == ARRAY_TYPE)
>> +    return bitint_or_aggr_of_bitint_p (TREE_TYPE (type));
>> +
>> +  /* If RECORD_TYPE or UNION_TYPE, check the fields' types.  */
>> +  if (RECORD_OR_UNION_TYPE_P (type))
>> +    for (tree field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
>> +      if (bitint_or_aggr_of_bitint_p (TREE_TYPE (field)))
>> +	return true;
>> +  return false;
>> +}
>> +
>>   /* Layout a function argument according to the AAPCS64 rules.  The rule
>>      numbers refer to the rule numbers in the AAPCS64.  ORIG_MODE is the
>>      mode that was originally given to us by the target hook, whereas the
>> @@ -6767,12 +6794,6 @@ aarch64_layout_arg (cumulative_args_t pcum_v, const function_arg_info &arg)
>>     if (pcum->aapcs_arg_processed)
>>       return;
>>   
>> -  bool warn_pcs_change
>> -    = (warn_psabi
>> -       && !pcum->silent_p
>> -       && (currently_expanding_function_start
>> -	   || currently_expanding_gimple_stmt));
>> -
>>     /* HFAs and HVAs can have an alignment greater than 16 bytes.  For example:
>>   
>>          typedef struct foo {
>> @@ -6907,6 +6928,18 @@ aarch64_layout_arg (cumulative_args_t pcum_v, const function_arg_info &arg)
>>   	      && (!alignment || abi_break_gcc_9 < alignment)
>>   	      && (!abi_break_gcc_13 || alignment < abi_break_gcc_13));
>>   
>> +
>> +  bool warn_pcs_change
>> +    = (warn_psabi
>> +       && !pcum->silent_p
>> +       && (currently_expanding_function_start
>> +	   || currently_expanding_gimple_stmt)
>> +      /* warn_pcs_change is currently used to gate diagnostics in case of
>> +	 abi_break_gcc_{9,13,14}.  These however, do not apply to _BitInt(N)
>> +	 types as they were only introduced in GCC 14.  */
>> +       && (!type || !bitint_or_aggr_of_bitint_p (type)));
> 
> How about making this a new variable such as:
> 
>    /* _BitInt(N) was only added in GCC 14.  */
>    bool warn_pcs_change_le_gcc14
>      = (warn_psabi && !bitint_or_aggr_of_bitint_p (type);
> 
> (and keeping warn_pcs_change where it is).  In principle, warn_pcs_change
> is meaningful for any future ABI breaks, and we might forget that it
> excludes bitints.  The name is just a suggestion.
> 
> OK with that change, thanks.
> 
> Richard
> 
>> +
>> +
>>     /* allocate_ncrn may be false-positive, but allocate_nvrn is quite reliable.
>>        The following code thus handles passing by SIMD/FP registers first.  */
>>   
>> @@ -21266,19 +21299,25 @@ aarch64_gimplify_va_arg_expr (tree valist, tree type, gimple_seq *pre_p,
>>         rsize = ROUND_UP (size, UNITS_PER_WORD);
>>         nregs = rsize / UNITS_PER_WORD;
>>   
>> -      if (align <= 8 && abi_break_gcc_13 && warn_psabi)
>> +      if (align <= 8
>> +	  && abi_break_gcc_13
>> +	  && warn_psabi
>> +	  && !bitint_or_aggr_of_bitint_p (type))
>>   	inform (input_location, "parameter passing for argument of type "
>>   		"%qT changed in GCC 13.1", type);
>>   
>>         if (warn_psabi
>>   	  && abi_break_gcc_14
>> -	  && (abi_break_gcc_14 > 8 * BITS_PER_UNIT) != (align > 8))
>> +	  && (abi_break_gcc_14 > 8 * BITS_PER_UNIT) != (align > 8)
>> +	  && !bitint_or_aggr_of_bitint_p (type))
>>   	inform (input_location, "parameter passing for argument of type "
>>   		"%qT changed in GCC 14.1", type);
>>   
>>         if (align > 8)
>>   	{
>> -	  if (abi_break_gcc_9 && warn_psabi)
>> +	  if (abi_break_gcc_9
>> +	      && warn_psabi
>> +	      && !bitint_or_aggr_of_bitint_p (type))
>>   	    inform (input_location, "parameter passing for argument of type "
>>   		    "%qT changed in GCC 9.1", type);
>>   	  dw_align = true;

[-- Attachment #2: aarch64_bitint1v3.patch --]
[-- Type: text/plain, Size: 5329 bytes --]

diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc
index 1ea84c8bd7386e399f6ffa3a5e36408cf8831fc6..81400cc666472ffeff40df14e98ae00ebc774d31 100644
--- a/gcc/config/aarch64/aarch64.cc
+++ b/gcc/config/aarch64/aarch64.cc
@@ -6744,6 +6744,37 @@ aarch64_function_arg_alignment (machine_mode mode, const_tree type,
   return alignment;
 }
 
+/* Return true if TYPE describes a _BitInt(N) or an angreggate that uses the
+   _BitInt(N) type.  These include ARRAY_TYPE's with an element that is a
+   _BitInt(N) or an aggregate that uses it, and a RECORD_TYPE or a UNION_TYPE
+   with a field member that is a _BitInt(N) or an aggregate that uses it.
+   Return false otherwise.  */
+
+static bool
+bitint_or_aggr_of_bitint_p (tree type)
+{
+  if (!type)
+    return false;
+
+  if (TREE_CODE (type) == BITINT_TYPE)
+    return true;
+
+  /* If ARRAY_TYPE, check it's element type.  */
+  if (TREE_CODE (type) == ARRAY_TYPE)
+    return bitint_or_aggr_of_bitint_p (TREE_TYPE (type));
+
+  /* If RECORD_TYPE or UNION_TYPE, check the fields' types.  */
+  if (RECORD_OR_UNION_TYPE_P (type))
+    for (tree field = TYPE_FIELDS (type); field; field = TREE_CHAIN (field))
+      {
+	if (TREE_CODE (field) != FIELD_DECL)
+	  continue;
+	if (bitint_or_aggr_of_bitint_p (TREE_TYPE (field)))
+	  return true;
+      }
+  return false;
+}
+
 /* Layout a function argument according to the AAPCS64 rules.  The rule
    numbers refer to the rule numbers in the AAPCS64.  ORIG_MODE is the
    mode that was originally given to us by the target hook, whereas the
@@ -6907,6 +6938,11 @@ aarch64_layout_arg (cumulative_args_t pcum_v, const function_arg_info &arg)
 	      && (!alignment || abi_break_gcc_9 < alignment)
 	      && (!abi_break_gcc_13 || alignment < abi_break_gcc_13));
 
+  /* _BitInt(N) was only added in GCC 14.  */
+  bool warn_pcs_change_le_gcc14
+    = warn_pcs_change && !bitint_or_aggr_of_bitint_p (type);
+
+
   /* allocate_ncrn may be false-positive, but allocate_nvrn is quite reliable.
      The following code thus handles passing by SIMD/FP registers first.  */
 
@@ -6978,14 +7014,14 @@ aarch64_layout_arg (cumulative_args_t pcum_v, const function_arg_info &arg)
 	{
 	  /* Emit a warning if the alignment changed when taking the
 	     'packed' attribute into account.  */
-	  if (warn_pcs_change
+	  if (warn_pcs_change_le_gcc14
 	      && abi_break_gcc_13
 	      && ((abi_break_gcc_13 == 16 * BITS_PER_UNIT)
 		  != (alignment == 16 * BITS_PER_UNIT)))
 	    inform (input_location, "parameter passing for argument of type "
 		    "%qT changed in GCC 13.1", type);
 
-	  if (warn_pcs_change
+	  if (warn_pcs_change_le_gcc14
 	      && abi_break_gcc_14
 	      && ((abi_break_gcc_14 == 16 * BITS_PER_UNIT)
 		  != (alignment == 16 * BITS_PER_UNIT)))
@@ -6998,7 +7034,8 @@ aarch64_layout_arg (cumulative_args_t pcum_v, const function_arg_info &arg)
 	     passed by reference rather than value.  */
 	  if (alignment == 16 * BITS_PER_UNIT)
 	    {
-	      if (warn_pcs_change && abi_break_gcc_9)
+	      if (warn_pcs_change_le_gcc14
+		  && abi_break_gcc_9)
 		inform (input_location, "parameter passing for argument of type "
 			"%qT changed in GCC 9.1", type);
 	      ++ncrn;
@@ -7056,14 +7093,14 @@ aarch64_layout_arg (cumulative_args_t pcum_v, const function_arg_info &arg)
 on_stack:
   pcum->aapcs_stack_words = size / UNITS_PER_WORD;
 
-  if (warn_pcs_change
+  if (warn_pcs_change_le_gcc14
       && abi_break_gcc_13
       && ((abi_break_gcc_13 >= 16 * BITS_PER_UNIT)
 	  != (alignment >= 16 * BITS_PER_UNIT)))
     inform (input_location, "parameter passing for argument of type "
 	    "%qT changed in GCC 13.1", type);
 
-  if (warn_pcs_change
+  if (warn_pcs_change_le_gcc14
       && abi_break_gcc_14
       && ((abi_break_gcc_14 >= 16 * BITS_PER_UNIT)
 	  != (alignment >= 16 * BITS_PER_UNIT)))
@@ -7075,7 +7112,8 @@ on_stack:
       int new_size = ROUND_UP (pcum->aapcs_stack_size, 16 / UNITS_PER_WORD);
       if (pcum->aapcs_stack_size != new_size)
 	{
-	  if (warn_pcs_change && abi_break_gcc_9)
+	  if (warn_pcs_change_le_gcc14
+	      && abi_break_gcc_9)
 	    inform (input_location, "parameter passing for argument of type "
 		    "%qT changed in GCC 9.1", type);
 	  pcum->aapcs_stack_size = new_size;
@@ -21266,19 +21304,25 @@ aarch64_gimplify_va_arg_expr (tree valist, tree type, gimple_seq *pre_p,
       rsize = ROUND_UP (size, UNITS_PER_WORD);
       nregs = rsize / UNITS_PER_WORD;
 
-      if (align <= 8 && abi_break_gcc_13 && warn_psabi)
+      if (align <= 8
+	  && abi_break_gcc_13
+	  && warn_psabi
+	  && !bitint_or_aggr_of_bitint_p (type))
 	inform (input_location, "parameter passing for argument of type "
 		"%qT changed in GCC 13.1", type);
 
       if (warn_psabi
 	  && abi_break_gcc_14
-	  && (abi_break_gcc_14 > 8 * BITS_PER_UNIT) != (align > 8))
+	  && (abi_break_gcc_14 > 8 * BITS_PER_UNIT) != (align > 8)
+	  && !bitint_or_aggr_of_bitint_p (type))
 	inform (input_location, "parameter passing for argument of type "
 		"%qT changed in GCC 14.1", type);
 
       if (align > 8)
 	{
-	  if (abi_break_gcc_9 && warn_psabi)
+	  if (abi_break_gcc_9
+	      && warn_psabi
+	      && !bitint_or_aggr_of_bitint_p (type))
 	    inform (input_location, "parameter passing for argument of type "
 		    "%qT changed in GCC 9.1", type);
 	  dw_align = true;