PATCH: PR target/46195: r165965 regresses i386 darwin
H.J. Lu
hjl.tools@gmail.com
Fri Oct 29 13:41:00 GMT 2010
On Thu, Oct 28, 2010 at 11:56 PM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Thu, Oct 28, 2010 at 7:33 PM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>
>> On Darwin, although long double is aligned to 16byte, it is aligned to
>> 4byte when passed on stack.
>>
>> Jack, please try this on Darwin. OK for trunk if there are no
>> regressions on Darwin and Linux?
>>
>> Thanks.
>>
>>
>> H.J.
>> ---
>> 2010-10-28 H.J. Lu <hongjiu.lu@intel.com>
>>
>> PR target/46195
>> * config/i386/i386.c (bigger_than_4byte_aligned_p): New.
>> (ix86_function_arg_boundary): Align long double parameters on
>> stack to 4byte in 32bit.
>>
>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>> index f2bd705..02650df 100644
>> --- a/gcc/config/i386/i386.c
>> +++ b/gcc/config/i386/i386.c
>> @@ -7032,6 +7032,59 @@ ix86_old_function_arg_boundary (enum machine_mode mode, const_tree type,
>> return align;
>> }
>>
>> +/* Return true when aggregate TYPE should be aligned at bigger than
>> + 4byte for 32bit argument passing ABI. */
>> +
>> +static bool
>> +bigger_than_4byte_aligned_p (const_tree type)
>
> I propose to change the function prototype and name to:
>
> int ix86_alignment_needed (const_tree_type)
>
> and this function will return alignment (in bits), as is customary in gcc.
This function is a simplified version of contains_aligned_value_p,
which should return true/false.
>> +{
>> + enum machine_mode mode = TYPE_MODE (type);
>> +
>> + if (mode == XFmode || mode == XCmode)
>> + return false;
>> +
>> + if (TYPE_ALIGN (type) < 128)
>> + return false;
>> +
>> + if (!AGGREGATE_TYPE_P (type))
>> + return TYPE_ALIGN (type) >= 128;
>> + else
>> + {
>> + /* Walk the aggregates recursively. */
>> + switch (TREE_CODE (type))
>> + {
>> + case RECORD_TYPE:
>> + case UNION_TYPE:
>> + case QUAL_UNION_TYPE:
>> + {
>> + tree field;
>> +
>> + /* Walk all the structure fields. */
>> + for (field = TYPE_FIELDS (type);
>> + field;
>> + field = DECL_CHAIN (field))
>> + {
>> + if (TREE_CODE (field) == FIELD_DECL
>> + && bigger_than_4byte_aligned_p (TREE_TYPE (field)))
>> + return true;
>> + }
>> + break;
>> + }
>> +
>> + case ARRAY_TYPE:
>> + /* Just for use if some languages passes arrays by value. */
>> + if (bigger_than_4byte_aligned_p (TREE_TYPE (type)))
>> + return true;
>> + break;
>> +
>> + default:
>> + gcc_unreachable ();
>> + }
>> + }
>> +
>> + return false;
>> +}
>> +
>> /* Gives the alignment boundary, in bits, of an argument with the
>> specified mode and type. */
>>
>> @@ -7055,7 +7108,18 @@ ix86_function_arg_boundary (enum machine_mode mode, const_tree type)
>> static bool warned;
>> int saved_align = align;
>>
>> - if (!TARGET_64BIT && align < 128)
>> + /* i386 ABI defines all arguments to be 4 byte aligned. Even if
>> + long double is aligned to 16 byte, we always align it at 4
>> + byte, whether it is a scalar or the part of aggregate, when
>> + passed as function argument. */
>> + if (!TARGET_64BIT
>> + && (align < 128
>> + || (align == 128
>> + && (mode == XFmode
>> + || mode == XCmode
>> + || (type
>> + && AGGREGATE_TYPE_P (type)
>> + && !bigger_than_4byte_aligned_p (type))))))
>> align = PARM_BOUNDARY;
>
> There is something wrong with the usage of utility function if it has
> to be surrounded by soo much extra checks. I propose to change all
> this to:
>
> align = ix86_alignment_needed (type)
>
> where all the knowledge of type alignment will be moved into the
> ix86_alignment_needed function.
We have to check mode since type may be NULL. Long double
is a very special case for 32bit psABI where normal alignment of a
type/mode != its alignment when passed on stack. So we have
to check when normal alignment is 128 with the alignment of mode/type
is determined by long double.
Here is the updated patch I changed the new function name to
function_arg_128bit_aligned_32_p.
--
H.J.
---
2010-10-29 H.J. Lu <hongjiu.lu@intel.com>
PR target/46195
* config/i386/i386.c (function_arg_128bit_aligned_32_p): New.
(ix86_function_arg_boundary): Align long double parameters on
stack to 4byte in 32bit.
-------------- next part --------------
2010-10-29 H.J. Lu <hongjiu.lu@intel.com>
PR target/46195
* config/i386/i386.c (function_arg_128bit_aligned_32_p): New.
(ix86_function_arg_boundary): Align long double parameters on
stack to 4byte in 32bit.
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index f2bd705..d6bfd8e 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -7032,6 +7032,59 @@ ix86_old_function_arg_boundary (enum machine_mode mode, const_tree type,
return align;
}
+/* Return true when aggregate TYPE should be aligned at 128bit for
+ 32bit argument passing ABI. */
+
+static bool
+function_arg_128bit_aligned_32_p (const_tree type)
+{
+ enum machine_mode mode = TYPE_MODE (type);
+
+ if (mode == XFmode || mode == XCmode)
+ return false;
+
+ if (TYPE_ALIGN (type) < 128)
+ return false;
+
+ if (!AGGREGATE_TYPE_P (type))
+ return TYPE_ALIGN (type) >= 128;
+ else
+ {
+ /* Walk the aggregates recursively. */
+ switch (TREE_CODE (type))
+ {
+ case RECORD_TYPE:
+ case UNION_TYPE:
+ case QUAL_UNION_TYPE:
+ {
+ tree field;
+
+ /* Walk all the structure fields. */
+ for (field = TYPE_FIELDS (type);
+ field;
+ field = DECL_CHAIN (field))
+ {
+ if (TREE_CODE (field) == FIELD_DECL
+ && function_arg_128bit_aligned_32_p (TREE_TYPE (field)))
+ return true;
+ }
+ break;
+ }
+
+ case ARRAY_TYPE:
+ /* Just for use if some languages passes arrays by value. */
+ if (function_arg_128bit_aligned_32_p (TREE_TYPE (type)))
+ return true;
+ break;
+
+ default:
+ gcc_unreachable ();
+ }
+ }
+
+ return false;
+}
+
/* Gives the alignment boundary, in bits, of an argument with the
specified mode and type. */
@@ -7055,7 +7108,18 @@ ix86_function_arg_boundary (enum machine_mode mode, const_tree type)
static bool warned;
int saved_align = align;
- if (!TARGET_64BIT && align < 128)
+ /* i386 ABI defines all arguments to be 4 byte aligned. Even if
+ long double is aligned to 16 byte, we always align it at 4
+ byte, whether it is a scalar or the part of aggregate, when
+ passed as function argument. */
+ if (!TARGET_64BIT
+ && (align < 128
+ || (align == 128
+ && (mode == XFmode
+ || mode == XCmode
+ || (type
+ && AGGREGATE_TYPE_P (type)
+ && !function_arg_128bit_aligned_32_p (type))))))
align = PARM_BOUNDARY;
if (warn_psabi
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