On Thu, Apr 14, 2011 at 7:09 AM, Richard Guenther
<richard.guent...@gmail.com> wrote:
> On Thu, Apr 14, 2011 at 4:01 PM, H.J. Lu <hjl.to...@gmail.com> wrote:
>> On Thu, Apr 14, 2011 at 6:57 AM, Richard Guenther
>> <richard.guent...@gmail.com> wrote:
>>> On Thu, Apr 14, 2011 at 3:34 PM, H.J. Lu <hongjiu...@intel.com> wrote:
>>>> We have
>>>>
>>>> static unsigned int
>>>> get_decl_align_unit (tree decl)
>>>> {
>>>> unsigned int align = LOCAL_DECL_ALIGNMENT (decl);
>>>> return align / BITS_PER_UNIT;
>>>> }
>>>>
>>>> LOCAL_DECL_ALIGNMENT may increase alignment for local variable. But it is
>>>> never saved. DECL_ALIGN (decl) returns the old alignment. This patch
>>>> updates DECL_ALIGN if needed. OK for trunk if there are no regressions?
>>>
>>> A get_* function does not seem like a good place to do such things.
>>
>> Any suggestion to how to do it properly? I can rename
>> get_decl_align_unit to align_local_variable.
>
> That works for me.
>
>>> Why does it matter that DECL_ALIGN is updated?
>>>
>>
>> My port needs accurate alignment information on local variables.
>
> I see.
Here is the updated patch. OK for trunk if there are no regressions?
Thanks.
--
H.J.
---
2011-04-14 H.J. Lu <hongjiu...@intel.com>
PR middle-end/48608
* cfgexpand.c (get_decl_align_unit): Renamed to ...
(align_local_variable): This. Update DECL_ALIGN if needed.
(add_stack_var): Updated.
(expand_one_stack_var): Likewise.
diff --git a/gcc/cfgexpand.c b/gcc/cfgexpand.c
index cc1382f..d38d2f9 100644
--- a/gcc/cfgexpand.c
+++ b/gcc/cfgexpand.c
@@ -205,13 +205,15 @@ static bool has_protected_decls;
smaller than our cutoff threshold. Used for -Wstack-protector. */
static bool has_short_buffer;
-/* Discover the byte alignment to use for DECL. Ignore alignment
+/* Compute the byte alignment to use for DECL. Ignore alignment
we can't do with expected alignment of the stack boundary. */
static unsigned int
-get_decl_align_unit (tree decl)
+align_local_variable (tree decl)
{
unsigned int align = LOCAL_DECL_ALIGNMENT (decl);
+ if (align > DECL_ALIGN (decl))
+ DECL_ALIGN (decl) = align;
return align / BITS_PER_UNIT;
}
@@ -273,7 +275,7 @@ add_stack_var (tree decl)
variables that are simultaneously live. */
if (v->size == 0)
v->size = 1;
- v->alignb = get_decl_align_unit (SSAVAR (decl));
+ v->alignb = align_local_variable (SSAVAR (decl));
/* All variables are initially in their own partition. */
v->representative = stack_vars_num;
@@ -905,7 +907,7 @@ expand_one_stack_var (tree var)
unsigned byte_align;
size = tree_low_cst (DECL_SIZE_UNIT (SSAVAR (var)), 1);
- byte_align = get_decl_align_unit (SSAVAR (var));
+ byte_align = align_local_variable (SSAVAR (var));
/* We handle highly aligned variables in expand_stack_vars. */
gcc_assert (byte_align * BITS_PER_UNIT <= MAX_SUPPORTED_STACK_ALIGNMENT);
