Re: [PATCH 1/2] select .rodata for const volatile variables.

[Jeff Law <jeffreyalaw@gmail.com>]

On 1/9/23 00:57, Richard Biener wrote:
> On Mon, Dec 5, 2022 at 7:07 PM Jeff Law via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>>
>>
>> On 12/2/22 10:52, Cupertino Miranda via Gcc-patches wrote:
>>> Changed target code to select .rodata section for 'const volatile'
>>> defined variables.
>>> This change is in the context of the bugzilla #170181.
>>>
>>> gcc/ChangeLog:
>>>
>>>        v850.c(v850_select_section): Changed function.
>> I'm not sure this is safe/correct.  ISTM that you need to look at the
>> underlying TREE_TYPE to check for const-volatile rather than
>> TREE_SIDE_EFFECTS.
> 
> Just to quote tree.h:
> 
> /* In any expression, decl, or constant, nonzero means it has side effects or
>     reevaluation of the whole expression could produce a different value.
>     This is set if any subexpression is a function call, a side effect or a
>     reference to a volatile variable.  In a ..._DECL, this is set only if the
>     declaration said `volatile'.  This will never be set for a constant.  */
> #define TREE_SIDE_EFFECTS(NODE) \
>    (NON_TYPE_CHECK (NODE)->base.side_effects_flag)
> 
> so if exp is a decl then that's the volatile check.
Ah, then we can just use TREE_SIDE_EFFECTS for testing if a _DECL node 
is volatile.  So that concern is a non-issue.  I think that was the only 
concern with patch #1.  I'll install it momentarily.

Jeff