[PATCH] PR jit/66812: Candidate fix for for the code generation issue, v1

[Dibyendu Majumdar]

On 10 July 2015 at 01:14, Dibyendu Majumdar <mobile@majumdar.org.uk> wrote:
> On 10 July 2015 at 00:30, David Malcolm <dmalcolm@redhat.com> wrote:
>> On Thu, 2015-07-09 at 23:20 +0100, Dibyendu Majumdar wrote:
>>> On 9 July 2015 at 22:24, David Malcolm <dmalcolm@redhat.com> wrote:
>>> > On Thu, 2015-07-09 at 17:15 -0400, David Malcolm wrote:
>>> >> On Thu, 2015-07-09 at 17:06 -0400, David Malcolm wrote:
>>> >>
>>> >> (snip)
>>> >>
>>> >> > The fix will be to implement the LANG_HOOKS_GET_ALIAS_SET internal GCC
>>> >> > API thus giving libgccjit some rules about aliasing.  Some options:
>>> >> >
>>> >> > (i) make it identical to C.
>>> >> > (ii) give the client code some control over this
>>> >> >
>>> >> > My initial gut feeling is to go with (i).
>>> >>
>>> >> ...or possibly to do what the link-time optimizer does, which is to use
>>> >> this internal API:
>>> >>
>>> >> /* Return the typed-based alias set for T, which may be an expression
>>> >>    or a type.  Return -1 if we don't do anything special.  */
>>> >>
>>> >> alias_set_type
>>> >> gimple_get_alias_set (tree t)
>>> >>
>>> >> which does almost all of what the C frontend does.  I'll try to cook up
>>> >> a patch.
>>> >
>>> > Attached is a patch [1] which fixes the minimal reproducer I created,
>>> > and the reproducer you sent.
>>> >
>>> > Does it work for you?
>>> >
>>>
>>> I get this error when compiling:
>>>
>>> In file included from ../../gcc-5.1.0/gcc/jit/dummy-frontend.c:54:0:
>>> ../../gcc-5.1.0/gcc/gimple.h: In function ‘void
>>> gimple_call_set_fndecl(gimple, tree)’:
>>> ../../gcc-5.1.0/gcc/gimple.h:2769:77: error:
>>> ‘build_fold_addr_expr_loc’ was not declared in this scope
>>>    gimple_set_op (gs, 1, build_fold_addr_expr_loc (gimple_location (gs), decl));
>>>                                                                              ^
>>> Am I missing something?
>>
>> The patch was for trunk, where GCC's internal headers have been
>> reorganized, so we need different #includes for gcc-5-branch.
>>
>> Does the attached work?  (it compiles; I haven't tested it though)
>>
>
> The isolated test works. Now running the full Lua test suite.

Tests worked however performance degraded similar to when
-fno-strict-aliasing is used.

Regards
Dibyendu