Re: Errors when invoking refs_may_alias_p_1

[Richard Guenther <richard dot guenther at gmail dot com>]

On Fri, Aug 27, 2010 at 8:37 PM, Hongtao <yu171@purdue.edu> wrote:
> On 08/27/10 14:29, Richard Guenther wrote:
>> On Fri, Aug 27, 2010 at 8:24 PM, Hongtao <yu171@purdue.edu> wrote:
>>
>>> On 08/27/10 12:35, Richard Guenther wrote:
>>>
>>>> On Fri, Aug 27, 2010 at 5:27 PM, Hongtao <yu171@purdue.edu> wrote:
>>>>
>>>>
>>>>> Hi all,
>>>>>
>>>>> I have instrumented a function call like foo(&a,&b) into the gimple SSA
>>>>> representation (gcc-4.5) and the consequent optimizations can not pass
>>>>> my instrumented code. The back traces are as followings. The error
>>>>> occurred when the pass dse tried to test if the call I inserted may use
>>>>> a memory reference. It is because the arguments &a is not a SSA_VAR or
>>>>> INDIRECT_REF, so the assert in function
>>>>>
>>>>> bool
>>>>> refs_may_alias_p_1 (ao_ref *ref1, ao_ref *ref2, bool tbaa_p)
>>>>>
>>>>> ?gcc_assert ((!ref1->ref
>>>>> ? ? ? ? ? || SSA_VAR_P (ref1->ref)
>>>>> ? ? ? ? ? || handled_component_p (ref1->ref)
>>>>> ? ? ? ? ? || INDIRECT_REF_P (ref1->ref)
>>>>> ? ? ? ? ? || TREE_CODE (ref1->ref) == TARGET_MEM_REF
>>>>> ? ? ? ? ? || TREE_CODE (ref1->ref) == CONST_DECL)
>>>>> ? ? ? ? ?&& (!ref2->ref
>>>>> ? ? ? ? ?|| SSA_VAR_P (ref2->ref)
>>>>> ? ? ? ? ?|| handled_component_p (ref2->ref)
>>>>> ? ? ? ? ?|| INDIRECT_REF_P (ref2->ref)
>>>>> ? ? ? ? ?|| TREE_CODE (ref2->ref) == TARGET_MEM_REF
>>>>> ? ? ? ? ?|| TREE_CODE (ref2->ref) == CONST_DECL));
>>>>> was violated.
>>>>>
>>>>> Does anyone know why the function arguments must be a SSA_VAR or
>>>>> INDIRECT_REF here? Have I missed to perform any actions to maintain the
>>>>> consistency of Gimple SSA?
>>>>>
>>>>>
>>>> Yes. ?is_gimple_val () will return false for your arguments as it seems that
>>>> the variables do not have function invariant addresses.
>>>>
>>>> Richard.
>>>>
>>>>
>>>>
>>> Thanks. But how can I change my argument to gimple_vals, using it with
>>> an assignment to a temp before and replacing my argument with the temp?
>>>
>> Yes, that will work.
>>
>> Richard.
>>
>>
> OK. Do we have to rewrite it like this everytime we insert a function
> call on Gimple body if the argument of that call is an expression?

If it isn't is_gimple_reg_type (TREE_TYPE (arg)) ? is_gimple_val (arg)
: is_gimple_lvalue (arg), then yes.  See gimplify_arg in gimplify.c.

Richard.

> Thanks,
> Hongtao
>
>>> Hongtao
>>>
>>>>> #0 ?0x00007ffff6fc8ee0 in exit () from /lib/libc.so.6
>>>>> #1 ?0x00000000005ae4ce in diagnostic_action_after_output
>>>>> (context=0x1323880, diagnostic=0x7fffffffd870) at
>>>>> ../../src/gcc/diagnostic.c:198
>>>>> #2 ?0x00000000005aed54 in diagnostic_report_diagnostic
>>>>> (context=0x1323880, diagnostic=0x7fffffffd870) at
>>>>> ../../src/gcc/diagnostic.c:424
>>>>> #3 ?0x00000000005afdc3 in internal_error (gmsgid=0xddfb57 "in %s, at
>>>>> %s:%d") at ../../src/gcc/diagnostic.c:709
>>>>> #4 ?0x00000000005aff4f in fancy_abort (file=0xe42670
>>>>> "../../src/gcc/tree-ssa-alias.c", line=786, function=0xe427e0
>>>>> "refs_may_alias_p_1")
>>>>> ? ?at ../../src/gcc/diagnostic.c:763
>>>>> #5 ?0x00000000008a1adb in refs_may_alias_p_1 (ref1=0x7fffffffdab0,
>>>>> ref2=0x7fffffffdb50, tbaa_p=1 '\001')
>>>>> ? ?at ../../src/gcc/tree-ssa-alias.c:775
>>>>> #6 ?0x00000000008a2b12 in ref_maybe_used_by_call_p_1
>>>>> (call=0x7ffff6790630, ref=0x7fffffffdb50) at
>>>>> ../../src/gcc/tree-ssa-alias.c:1133
>>>>> #7 ?0x00000000008a2d2e in ref_maybe_used_by_call_p (call=0x7ffff6790630,
>>>>> ref=0x7ffff6848048) at ../../src/gcc/tree-ssa-alias.c:1147
>>>>> #8 ?0x00000000008a2dfa in ref_maybe_used_by_stmt_p (stmt=0x7ffff6790630,
>>>>> ref=0x7ffff6848048) at ../../src/gcc/tree-ssa-alias.c:1179
>>>>> #9 ?0x00000000008bf275 in dse_possible_dead_store_p
>>>>> (stmt=0x7ffff683e820, use_stmt=0x7fffffffdca8) at
>>>>> ../../src/gcc/tree-ssa-dse.c:212
>>>>> #10 0x00000000008bfeb9 in dse_optimize_stmt (dse_gd=0x7fffffffddd0,
>>>>> bd=0x156bd30, gsi=...) at ../../src/gcc/tree-ssa-dse.c:297
>>>>> #11 0x00000000008c029d in dse_enter_block (walk_data=0x7fffffffdde0,
>>>>> bb=0x7ffff6a75068) at ../../src/gcc/tree-ssa-dse.c:370
>>>>> #12 0x0000000000cc26a5 in walk_dominator_tree (walk_data=0x7fffffffdde0,
>>>>> bb=0x7ffff6a75068) at ../../src/gcc/domwalk.c:185
>>>>> #13 0x00000000008c0812 in tree_ssa_dse () at
>>>>> ../../src/gcc/tree-ssa-dse.c:430
>>>>> #14 0x000000000073af0a in execute_one_pass (pass=0x13cced0) at
>>>>> ../../src/gcc/passes.c:1572
>>>>> #15 0x000000000073b21a in execute_pass_list (pass=0x13cced0) at
>>>>> ../../src/gcc/passes.c:1627
>>>>> #16 0x000000000073b238 in execute_pass_list (pass=0x1312720) at
>>>>> ../../src/gcc/passes.c:1628
>>>>> #17 0x000000000086e372 in tree_rest_of_compilation
>>>>> (fndecl=0x7ffff6b93500) at ../../src/gcc/tree-optimize.c:413
>>>>> #18 0x00000000009fa7c5 in cgraph_expand_function (node=0x7ffff6be7000)
>>>>> at ../../src/gcc/cgraphunit.c:1548
>>>>> #19 0x00000000009faa49 in cgraph_expand_all_functions () at
>>>>> ../../src/gcc/cgraphunit.c:1627
>>>>> #20 0x00000000009fb07e in cgraph_optimize () at
>>>>> ../../src/gcc/cgraphunit.c:1875
>>>>> #21 0x00000000009f9461 in cgraph_finalize_compilation_unit () at
>>>>> ../../src/gcc/cgraphunit.c:1096
>>>>> #22 0x00000000004a9e93 in c_write_global_declarations () at
>>>>> ../../src/gcc/c-decl.c:9519
>>>>> #23 0x00000000008180d4 in compile_file () at ../../src/gcc/toplev.c:1065
>>>>> #24 0x000000000081a1c5 in do_compile () at ../../src/gcc/toplev.c:2417
>>>>> #25 0x000000000081a286 in toplev_main (argc=21, argv=0x7fffffffe0f8) at
>>>>> ../../src/gcc/toplev.c:2459
>>>>> #26 0x0000000000519c6b in main (argc=21, argv=0x7fffffffe0f8) at
>>>>> ../../src/gcc/main.c:35
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Hongtao
>>>>> Purdue University
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>