[ping][PATCH][1 of 2] Add value range info to SSA_NAME for zero sign extension elimination in RTL
Kugan
kugan.vivekanandarajah@linaro.org
Mon Sep 2 09:31:00 GMT 2013
I'd like to ping this patch 1 of 2 that removes redundant zero/sign
extension using value range information.
Bootstrapped and no new regression for x86_64-unknown-linux-gnu and
arm-none-linux-gnueabi.
Thanks you for your time.
Kugan
n 14/08/13 16:49, Kugan wrote:
> Hi Richard,
>
> Here is an attempt to address your earlier review comments. Bootstrapped
> and there is no new regression for X86_64 and arm. Thank you very much
> for your time.
>
> Thanks,
> Kugan
>
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,25 @@
> +2013-08-14 Kugan Vivekanandarajah <kuganv@linaro.org>
> +
> + * tree-flow.h (mark_range_info_unknown): New function definition.
> + * tree-ssa-alias.c (dump_alias_info) : Check pointer type.
> + * tree-ssa-copy.c (fini_copy_prop) : Check pointer type and copy
> + range info.
> + * tree-ssanames.c (make_ssa_name_fn) : Check pointer type in
> + initialize.
> + * (mark_range_info_unknown) : New function.
> + * (duplicate_ssa_name_range_info) : Likewise.
> + * (duplicate_ssa_name_fn) : Check pointer type and call correct
> + duplicate function.
> + * tree-vrp.c (extract_exp_value_range): New function.
> + * (simplify_stmt_using_ranges): Call extract_exp_value_range and
> + tree_ssa_set_value_range.
> + * tree-ssaname.c (ssa_range_info): New function.
> + * tree.h (SSA_NAME_PTR_INFO) : changed to access via union
> + * tree.h (SSA_NAME_RANGE_INFO) : New macro
> + * gimple-pretty-print.c (print_double_int) : New function.
> + * gimple-pretty-print.c (dump_gimple_phi) : Dump range info.
> + * (pp_gimple_stmt_1) : Likewise.
> +
> 2013-08-09 Jan Hubicka <jh@suse.cz>
>
> * cgraph.c (cgraph_create_edge_1): Clear speculative flag.
>
> On 03/07/13 21:55, Kugan wrote:
>> On 17/06/13 18:33, Richard Biener wrote:
>>> On Mon, 17 Jun 2013, Kugan wrote:
>>> +/* Extract the value range of assigned exprassion for GIMPLE_ASSIGN
>>> stmt.
>>> + If the extracted value range is valid, return true else return
>>> + false. */
>>> +static bool
>>> +extract_exp_value_range (gimple stmt, value_range_t *vr)
>>> +{
>>> + gcc_assert (is_gimple_assign (stmt));
>>> + tree rhs1 = gimple_assign_rhs1 (stmt);
>>> + tree lhs = gimple_assign_lhs (stmt);
>>> + enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
>>> ...
>>> @@ -8960,6 +9016,23 @@ simplify_stmt_using_ranges (gimple_stmt_iterator
>>> *gsi)
>>> {
>>> enum tree_code rhs_code = gimple_assign_rhs_code (stmt);
>>> tree rhs1 = gimple_assign_rhs1 (stmt);
>>> + tree lhs = gimple_assign_lhs (stmt);
>>> +
>>> + /* Set value range information for ssa. */
>>> + if (!POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt)))
>>> + && (TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME)
>>> + && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt)))
>>> + && !SSA_NAME_RANGE_INFO (lhs))
>>> + {
>>> + value_range_t vr = VR_INITIALIZER;
>>> ...
>>> + if (extract_exp_value_range (stmt, &vr))
>>> + tree_ssa_set_value_range (lhs,
>>> + tree_to_double_int (vr.min),
>>> + tree_to_double_int (vr.max),
>>> + vr.type == VR_RANGE);
>>> + }
>>>
>>> This looks overly complicated to me. In vrp_finalize you can simply do
>>>
>>> for (i = 0; i < num_vr_values; i++)
>>> if (vr_value[i])
>>> {
>>> tree name = ssa_name (i);
>>> if (POINTER_TYPE_P (name))
>>> continue;
>>> if (vr_value[i].type == VR_RANGE
>>> || vr_value[i].type == VR_ANTI_RANGE)
>>> tree_ssa_set_value_range (name, tree_to_double_int
>>> (vr_value[i].min), tree_to_double_int (vr_value[i].max),
>>> vr_value[i].type
>>> == VR_RANGE);
>>> }
>>>
>>
>> Thanks Richard for taking time to review it.
>>
>> I was doing something like what you are suggesting earlier but noticed
>> some problems and thatÂ’s the reason why I changed.
>>
>> For example, for the following testcase from the test suite,
>>
>> unsigned long l = (unsigned long)-2;
>> unsigned short s;
>>
>> int main () {
>> long t = l + 1;
>> s = l;
>> if (s != (unsigned short) -2)
>> abort ();
>> exit (0);
>> }
>>
>> with the following gimple stmts
>>
>> main ()
>> {
>> short unsigned int s.1;
>> long unsigned int l.0;
>>
>> ;; basic block 2, loop depth 0
>> ;; pred: ENTRY
>> l.0_2 = l;
>> s.1_3 = (short unsigned int) l.0_2;
>> s = s.1_3;
>> if (s.1_3 != 65534)
>> goto <bb 3>;
>> else
>> goto <bb 4>;
>> ;; succ: 3
>> ;; 4
>>
>> ;; basic block 3, loop depth 0
>> ;; pred: 2
>> abort ();
>> ;; succ:
>>
>> ;; basic block 4, loop depth 0
>> ;; pred: 2
>> exit (0);
>> ;; succ:
>>
>> }
>>
>>
>>
>> has the following value range.
>>
>> l.0_2: VARYING
>> s.1_3: [0, +INF]
>>
>>
>> From zero/sign extension point of view, the variable s.1_3 is expected
>> to have a value that will overflow (or varying) as this is what is
>> assigned to a smaller variable. extract_range_from_assignment initially
>> calculates the value range as VARYING but later changed to [0, +INF] by
>> extract_range_basic. What I need here is the value that will be assigned
>> from the rhs expression and not the value that we will have with proper
>> assignment.
>>
>> I understand that the above code of mine needs to be changed but not
>> convinced about the best way to do that.
>>
>> I can possibly re-factor extract_range_from_assignment to give me this
>> information with an additional argument. Could you kindly let me know
>> your preference.
>>
>
>>>
>>> /* SSA name annotations. */
>>>
>>> + union vrp_info_type {
>>> + /* Pointer attributes used for alias analysis. */
>>> + struct GTY ((tag ("TREE_SSA_PTR_INFO"))) ptr_info_def *ptr_info;
>>> + /* Value range attributes used for zero/sign extension elimination.
>>> */
>>>
>>> /* Value range information. */
>>>
>>> + struct GTY ((tag ("TREE_SSA_RANGE_INFO"))) range_info_def
>>> *range_info;
>>> + } GTY ((desc ("%1.def_stmt && !POINTER_TYPE_P (TREE_TYPE
>>> ((tree)&%1))"))) vrp;
>>>
>>> why do you need to test %1.def_stmt here?
>>
>>
>> I have seen some tree_ssa_name with def_stmt NULL. Thats why I added
>> this. Is that something that should never happen.
>>
>>
>> Thanks,
>> Kugan
>
>
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