On June 9, 2017 5:32:10 PM GMT+02:00, Christophe Lyon
<christophe.l...@linaro.org> wrote:
>On 8 June 2017 at 15:49, Richard Biener <rguent...@suse.de> wrote:
>> On Thu, 8 Jun 2017, Richard Biener wrote:
>>
>>>
>>> The following fixes unsafe vectorization of reductions in outer loop
>>> vectorization. It combines it with a bit of cleanup in the affected
>>> function.
>>>
>>> Bootstrap and regtest running on x86_64-unknown-linux-gnu.
>>
>> Re-testing the following variant -- multiple loop-closed PHI nodes
>> for the same SSA name happen.
>>
>> Richard.
>>
>> 2017-06-08 Richard Biener <rguent...@suse.de>
>>
>> PR tree-optimization/66623
>> * tree-vect-loop.c (vect_is_simple_reduction): Cleanup,
>> refactor check_reduction into two parts, properly computing
>> whether we have to check reduction validity for outer loop
>> vectorization.
>>
>> * gcc.dg/vect/pr66623.c: New testcase.
>>
>
>Hi Richard,
>
>The new testcase fails on armeb* targets:
>FAIL: gcc.dg/vect/pr66623.c -flto -ffat-lto-objects execution test
>FAIL: gcc.dg/vect/pr66623.c execution test
Ah, the xfail probably isn't enough. Can you try a dg-skip or so?
>Christophe
>
>
>> Index: gcc/tree-vect-loop.c
>> ===================================================================
>> --- gcc/tree-vect-loop.c (revision 249007)
>> +++ gcc/tree-vect-loop.c (working copy)
>> @@ -2727,8 +2727,6 @@ vect_is_simple_reduction (loop_vec_info
>> {
>> struct loop *loop = (gimple_bb (phi))->loop_father;
>> struct loop *vect_loop = LOOP_VINFO_LOOP (loop_info);
>> - edge latch_e = loop_latch_edge (loop);
>> - tree loop_arg = PHI_ARG_DEF_FROM_EDGE (phi, latch_e);
>> gimple *def_stmt, *def1 = NULL, *def2 = NULL, *phi_use_stmt =
>NULL;
>> enum tree_code orig_code, code;
>> tree op1, op2, op3 = NULL_TREE, op4 = NULL_TREE;
>> @@ -2742,11 +2740,6 @@ vect_is_simple_reduction (loop_vec_info
>> *double_reduc = false;
>> *v_reduc_type = TREE_CODE_REDUCTION;
>>
>> - /* Check validity of the reduction only for the innermost loop.
>*/
>> - bool check_reduction = ! flow_loop_nested_p (vect_loop, loop);
>> - gcc_assert ((check_reduction && loop == vect_loop)
>> - || (!check_reduction && flow_loop_nested_p (vect_loop,
>loop)));
>> -
>> name = PHI_RESULT (phi);
>> /* ??? If there are no uses of the PHI result the inner loop
>reduction
>> won't be detected as possibly double-reduction by
>vectorizable_reduction
>> @@ -2775,13 +2768,15 @@ vect_is_simple_reduction (loop_vec_info
>> {
>> if (dump_enabled_p ())
>> dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> - "reduction used in loop.\n");
>> + "reduction value used in loop.\n");
>> return NULL;
>> }
>>
>> phi_use_stmt = use_stmt;
>> }
>>
>> + edge latch_e = loop_latch_edge (loop);
>> + tree loop_arg = PHI_ARG_DEF_FROM_EDGE (phi, latch_e);
>> if (TREE_CODE (loop_arg) != SSA_NAME)
>> {
>> if (dump_enabled_p ())
>> @@ -2795,18 +2790,22 @@ vect_is_simple_reduction (loop_vec_info
>> }
>>
>> def_stmt = SSA_NAME_DEF_STMT (loop_arg);
>> - if (!def_stmt)
>> + if (gimple_nop_p (def_stmt))
>> {
>> if (dump_enabled_p ())
>> dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> - "reduction: no def_stmt.\n");
>> + "reduction: no def_stmt\n");
>> return NULL;
>> }
>>
>> if (!is_gimple_assign (def_stmt) && gimple_code (def_stmt) !=
>GIMPLE_PHI)
>> {
>> if (dump_enabled_p ())
>> - dump_gimple_stmt (MSG_NOTE, TDF_SLIM, def_stmt, 0);
>> + {
>> + dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
>> + "reduction: unhandled reduction operation:
>");
>> + dump_gimple_stmt (MSG_MISSED_OPTIMIZATION, TDF_SLIM,
>def_stmt, 0);
>> + }
>> return NULL;
>> }
>>
>> @@ -2822,6 +2821,7 @@ vect_is_simple_reduction (loop_vec_info
>> }
>>
>> nloop_uses = 0;
>> + auto_vec<gphi *, 3> lcphis;
>> FOR_EACH_IMM_USE_FAST (use_p, imm_iter, name)
>> {
>> gimple *use_stmt = USE_STMT (use_p);
>> @@ -2829,6 +2829,9 @@ vect_is_simple_reduction (loop_vec_info
>> continue;
>> if (flow_bb_inside_loop_p (loop, gimple_bb (use_stmt)))
>> nloop_uses++;
>> + else
>> + /* We can have more than one loop-closed PHI. */
>> + lcphis.safe_push (as_a <gphi *> (use_stmt));
>> if (nloop_uses > 1)
>> {
>> if (dump_enabled_p ())
>> @@ -2873,6 +2876,27 @@ vect_is_simple_reduction (loop_vec_info
>> return NULL;
>> }
>>
>> + /* If we are vectorizing an inner reduction we are executing that
>> + in the original order only in case we are not dealing with a
>> + double reduction. */
>> + bool check_reduction = true;
>> + if (flow_loop_nested_p (vect_loop, loop))
>> + {
>> + gphi *lcphi;
>> + unsigned i;
>> + check_reduction = false;
>> + FOR_EACH_VEC_ELT (lcphis, i, lcphi)
>> + FOR_EACH_IMM_USE_FAST (use_p, imm_iter, gimple_phi_result
>(lcphi))
>> + {
>> + gimple *use_stmt = USE_STMT (use_p);
>> + if (is_gimple_debug (use_stmt))
>> + continue;
>> + if (! flow_bb_inside_loop_p (vect_loop, gimple_bb
>(use_stmt)))
>> + check_reduction = true;
>> + }
>> + }
>> +
>> + bool nested_in_vect_loop = flow_loop_nested_p (vect_loop, loop);
>> code = orig_code = gimple_assign_rhs_code (def_stmt);
>>
>> /* We can handle "res -= x[i]", which is non-associative by
>> @@ -2887,27 +2911,8 @@ vect_is_simple_reduction (loop_vec_info
>>
>> if (code == COND_EXPR)
>> {
>> - if (check_reduction)
>> + if (! nested_in_vect_loop)
>> *v_reduc_type = COND_REDUCTION;
>> - }
>> - else if (!commutative_tree_code (code) || !associative_tree_code
>(code))
>> - {
>> - if (dump_enabled_p ())
>> - report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> - "reduction: not commutative/associative: ");
>> - return NULL;
>> - }
>> -
>> - if (get_gimple_rhs_class (code) != GIMPLE_BINARY_RHS)
>> - {
>> - if (code != COND_EXPR)
>> - {
>> - if (dump_enabled_p ())
>> - report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> - "reduction: not binary operation: ");
>> -
>> - return NULL;
>> - }
>>
>> op3 = gimple_assign_rhs1 (def_stmt);
>> if (COMPARISON_CLASS_P (op3))
>> @@ -2918,30 +2923,35 @@ vect_is_simple_reduction (loop_vec_info
>>
>> op1 = gimple_assign_rhs2 (def_stmt);
>> op2 = gimple_assign_rhs3 (def_stmt);
>> -
>> - if (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op2) !=
>SSA_NAME)
>> - {
>> - if (dump_enabled_p ())
>> - report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> - "reduction: uses not ssa_names: ");
>> -
>> - return NULL;
>> - }
>> }
>> - else
>> + else if (!commutative_tree_code (code) || !associative_tree_code
>(code))
>> + {
>> + if (dump_enabled_p ())
>> + report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> + "reduction: not commutative/associative: ");
>> + return NULL;
>> + }
>> + else if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS)
>> {
>> op1 = gimple_assign_rhs1 (def_stmt);
>> op2 = gimple_assign_rhs2 (def_stmt);
>> + }
>> + else
>> + {
>> + if (dump_enabled_p ())
>> + report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> + "reduction: not handled operation: ");
>> + return NULL;
>> + }
>>
>> - if (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op2) !=
>SSA_NAME)
>> - {
>> - if (dump_enabled_p ())
>> - report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> - "reduction: uses not ssa_names: ");
>> + if (TREE_CODE (op1) != SSA_NAME && TREE_CODE (op2) != SSA_NAME)
>> + {
>> + if (dump_enabled_p ())
>> + report_vect_op (MSG_MISSED_OPTIMIZATION, def_stmt,
>> + "reduction: both uses not ssa_names: ");
>>
>> - return NULL;
>> - }
>> - }
>> + return NULL;
>> + }
>>
>> type = TREE_TYPE (gimple_assign_lhs (def_stmt));
>> if ((TREE_CODE (op1) == SSA_NAME
>> @@ -3091,7 +3101,7 @@ vect_is_simple_reduction (loop_vec_info
>> == vect_internal_def
>> && !is_loop_header_bb_p (gimple_bb (def2)))))))
>> {
>> - if (check_reduction && orig_code != MINUS_EXPR)
>> + if (! nested_in_vect_loop && orig_code != MINUS_EXPR)
>> {
>> /* Check if we can swap operands (just for simplicity - so
>that
>> the rest of the code can assume that the reduction
>variable
>> @@ -3145,7 +3155,8 @@ vect_is_simple_reduction (loop_vec_info
>> }
>>
>> /* Try to find SLP reduction chain. */
>> - if (check_reduction && code != COND_EXPR
>> + if (! nested_in_vect_loop
>> + && code != COND_EXPR
>> && vect_is_slp_reduction (loop_info, phi, def_stmt))
>> {
>> if (dump_enabled_p ())
>> Index: gcc/testsuite/gcc.dg/vect/pr66623.c
>> ===================================================================
>> --- gcc/testsuite/gcc.dg/vect/pr66623.c (revision 0)
>> +++ gcc/testsuite/gcc.dg/vect/pr66623.c (working copy)
>> @@ -0,0 +1,86 @@
>> +/* { dg-require-effective-target vect_float } */
>> +
>> +#include "tree-vect.h"
>> +
>> +extern void abort (void);
>> +
>> +#define OP *
>> +#define INIT 1.0
>> +
>> +float __attribute__((noinline,noclone))
>> +foo (float *__restrict__ i)
>> +{
>> + float l = INIT;
>> + int a;
>> + int b;
>> +
>> + for (a = 0; a < 4; a++)
>> + for (b = 0; b < 4; b++)
>> + l = l OP i[b];
>> +
>> + return l;
>> +}
>> +
>> +float __attribute__((noinline,noclone))
>> +foo_ref (float *__restrict__ i)
>> +{
>> + float l = INIT;
>> +
>> + l = l OP i[0];
>> + l = l OP i[1];
>> + l = l OP i[2];
>> + l = l OP i[3];
>> +
>> + l = l OP i[0];
>> + l = l OP i[1];
>> + l = l OP i[2];
>> + l = l OP i[3];
>> +
>> + l = l OP i[0];
>> + l = l OP i[1];
>> + l = l OP i[2];
>> + l = l OP i[3];
>> +
>> + l = l OP i[0];
>> + l = l OP i[1];
>> + l = l OP i[2];
>> + l = l OP i[3];
>> +
>> + return l;
>> +}
>> +
>> +union u
>> +{
>> + float f;
>> + unsigned int u;
>> +};
>> +
>> +int
>> +main (void)
>> +{
>> + union u res, res2;
>> + float a[4];
>> +
>> + if (sizeof (float) != sizeof (unsigned int))
>> + return 0;
>> +
>> + check_vect ();
>> +
>> + a[0] = 0.01;
>> + a[1] = 0.01;
>> + a[2] = 0.01;
>> + a[3] = 1.0;
>> +
>> + res.f = foo_ref (a);
>> +
>> + res2.f = foo (a);
>> +
>> + if (res.u != res2.u)
>> + abort ();
>> +
>> + return 0;
>> +}
>> +
>> +/* need -ffast-math to vectorize this loop. */
>> +/* ARM NEON passes -ffast-math to these tests, so expect this to
>fail. */
>> +/* { dg-final { scan-tree-dump-times "vectorized 0 loops" 1 "vect" {
>xfail arm_neon_ok } } } */
