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tree-optimization/97241 - fix ICE in reduction vectorization

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The following moves an ad-hoc attempt at discovering the SLP node
for a stmt to the place where we can find it in lock-step when
we find the stmt itself.

2020-09-29  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/97241
	* tree-vect-loop.c (vectorizable_reduction): Move finding
	the SLP node for the reduction stmt to a better place.

	* gcc.dg/vect/pr97241.c: New testcase.
This commit is contained in:
Richard Biener 2020-09-29 15:02:47 +02:00
parent b1570930df
commit 39a27bb01a
2 changed files with 24 additions and 12 deletions
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19
gcc/testsuite/gcc.dg/vect/pr97241.c Normal file
View File

@ -0,0 +1,19 @@
/* { dg-do compile } */
/* { dg-options "-O3 --param max-loop-header-insns=2" } */
short int *ev;
int l4;
short int
a7 (void)
{
short int uo = ev[0], ie = uo;
for (int kp = 0; kp < l4; kp += 4)
{
uo += ev[kp + 1];
ie += ev[kp];
}
return uo + ie;
}

17
gcc/tree-vect-loop.c
View File

@ -6357,12 +6357,14 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
gphi *reduc_def_phi = as_a <gphi *> (phi_info->stmt);
/* Verify following REDUC_IDX from the latch def leads us back to the PHI
and compute the reduction chain length. */
and compute the reduction chain length. Discover the real
reduction operation stmt on the way (stmt_info and slp_for_stmt_info). */
tree reduc_def = PHI_ARG_DEF_FROM_EDGE (reduc_def_phi,
loop_latch_edge (loop));
unsigned reduc_chain_length = 0;
bool only_slp_reduc_chain = true;
stmt_info = NULL;
slp_tree slp_for_stmt_info = slp_node ? slp_node_instance->root : NULL;
while (reduc_def != PHI_RESULT (reduc_def_phi))
{
stmt_vec_info def = loop_vinfo->lookup_def (reduc_def);
@ -6405,6 +6407,8 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
stmt_info = vdef;
reduc_def = gimple_op (vdef->stmt, 1 + STMT_VINFO_REDUC_IDX (vdef));
reduc_chain_length++;
if (!stmt_info && slp_node)
slp_for_stmt_info = SLP_TREE_CHILDREN (slp_for_stmt_info)[0];
}
/* PHIs should not participate in patterns. */
gcc_assert (!STMT_VINFO_RELATED_STMT (phi_info));
@ -6491,17 +6495,6 @@ vectorizable_reduction (loop_vec_info loop_vinfo,
The last use is the reduction variable. In case of nested cycle this
assumption is not true: we use reduc_index to record the index of the
reduction variable. */
/* ??? To get at invariant/constant uses on the SLP node we have to
get to it here, slp_node is still the reduction PHI. */
slp_tree slp_for_stmt_info = NULL;
if (slp_node)
{
slp_for_stmt_info = slp_node_instance->root;
/* And then there's reduction chain with a conversion ... */
if (SLP_TREE_REPRESENTATIVE (slp_for_stmt_info) != stmt_info)
slp_for_stmt_info = SLP_TREE_CHILDREN (slp_for_stmt_info)[0];
gcc_assert (SLP_TREE_REPRESENTATIVE (slp_for_stmt_info) == stmt_info);
}
slp_tree *slp_op = XALLOCAVEC (slp_tree, op_type);
/* We need to skip an extra operand for COND_EXPRs with embedded
comparison. */