> -----Original Message-----
> From: Richard Biener <[email protected]>
> Sent: 14 October 2025 13:09
> To: Tamar Christina <[email protected]>
> Cc: [email protected]; RISC-V <[email protected]>;
> [email protected]
> Subject: RE: [PATCH] Rewrite reduction chain handling
>
> On Tue, 14 Oct 2025, Tamar Christina wrote:
>
> > > -----Original Message-----
> > > From: Richard Biener <[email protected]>
> > > Sent: 13 October 2025 13:08
> > > To: [email protected]
> > > Cc: RISC-V <[email protected]>; [email protected];
> > > Tamar Christina <[email protected]>
> > > Subject: [PATCH] Rewrite reduction chain handling
> > >
> > > The following moves us (almost) away from REDUC_GROUP_* to recognize
> > > reduction chaings towards making this a SLP discovery artifact.
> > > Reduction chains are now explicitly marked in the reduction info
> > > and discovery is done during SLP discovery rather than during
> > > analysis of scalar cycles. This gets rid of interactions with
> > > patterns and it also allows to transparently fall back to non-chained
> > > reductions even when there is a conversion involved. This also
> > > spurred some major TLC in vectorizable_reduction.
> >
> > Yeah this looks like an awesome cleanup. It should make it easier to do
> > widening reductions which I've been struggling to find a good place to
> > place as well.
> >
> > >
> > > What's still missing is to get rid of the last REDUC_GROUP_FIRST_ELEMENT
> > > usage in SLP discovery - by not claiming we can handle the reduction
> > > chain itself there. I'm leaving this for a followup (this was big
> > > enough).
> > >
> >
> > Yeah I was wondering why we splat the values, I guess it's because for
> > Non-single lane SLP we need to be sure that the reductions are on the
> > same reference? But in this case we already know so this is just building a
> > no-op essentially?
> >
> > To get rid of it is the idea that you move the group info to the slp
> > instance?
>
> We shouldn't need the group info at all - we currently use it only to
> make the operations match and possibly swap operands correctly. And
> we create "bogus" SLP_TREE_SCALAR_STMTS given they do not match up
> any lane with any of the computed values. One approach is to SLP discover
> only operands and build the rest manually, but that's quite elaborate
> (we do that for the leading conversion already if there is any). Sofar
> quick tinkering didn't come up with sth I like more than the current
> way of doing, so I'll "defer". We'll have to solve this when we want
> to perform re-association (of signed ints) to form reduction chains,
> at least the current vect_slp_linearize_chain gives you only "leaf"
> defs. That was my original reason for all of this, to not have to
> rely on the reassoc pass to form perfect reduction chains.
>
Would the group info not be required/useful if we're still planning on
trying to change SLP discovery to build only single lane SLP trees and then
merge together?
Cheers,
Tamar
> Richard.
>
> > Thanks,
> > Tamar
> >
> > > At least on x86-64 I now see XPASSes for gcc.dg/vect/vect-reduc-dot-s8b.c
> > > and gcc.dg/vect/vect-reduc-pattern-2c.c. I have not done careful
> > > analysis yet, will wait for the CI with that.
> > >
> > > Bootstrap and regtest running on x86_64-unknown-linux-gnu, comments
> > > welcome.
> > >
> > > Thanks,
> > > Richard.
> > >
> > > * tree-vectorizer.h (vect_reduc_info_s::is_reduc_chain): New.
> > > (_loop_vec_info::reduction_chains): Remove.
> > > (LOOP_VINFO_REDUCTION_CHAINS): Likewise.
> > > * tree-vect-patterns.cc (vect_reassociating_reduction_p):
> > > Do not special-case reduction group stmts.
> > > * tree-vect-loop.cc (vect_is_simple_reduction): Remove
> > > reduction chain handling.
> > > (vect_analyze_scalar_cycles_1): Remove slp parameter and adjust.
> > > (vect_analyze_scalar_cycles): Likewise.
> > > (vect_fixup_reduc_chain): Remove.
> > > (vect_fixup_scalar_cycles_with_patterns): Likewise.
> > > (vect_analyze_loop_2): Adjust.
> > > (vect_create_epilog_for_reduction): Check the reduction info
> > > for whether this is a reduction chain.
> > > (vect_transform_cycle_phi): Likewise.
> > > (vectorizable_reduction): Likewise. Simplify code for all-SLP.
> > > * tree-vect-slp.cc (vect_analyze_slp_reduc_chain): Simplify.
> > > (vect_analyze_slp_reduction): New function, perform reduction
> > > chain discovery here.
> > > (vect_analyze_slp): Remove reduction chain handling.
> > > Use vect_analyze_slp_reduction for possible reduction chain
> > > processing.
> > >
> > > * gcc.dg/vect/pr120687-1.c: Adjust.
> > > * gcc.dg/vect/pr120687-2.c: Likewise.
> > > * gcc.dg/vect/pr120687-3.c: Likewise.
> > > ---
> > > gcc/testsuite/gcc.dg/vect/pr120687-1.c | 2 +-
> > > gcc/testsuite/gcc.dg/vect/pr120687-2.c | 2 +-
> > > gcc/testsuite/gcc.dg/vect/pr120687-3.c | 2 +-
> > > gcc/tree-vect-loop.cc | 245 +++-----------
> > > gcc/tree-vect-patterns.cc | 12 +-
> > > gcc/tree-vect-slp.cc | 432 +++++++++++++------------
> > > gcc/tree-vectorizer.h | 8 +-
> > > 7 files changed, 283 insertions(+), 420 deletions(-)
> > >
> > > diff --git a/gcc/testsuite/gcc.dg/vect/pr120687-1.c
> > > b/gcc/testsuite/gcc.dg/vect/pr120687-1.c
> > > index ce9cf6301ce..ac684c0e826 100644
> > > --- a/gcc/testsuite/gcc.dg/vect/pr120687-1.c
> > > +++ b/gcc/testsuite/gcc.dg/vect/pr120687-1.c
> > > @@ -11,6 +11,6 @@ frd (unsigned *p, unsigned *lastone)
> > > return sum;
> > > }
> > >
> > > -/* { dg-final { scan-tree-dump "reduction: detected reduction chain"
> "vect" } }
> > > */
> > > +/* { dg-final { scan-tree-dump "Starting SLP discovery of reduction
> > > chain"
> > > "vect" } } */
> > > /* { dg-final { scan-tree-dump-not "SLP discovery of reduction chain
> > > failed"
> > > "vect" } } */
> > > /* { dg-final { scan-tree-dump "optimized: loop vectorized" "vect" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/vect/pr120687-2.c
> > > b/gcc/testsuite/gcc.dg/vect/pr120687-2.c
> > > index dfc6dc726e9..25f03555ba1 100644
> > > --- a/gcc/testsuite/gcc.dg/vect/pr120687-2.c
> > > +++ b/gcc/testsuite/gcc.dg/vect/pr120687-2.c
> > > @@ -12,6 +12,6 @@ frd (float *p, float *lastone)
> > > return sum;
> > > }
> > >
> > > -/* { dg-final { scan-tree-dump "reduction: detected reduction chain"
> "vect" } }
> > > */
> > > +/* { dg-final { scan-tree-dump "Starting SLP discovery of reduction
> > > chain"
> > > "vect" } } */
> > > /* { dg-final { scan-tree-dump-not "SLP discovery of reduction chain
> > > failed"
> > > "vect" } } */
> > > /* { dg-final { scan-tree-dump "optimized: loop vectorized" "vect" } } */
> > > diff --git a/gcc/testsuite/gcc.dg/vect/pr120687-3.c
> > > b/gcc/testsuite/gcc.dg/vect/pr120687-3.c
> > > index f20a66a6223..31a6c9419ec 100644
> > > --- a/gcc/testsuite/gcc.dg/vect/pr120687-3.c
> > > +++ b/gcc/testsuite/gcc.dg/vect/pr120687-3.c
> > > @@ -11,6 +11,6 @@ frd (float *p, float *lastone)
> > > return sum;
> > > }
> > >
> > > -/* { dg-final { scan-tree-dump "reduction: detected reduction chain"
> "vect" } }
> > > */
> > > +/* { dg-final { scan-tree-dump "Starting SLP discovery of reduction
> > > chain"
> > > "vect" } } */
> > > /* { dg-final { scan-tree-dump-not "SLP discovery of reduction chain
> > > failed"
> > > "vect" } } */
> > > /* { dg-final { scan-tree-dump "optimized: loop vectorized" "vect" } } */
> > > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> > > index 003dc734c01..ac30352b630 100644
> > > --- a/gcc/tree-vect-loop.cc
> > > +++ b/gcc/tree-vect-loop.cc
> > > @@ -161,7 +161,7 @@ along with GCC; see the file COPYING3. If not see
> > > static void vect_estimate_min_profitable_iters (loop_vec_info, int *,
> > > int *,
> > > unsigned *);
> > > static stmt_vec_info vect_is_simple_reduction (loop_vec_info,
> stmt_vec_info,
> > > - gphi **, bool *, bool);
> > > + gphi **);
> > >
> > >
> > > /* Function vect_is_simple_iv_evolution.
> > > @@ -341,8 +341,7 @@ vect_phi_first_order_recurrence_p (loop_vec_info
> > > loop_vinfo, class loop *loop,
> > > slp analyses or not. */
> > >
> > > static void
> > > -vect_analyze_scalar_cycles_1 (loop_vec_info loop_vinfo, class loop *loop,
> > > - bool slp)
> > > +vect_analyze_scalar_cycles_1 (loop_vec_info loop_vinfo, class loop *loop)
> > > {
> > > basic_block bb = loop->header;
> > > auto_vec<stmt_vec_info, 64> worklist;
> > > @@ -425,19 +424,15 @@ vect_analyze_scalar_cycles_1 (loop_vec_info
> > > loop_vinfo, class loop *loop,
> > > && STMT_VINFO_DEF_TYPE (stmt_vinfo) ==
> > > vect_unknown_def_type);
> > >
> > > gphi *double_reduc;
> > > - bool reduc_chain;
> > > stmt_vec_info reduc_stmt_info
> > > - = vect_is_simple_reduction (loop_vinfo, stmt_vinfo, &double_reduc,
> > > - &reduc_chain, slp);
> > > + = vect_is_simple_reduction (loop_vinfo, stmt_vinfo, &double_reduc);
> > > if (reduc_stmt_info && double_reduc)
> > > {
> > > - bool inner_chain;
> > > stmt_vec_info inner_phi_info
> > > = loop_vinfo->lookup_stmt (double_reduc);
> > > /* ??? Pass down flag we're the inner loop of a double reduc. */
> > > stmt_vec_info inner_reduc_info
> > > - = vect_is_simple_reduction (loop_vinfo, inner_phi_info,
> > > - NULL, &inner_chain, slp);
> > > + = vect_is_simple_reduction (loop_vinfo, inner_phi_info, NULL);
> > > if (inner_reduc_info)
> > > {
> > > STMT_VINFO_REDUC_DEF (stmt_vinfo) = reduc_stmt_info;
> > > @@ -478,12 +473,7 @@ vect_analyze_scalar_cycles_1 (loop_vec_info
> > > loop_vinfo, class loop *loop,
> > >
> > > STMT_VINFO_DEF_TYPE (stmt_vinfo) = vect_reduction_def;
> > > STMT_VINFO_DEF_TYPE (reduc_stmt_info) = vect_reduction_def;
> > > - /* Store the reduction cycles for possible vectorization in
> > > - loop-aware SLP if it was not detected as reduction
> > > - chain. */
> > > - if (! reduc_chain)
> > > - LOOP_VINFO_REDUCTIONS (loop_vinfo).safe_push
> > > - (reduc_stmt_info);
> > > + LOOP_VINFO_REDUCTIONS (loop_vinfo).safe_push
> > > (reduc_stmt_info);
> > > }
> > > }
> > > else if (vect_phi_first_order_recurrence_p (loop_vinfo, loop, phi))
> > > @@ -518,11 +508,11 @@ vect_analyze_scalar_cycles_1 (loop_vec_info
> > > loop_vinfo, class loop *loop,
> > > a[i] = i; */
> > >
> > > static void
> > > -vect_analyze_scalar_cycles (loop_vec_info loop_vinfo, bool slp)
> > > +vect_analyze_scalar_cycles (loop_vec_info loop_vinfo)
> > > {
> > > class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
> > >
> > > - vect_analyze_scalar_cycles_1 (loop_vinfo, loop, slp);
> > > + vect_analyze_scalar_cycles_1 (loop_vinfo, loop);
> > >
> > > /* When vectorizing an outer-loop, the inner-loop is executed
> sequentially.
> > > Reductions in such inner-loop therefore have different properties
> > > than
> > > @@ -534,87 +524,7 @@ vect_analyze_scalar_cycles (loop_vec_info
> > > loop_vinfo, bool slp)
> > > current checks are too strict. */
> > >
> > > if (loop->inner)
> > > - vect_analyze_scalar_cycles_1 (loop_vinfo, loop->inner, slp);
> > > -}
> > > -
> > > -/* Transfer group and reduction information from STMT_INFO to its
> > > - pattern stmt. */
> > > -
> > > -static void
> > > -vect_fixup_reduc_chain (stmt_vec_info stmt_info)
> > > -{
> > > - stmt_vec_info firstp = STMT_VINFO_RELATED_STMT (stmt_info);
> > > - stmt_vec_info stmtp;
> > > - gcc_assert (!REDUC_GROUP_FIRST_ELEMENT (firstp)
> > > - && REDUC_GROUP_FIRST_ELEMENT (stmt_info));
> > > - REDUC_GROUP_SIZE (firstp) = REDUC_GROUP_SIZE (stmt_info);
> > > - do
> > > - {
> > > - stmtp = STMT_VINFO_RELATED_STMT (stmt_info);
> > > - gcc_checking_assert (STMT_VINFO_DEF_TYPE (stmtp)
> > > - == STMT_VINFO_DEF_TYPE (stmt_info));
> > > - REDUC_GROUP_FIRST_ELEMENT (stmtp) = firstp;
> > > - stmt_info = REDUC_GROUP_NEXT_ELEMENT (stmt_info);
> > > - if (stmt_info)
> > > - REDUC_GROUP_NEXT_ELEMENT (stmtp)
> > > - = STMT_VINFO_RELATED_STMT (stmt_info);
> > > - }
> > > - while (stmt_info);
> > > -}
> > > -
> > > -/* Fixup scalar cycles that now have their stmts detected as patterns.
> > > */
> > > -
> > > -static void
> > > -vect_fixup_scalar_cycles_with_patterns (loop_vec_info loop_vinfo)
> > > -{
> > > - stmt_vec_info first;
> > > - unsigned i;
> > > -
> > > - FOR_EACH_VEC_ELT (LOOP_VINFO_REDUCTION_CHAINS (loop_vinfo), i,
> > > first)
> > > - {
> > > - stmt_vec_info next = REDUC_GROUP_NEXT_ELEMENT (first);
> > > - while (next)
> > > - {
> > > - if ((STMT_VINFO_IN_PATTERN_P (next)
> > > - != STMT_VINFO_IN_PATTERN_P (first))
> > > - || STMT_VINFO_REDUC_IDX (vect_stmt_to_vectorize (next)) == -
> > > 1)
> > > - break;
> > > - next = REDUC_GROUP_NEXT_ELEMENT (next);
> > > - }
> > > - /* If all reduction chain members are well-formed patterns adjust
> > > - the group to group the pattern stmts instead. */
> > > - if (! next
> > > - && STMT_VINFO_REDUC_IDX (vect_stmt_to_vectorize (first)) != -1)
> > > - {
> > > - if (STMT_VINFO_IN_PATTERN_P (first))
> > > - {
> > > - vect_fixup_reduc_chain (first);
> > > - LOOP_VINFO_REDUCTION_CHAINS (loop_vinfo)[i]
> > > - = STMT_VINFO_RELATED_STMT (first);
> > > - }
> > > - }
> > > - /* If not all stmt in the chain are patterns or if we failed
> > > - to update STMT_VINFO_REDUC_IDX dissolve the chain and handle
> > > - it as regular reduction instead. */
> > > - else
> > > - {
> > > - stmt_vec_info vinfo = first;
> > > - stmt_vec_info last = NULL;
> > > - while (vinfo)
> > > - {
> > > - next = REDUC_GROUP_NEXT_ELEMENT (vinfo);
> > > - REDUC_GROUP_FIRST_ELEMENT (vinfo) = NULL;
> > > - REDUC_GROUP_NEXT_ELEMENT (vinfo) = NULL;
> > > - last = vinfo;
> > > - vinfo = next;
> > > - }
> > > - STMT_VINFO_DEF_TYPE (vect_stmt_to_vectorize (first))
> > > - = vect_internal_def;
> > > - loop_vinfo->reductions.safe_push (vect_stmt_to_vectorize (last));
> > > - LOOP_VINFO_REDUCTION_CHAINS (loop_vinfo).unordered_remove
> > > (i);
> > > - --i;
> > > - }
> > > - }
> > > + vect_analyze_scalar_cycles_1 (loop_vinfo, loop->inner);
> > > }
> > >
> > > /* Function vect_get_loop_niters.
> > > @@ -2267,12 +2177,10 @@ vect_analyze_loop_2 (loop_vec_info
> loop_vinfo,
> > > bool &fatal,
> > >
> > > /* Classify all cross-iteration scalar data-flow cycles.
> > > Cross-iteration cycles caused by virtual phis are analyzed
> > > separately. */
> > > - vect_analyze_scalar_cycles (loop_vinfo, !force_single_lane);
> > > + vect_analyze_scalar_cycles (loop_vinfo);
> > >
> > > vect_pattern_recog (loop_vinfo);
> > >
> > > - vect_fixup_scalar_cycles_with_patterns (loop_vinfo);
> > > -
> > > /* Analyze the access patterns of the data-refs in the loop
> > > (consecutive,
> > > complex, etc.). FORNOW: Only handle consecutive access pattern. */
> > >
> > > @@ -2681,10 +2589,6 @@ again:
> > > if (applying_suggested_uf)
> > > return ok;
> > >
> > > - /* If there are reduction chains re-trying will fail anyway. */
> > > - if (! LOOP_VINFO_REDUCTION_CHAINS (loop_vinfo).is_empty ())
> > > - return ok;
> > > -
> > > /* Likewise if the grouped loads or stores in the SLP cannot be handled
> > > via interleaving or lane instructions. */
> > > slp_instance instance;
> > > @@ -3762,7 +3666,7 @@ check_reduction_path (dump_user_location_t
> loc,
> > > loop_p loop, gphi *phi,
> > >
> > > static stmt_vec_info
> > > vect_is_simple_reduction (loop_vec_info loop_info, stmt_vec_info
> phi_info,
> > > - gphi **double_reduc, bool *reduc_chain_p, bool slp)
> > > + gphi **double_reduc)
> > > {
> > > gphi *phi = as_a <gphi *> (phi_info->stmt);
> > > gimple *phi_use_stmt = NULL;
> > > @@ -3774,7 +3678,6 @@ vect_is_simple_reduction (loop_vec_info
> > > loop_info, stmt_vec_info phi_info,
> > > bool inner_loop_of_double_reduc = double_reduc == NULL;
> > > if (double_reduc)
> > > *double_reduc = NULL;
> > > - *reduc_chain_p = false;
> > > STMT_VINFO_REDUC_TYPE (phi_info) = TREE_CODE_REDUCTION;
> > >
> > > tree phi_name = PHI_RESULT (phi);
> > > @@ -3924,12 +3827,8 @@ vect_is_simple_reduction (loop_vec_info
> > > loop_info, stmt_vec_info phi_info,
> > > if (code == COND_EXPR && !nested_in_vect_loop)
> > > STMT_VINFO_REDUC_TYPE (phi_info) = COND_REDUCTION;
> > >
> > > - /* Fill in STMT_VINFO_REDUC_IDX and gather stmts for an SLP
> > > - reduction chain for which the additional restriction is that
> > > - all operations in the chain are the same. */
> > > - auto_vec<stmt_vec_info, 8> reduc_chain;
> > > + /* Fill in STMT_VINFO_REDUC_IDX. */
> > > unsigned i;
> > > - bool is_slp_reduc = !nested_in_vect_loop && code != COND_EXPR;
> > > for (i = path.length () - 1; i >= 1; --i)
> > > {
> > > gimple *stmt = USE_STMT (path[i].second);
> > > @@ -3946,39 +3845,8 @@ vect_is_simple_reduction (loop_vec_info
> > > loop_info, stmt_vec_info phi_info,
> > > STMT_VINFO_REDUC_IDX (stmt_info)
> > > = path[i].second->use - gimple_call_arg_ptr (call, 0);
> > > }
> > > - bool leading_conversion = (CONVERT_EXPR_CODE_P (op.code)
> > > - && (i == 1 || i == path.length () - 1));
> > > - if ((op.code != code && !leading_conversion)
> > > - /* We can only handle the final value in epilogue
> > > - generation for reduction chains. */
> > > - || (i != 1 && !has_single_use (gimple_get_lhs (stmt))))
> > > - is_slp_reduc = false;
> > > - /* For reduction chains we support a trailing/leading
> > > - conversions. We do not store those in the actual chain. */
> > > - if (leading_conversion)
> > > - continue;
> > > - reduc_chain.safe_push (stmt_info);
> > > }
> > > - if (slp && is_slp_reduc && reduc_chain.length () > 1)
> > > - {
> > > - for (unsigned i = 0; i < reduc_chain.length () - 1; ++i)
> > > - {
> > > - REDUC_GROUP_FIRST_ELEMENT (reduc_chain[i]) =
> > > reduc_chain[0];
> > > - REDUC_GROUP_NEXT_ELEMENT (reduc_chain[i]) =
> > > reduc_chain[i+1];
> > > - }
> > > - REDUC_GROUP_FIRST_ELEMENT (reduc_chain.last ()) =
> > > reduc_chain[0];
> > > - REDUC_GROUP_NEXT_ELEMENT (reduc_chain.last ()) = NULL;
> > > -
> > > - /* Save the chain for further analysis in SLP detection. */
> > > - LOOP_VINFO_REDUCTION_CHAINS (loop_info).safe_push
> > > (reduc_chain[0]);
> > > - REDUC_GROUP_SIZE (reduc_chain[0]) = reduc_chain.length ();
> > > -
> > > - *reduc_chain_p = true;
> > > - if (dump_enabled_p ())
> > > - dump_printf_loc (MSG_NOTE, vect_location,
> > > - "reduction: detected reduction chain\n");
> > > - }
> > > - else if (dump_enabled_p ())
> > > + if (dump_enabled_p ())
> > > dump_printf_loc (MSG_NOTE, vect_location,
> > > "reduction: detected reduction\n");
> > >
> > > @@ -5411,8 +5279,7 @@ vect_create_epilog_for_reduction
> (loop_vec_info
> > > loop_vinfo,
> > > # b1 = phi <b2, b0>
> > > a2 = operation (a1)
> > > b2 = operation (b1) */
> > > - const bool slp_reduc
> > > - = SLP_INSTANCE_KIND (slp_node_instance) !=
> slp_inst_kind_reduc_chain;
> > > + const bool slp_reduc = !reduc_info->is_reduc_chain;
> > > tree induction_index = NULL_TREE;
> > >
> > > unsigned int group_size = SLP_TREE_LANES (slp_node);
> > > @@ -6962,8 +6829,6 @@ vectorizable_reduction (loop_vec_info
> loop_vinfo,
> > > bool single_defuse_cycle = false;
> > > tree cr_index_scalar_type = NULL_TREE, cr_index_vector_type =
> NULL_TREE;
> > > tree cond_reduc_val = NULL_TREE;
> > > - const bool reduc_chain
> > > - = SLP_INSTANCE_KIND (slp_node_instance) ==
> slp_inst_kind_reduc_chain;
> > >
> > > /* Make sure it was already recognized as a reduction computation. */
> > > if (STMT_VINFO_DEF_TYPE (stmt_info) != vect_reduction_def
> > > @@ -7025,6 +6890,7 @@ vectorizable_reduction (loop_vec_info
> loop_vinfo,
> > > double_reduc = true;
> > > }
> > >
> > > + const bool reduc_chain = reduc_info->is_reduc_chain;
> > > slp_node_instance->reduc_phis = slp_node;
> > > /* ??? We're leaving slp_node to point to the PHIs, we only
> > > need it to get at the number of vector stmts which wasn't
> > > @@ -7036,33 +6902,28 @@ vectorizable_reduction (loop_vec_info
> > > loop_vinfo,
> > >
> > > /* Verify following REDUC_IDX from the latch def leads us back to the
> > > PHI
> > > 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));
> > > + reduction operation stmt on the way (slp_for_stmt_info). */
> > > unsigned reduc_chain_length = 0;
> > > - bool only_slp_reduc_chain = true;
> > > stmt_info = NULL;
> > > slp_tree slp_for_stmt_info = NULL;
> > > slp_tree vdef_slp = slp_node_instance->root;
> > > - /* For double-reductions we start SLP analysis at the inner loop LC PHI
> > > - which is the def of the outer loop live stmt. */
> > > - if (double_reduc)
> > > - vdef_slp = SLP_TREE_CHILDREN (vdef_slp)[0];
> > > - while (reduc_def != PHI_RESULT (reduc_def_phi))
> > > + while (vdef_slp != slp_node)
> > > {
> > > - stmt_vec_info def = loop_vinfo->lookup_def (reduc_def);
> > > - stmt_vec_info vdef = vect_stmt_to_vectorize (def);
> > > - int reduc_idx = STMT_VINFO_REDUC_IDX (vdef);
> > > - if (STMT_VINFO_REDUC_IDX (vdef) == -1
> > > - || SLP_TREE_REDUC_IDX (vdef_slp) == -1)
> > > + int reduc_idx = SLP_TREE_REDUC_IDX (vdef_slp);
> > > + if (reduc_idx == -1)
> > > {
> > > if (dump_enabled_p ())
> > > dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> > > "reduction chain broken by patterns.\n");
> > > return false;
> > > }
> > > - if (!REDUC_GROUP_FIRST_ELEMENT (vdef))
> > > - only_slp_reduc_chain = false;
> > > + stmt_vec_info vdef = SLP_TREE_REPRESENTATIVE (vdef_slp);
> > > + if (is_a <gphi *> (vdef->stmt))
> > > + {
> > > + vdef_slp = SLP_TREE_CHILDREN (vdef_slp)[reduc_idx];
> > > + /* Do not count PHIs towards the chain length. */
> > > + continue;
> > > + }
> > > gimple_match_op op;
> > > if (!gimple_extract_op (vdef->stmt, &op))
> > > {
> > > @@ -7086,11 +6947,8 @@ vectorizable_reduction (loop_vec_info
> > > loop_vinfo,
> > > else
> > > {
> > > /* First non-conversion stmt. */
> > > - if (!stmt_info)
> > > - {
> > > - stmt_info = vdef;
> > > - slp_for_stmt_info = vdef_slp;
> > > - }
> > > + if (!slp_for_stmt_info)
> > > + slp_for_stmt_info = vdef_slp;
> > >
> > > if (lane_reducing_op_p (op.code))
> > > {
> > > @@ -7122,29 +6980,15 @@ vectorizable_reduction (loop_vec_info
> > > loop_vinfo,
> > > }
> > > else if (!vectype_in)
> > > vectype_in = SLP_TREE_VECTYPE (slp_node);
> > > - if (!REDUC_GROUP_FIRST_ELEMENT (vdef))
> > > - {
> > > - gcc_assert (reduc_idx == SLP_TREE_REDUC_IDX (vdef_slp));
> > > - vdef_slp = SLP_TREE_CHILDREN (vdef_slp)[reduc_idx];
> > > - }
> > > + vdef_slp = SLP_TREE_CHILDREN (vdef_slp)[reduc_idx];
> > > }
> > > -
> > > - reduc_def = op.ops[reduc_idx];
> > > reduc_chain_length++;
> > > }
> > > + stmt_info = SLP_TREE_REPRESENTATIVE (slp_for_stmt_info);
> > > +
> > > /* PHIs should not participate in patterns. */
> > > gcc_assert (!STMT_VINFO_RELATED_STMT (phi_info));
> > >
> > > - /* STMT_VINFO_REDUC_DEF doesn't point to the first but the last
> > > - element. */
> > > - if (REDUC_GROUP_FIRST_ELEMENT (stmt_info))
> > > - {
> > > - gcc_assert (!REDUC_GROUP_NEXT_ELEMENT (stmt_info));
> > > - stmt_info = REDUC_GROUP_FIRST_ELEMENT (stmt_info);
> > > - }
> > > - if (REDUC_GROUP_FIRST_ELEMENT (stmt_info))
> > > - gcc_assert (REDUC_GROUP_FIRST_ELEMENT (stmt_info) == stmt_info);
> > > -
> > > /* 1. Is vectorizable reduction? */
> > > /* Not supportable if the reduction variable is used in the loop,
> > > unless
> > > it's a reduction chain. */
> > > @@ -7459,8 +7303,7 @@ vectorizable_reduction (loop_vec_info
> loop_vinfo,
> > > {
> > > /* When vectorizing a reduction chain w/o SLP the reduction PHI
> > > is not directy used in stmt. */
> > > - if (!only_slp_reduc_chain
> > > - && reduc_chain_length != 1)
> > > + if (reduc_chain_length != 1)
> > > {
> > > if (dump_enabled_p ())
> > > dump_printf_loc (MSG_MISSED_OPTIMIZATION,
> > > vect_location,
> > > @@ -7795,22 +7638,18 @@ vectorizable_reduction (loop_vec_info
> > > loop_vinfo,
> > >
> > > /* All but single defuse-cycle optimized and fold-left reductions go
> > > through their own vectorizable_* routines. */
> > > + stmt_vec_info tem
> > > + = SLP_TREE_REPRESENTATIVE (SLP_INSTANCE_TREE
> (slp_node_instance));
> > > if (!single_defuse_cycle && reduction_type != FOLD_LEFT_REDUCTION)
> > > + STMT_VINFO_DEF_TYPE (tem) = vect_internal_def;
> > > + else
> > > {
> > > - stmt_vec_info tem
> > > - = vect_stmt_to_vectorize (STMT_VINFO_REDUC_DEF (phi_info));
> > > - if (REDUC_GROUP_FIRST_ELEMENT (tem))
> > > - {
> > > - gcc_assert (!REDUC_GROUP_NEXT_ELEMENT (tem));
> > > - tem = REDUC_GROUP_FIRST_ELEMENT (tem);
> > > - }
> > > - STMT_VINFO_DEF_TYPE (vect_orig_stmt (tem)) = vect_internal_def;
> > > - STMT_VINFO_DEF_TYPE (tem) = vect_internal_def;
> > > + STMT_VINFO_DEF_TYPE (tem) = vect_reduction_def;
> > > + if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
> > > + vect_reduction_update_partial_vector_usage (loop_vinfo, reduc_info,
> > > + slp_node, op.code, op.type,
> > > + vectype_in);
> > > }
> > > - else if (LOOP_VINFO_CAN_USE_PARTIAL_VECTORS_P (loop_vinfo))
> > > - vect_reduction_update_partial_vector_usage (loop_vinfo, reduc_info,
> > > - slp_node, op.code, op.type,
> > > - vectype_in);
> > > return true;
> > > }
> > >
> > > @@ -8244,8 +8083,6 @@ vect_transform_cycle_phi (loop_vec_info
> > > loop_vinfo,
> > > int i;
> > > bool nested_cycle = false;
> > > int vec_num;
> > > - const bool reduc_chain
> > > - = SLP_INSTANCE_KIND (slp_node_instance) ==
> slp_inst_kind_reduc_chain;
> > >
> > > if (nested_in_vect_loop_p (loop, stmt_info))
> > > {
> > > @@ -8314,7 +8151,7 @@ vect_transform_cycle_phi (loop_vec_info
> > > loop_vinfo,
> > > vec<stmt_vec_info> &stmts = SLP_TREE_SCALAR_STMTS (slp_node);
> > >
> > > unsigned int num_phis = stmts.length ();
> > > - if (reduc_chain)
> > > + if (reduc_info->is_reduc_chain)
> > > num_phis = 1;
> > > initial_values.reserve (num_phis);
> > > for (unsigned int i = 0; i < num_phis; ++i)
> > > diff --git a/gcc/tree-vect-patterns.cc b/gcc/tree-vect-patterns.cc
> > > index 74a9a1929ba..6a377e384a0 100644
> > > --- a/gcc/tree-vect-patterns.cc
> > > +++ b/gcc/tree-vect-patterns.cc
> > > @@ -1022,13 +1022,11 @@ vect_reassociating_reduction_p (vec_info
> > > *vinfo,
> > > if (loop && nested_in_vect_loop_p (loop, stmt_info))
> > > return false;
> > >
> > > - if (STMT_VINFO_DEF_TYPE (stmt_info) == vect_reduction_def)
> > > - {
> > > - if (needs_fold_left_reduction_p (TREE_TYPE (gimple_assign_lhs
> (assign)),
> > > - code))
> > > - return false;
> > > - }
> > > - else if (REDUC_GROUP_FIRST_ELEMENT (stmt_info) == NULL)
> > > + if (!vect_is_reduction (stmt_info))
> > > + return false;
> > > +
> > > + if (needs_fold_left_reduction_p (TREE_TYPE (gimple_assign_lhs
> > > (assign)),
> > > + code))
> > > return false;
> > >
> > > *op0_out = gimple_assign_rhs1 (assign);
> > > diff --git a/gcc/tree-vect-slp.cc b/gcc/tree-vect-slp.cc
> > > index f553e8fba19..fe3bcff94a7 100644
> > > --- a/gcc/tree-vect-slp.cc
> > > +++ b/gcc/tree-vect-slp.cc
> > > @@ -4187,41 +4187,24 @@ vect_build_slp_instance (vec_info *vinfo,
> > > Return FALSE if SLP build fails. */
> > >
> > > static bool
> > > -vect_analyze_slp_reduc_chain (vec_info *vinfo,
> > > +vect_analyze_slp_reduc_chain (loop_vec_info vinfo,
> > > scalar_stmts_to_slp_tree_map_t *bst_map,
> > > - stmt_vec_info stmt_info,
> > > + vec<stmt_vec_info> &scalar_stmts,
> > > + stmt_vec_info reduc_phi_info,
> > > unsigned max_tree_size, unsigned *limit)
> > > {
> > > - vec<stmt_vec_info> scalar_stmts;
> > > -
> > > - /* Collect the reduction stmts and store them in scalar_stmts. */
> > > - scalar_stmts.create (REDUC_GROUP_SIZE (stmt_info));
> > > - stmt_vec_info next_info = stmt_info;
> > > - while (next_info)
> > > - {
> > > - scalar_stmts.quick_push (vect_stmt_to_vectorize (next_info));
> > > - next_info = REDUC_GROUP_NEXT_ELEMENT (next_info);
> > > - }
> > > - /* Mark the first element of the reduction chain as reduction to
> > > properly
> > > - transform the node. In the reduction analysis phase only the last
> > > - element of the chain is marked as reduction. */
> > > - STMT_VINFO_DEF_TYPE (stmt_info)
> > > - = STMT_VINFO_DEF_TYPE (scalar_stmts.last ());
> > > - STMT_VINFO_REDUC_DEF (vect_orig_stmt (stmt_info))
> > > - = STMT_VINFO_REDUC_DEF (vect_orig_stmt (scalar_stmts.last ()));
> > > + /* If there's no budget left bail out early. */
> > > + if (*limit == 0)
> > > + return false;
> > >
> > > /* Build the tree for the SLP instance. */
> > > vec<stmt_vec_info> root_stmt_infos = vNULL;
> > > vec<tree> remain = vNULL;
> > >
> > > - /* If there's no budget left bail out early. */
> > > - if (*limit == 0)
> > > - return false;
> > > -
> > > if (dump_enabled_p ())
> > > {
> > > dump_printf_loc (MSG_NOTE, vect_location,
> > > - "Starting SLP discovery for\n");
> > > + "Starting SLP discovery of reduction chain for\n");
> > > for (unsigned i = 0; i < scalar_stmts.length (); ++i)
> > > dump_printf_loc (MSG_NOTE, vect_location,
> > > " %G", scalar_stmts[i]->stmt);
> > > @@ -4233,136 +4216,234 @@ vect_analyze_slp_reduc_chain (vec_info
> > > *vinfo,
> > > poly_uint64 max_nunits = 1;
> > > unsigned tree_size = 0;
> > >
> > > + /* ??? We need this only for SLP discovery. */
> > > + for (unsigned i = 0; i < scalar_stmts.length (); ++i)
> > > + REDUC_GROUP_FIRST_ELEMENT (scalar_stmts[i]) = scalar_stmts[0];
> > > +
> > > slp_tree node = vect_build_slp_tree (vinfo, scalar_stmts, group_size,
> > > &max_nunits, matches, limit,
> > > &tree_size, bst_map);
> > > +
> > > + for (unsigned i = 0; i < scalar_stmts.length (); ++i)
> > > + REDUC_GROUP_FIRST_ELEMENT (scalar_stmts[i]) = NULL;
> > > +
> > > if (node != NULL)
> > > {
> > > - /* Calculate the unrolling factor based on the smallest type. */
> > > - poly_uint64 unrolling_factor
> > > - = calculate_unrolling_factor (max_nunits, group_size);
> > > + /* Create a new SLP instance. */
> > > + slp_instance new_instance = XNEW (class _slp_instance);
> > > + SLP_INSTANCE_TREE (new_instance) = node;
> > > + SLP_INSTANCE_LOADS (new_instance) = vNULL;
> > > + SLP_INSTANCE_ROOT_STMTS (new_instance) = root_stmt_infos;
> > > + SLP_INSTANCE_REMAIN_DEFS (new_instance) = remain;
> > > + SLP_INSTANCE_KIND (new_instance) = slp_inst_kind_reduc_chain;
> > > + new_instance->reduc_phis = NULL;
> > > + new_instance->cost_vec = vNULL;
> > > + new_instance->subgraph_entries = vNULL;
> > >
> > > - if (maybe_ne (unrolling_factor, 1U)
> > > - && is_a <bb_vec_info> (vinfo))
> > > + vect_reduc_info reduc_info = info_for_reduction (vinfo, node);
> > > + reduc_info->is_reduc_chain = true;
> > > +
> > > + if (dump_enabled_p ())
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + "SLP size %u vs. limit %u.\n",
> > > + tree_size, max_tree_size);
> > > +
> > > + /* Fixup SLP reduction chains. If this is a reduction chain with
> > > + a conversion in front amend the SLP tree with a node for that. */
> > > + gimple *scalar_def = STMT_VINFO_REDUC_DEF (reduc_phi_info)-
> >stmt;
> > > + if (is_gimple_assign (scalar_def)
> > > + && CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (scalar_def)))
> > > + {
> > > + stmt_vec_info conv_info = vect_stmt_to_vectorize
> > > + (STMT_VINFO_REDUC_DEF
> > > (reduc_phi_info));
> > > + scalar_stmts = vNULL;
> > > + scalar_stmts.create (group_size);
> > > + for (unsigned i = 0; i < group_size; ++i)
> > > + scalar_stmts.quick_push (conv_info);
> > > + slp_tree conv = vect_create_new_slp_node (scalar_stmts, 1);
> > > + SLP_TREE_VECTYPE (conv)
> > > + = get_vectype_for_scalar_type (vinfo,
> > > + TREE_TYPE
> > > + (gimple_assign_lhs (scalar_def)),
> > > + group_size);
> > > + SLP_TREE_REDUC_IDX (conv) = 0;
> > > + conv->cycle_info.id = node->cycle_info.id;
> > > + SLP_TREE_CHILDREN (conv).quick_push (node);
> > > + SLP_INSTANCE_TREE (new_instance) = conv;
> > > + }
> > > + /* Fill the backedge child of the PHI SLP node. The
> > > + general matching code cannot find it because the
> > > + scalar code does not reflect how we vectorize the
> > > + reduction. */
> > > + use_operand_p use_p;
> > > + imm_use_iterator imm_iter;
> > > + class loop *loop = LOOP_VINFO_LOOP (vinfo);
> > > + FOR_EACH_IMM_USE_FAST (use_p, imm_iter,
> > > + gimple_get_lhs (scalar_def))
> > > + /* There are exactly two non-debug uses, the reduction
> > > + PHI and the loop-closed PHI node. */
> > > + if (!is_gimple_debug (USE_STMT (use_p))
> > > + && gimple_bb (USE_STMT (use_p)) == loop->header)
> > > + {
> > > + auto_vec<stmt_vec_info, 64> phis (group_size);
> > > + stmt_vec_info phi_info = vinfo->lookup_stmt (USE_STMT (use_p));
> > > + for (unsigned i = 0; i < group_size; ++i)
> > > + phis.quick_push (phi_info);
> > > + slp_tree *phi_node = bst_map->get (phis);
> > > + unsigned dest_idx = loop_latch_edge (loop)->dest_idx;
> > > + SLP_TREE_CHILDREN (*phi_node)[dest_idx]
> > > + = SLP_INSTANCE_TREE (new_instance);
> > > + SLP_INSTANCE_TREE (new_instance)->refcnt++;
> > > + }
> > > +
> > > + vinfo->slp_instances.safe_push (new_instance);
> > > +
> > > + /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> > > + the number of scalar stmts in the root in a few places.
> > > + Verify that assumption holds. */
> > > + gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE
> > > (new_instance))
> > > + .length () == group_size);
> > > +
> > > + if (dump_enabled_p ())
> > > {
> > > - unsigned HOST_WIDE_INT const_max_nunits;
> > > - if (!max_nunits.is_constant (&const_max_nunits)
> > > - || const_max_nunits > group_size)
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + "Final SLP tree for instance %p:\n",
> > > + (void *) new_instance);
> > > + vect_print_slp_graph (MSG_NOTE, vect_location,
> > > + SLP_INSTANCE_TREE (new_instance));
> > > + }
> > > +
> > > + return true;
> > > + }
> > > + /* Failed to SLP. */
> > > + if (dump_enabled_p ())
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + "SLP discovery of reduction chain failed\n");
> > > + return false;
> > > +}
> > > +
> > > +/* Analyze an SLP instance starting from SCALAR_STMTS which are a
> group
> > > + of KIND. Return true if successful. */
> > > +
> > > +static bool
> > > +vect_analyze_slp_reduction (loop_vec_info vinfo,
> > > + stmt_vec_info scalar_stmt,
> > > + unsigned max_tree_size, unsigned *limit,
> > > + scalar_stmts_to_slp_tree_map_t *bst_map,
> > > + bool force_single_lane)
> > > +{
> > > + slp_instance_kind kind = slp_inst_kind_reduc_group;
> > > +
> > > + /* If there's no budget left bail out early. */
> > > + if (*limit == 0)
> > > + return false;
> > > +
> > > + vec<stmt_vec_info> scalar_stmts = vNULL;
> > > + /* Try to gather a reduction chain. */
> > > + if (! force_single_lane
> > > + && STMT_VINFO_DEF_TYPE (scalar_stmt) == vect_reduction_def)
> > > + {
> > > + bool fail = false;
> > > + /* ??? We could leave operation code checking to SLP discovery.
> > > */
> > > + code_helper code
> > > + = STMT_VINFO_REDUC_CODE (STMT_VINFO_REDUC_DEF
> > > + (vect_orig_stmt (scalar_stmt)));
> > > + bool first = true;
> > > + stmt_vec_info next_stmt = scalar_stmt;
> > > + do
> > > + {
> > > + stmt_vec_info stmt = next_stmt;
> > > + gimple_match_op op;
> > > + if (!gimple_extract_op (STMT_VINFO_STMT (stmt), &op))
> > > + gcc_unreachable ();
> > > + tree reduc_def = gimple_arg (STMT_VINFO_STMT (stmt),
> > > + STMT_VINFO_REDUC_IDX (stmt));
> > > + next_stmt = vect_stmt_to_vectorize (vinfo->lookup_def
> > > (reduc_def));
> > > + gcc_assert (is_a <gphi *> (STMT_VINFO_STMT (next_stmt))
> > > + || STMT_VINFO_REDUC_IDX (next_stmt) != -1);
> > > + if (!gimple_extract_op (STMT_VINFO_STMT (vect_orig_stmt (stmt)),
> > > &op))
> > > + gcc_unreachable ();
> > > + if (CONVERT_EXPR_CODE_P (op.code)
> > > + && (first
> > > + || is_a <gphi *> (STMT_VINFO_STMT (next_stmt))))
> > > + ;
> > > + else if (code != op.code)
> > > {
> > > - if (dump_enabled_p ())
> > > - dump_printf_loc (MSG_MISSED_OPTIMIZATION,
> > > vect_location,
> > > - "Build SLP failed: store group "
> > > - "size not a multiple of the vector size "
> > > - "in basic block SLP\n");
> > > - vect_free_slp_tree (node);
> > > - return false;
> > > + fail = true;
> > > + break;
> > > }
> > > - /* Fatal mismatch. */
> > > - if (dump_enabled_p ())
> > > - dump_printf_loc (MSG_NOTE, vect_location,
> > > - "SLP discovery succeeded but node needs "
> > > - "splitting\n");
> > > - memset (matches, true, group_size);
> > > - matches[group_size / const_max_nunits * const_max_nunits] = false;
> > > - vect_free_slp_tree (node);
> > > + else
> > > + scalar_stmts.safe_push (stmt);
> > > + first = false;
> > > }
> > > - else
> > > + while (!is_a <gphi *> (STMT_VINFO_STMT (next_stmt)));
> > > + if (!fail && scalar_stmts.length () > 1)
> > > {
> > > - /* Create a new SLP instance. */
> > > - slp_instance new_instance = XNEW (class _slp_instance);
> > > - SLP_INSTANCE_TREE (new_instance) = node;
> > > - SLP_INSTANCE_LOADS (new_instance) = vNULL;
> > > - SLP_INSTANCE_ROOT_STMTS (new_instance) = root_stmt_infos;
> > > - SLP_INSTANCE_REMAIN_DEFS (new_instance) = remain;
> > > - SLP_INSTANCE_KIND (new_instance) = slp_inst_kind_reduc_chain;
> > > - new_instance->reduc_phis = NULL;
> > > - new_instance->cost_vec = vNULL;
> > > - new_instance->subgraph_entries = vNULL;
> > > + scalar_stmts.reverse ();
> > > + if (vect_analyze_slp_reduc_chain (vinfo, bst_map, scalar_stmts,
> > > + next_stmt, max_tree_size, limit))
> > > + return true;
> > > + scalar_stmts.release ();
> > > + }
> > > + }
> > >
> > > - if (dump_enabled_p ())
> > > - dump_printf_loc (MSG_NOTE, vect_location,
> > > - "SLP size %u vs. limit %u.\n",
> > > - tree_size, max_tree_size);
> > > + scalar_stmts.create (1);
> > > + scalar_stmts.quick_push (scalar_stmt);
> > >
> > > - /* Fixup SLP reduction chains. If this is a reduction chain with
> > > - a conversion in front amend the SLP tree with a node for that. */
> > > - gimple *scalar_def
> > > - = vect_orig_stmt (scalar_stmts[group_size - 1])->stmt;
> > > - if (STMT_VINFO_DEF_TYPE (scalar_stmts[0]) != vect_reduction_def)
> > > - {
> > > - /* Get at the conversion stmt - we know it's the single use
> > > - of the last stmt of the reduction chain. */
> > > - use_operand_p use_p;
> > > - bool r = single_imm_use (gimple_assign_lhs (scalar_def),
> > > - &use_p, &scalar_def);
> > > - gcc_assert (r);
> > > - stmt_vec_info next_info = vinfo->lookup_stmt (scalar_def);
> > > - next_info = vect_stmt_to_vectorize (next_info);
> > > - scalar_stmts = vNULL;
> > > - scalar_stmts.create (group_size);
> > > - for (unsigned i = 0; i < group_size; ++i)
> > > - scalar_stmts.quick_push (next_info);
> > > - slp_tree conv = vect_create_new_slp_node (scalar_stmts, 1);
> > > - SLP_TREE_VECTYPE (conv)
> > > - = get_vectype_for_scalar_type (vinfo,
> > > - TREE_TYPE
> > > - (gimple_assign_lhs (scalar_def)),
> > > - group_size);
> > > - SLP_TREE_REDUC_IDX (conv) = 0;
> > > - conv->cycle_info.id = node->cycle_info.id;
> > > - SLP_TREE_CHILDREN (conv).quick_push (node);
> > > - SLP_INSTANCE_TREE (new_instance) = conv;
> > > - /* We also have to fake this conversion stmt as SLP reduction
> > > - group so we don't have to mess with too much code
> > > - elsewhere. */
> > > - REDUC_GROUP_FIRST_ELEMENT (next_info) = next_info;
> > > - REDUC_GROUP_NEXT_ELEMENT (next_info) = NULL;
> > > - }
> > > - /* Fill the backedge child of the PHI SLP node. The
> > > - general matching code cannot find it because the
> > > - scalar code does not reflect how we vectorize the
> > > - reduction. */
> > > - use_operand_p use_p;
> > > - imm_use_iterator imm_iter;
> > > - class loop *loop = LOOP_VINFO_LOOP (as_a <loop_vec_info>
> > > (vinfo));
> > > - FOR_EACH_IMM_USE_FAST (use_p, imm_iter,
> > > - gimple_get_lhs (scalar_def))
> > > - /* There are exactly two non-debug uses, the reduction
> > > - PHI and the loop-closed PHI node. */
> > > - if (!is_gimple_debug (USE_STMT (use_p))
> > > - && gimple_bb (USE_STMT (use_p)) == loop->header)
> > > - {
> > > - auto_vec<stmt_vec_info, 64> phis (group_size);
> > > - stmt_vec_info phi_info
> > > - = vinfo->lookup_stmt (USE_STMT (use_p));
> > > - for (unsigned i = 0; i < group_size; ++i)
> > > - phis.quick_push (phi_info);
> > > - slp_tree *phi_node = bst_map->get (phis);
> > > - unsigned dest_idx = loop_latch_edge (loop)->dest_idx;
> > > - SLP_TREE_CHILDREN (*phi_node)[dest_idx]
> > > - = SLP_INSTANCE_TREE (new_instance);
> > > - SLP_INSTANCE_TREE (new_instance)->refcnt++;
> > > - }
> > > + if (dump_enabled_p ())
> > > + {
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + "Starting SLP discovery for\n");
> > > + for (unsigned i = 0; i < scalar_stmts.length (); ++i)
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + " %G", scalar_stmts[i]->stmt);
> > > + }
> > >
> > > - vinfo->slp_instances.safe_push (new_instance);
> > > + /* Build the tree for the SLP instance. */
> > > + unsigned int group_size = scalar_stmts.length ();
> > > + bool *matches = XALLOCAVEC (bool, group_size);
> > > + poly_uint64 max_nunits = 1;
> > > + unsigned tree_size = 0;
> > >
> > > - /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> > > - the number of scalar stmts in the root in a few places.
> > > - Verify that assumption holds. */
> > > - gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE
> > > (new_instance))
> > > - .length () == group_size);
> > > + slp_tree node = vect_build_slp_tree (vinfo, scalar_stmts, group_size,
> > > + &max_nunits, matches, limit,
> > > + &tree_size, bst_map);
> > > + if (node != NULL)
> > > + {
> > > + /* Create a new SLP instance. */
> > > + slp_instance new_instance = XNEW (class _slp_instance);
> > > + SLP_INSTANCE_TREE (new_instance) = node;
> > > + SLP_INSTANCE_LOADS (new_instance) = vNULL;
> > > + SLP_INSTANCE_ROOT_STMTS (new_instance) = vNULL;
> > > + SLP_INSTANCE_REMAIN_DEFS (new_instance) = vNULL;
> > > + SLP_INSTANCE_KIND (new_instance) = kind;
> > > + new_instance->reduc_phis = NULL;
> > > + new_instance->cost_vec = vNULL;
> > > + new_instance->subgraph_entries = vNULL;
> > >
> > > - if (dump_enabled_p ())
> > > - {
> > > - dump_printf_loc (MSG_NOTE, vect_location,
> > > - "Final SLP tree for instance %p:\n",
> > > - (void *) new_instance);
> > > - vect_print_slp_graph (MSG_NOTE, vect_location,
> > > - SLP_INSTANCE_TREE (new_instance));
> > > - }
> > > + if (dump_enabled_p ())
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + "SLP size %u vs. limit %u.\n",
> > > + tree_size, max_tree_size);
> > >
> > > - return true;
> > > + vinfo->slp_instances.safe_push (new_instance);
> > > +
> > > + /* ??? We've replaced the old SLP_INSTANCE_GROUP_SIZE with
> > > + the number of scalar stmts in the root in a few places.
> > > + Verify that assumption holds. */
> > > + gcc_assert (SLP_TREE_SCALAR_STMTS (SLP_INSTANCE_TREE
> > > (new_instance))
> > > + .length () == group_size);
> > > +
> > > + if (dump_enabled_p ())
> > > + {
> > > + dump_printf_loc (MSG_NOTE, vect_location,
> > > + "Final SLP tree for instance %p:\n",
> > > + (void *) new_instance);
> > > + vect_print_slp_graph (MSG_NOTE, vect_location,
> > > + SLP_INSTANCE_TREE (new_instance));
> > > }
> > > +
> > > + return true;
> > > }
> > > /* Failed to SLP. */
> > >
> > > @@ -5256,40 +5337,6 @@ vect_analyze_slp (vec_info *vinfo, unsigned
> > > max_tree_size,
> > >
> > > if (loop_vec_info loop_vinfo = dyn_cast <loop_vec_info> (vinfo))
> > > {
> > > - /* Find SLP sequences starting from reduction chains. */
> > > - FOR_EACH_VEC_ELT (loop_vinfo->reduction_chains, i, first_element)
> > > - if (! STMT_VINFO_RELEVANT_P (first_element)
> > > - && ! STMT_VINFO_LIVE_P (first_element))
> > > - ;
> > > - else if (force_single_lane
> > > - || ! vect_analyze_slp_reduc_chain (vinfo, bst_map,
> > > - first_element,
> > > - max_tree_size, &limit))
> > > - {
> > > - if (dump_enabled_p ())
> > > - dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> > > - "SLP discovery of reduction chain failed\n");
> > > - /* Dissolve reduction chain group. */
> > > - stmt_vec_info vinfo = first_element;
> > > - stmt_vec_info last = NULL;
> > > - while (vinfo)
> > > - {
> > > - stmt_vec_info next = REDUC_GROUP_NEXT_ELEMENT (vinfo);
> > > - REDUC_GROUP_FIRST_ELEMENT (vinfo) = NULL;
> > > - REDUC_GROUP_NEXT_ELEMENT (vinfo) = NULL;
> > > - last = vinfo;
> > > - vinfo = next;
> > > - }
> > > - STMT_VINFO_DEF_TYPE (first_element) = vect_internal_def;
> > > - /* ??? When there's a conversion around the reduction
> > > - chain 'last' isn't the entry of the reduction. */
> > > - if (STMT_VINFO_DEF_TYPE (last) != vect_reduction_def)
> > > - return opt_result::failure_at (vect_location,
> > > - "SLP build failed.\n");
> > > - /* It can be still vectorized as part of an SLP reduction. */
> > > - loop_vinfo->reductions.safe_push (last);
> > > - }
> > > -
> > > /* Find SLP sequences starting from groups of reductions. */
> > > if (loop_vinfo->reductions.length () > 0)
> > > {
> > > @@ -5315,23 +5362,13 @@ vect_analyze_slp (vec_info *vinfo, unsigned
> > > max_tree_size,
> > > if (!force_single_lane
> > > && !lane_reducing_stmt_p (STMT_VINFO_STMT
> > > (next_info)))
> > > scalar_stmts.quick_push (next_info);
> > > - else
> > > - {
> > > - /* Do SLP discovery for single-lane reductions. */
> > > - vec<stmt_vec_info> stmts;
> > > - vec<stmt_vec_info> roots = vNULL;
> > > - vec<tree> remain = vNULL;
> > > - stmts.create (1);
> > > - stmts.quick_push (next_info);
> > > - if (! vect_build_slp_instance (vinfo,
> > > - slp_inst_kind_reduc_group,
> > > - stmts, roots, remain,
> > > - max_tree_size, &limit,
> > > - bst_map,
> > > - force_single_lane))
> > > - return opt_result::failure_at (vect_location,
> > > - "SLP build failed.\n");
> > > - }
> > > + /* Do SLP discovery for single-lane reductions. */
> > > + else if (! vect_analyze_slp_reduction (loop_vinfo, next_info,
> > > + max_tree_size,
> > > &limit,
> > > + bst_map,
> > > + force_single_lane))
> > > + return opt_result::failure_at (vect_location,
> > > + "SLP build failed.\n");
> > > }
> > > }
> > > /* Save for re-processing on failure. */
> > > @@ -5349,20 +5386,13 @@ vect_analyze_slp (vec_info *vinfo, unsigned
> > > max_tree_size,
> > > scalar_stmts.release ();
> > > /* Do SLP discovery for single-lane reductions. */
> > > for (auto stmt_info : saved_stmts)
> > > - {
> > > - vec<stmt_vec_info> stmts;
> > > - vec<stmt_vec_info> roots = vNULL;
> > > - vec<tree> remain = vNULL;
> > > - stmts.create (1);
> > > - stmts.quick_push (vect_stmt_to_vectorize (stmt_info));
> > > - if (! vect_build_slp_instance (vinfo,
> > > - slp_inst_kind_reduc_group,
> > > - stmts, roots, remain,
> > > - max_tree_size, &limit,
> > > - bst_map, force_single_lane))
> > > - return opt_result::failure_at (vect_location,
> > > - "SLP build failed.\n");
> > > - }
> > > + if (! vect_analyze_slp_reduction (loop_vinfo,
> > > + vect_stmt_to_vectorize
> > > + (stmt_info),
> > > + max_tree_size, &limit,
> > > + bst_map, force_single_lane))
> > > + return opt_result::failure_at (vect_location,
> > > + "SLP build failed.\n");
> > > }
> > > saved_stmts.release ();
> > > }
> > > diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> > > index 18e672b26a7..91d5ee08ac5 100644
> > > --- a/gcc/tree-vectorizer.h
> > > +++ b/gcc/tree-vectorizer.h
> > > @@ -843,6 +843,9 @@ public:
> > > following land-reducing operation would be assigned to. */
> > > unsigned int reduc_result_pos;
> > >
> > > + /* Whether this represents a reduction chain. */
> > > + bool is_reduc_chain;
> > > +
> > > /* Whether we force a single cycle PHI during reduction vectorization.
> > > */
> > > bool force_single_cycle;
> > >
> > > @@ -1065,10 +1068,6 @@ public:
> > > /* Reduction cycles detected in the loop. Used in loop-aware SLP. */
> > > auto_vec<stmt_vec_info> reductions;
> > >
> > > - /* All reduction chains in the loop, represented by the first
> > > - stmt in the chain. */
> > > - auto_vec<stmt_vec_info> reduction_chains;
> > > -
> > > /* Defs that could not be analyzed such as OMP SIMD calls without
> > > a LHS. */
> > > auto_vec<stmt_vec_info> alternate_defs;
> > > @@ -1289,7 +1288,6 @@ public:
> > > #define LOOP_VINFO_SLP_INSTANCES(L) (L)->slp_instances
> > > #define LOOP_VINFO_SLP_UNROLLING_FACTOR(L) (L)-
> >slp_unrolling_factor
> > > #define LOOP_VINFO_REDUCTIONS(L) (L)->reductions
> > > -#define LOOP_VINFO_REDUCTION_CHAINS(L) (L)->reduction_chains
> > > #define LOOP_VINFO_PEELING_FOR_GAPS(L) (L)->peeling_for_gaps
> > > #define LOOP_VINFO_PEELING_FOR_NITER(L) (L)->peeling_for_niter
> > > #define LOOP_VINFO_EARLY_BREAKS(L) (L)->early_breaks
> > > --
> > > 2.51.0
> >
>
> --
> Richard Biener <[email protected]>
> SUSE Software Solutions Germany GmbH,
> Frankenstrasse 146, 90461 Nuernberg, Germany;
> GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG
> Nuernberg)
