Re: [PATCH V2] Extend vectorizer to handle nonlinear induction for neg, mul/lshift/rshift with a constant.

[Richard Biener <richard.guenther@gmail.com>]

On Mon, Aug 29, 2022 at 7:29 AM liuhongt via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> >Looks good overall - a few comments inline.  Also can you please add
> >SLP support?
> >I've tried hard to fill in gaps where SLP support is missing since my
> >goal is still to get
> >rid of non-SLP.
> For slp with different induction type, they need separate iv update and
> an vector permutation. And if they are the same induction type, iv can
> be updated with 1 instructions w/o permutation.
> I'll add a incremental patch for that.
>
> >gcc_assert (is_a <gphi *> (loop_phi_node));
> >is shorter
> It looks like it doesn't support gphi*, just support gimple*. Since it's
> already gphi* here, I've removed the assert.
>
> >I think you should use
> >init_expr = PHI_ARG_DEF_FROM_EDGE (loop_phi_node,loop_preheader_edge (loop));
> >and loop_latch_edge (loop) for ev_expr, you can't rely on them being arg 0 / 1.
> Changed.
>
> >Likewise.  Use preheader/latch edge.
> Changed.
>
> >and those two should then go away.
> Removed.
>
> >is not vectorized?  I think it should be possible to relax
> >this.
> Relaxed.
>
> >def is never NULL so a cheaper way to write this is
> >    || ((def = SSA_NAME_DEF_STMT (ev_expr)), true)
> Changed.
>
> >not sure if we need to bother here - ideally vectorizable_live_operation would
> >give up instead (but I suppose the regular IV / induction analysis gives up
> >here as well?)
> Removed.
>
> >the above can at least go into the combined switch case
> Changed.
>
> >Seeing this - did you check whether you handle prologue peeling correctly?  The
> >same issue might show up with a vectorized epilogue.  I think you can force a
> >peeled prologue with storing unaligned and -fno-vect-cost-model (that IIRC will
> >simply optimize for the larger number of aligned memory ops)
> Update in vect_update_ivs_after_vectorizer, also support peel for unaligned cases.
>
> >since you only handle inner loop nonlinear IVs you should probably
> >swap the two checks?
> Changed.
>
> >There might be a more canonical way to build the series expr
> build_vec_series doens't add stmt to sequence, so i'll still keep VEC_SERY_EXPR here?
>
> >use types_compatible_p (...) instead of comparing TYPE_CANONICAL.
> >A small enhancement would be to support different signedness
> >(use tree_nop_conversion_p then).
> Support different signedness.
>
> >above you asserted that the conversion is only necessary for constants
> >but then fold_convert will also generate a tree NOP_EXPR for
> >some types_compatible_p types.  So maybe only do this for INTEGER_CST
> >init_expr or use init_expr = gimple_convert (...) and insert required stmts
> >on the preheader.
> Changed.
>
> >Alternatively you could perform the vector IV updates in an unsigned type?
> Changed.
>
> >why's that necessary?  can we do a MIN (vector_step, { prec-1, prec-1,
> >prec-1 ... })
> It's true for ashr, but not for ashl, lshr. For the later 2, when vector_step >= precision
> The result should be zero instead of shift by prec - 1.
>
> >> +      new_name = vect_create_nonlinear_iv_step (&stmts, step_expr,
> >> +                                               nunits, induction_type);
> >> +
> >> +      vec_step = vect_create_nonlinear_iv_vec_step (loop_vinfo, stmt_info,
> >> +                                                   new_name, vectype,
> >> +                                                   induction_type);
>
> >are these not the same as created above?are these not the same as created above?
>
> They are different, the first one is vf, this is nunits, vf could be multi copy of nunits which
> is exact this code is handled and phi_latch is updated in the former vf place.
>
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.

OK, and sorry for the delay.

Thanks.
Richard.

>
> For neg, the patch create a vec_init as [ a, -a, a, -a, ...  ] and no
> vec_step is needed to update vectorized iv since vf is always multiple
> of 2(negative * negative is positive).
>
> For shift, the patch create a vec_init as [ a, a >> c, a >> 2*c, ..]
> as vec_step as [ c * nunits, c * nunits, c * nunits, ... ], vectorized iv is
> updated as vec_def = vec_init >>/<< vec_step.
>
> For mul, the patch create a vec_init as [ a, a * c, a * pow(c, 2), ..]
> as vec_step as [ pow(c,nunits), pow(c,nunits),...] iv is updated as vec_def =
> vec_init * vec_step.
>
> The patch handles nonlinear iv for
> 1. Integer type only, floating point is not handled.
> 2. No slp_node.
> 3. iv_loop should be same as vector loop, not nested loop.
> 4. No UD is created, for mul, use unsigned mult to avoid UD, for
>    shift, shift count should be less than type precision.
>
> gcc/ChangeLog:
>
>         PR tree-optimization/103144
>         * tree-vect-loop.cc (vect_is_nonlinear_iv_evolution): New function.
>         (vect_analyze_scalar_cycles_1): Detect nonlinear iv by upper function.
>         (vect_create_nonlinear_iv_init): New function.
>         (vect_peel_nonlinear_iv_init): Ditto.
>         (vect_create_nonlinear_iv_step): Ditto
>         (vect_create_nonlinear_iv_vec_step): Ditto
>         (vect_update_nonlinear_iv): Ditto
>         (vectorizable_nonlinear_induction): Ditto.
>         (vectorizable_induction): Call
>         vectorizable_nonlinear_induction when induction_type is not
>         vect_step_op_add.
>         * tree-vect-loop-manip.cc (vect_update_ivs_after_vectorizer):
>         Update nonlinear iv for epilogue loop.
>         * tree-vectorizer.h (enum vect_induction_op_type): New enum.
>         (STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE): New Macro.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/pr103144-mul-1.c: New test.
>         * gcc.target/i386/pr103144-mul-2.c: New test.
>         * gcc.target/i386/pr103144-neg-1.c: New test.
>         * gcc.target/i386/pr103144-neg-2.c: New test.
>         * gcc.target/i386/pr103144-shift-1.c: New test.
>         * gcc.target/i386/pr103144-shift-2.c: New test.
> ---
>  .../gcc.target/i386/pr103144-mul-1.c          |  51 ++
>  .../gcc.target/i386/pr103144-mul-2.c          |  51 ++
>  .../gcc.target/i386/pr103144-neg-1.c          |  51 ++
>  .../gcc.target/i386/pr103144-neg-2.c          |  44 ++
>  .../gcc.target/i386/pr103144-shift-1.c        |  70 ++
>  .../gcc.target/i386/pr103144-shift-2.c        |  79 ++
>  gcc/tree-vect-loop-manip.cc                   |  37 +-
>  gcc/tree-vect-loop.cc                         | 678 +++++++++++++++++-
>  gcc/tree-vectorizer.h                         |  15 +
>  9 files changed, 1062 insertions(+), 14 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr103144-mul-1.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr103144-mul-2.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr103144-neg-1.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr103144-neg-2.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr103144-shift-1.c
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr103144-shift-2.c
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr103144-mul-1.c b/gcc/testsuite/gcc.target/i386/pr103144-mul-1.c
> new file mode 100644
> index 00000000000..640c34fd959
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103144-mul-1.c
> @@ -0,0 +1,51 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mavx2 -ftree-vectorize -fvect-cost-model=unlimited -fdump-tree-vect-details -mprefer-vector-width=256" } */
> +/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 4 "vect" } } */
> +
> +#define N 10000
> +
> +void
> +__attribute__((noipa))
> +foo_mul (int* a, int b)
> +{
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b *= 3;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_mul_const (int* a)
> +{
> +  int b = 1;
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b *= 3;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_mul_peel (int* a, int b)
> +{
> +  for (int i = 0; i != 39; i++)
> +    {
> +      a[i] = b;
> +      b *= 3;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_mul_peel_const (int* a)
> +{
> +  int b = 1;
> +  for (int i = 0; i != 39; i++)
> +    {
> +      a[i] = b;
> +      b *= 3;
> +    }
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103144-mul-2.c b/gcc/testsuite/gcc.target/i386/pr103144-mul-2.c
> new file mode 100644
> index 00000000000..39fdea3a69d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103144-mul-2.c
> @@ -0,0 +1,51 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -mavx2 -ftree-vectorize -fvect-cost-model=unlimited -mprefer-vector-width=256" } */
> +/* { dg-require-effective-target avx2 } */
> +
> +#include "avx2-check.h"
> +#include <string.h>
> +#include "pr103144-mul-1.c"
> +
> +typedef int v8si __attribute__((vector_size(32)));
> +
> +void
> +avx2_test (void)
> +{
> +  int* epi32_exp = (int*) malloc (N * sizeof (int));
> +  int* epi32_dst = (int*) malloc (N * sizeof (int));
> +
> +  __builtin_memset (epi32_exp, 0, N * sizeof (int));
> +  int b = 8;
> +  v8si init = __extension__(v8si) { b, b * 3, b * 9, b * 27, b * 81, b * 243, b * 729, b * 2187 };
> +
> +  for (int i = 0; i != N / 8; i++)
> +    {
> +      memcpy (epi32_exp + i * 8, &init, 32);
> +      init *= 6561;
> +    }
> +
> +  foo_mul (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_mul_peel (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, 39 * 4) != 0)
> +    __builtin_abort ();
> +
> +  init = __extension__(v8si) { 1, 3, 9, 27, 81, 243, 729, 2187 };
> +  for (int i = 0; i != N / 8; i++)
> +    {
> +      memcpy (epi32_exp + i * 8, &init, 32);
> +      init *= 6561;
> +    }
> +
> +  foo_mul_const (epi32_dst);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_mul_peel_const (epi32_dst);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, 39 * 4) != 0)
> +    __builtin_abort ();
> +
> +  return;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103144-neg-1.c b/gcc/testsuite/gcc.target/i386/pr103144-neg-1.c
> new file mode 100644
> index 00000000000..f87b1d6e529
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103144-neg-1.c
> @@ -0,0 +1,51 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mavx2 -ftree-vectorize -fvect-cost-model=unlimited -fdump-tree-vect-details -mprefer-vector-width=256" } */
> +/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 4 "vect" } } */
> +
> +#define N 10000
> +
> +void
> +__attribute__((noipa))
> +foo_neg (int* a, int b)
> +{
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b = -b;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_neg_const (int* a)
> +{
> +  int b = 1;
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b = -b;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_neg_peel (int* a, int b, int n)
> +{
> +  for (int i = 0; i != n; i++)
> +    {
> +      a[i] = b;
> +      b = -b;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_neg_const_peel (int* a, int n)
> +{
> +  int b = 1;
> +  for (int i = 0; i != n; i++)
> +    {
> +      a[i] = b;
> +      b = -b;
> +    }
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103144-neg-2.c b/gcc/testsuite/gcc.target/i386/pr103144-neg-2.c
> new file mode 100644
> index 00000000000..bb8c22b9f9e
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103144-neg-2.c
> @@ -0,0 +1,44 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -mavx2 -ftree-vectorize -fvect-cost-model=unlimited -mprefer-vector-width=256" } */
> +/* { dg-require-effective-target avx2 } */
> +
> +#include "avx2-check.h"
> +#include <string.h>
> +#include "pr103144-neg-1.c"
> +
> +void
> +avx2_test (void)
> +{
> +  int* epi32_exp = (int*) malloc (N * sizeof (int));
> +  int* epi32_dst = (int*) malloc (N * sizeof (int));
> +  long long* epi64_exp = (long long*) malloc (N * sizeof (int));
> +
> +  __builtin_memset (epi32_exp, 0, N * sizeof (int));
> +  int b = 100;
> +
> +  for (int i = 0; i != N / 2; i++)
> +    epi64_exp[i] = ((long long) b) | (((long long) -b) << 32);
> +
> +  memcpy (epi32_exp, epi64_exp, N * sizeof (int));
> +  foo_neg (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_neg_peel (epi32_dst, b, 39);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, 39 * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  for (int i = 0; i != N / 2; i++)
> +    epi64_exp[i] = ((long long) 1) | (((long long) -1) << 32);
> +
> +  memcpy (epi32_exp, epi64_exp, N * sizeof (int));
> +  foo_neg_const (epi32_dst);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_neg_const_peel (epi32_dst, 39);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, 39 * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  return;
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103144-shift-1.c b/gcc/testsuite/gcc.target/i386/pr103144-shift-1.c
> new file mode 100644
> index 00000000000..2a6920350dd
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103144-shift-1.c
> @@ -0,0 +1,70 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mavx2 -ftree-vectorize -fvect-cost-model=unlimited -fdump-tree-vect-details -mprefer-vector-width=256" } */
> +/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 6 "vect" } } */
> +
> +#define N 10000
> +void
> +__attribute__((noipa))
> +foo_shl (int* a, int b)
> +{
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b <<= 1;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_ashr (int* a, int b)
> +{
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b >>= 1;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_lshr (unsigned int* a, unsigned int b)
> +{
> +  for (int i = 0; i != N; i++)
> +    {
> +      a[i] = b;
> +      b >>= 1U;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_shl_peel (int* a, int b)
> +{
> +  for (int i = 0; i != 39; i++)
> +    {
> +      a[i] = b;
> +      b <<= 1;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_ashr_peel (int* a, int b)
> +{
> +  for (int i = 0; i != 39; i++)
> +    {
> +      a[i] = b;
> +      b >>= 1;
> +    }
> +}
> +
> +void
> +__attribute__((noipa))
> +foo_lshr_peel (unsigned int* a, unsigned int b)
> +{
> +  for (int i = 0; i != 39; i++)
> +    {
> +      a[i] = b;
> +      b >>= 1U;
> +    }
> +}
> diff --git a/gcc/testsuite/gcc.target/i386/pr103144-shift-2.c b/gcc/testsuite/gcc.target/i386/pr103144-shift-2.c
> new file mode 100644
> index 00000000000..6f477191d96
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr103144-shift-2.c
> @@ -0,0 +1,79 @@
> +/* { dg-do run } */
> +/* { dg-options "-O2 -mavx2 -ftree-vectorize -fvect-cost-model=unlimited -mprefer-vector-width=256" } */
> +/* { dg-require-effective-target avx2 } */
> +
> +#include "avx2-check.h"
> +#include <string.h>
> +#include "pr103144-shift-1.c"
> +
> +typedef int v8si __attribute__((vector_size(32)));
> +typedef unsigned int v8usi __attribute__((vector_size(32)));
> +
> +void
> +avx2_test (void)
> +{
> +  int* epi32_exp = (int*) malloc (N * sizeof (int));
> +  int* epi32_dst = (int*) malloc (N * sizeof (int));
> +  unsigned int* epu32_exp = (unsigned int*) malloc (N * sizeof (int));
> +  unsigned int* epu32_dst = (unsigned int*) malloc (N * sizeof (int));
> +
> +  __builtin_memset (epi32_exp, 0, N * sizeof (int));
> +  int b = 8;
> +  v8si init = __extension__(v8si) { b, b << 1, b << 2, b << 3, b << 4, b << 5, b << 6, b << 7 };
> +
> +  for (int i = 0; i != N / 8; i++)
> +    {
> +      memcpy (epi32_exp + i * 8, &init, 32);
> +      init <<= 8;
> +    }
> +
> +  foo_shl (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_shl_peel (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, 39 * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  b = -11111;
> +  init = __extension__(v8si) { b, b >> 1, b >> 2, b >> 3, b >> 4, b >> 5, b >> 6, b >> 7 };
> +  for (int i = 0; i != N / 8; i++)
> +    {
> +      memcpy (epi32_exp + i * 8, &init, 32);
> +      init >>= 8;
> +    }
> +
> +  foo_ashr (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_ashr_peel (epi32_dst, b);
> +  if (__builtin_memcmp (epi32_dst, epi32_exp, 39 * sizeof (int)) != 0)
> +    {
> +      for (int i = 0; i != 39; i++)
> +       {
> +         printf ("epi32_dst[%d] is %d ----", i, epi32_dst[i]);
> +         printf ("epi32_exp[%d] is %d\n", i, epi32_exp[i]);
> +       }
> +         __builtin_abort ();
> +    }
> +
> +  __builtin_memset (epu32_exp, 0, N * sizeof (int));
> +  unsigned int c = 11111111;
> +  v8usi initu = __extension__(v8usi) { c, c >> 1U, c >> 2U, c >> 3U, c >> 4U, c >> 5U, c >> 6U, c >> 7U };
> +  for (int i = 0; i != N / 8; i++)
> +    {
> +      memcpy (epu32_exp + i * 8, &initu, 32);
> +      initu >>= 8U;
> +    }
> +
> +  foo_lshr (epu32_dst, c);
> +  if (__builtin_memcmp (epu32_dst, epu32_exp, N * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  foo_lshr_peel (epu32_dst, c);
> +  if (__builtin_memcmp (epu32_dst, epu32_exp, 39 * sizeof (int)) != 0)
> +    __builtin_abort ();
> +
> +  return;
> +}
> diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc
> index 86d2264054a..fc7901d8a8a 100644
> --- a/gcc/tree-vect-loop-manip.cc
> +++ b/gcc/tree-vect-loop-manip.cc
> @@ -1559,15 +1559,28 @@ vect_update_ivs_after_vectorizer (loop_vec_info loop_vinfo,
>        gcc_assert (!tree_is_chrec (step_expr));
>
>        init_expr = PHI_ARG_DEF_FROM_EDGE (phi, loop_preheader_edge (loop));
> +      gimple_seq stmts = NULL;
> +      enum vect_induction_op_type induction_type
> +       = STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (phi_info);
>
> -      off = fold_build2 (MULT_EXPR, TREE_TYPE (step_expr),
> -                        fold_convert (TREE_TYPE (step_expr), niters),
> -                        step_expr);
> -      if (POINTER_TYPE_P (type))
> -       ni = fold_build_pointer_plus (init_expr, off);
> +      if (induction_type == vect_step_op_add)
> +       {
> +         off = fold_build2 (MULT_EXPR, TREE_TYPE (step_expr),
> +                            fold_convert (TREE_TYPE (step_expr), niters),
> +                            step_expr);
> +         if (POINTER_TYPE_P (type))
> +           ni = fold_build_pointer_plus (init_expr, off);
> +         else
> +           ni = fold_build2 (PLUS_EXPR, type,
> +                             init_expr, fold_convert (type, off));
> +       }
> +      /* Don't bother call vect_peel_nonlinear_iv_init.  */
> +      else if (induction_type == vect_step_op_neg)
> +       ni = init_expr;
>        else
> -       ni = fold_build2 (PLUS_EXPR, type,
> -                         init_expr, fold_convert (type, off));
> +       ni = vect_peel_nonlinear_iv_init (&stmts, init_expr,
> +                                         niters, step_expr,
> +                                         induction_type);
>
>        var = create_tmp_var (type, "tmp");
>
> @@ -1576,9 +1589,15 @@ vect_update_ivs_after_vectorizer (loop_vec_info loop_vinfo,
>        ni_name = force_gimple_operand (ni, &new_stmts, false, var);
>        /* Exit_bb shouldn't be empty.  */
>        if (!gsi_end_p (last_gsi))
> -       gsi_insert_seq_after (&last_gsi, new_stmts, GSI_SAME_STMT);
> +       {
> +         gsi_insert_seq_after (&last_gsi, stmts, GSI_SAME_STMT);
> +         gsi_insert_seq_after (&last_gsi, new_stmts, GSI_SAME_STMT);
> +       }
>        else
> -       gsi_insert_seq_before (&last_gsi, new_stmts, GSI_SAME_STMT);
> +       {
> +         gsi_insert_seq_before (&last_gsi, stmts, GSI_SAME_STMT);
> +         gsi_insert_seq_before (&last_gsi, new_stmts, GSI_SAME_STMT);
> +       }
>
>        /* Fix phi expressions in the successor bb.  */
>        adjust_phi_and_debug_stmts (phi1, update_e, ni_name);
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 2257b29a652..c2293466c1c 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -425,6 +425,77 @@ vect_is_simple_iv_evolution (unsigned loop_nb, tree access_fn, tree * init,
>    return true;
>  }
>
> +/* Function vect_is_nonlinear_iv_evolution
> +
> +   Only support nonlinear induction for integer type
> +   1. neg
> +   2. mul by constant
> +   3. lshift/rshift by constant.
> +
> +   For neg induction, return a fake step as integer -1.  */
> +static bool
> +vect_is_nonlinear_iv_evolution (class loop* loop, stmt_vec_info stmt_info,
> +                               gphi* loop_phi_node, tree *init, tree *step)
> +{
> +  tree init_expr, ev_expr, result, op1, op2;
> +  gimple* def;
> +
> +  if (gimple_phi_num_args (loop_phi_node) != 2)
> +    return false;
> +
> +  init_expr = PHI_ARG_DEF_FROM_EDGE (loop_phi_node, loop_preheader_edge (loop));
> +  ev_expr = PHI_ARG_DEF_FROM_EDGE (loop_phi_node, loop_latch_edge (loop));
> +
> +  /* Support nonlinear induction only for integer type.  */
> +  if (!INTEGRAL_TYPE_P (TREE_TYPE (init_expr)))
> +    return false;
> +
> +  *init = init_expr;
> +  result = PHI_RESULT (loop_phi_node);
> +
> +  if (TREE_CODE (ev_expr) != SSA_NAME
> +      || ((def = SSA_NAME_DEF_STMT (ev_expr)), false)
> +      || !is_gimple_assign (def))
> +    return false;
> +
> +  enum tree_code t_code = gimple_assign_rhs_code (def);
> +  switch (t_code)
> +    {
> +    case NEGATE_EXPR:
> +      if (gimple_assign_rhs1 (def) != result)
> +       return false;
> +      *step = build_int_cst (TREE_TYPE (init_expr), -1);
> +      STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info) = vect_step_op_neg;
> +      break;
> +
> +    case RSHIFT_EXPR:
> +    case LSHIFT_EXPR:
> +    case MULT_EXPR:
> +      op1 = gimple_assign_rhs1 (def);
> +      op2 = gimple_assign_rhs2 (def);
> +      if (TREE_CODE (op2) != INTEGER_CST
> +         || op1 != result)
> +       return false;
> +      *step = op2;
> +      if (t_code == LSHIFT_EXPR)
> +       STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info) = vect_step_op_shl;
> +      else if (t_code == RSHIFT_EXPR)
> +       STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info) = vect_step_op_shr;
> +      /* NEGATE_EXPR and MULT_EXPR are both vect_step_op_mul.  */
> +      else
> +       STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info) = vect_step_op_mul;
> +      break;
> +
> +    default:
> +      return false;
> +    }
> +
> +  STMT_VINFO_LOOP_PHI_EVOLUTION_BASE_UNCHANGED (stmt_info) = *init;
> +  STMT_VINFO_LOOP_PHI_EVOLUTION_PART (stmt_info) = *step;
> +
> +  return true;
> +}
> +
>  /* Return true if PHI, described by STMT_INFO, is the inner PHI in
>     what we are assuming is a double reduction.  For example, given
>     a structure like this:
> @@ -512,11 +583,16 @@ vect_analyze_scalar_cycles_1 (loop_vec_info loop_vinfo, class loop *loop,
>             = evolution_part_in_loop_num (access_fn, loop->num);
>         }
>
> -      if (!access_fn
> -         || vect_inner_phi_in_double_reduction_p (loop_vinfo, phi)
> -         || !vect_is_simple_iv_evolution (loop->num, access_fn, &init, &step)
> -         || (LOOP_VINFO_LOOP (loop_vinfo) != loop
> -             && TREE_CODE (step) != INTEGER_CST))
> +      if ((!access_fn
> +          || vect_inner_phi_in_double_reduction_p (loop_vinfo, phi)
> +          || !vect_is_simple_iv_evolution (loop->num, access_fn,
> +                                           &init, &step)
> +          || (LOOP_VINFO_LOOP (loop_vinfo) != loop
> +              && TREE_CODE (step) != INTEGER_CST))
> +         /* Only handle nonlinear iv for same loop.  */
> +         && (LOOP_VINFO_LOOP (loop_vinfo) != loop
> +             || !vect_is_nonlinear_iv_evolution (loop, stmt_vinfo,
> +                                                 phi, &init, &step)))
>         {
>           worklist.safe_push (stmt_vinfo);
>           continue;
> @@ -8229,6 +8305,591 @@ vect_can_vectorize_without_simd_p (code_helper code)
>           && vect_can_vectorize_without_simd_p (tree_code (code)));
>  }
>
> +/* Create vector init for vectorized iv.  */
> +static tree
> +vect_create_nonlinear_iv_init (gimple_seq* stmts, tree init_expr,
> +                              tree step_expr, poly_uint64 nunits,
> +                              tree vectype,
> +                              enum vect_induction_op_type induction_type)
> +{
> +  unsigned HOST_WIDE_INT const_nunits;
> +  tree vec_shift, vec_init, new_name;
> +  unsigned i;
> +  tree itype = TREE_TYPE (vectype);
> +
> +  /* iv_loop is the loop to be vectorized. Create:
> +     vec_init = [X, X+S, X+2*S, X+3*S] (S = step_expr, X = init_expr).  */
> +  new_name = gimple_convert (stmts, itype, init_expr);
> +  switch (induction_type)
> +    {
> +    case vect_step_op_shr:
> +    case vect_step_op_shl:
> +      /* Build the Initial value from shift_expr.  */
> +      vec_init = gimple_build_vector_from_val (stmts,
> +                                              vectype,
> +                                              new_name);
> +      vec_shift = gimple_build (stmts, VEC_SERIES_EXPR, vectype,
> +                               build_zero_cst (itype), step_expr);
> +      vec_init = gimple_build (stmts,
> +                              (induction_type == vect_step_op_shr
> +                               ? RSHIFT_EXPR : LSHIFT_EXPR),
> +                              vectype, vec_init, vec_shift);
> +      break;
> +
> +    case vect_step_op_neg:
> +      {
> +       vec_init = gimple_build_vector_from_val (stmts,
> +                                                vectype,
> +                                                new_name);
> +       tree vec_neg = gimple_build (stmts, NEGATE_EXPR,
> +                                    vectype, vec_init);
> +       /* The encoding has 2 interleaved stepped patterns.  */
> +       vec_perm_builder sel (nunits, 2, 3);
> +       sel.quick_grow (6);
> +       for (i = 0; i < 3; i++)
> +         {
> +           sel[2 * i] = i;
> +           sel[2 * i + 1] = i + nunits;
> +         }
> +       vec_perm_indices indices (sel, 2, nunits);
> +       tree perm_mask_even
> +         = vect_gen_perm_mask_checked (vectype, indices);
> +       vec_init = gimple_build (stmts, VEC_PERM_EXPR,
> +                                vectype,
> +                                vec_init, vec_neg,
> +                                perm_mask_even);
> +      }
> +      break;
> +
> +    case vect_step_op_mul:
> +      {
> +       /* Use unsigned mult to avoid UD integer overflow.  */
> +       gcc_assert (nunits.is_constant (&const_nunits));
> +       tree utype = unsigned_type_for (itype);
> +       tree uvectype = build_vector_type (utype,
> +                                          TYPE_VECTOR_SUBPARTS (vectype));
> +       new_name = gimple_convert (stmts, utype, new_name);
> +       vec_init = gimple_build_vector_from_val (stmts,
> +                                                uvectype,
> +                                                new_name);
> +       tree_vector_builder elts (uvectype, const_nunits, 1);
> +       tree elt_step = build_one_cst (utype);
> +
> +       elts.quick_push (elt_step);
> +       for (i = 1; i < const_nunits; i++)
> +         {
> +           /* Create: new_name_i = new_name + step_expr.  */
> +           elt_step = gimple_build (stmts, MULT_EXPR,
> +                                    utype, elt_step, step_expr);
> +           elts.quick_push (elt_step);
> +         }
> +       /* Create a vector from [new_name_0, new_name_1, ...,
> +          new_name_nunits-1].  */
> +       tree vec_mul = gimple_build_vector (stmts, &elts);
> +       vec_init = gimple_build (stmts, MULT_EXPR, uvectype,
> +                                vec_init, vec_mul);
> +       vec_init = gimple_convert (stmts, vectype, vec_init);
> +      }
> +      break;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return vec_init;
> +}
> +
> +/* Peel init_expr by skip_niter for induction_type.  */
> +tree
> +vect_peel_nonlinear_iv_init (gimple_seq* stmts, tree init_expr,
> +                            tree skip_niters, tree step_expr,
> +                            enum vect_induction_op_type induction_type)
> +{
> +  gcc_assert (TREE_CODE (skip_niters) == INTEGER_CST);
> +  tree type = TREE_TYPE (init_expr);
> +  unsigned prec = TYPE_PRECISION (type);
> +  switch (induction_type)
> +    {
> +    case vect_step_op_neg:
> +      if (TREE_INT_CST_LOW (skip_niters) % 2)
> +       init_expr = gimple_build (stmts, NEGATE_EXPR, type, init_expr);
> +      /* else no change.  */
> +      break;
> +
> +    case vect_step_op_shr:
> +    case vect_step_op_shl:
> +      skip_niters = gimple_convert (stmts, type, skip_niters);
> +      step_expr = gimple_build (stmts, MULT_EXPR, type, step_expr, skip_niters);
> +      /* When shift mount >= precision, need to avoid UD.
> +        In the original loop, there's no UD, and according to semantic,
> +        init_expr should be 0 for lshr, ashl, and >>= (prec - 1) for ashr.  */
> +      if (!tree_fits_uhwi_p (step_expr)
> +         || tree_to_uhwi (step_expr) >= prec)
> +       {
> +         if (induction_type == vect_step_op_shl
> +             || TYPE_UNSIGNED (type))
> +           init_expr = build_zero_cst (type);
> +         else
> +           init_expr = gimple_build (stmts, RSHIFT_EXPR, type,
> +                                     init_expr,
> +                                     wide_int_to_tree (type, prec - 1));
> +       }
> +      else
> +       init_expr = gimple_build (stmts, (induction_type == vect_step_op_shr
> +                                         ? RSHIFT_EXPR : LSHIFT_EXPR),
> +                                 type, init_expr, step_expr);
> +      break;
> +
> +    case vect_step_op_mul:
> +      {
> +       tree utype = unsigned_type_for (type);
> +       init_expr = gimple_convert (stmts, utype, init_expr);
> +       unsigned skipn = TREE_INT_CST_LOW (skip_niters);
> +       wide_int begin = wi::to_wide (step_expr);
> +       for (unsigned i = 0; i != skipn - 1; i++)
> +         begin = wi::mul (begin, wi::to_wide (step_expr));
> +       tree mult_expr = wide_int_to_tree (utype, begin);
> +       init_expr = gimple_build (stmts, MULT_EXPR, utype, init_expr, mult_expr);
> +       init_expr = gimple_convert (stmts, type, init_expr);
> +      }
> +      break;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return init_expr;
> +}
> +
> +/* Create vector step for vectorized iv.  */
> +static tree
> +vect_create_nonlinear_iv_step (gimple_seq* stmts, tree step_expr,
> +                              poly_uint64 vf,
> +                              enum vect_induction_op_type induction_type)
> +{
> +  tree expr = build_int_cst (TREE_TYPE (step_expr), vf);
> +  tree new_name = NULL;
> +  /* Step should be pow (step, vf) for mult induction.  */
> +  if (induction_type == vect_step_op_mul)
> +    {
> +      gcc_assert (vf.is_constant ());
> +      wide_int begin = wi::to_wide (step_expr);
> +
> +      for (unsigned i = 0; i != vf.to_constant () - 1; i++)
> +       begin = wi::mul (begin, wi::to_wide (step_expr));
> +
> +      new_name = wide_int_to_tree (TREE_TYPE (step_expr), begin);
> +    }
> +  else if (induction_type == vect_step_op_neg)
> +    /* Do nothing.  */
> +    ;
> +  else
> +    new_name = gimple_build (stmts, MULT_EXPR, TREE_TYPE (step_expr),
> +                            expr, step_expr);
> +  return new_name;
> +}
> +
> +static tree
> +vect_create_nonlinear_iv_vec_step (loop_vec_info loop_vinfo,
> +                                  stmt_vec_info stmt_info,
> +                                  tree new_name, tree vectype,
> +                                  enum vect_induction_op_type induction_type)
> +{
> +  /* No step is needed for neg induction.  */
> +  if (induction_type == vect_step_op_neg)
> +    return NULL;
> +
> +  tree t = unshare_expr (new_name);
> +  gcc_assert (CONSTANT_CLASS_P (new_name)
> +             || TREE_CODE (new_name) == SSA_NAME);
> +  tree new_vec = build_vector_from_val (vectype, t);
> +  tree vec_step = vect_init_vector (loop_vinfo, stmt_info,
> +                                   new_vec, vectype, NULL);
> +  return vec_step;
> +}
> +
> +/* Update vectorized iv with vect_step, induc_def is init.  */
> +static tree
> +vect_update_nonlinear_iv (gimple_seq* stmts, tree vectype,
> +                         tree induc_def, tree vec_step,
> +                         enum vect_induction_op_type induction_type)
> +{
> +  tree vec_def = induc_def;
> +  switch (induction_type)
> +    {
> +    case vect_step_op_mul:
> +      {
> +       /* Use unsigned mult to avoid UD integer overflow.  */
> +       tree uvectype
> +         = build_vector_type (unsigned_type_for (TREE_TYPE (vectype)),
> +                              TYPE_VECTOR_SUBPARTS (vectype));
> +       vec_def = gimple_convert (stmts, uvectype, vec_def);
> +       vec_step = gimple_convert (stmts, uvectype, vec_step);
> +       vec_def = gimple_build (stmts, MULT_EXPR, uvectype,
> +                               vec_def, vec_step);
> +       vec_def = gimple_convert (stmts, vectype, vec_def);
> +      }
> +      break;
> +
> +    case vect_step_op_shr:
> +      vec_def = gimple_build (stmts, RSHIFT_EXPR, vectype,
> +                             vec_def, vec_step);
> +      break;
> +
> +    case vect_step_op_shl:
> +      vec_def = gimple_build (stmts, LSHIFT_EXPR, vectype,
> +                             vec_def, vec_step);
> +      break;
> +    case vect_step_op_neg:
> +      vec_def = induc_def;
> +      /* Do nothing.  */
> +      break;
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  return vec_def;
> +
> +}
> +/* Function vectorizable_induction
> +
> +   Check if STMT_INFO performs an nonlinear induction computation that can be
> +   vectorized. If VEC_STMT is also passed, vectorize the induction PHI: create
> +   a vectorized phi to replace it, put it in VEC_STMT, and add it to the same
> +   basic block.
> +   Return true if STMT_INFO is vectorizable in this way.  */
> +
> +static bool
> +vectorizable_nonlinear_induction (loop_vec_info loop_vinfo,
> +                                 stmt_vec_info stmt_info,
> +                                 gimple **vec_stmt, slp_tree slp_node,
> +                                 stmt_vector_for_cost *cost_vec)
> +{
> +  class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
> +  unsigned ncopies;
> +  bool nested_in_vect_loop = false;
> +  class loop *iv_loop;
> +  tree vec_def;
> +  edge pe = loop_preheader_edge (loop);
> +  basic_block new_bb;
> +  tree vec_init, vec_step;
> +  tree new_name;
> +  gimple *new_stmt;
> +  gphi *induction_phi;
> +  tree induc_def, vec_dest;
> +  tree init_expr, step_expr;
> +  tree niters_skip;
> +  poly_uint64 vf = LOOP_VINFO_VECT_FACTOR (loop_vinfo);
> +  unsigned i;
> +  gimple_stmt_iterator si;
> +
> +  gphi *phi = dyn_cast <gphi *> (stmt_info->stmt);
> +
> +  tree vectype = STMT_VINFO_VECTYPE (stmt_info);
> +  poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (vectype);
> +  enum vect_induction_op_type induction_type
> +    = STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info);
> +
> +  gcc_assert (induction_type > vect_step_op_add);
> +
> +  if (slp_node)
> +    ncopies = 1;
> +  else
> +    ncopies = vect_get_num_copies (loop_vinfo, vectype);
> +  gcc_assert (ncopies >= 1);
> +
> +  /* FORNOW. Only handle nonlinear induction in the same loop.  */
> +  if (nested_in_vect_loop_p (loop, stmt_info))
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "nonlinear induction in nested loop.\n");
> +      return false;
> +    }
> +
> +  iv_loop = loop;
> +  gcc_assert (iv_loop == (gimple_bb (phi))->loop_father);
> +
> +  /* TODO: Support slp for nonlinear iv. There should be separate vector iv
> +     update for each iv and a permutation to generate wanted vector iv.  */
> +  if (slp_node)
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "SLP induction not supported for nonlinear"
> +                        " induction.\n");
> +      return false;
> +    }
> +
> +  /* Init_expr will be update by vect_update_ivs_after_vectorizer,
> +     if niters is unkown:
> +     For shift, when shift mount >= precision, there would be UD.
> +     For mult, don't known how to generate
> +     init_expr * pow (step, niters) for variable niters.
> +     For neg, it should be ok, since niters of vectorized main loop
> +     will always be multiple of 2.  */
> +  if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> +      && induction_type != vect_step_op_neg)
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "Peeling for epilogue is not supported"
> +                        " for nonlinear induction except neg"
> +                        " when iteration count is unknown.\n");
> +      return false;
> +    }
> +
> +  /* Also doens't support peel for neg when niter is variable.
> +     ??? generate something like niter_expr & 1 ? init_expr : -init_expr?  */
> +  niters_skip = LOOP_VINFO_MASK_SKIP_NITERS (loop_vinfo);
> +  if (niters_skip != NULL_TREE
> +      && TREE_CODE (niters_skip) != INTEGER_CST)
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "Peeling for alignement is not supported"
> +                        " for nonlinear induction when niters_skip"
> +                        " is not constant.\n");
> +      return false;
> +    }
> +
> +  if (!LOOP_VINFO_NITERS_KNOWN_P (loop_vinfo)
> +      && induction_type == vect_step_op_mul)
> +  if (!INTEGRAL_TYPE_P (TREE_TYPE (vectype)))
> +    {
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
> +                        "floating point nonlinear induction vectorization"
> +                        " not supported.\n");
> +      return false;
> +    }
> +
> +  step_expr = STMT_VINFO_LOOP_PHI_EVOLUTION_PART (stmt_info);
> +  init_expr = vect_phi_initial_value (phi);
> +  gcc_assert (step_expr != NULL_TREE && init_expr != NULL
> +             && TREE_CODE (step_expr) == INTEGER_CST);
> +  /* step_expr should be aligned with init_expr,
> +     .i.e. uint64 a >> 1, step is int, but vector<uint64> shift is used.  */
> +  step_expr = fold_convert (TREE_TYPE (vectype), step_expr);
> +
> +  if (TREE_CODE (init_expr) == INTEGER_CST)
> +    init_expr = fold_convert (TREE_TYPE (vectype), init_expr);
> +  else
> +    gcc_assert (tree_nop_conversion_p (TREE_TYPE (vectype),
> +                                      TREE_TYPE (init_expr)));
> +
> +  switch (induction_type)
> +    {
> +    case vect_step_op_neg:
> +      if (TREE_CODE (init_expr) != INTEGER_CST
> +         && TREE_CODE (init_expr) != REAL_CST)
> +       {
> +         /* Check for backend support of NEGATE_EXPR and vec_perm.  */
> +         if (!directly_supported_p (NEGATE_EXPR, vectype))
> +           return false;
> +
> +         /* The encoding has 2 interleaved stepped patterns.  */
> +         vec_perm_builder sel (nunits, 2, 3);
> +         machine_mode mode = TYPE_MODE (vectype);
> +         sel.quick_grow (6);
> +         for (i = 0; i < 3; i++)
> +           {
> +             sel[i * 2] = i;
> +             sel[i * 2 + 1] = i + nunits;
> +           }
> +         vec_perm_indices indices (sel, 2, nunits);
> +         if (!can_vec_perm_const_p (mode, mode, indices))
> +           return false;
> +       }
> +      break;
> +
> +    case vect_step_op_mul:
> +      {
> +       /* Check for backend support of MULT_EXPR.  */
> +       if (!directly_supported_p (MULT_EXPR, vectype))
> +         return false;
> +
> +       /* ?? How to construct vector step for variable number vector.
> +          [ 1, step, pow (step, 2), pow (step, 4), .. ].  */
> +       if (!vf.is_constant ())
> +         return false;
> +      }
> +      break;
> +
> +    case vect_step_op_shr:
> +      /* Check for backend support of RSHIFT_EXPR.  */
> +      if (!directly_supported_p (RSHIFT_EXPR, vectype, optab_vector))
> +       return false;
> +
> +      /* Don't shift more than type precision to avoid UD.  */
> +      if (!tree_fits_uhwi_p (step_expr)
> +         || maybe_ge (nunits * tree_to_uhwi (step_expr),
> +                      TYPE_PRECISION (TREE_TYPE (init_expr))))
> +       return false;
> +      break;
> +
> +    case vect_step_op_shl:
> +      /* Check for backend support of RSHIFT_EXPR.  */
> +      if (!directly_supported_p (LSHIFT_EXPR, vectype, optab_vector))
> +       return false;
> +
> +      /* Don't shift more than type precision to avoid UD.  */
> +      if (!tree_fits_uhwi_p (step_expr)
> +         || maybe_ge (nunits * tree_to_uhwi (step_expr),
> +                      TYPE_PRECISION (TREE_TYPE (init_expr))))
> +       return false;
> +
> +      break;
> +
> +    default:
> +      gcc_unreachable ();
> +    }
> +
> +  if (!vec_stmt) /* transformation not required.  */
> +    {
> +      unsigned inside_cost = 0, prologue_cost = 0;
> +      /* loop cost for vec_loop. Neg induction doesn't have any
> +        inside_cost.  */
> +      inside_cost = record_stmt_cost (cost_vec, ncopies, vector_stmt,
> +                                     stmt_info, 0, vect_body);
> +
> +      /* loop cost for vec_loop. Neg induction doesn't have any
> +        inside_cost.  */
> +      if (induction_type == vect_step_op_neg)
> +       inside_cost = 0;
> +
> +      /* prologue cost for vec_init and vec_step.  */
> +      prologue_cost = record_stmt_cost (cost_vec, 2, scalar_to_vec,
> +                                       stmt_info, 0, vect_prologue);
> +
> +      if (dump_enabled_p ())
> +       dump_printf_loc (MSG_NOTE, vect_location,
> +                        "vect_model_induction_cost: inside_cost = %d, "
> +                        "prologue_cost = %d. \n", inside_cost,
> +                        prologue_cost);
> +
> +      STMT_VINFO_TYPE (stmt_info) = induc_vec_info_type;
> +      DUMP_VECT_SCOPE ("vectorizable_nonlinear_induction");
> +      return true;
> +    }
> +
> +  /* Transform.  */
> +
> +  /* Compute a vector variable, initialized with the first VF values of
> +     the induction variable.  E.g., for an iv with IV_PHI='X' and
> +     evolution S, for a vector of 4 units, we want to compute:
> +     [X, X + S, X + 2*S, X + 3*S].  */
> +
> +  if (dump_enabled_p ())
> +    dump_printf_loc (MSG_NOTE, vect_location, "transform induction phi.\n");
> +
> +  pe = loop_preheader_edge (iv_loop);
> +  /* Find the first insertion point in the BB.  */
> +  basic_block bb = gimple_bb (phi);
> +  si = gsi_after_labels (bb);
> +
> +  gimple_seq stmts = NULL;
> +
> +  /* If we are using the loop mask to "peel" for alignment then we need
> +     to adjust the start value here.  */
> +  if (niters_skip != NULL_TREE)
> +    init_expr = vect_peel_nonlinear_iv_init (&stmts, init_expr, niters_skip,
> +                                            step_expr, induction_type);
> +
> +  vec_init = vect_create_nonlinear_iv_init (&stmts, init_expr,
> +                                           step_expr, nunits, vectype,
> +                                           induction_type);
> +  if (stmts)
> +    {
> +      new_bb = gsi_insert_seq_on_edge_immediate (pe, stmts);
> +      gcc_assert (!new_bb);
> +    }
> +
> +  stmts = NULL;
> +  new_name = vect_create_nonlinear_iv_step (&stmts, step_expr,
> +                                           vf, induction_type);
> +  if (stmts)
> +    {
> +      new_bb = gsi_insert_seq_on_edge_immediate (pe, stmts);
> +      gcc_assert (!new_bb);
> +    }
> +
> +  vec_step = vect_create_nonlinear_iv_vec_step (loop_vinfo, stmt_info,
> +                                               new_name, vectype,
> +                                               induction_type);
> +  /* Create the following def-use cycle:
> +     loop prolog:
> +     vec_init = ...
> +     vec_step = ...
> +     loop:
> +     vec_iv = PHI <vec_init, vec_loop>
> +     ...
> +     STMT
> +     ...
> +     vec_loop = vec_iv + vec_step;  */
> +
> +  /* Create the induction-phi that defines the induction-operand.  */
> +  vec_dest = vect_get_new_vect_var (vectype, vect_simple_var, "vec_iv_");
> +  induction_phi = create_phi_node (vec_dest, iv_loop->header);
> +  induc_def = PHI_RESULT (induction_phi);
> +
> +  /* Create the iv update inside the loop.  */
> +  stmts = NULL;
> +  vec_def = vect_update_nonlinear_iv (&stmts, vectype,
> +                                     induc_def, vec_step,
> +                                     induction_type);
> +
> +  gsi_insert_seq_before (&si, stmts, GSI_SAME_STMT);
> +  new_stmt = SSA_NAME_DEF_STMT (vec_def);
> +
> +  /* Set the arguments of the phi node:  */
> +  add_phi_arg (induction_phi, vec_init, pe, UNKNOWN_LOCATION);
> +  add_phi_arg (induction_phi, vec_def, loop_latch_edge (iv_loop),
> +              UNKNOWN_LOCATION);
> +
> +  STMT_VINFO_VEC_STMTS (stmt_info).safe_push (induction_phi);
> +  *vec_stmt = induction_phi;
> +
> +  /* In case that vectorization factor (VF) is bigger than the number
> +     of elements that we can fit in a vectype (nunits), we have to generate
> +     more than one vector stmt - i.e - we need to "unroll" the
> +     vector stmt by a factor VF/nunits.  For more details see documentation
> +     in vectorizable_operation.  */
> +
> +  if (ncopies > 1)
> +    {
> +      stmts = NULL;
> +      /* FORNOW. This restriction should be relaxed.  */
> +      gcc_assert (!nested_in_vect_loop);
> +
> +      new_name = vect_create_nonlinear_iv_step (&stmts, step_expr,
> +                                               nunits, induction_type);
> +
> +      vec_step = vect_create_nonlinear_iv_vec_step (loop_vinfo, stmt_info,
> +                                                   new_name, vectype,
> +                                                   induction_type);
> +      vec_def = induc_def;
> +      for (i = 1; i < ncopies; i++)
> +       {
> +         /* vec_i = vec_prev + vec_step.  */
> +         stmts = NULL;
> +         vec_def = vect_update_nonlinear_iv (&stmts, vectype,
> +                                             vec_def, vec_step,
> +                                             induction_type);
> +         gsi_insert_seq_before (&si, stmts, GSI_SAME_STMT);
> +         new_stmt = SSA_NAME_DEF_STMT (vec_def);
> +         STMT_VINFO_VEC_STMTS (stmt_info).safe_push (new_stmt);
> +       }
> +    }
> +
> +  if (dump_enabled_p ())
> +    dump_printf_loc (MSG_NOTE, vect_location,
> +                    "transform induction: created def-use cycle: %G%G",
> +                    induction_phi, SSA_NAME_DEF_STMT (vec_def));
> +
> +  return true;
> +}
> +
>  /* Function vectorizable_induction
>
>     Check if STMT_INFO performs an induction computation that can be vectorized.
> @@ -8259,6 +8920,8 @@ vectorizable_induction (loop_vec_info loop_vinfo,
>    unsigned i;
>    tree expr;
>    gimple_stmt_iterator si;
> +  enum vect_induction_op_type induction_type
> +    = STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE (stmt_info);
>
>    gphi *phi = dyn_cast <gphi *> (stmt_info->stmt);
>    if (!phi)
> @@ -8271,6 +8934,11 @@ vectorizable_induction (loop_vec_info loop_vinfo,
>    if (STMT_VINFO_DEF_TYPE (stmt_info) != vect_induction_def)
>      return false;
>
> +  /* Handle nonlinear induction in a separate place.  */
> +  if (induction_type != vect_step_op_add)
> +    return vectorizable_nonlinear_induction (loop_vinfo, stmt_info,
> +                                            vec_stmt, slp_node, cost_vec);
> +
>    tree vectype = STMT_VINFO_VECTYPE (stmt_info);
>    poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (vectype);
>
> diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> index e5fdc9e0a14..1fa08126ad8 100644
> --- a/gcc/tree-vectorizer.h
> +++ b/gcc/tree-vectorizer.h
> @@ -68,6 +68,15 @@ enum vect_def_type {
>    vect_unknown_def_type
>  };
>
> +/* Define operation type of linear/non-linear induction variable.  */
> +enum vect_induction_op_type {
> +   vect_step_op_add = 0,
> +   vect_step_op_neg,
> +   vect_step_op_mul,
> +   vect_step_op_shl,
> +   vect_step_op_shr
> +};
> +
>  /* Define type of reduction.  */
>  enum vect_reduction_type {
>    TREE_CODE_REDUCTION,
> @@ -1188,6 +1197,7 @@ public:
>       the version here.  */
>    tree loop_phi_evolution_base_unchanged;
>    tree loop_phi_evolution_part;
> +  enum vect_induction_op_type loop_phi_evolution_type;
>
>    /* Used for various bookkeeping purposes, generally holding a pointer to
>       some other stmt S that is in some way "related" to this stmt.
> @@ -1421,6 +1431,7 @@ struct gather_scatter_info {
>    ((S)->dr_aux.dr && DR_GROUP_FIRST_ELEMENT(S))
>  #define STMT_VINFO_LOOP_PHI_EVOLUTION_BASE_UNCHANGED(S) (S)->loop_phi_evolution_base_unchanged
>  #define STMT_VINFO_LOOP_PHI_EVOLUTION_PART(S) (S)->loop_phi_evolution_part
> +#define STMT_VINFO_LOOP_PHI_EVOLUTION_TYPE(S) (S)->loop_phi_evolution_type
>  #define STMT_VINFO_MIN_NEG_DIST(S)     (S)->min_neg_dist
>  #define STMT_VINFO_REDUC_TYPE(S)       (S)->reduc_type
>  #define STMT_VINFO_REDUC_CODE(S)       (S)->reduc_code
> @@ -2327,6 +2338,10 @@ extern int vect_get_known_peeling_cost (loop_vec_info, int, int *,
>                                         stmt_vector_for_cost *);
>  extern tree cse_and_gimplify_to_preheader (loop_vec_info, tree);
>
> +/* Nonlinear induction.  */
> +extern tree vect_peel_nonlinear_iv_init (gimple_seq*, tree, tree,
> +                                        tree, enum vect_induction_op_type);
> +
>  /* In tree-vect-slp.cc.  */
>  extern void vect_slp_init (void);
>  extern void vect_slp_fini (void);
> --
> 2.18.1
>