RE: [PATCH 5/8 v9]middle-end slp: support complex multiply and complex multiply conjugate

[Tamar Christina <Tamar.Christina@arm.com>]

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Hi Richi,

This adds support for complex multiply and complex multiply and accumulate to
the vect pattern detector.

Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
and no issues.

Ok for master? (I replied to a comment at the very end of the mail from the previous patch)

Example of instructions matched:

#include <stdio.h>
#include <complex.h>

#define N 200
#define ROT
#define TYPE float
#define TYPE2 float


void g (TYPE2 complex a[restrict N], TYPE complex b[restrict N], TYPE complex c[restrict N])
{
  for (int i=0; i < N; i++)
    {
      c[i] =  a[i] * (b[i] ROT);
    }
}

void g_f1 (TYPE2 complex a[restrict N], TYPE complex b[restrict N], TYPE complex c[restrict N])
{
  for (int i=0; i < N; i++)
    {
      c[i] =  conjf (a[i]) * (b[i] ROT);
    }
}

void g_s1 (TYPE2 complex a[restrict N], TYPE complex b[restrict N], TYPE complex c[restrict N])
{
  for (int i=0; i < N; i++)
    {
      c[i] =  a[i] * conjf (b[i] ROT);
    }
}

Thanks,
Tamar

gcc/ChangeLog:

	* internal-fn.def (COMPLEX_MUL, COMPLEX_MUL_CONJ): New.
	* optabs.def (cmul_optab, cmul_conj_optab): New.
	* doc/md.texi: Document them.
	* tree-vect-slp-patterns.c (vect_match_call_complex_mla,
	vect_normalize_conj_loc, is_eq_or_top, vect_validate_multiplication,
	vect_build_combine_node, class complex_mul_pattern,
	complex_mul_pattern::matches, complex_mul_pattern::recognize,
	complex_mul_pattern::build): New.

--- inline copy of patch --

diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index ec6ec180b91fcf9f481b6754c044483787fd923c..b8cc90e1a75e402abbf8a8cf2efefc1a333f8b3a 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -6202,6 +6202,50 @@ The operation is only supported for vector modes @var{m}.
 
 This pattern is not allowed to @code{FAIL}.
 
+@cindex @code{cmul@var{m}4} instruction pattern
+@item @samp{cmul@var{m}4}
+Perform a vector multiply that is semantically the same as multiply of
+complex numbers.
+
+@smallexample
+  complex TYPE c[N];
+  complex TYPE a[N];
+  complex TYPE b[N];
+  for (int i = 0; i < N; i += 1)
+    @{
+      c[i] = a[i] * b[i];
+    @}
+@end smallexample
+
+In GCC lane ordering the real part of the number must be in the even lanes with
+the imaginary part in the odd lanes.
+
+The operation is only supported for vector modes @var{m}.
+
+This pattern is not allowed to @code{FAIL}.
+
+@cindex @code{cmul_conj@var{m}4} instruction pattern
+@item @samp{cmul_conj@var{m}4}
+Perform a vector multiply by conjugate that is semantically the same as a
+multiply of complex numbers where the second multiply arguments is conjugated.
+
+@smallexample
+  complex TYPE c[N];
+  complex TYPE a[N];
+  complex TYPE b[N];
+  for (int i = 0; i < N; i += 1)
+    @{
+      c[i] = a[i] * conj (b[i]);
+    @}
+@end smallexample
+
+In GCC lane ordering the real part of the number must be in the even lanes with
+the imaginary part in the odd lanes.
+
+The operation is only supported for vector modes @var{m}.
+
+This pattern is not allowed to @code{FAIL}.
+
 @cindex @code{ffs@var{m}2} instruction pattern
 @item @samp{ffs@var{m}2}
 Store into operand 0 one plus the index of the least significant 1-bit
diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
index 511fe70162b5d9db3a61a5285d31c008f6835487..5a0bbe3fe5dee591d54130e60f6996b28164ae38 100644
--- a/gcc/internal-fn.def
+++ b/gcc/internal-fn.def
@@ -279,6 +279,8 @@ DEF_INTERNAL_FLT_FLOATN_FN (FMAX, ECF_CONST, fmax, binary)
 DEF_INTERNAL_OPTAB_FN (XORSIGN, ECF_CONST, xorsign, binary)
 DEF_INTERNAL_OPTAB_FN (COMPLEX_ADD_ROT90, ECF_CONST, cadd90, binary)
 DEF_INTERNAL_OPTAB_FN (COMPLEX_ADD_ROT270, ECF_CONST, cadd270, binary)
+DEF_INTERNAL_OPTAB_FN (COMPLEX_MUL, ECF_CONST, cmul, binary)
+DEF_INTERNAL_OPTAB_FN (COMPLEX_MUL_CONJ, ECF_CONST, cmul_conj, binary)
 
 
 /* FP scales.  */
diff --git a/gcc/optabs.def b/gcc/optabs.def
index e9727def4dbf941bb9ac8b56f83f8ea0f52b262c..e82396bae1117c6de91304761a560b7fbcb69ce1 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -292,6 +292,8 @@ OPTAB_D (copysign_optab, "copysign$F$a3")
 OPTAB_D (xorsign_optab, "xorsign$F$a3")
 OPTAB_D (cadd90_optab, "cadd90$a3")
 OPTAB_D (cadd270_optab, "cadd270$a3")
+OPTAB_D (cmul_optab, "cmul$a3")
+OPTAB_D (cmul_conj_optab, "cmul_conj$a3")
 OPTAB_D (cos_optab, "cos$a2")
 OPTAB_D (cosh_optab, "cosh$a2")
 OPTAB_D (exp10_optab, "exp10$a2")
diff --git a/gcc/tree-vect-slp-patterns.c b/gcc/tree-vect-slp-patterns.c
index dbc58f7c53868ed431fc67de1f0162eb0d3b2c24..fb58b45602f00a440ef7c27853276945ba696522 100644
--- a/gcc/tree-vect-slp-patterns.c
+++ b/gcc/tree-vect-slp-patterns.c
@@ -719,6 +719,375 @@ complex_add_pattern::recognize (slp_tree_to_load_perm_map_t *perm_cache,
   return new complex_add_pattern (node, &ops, ifn);
 }
 
+/*******************************************************************************
+ * complex_mul_pattern
+ ******************************************************************************/
+
+/* Helper function of that looks for a match in the CHILDth child of NODE.  The
+   child used is stored in RES.
+
+   If the match is successful then ARGS will contain the operands matched
+   and the complex_operation_t type is returned.  If match is not successful
+   then CMPLX_NONE is returned and ARGS is left unmodified.  */
+
+static inline complex_operation_t
+vect_match_call_complex_mla (slp_tree node, unsigned child,
+			     vec<slp_tree> *args = NULL, slp_tree *res = NULL)
+{
+  gcc_assert (child < SLP_TREE_CHILDREN (node).length ());
+
+  slp_tree data = SLP_TREE_CHILDREN (node)[child];
+
+  if (res)
+    *res = data;
+
+  return vect_detect_pair_op (data, false, args);
+}
+
+/* Check to see if either of the trees in ARGS are a NEGATE_EXPR.  If the first
+   child (args[0]) is a NEGATE_EXPR then NEG_FIRST_P is set to TRUE.
+
+   If a negate is found then the values in ARGS are reordered such that the
+   negate node is always the second one and the entry is replaced by the child
+   of the negate node.  */
+
+static inline bool
+vect_normalize_conj_loc (vec<slp_tree> args, bool *neg_first_p = NULL)
+{
+  gcc_assert (args.length () == 2);
+  bool neg_found = false;
+
+  if (vect_match_expression_p (args[0], NEGATE_EXPR))
+    {
+      std::swap (args[0], args[1]);
+      neg_found = true;
+      if (neg_first_p)
+	*neg_first_p = true;
+    }
+  else if (vect_match_expression_p (args[1], NEGATE_EXPR))
+    {
+      neg_found = true;
+      if (neg_first_p)
+	*neg_first_p = false;
+    }
+
+  if (neg_found)
+    args[1] = SLP_TREE_CHILDREN (args[1])[0];
+
+  return neg_found;
+}
+
+/* Helper function to check if PERM is KIND or PERM_TOP.  */
+
+static inline bool
+is_eq_or_top (complex_load_perm_t perm, complex_perm_kinds_t kind)
+{
+  return perm.first == kind || perm.first == PERM_TOP;
+}
+
+/* Helper function that checks to see if LEFT_OP and RIGHT_OP are both MULT_EXPR
+   nodes but also that they represent an operation that is either a complex
+   multiplication or a complex multiplication by conjugated value.
+
+   Of the negation is expected to be in the first half of the tree (As required
+   by an FMS pattern) then NEG_FIRST is true.  If the operation is a conjugate
+   operation then CONJ_FIRST_OPERAND is set to indicate whether the first or
+   second operand contains the conjugate operation.  */
+
+static inline bool
+vect_validate_multiplication (slp_tree_to_load_perm_map_t *perm_cache,
+			     vec<slp_tree> left_op, vec<slp_tree> right_op,
+			     bool neg_first, bool *conj_first_operand,
+			     bool fms)
+{
+  /* The presence of a negation indicates that we have either a conjugate or a
+     rotation.  We need to distinguish which one.  */
+  *conj_first_operand = false;
+  complex_perm_kinds_t kind;
+
+  /* Complex conjugates have the negation on the imaginary part of the
+     number where rotations affect the real component.  So check if the
+     negation is on a dup of lane 1.  */
+  if (fms)
+    {
+      /* Canonicalization for fms is not consistent. So have to test both
+	 variants to be sure.  This needs to be fixed in the mid-end so
+	 this part can be simpler.  */
+      kind = linear_loads_p (perm_cache, right_op[0]).first;
+      if (!((kind == PERM_ODDODD
+	   && is_eq_or_top (linear_loads_p (perm_cache, right_op[1]),
+			     PERM_ODDEVEN))
+	  || (kind == PERM_ODDEVEN
+	      && is_eq_or_top (linear_loads_p (perm_cache, right_op[1]),
+			     PERM_ODDODD))))
+	return false;
+    }
+  else
+    {
+      if (linear_loads_p (perm_cache, right_op[1]).first != PERM_ODDODD
+	  && !is_eq_or_top (linear_loads_p (perm_cache, right_op[0]),
+			    PERM_ODDEVEN))
+	return false;
+    }
+
+  /* Deal with differences in indexes.  */
+  int index1 = fms ? 1 : 0;
+  int index2 = fms ? 0 : 1;
+
+  /* Check if the conjugate is on the second first or second operand.  The
+     order of the node with the conjugate value determines this, and the dup
+     node must be one of lane 0 of the same DR as the neg node.  */
+  kind = linear_loads_p (perm_cache, left_op[index1]).first;
+  if (kind == PERM_TOP)
+    {
+      if (linear_loads_p (perm_cache, left_op[index2]).first == PERM_EVENODD)
+	return true;
+    }
+  else if (kind == PERM_EVENODD)
+    {
+      if ((kind = linear_loads_p (perm_cache, left_op[index2]).first) == PERM_EVENODD)
+	return false;
+    }
+  else if (!neg_first)
+    *conj_first_operand = true;
+  else
+    return false;
+
+  if (kind != PERM_EVENEVEN)
+    return false;
+
+  return true;
+}
+
+/* Helper function to help distinguish between a conjugate and a rotation in a
+   complex multiplication.  The operations have similar shapes but the order of
+   the load permutes are different.  This function returns TRUE when the order
+   is consistent with a multiplication or multiplication by conjugated
+   operand but returns FALSE if it's a multiplication by rotated operand.  */
+
+static inline bool
+vect_validate_multiplication (slp_tree_to_load_perm_map_t *perm_cache,
+			     vec<slp_tree> op, complex_perm_kinds_t permKind)
+{
+  /* The left node is the more common case, test it first.  */
+  if (!is_eq_or_top (linear_loads_p (perm_cache, op[0]), permKind))
+    {
+      if (!is_eq_or_top (linear_loads_p (perm_cache, op[1]), permKind))
+	return false;
+    }
+  return true;
+}
+
+/* This function combines two nodes containing only even and only odd lanes
+   together into a single node which contains the nodes in even/odd order
+   by using a lane permute.
+
+   The lanes in EVEN and ODD are duplicated 2 times inside the vectors.
+   So for a lanes = 4 EVEN contains {EVEN1, EVEN1, EVEN2, EVEN2}.
+
+   The tree REPRESENTATION is taken from the supplied REP along with the
+   vectype which must be the same between all three nodes.
+*/
+
+static slp_tree
+vect_build_combine_node (slp_tree even, slp_tree odd, slp_tree rep)
+{
+  vec<std::pair<unsigned, unsigned> > perm;
+  perm.create (SLP_TREE_LANES (rep));
+
+  for (unsigned x = 0; x < SLP_TREE_LANES (rep); x+=2)
+    {
+      perm.quick_push (std::make_pair (0, x));
+      perm.quick_push (std::make_pair (1, x+1));
+    }
+
+  slp_tree vnode = vect_create_new_slp_node (2, SLP_TREE_CODE (even));
+  SLP_TREE_CODE (vnode) = VEC_PERM_EXPR;
+  SLP_TREE_LANE_PERMUTATION (vnode) = perm;
+
+  SLP_TREE_CHILDREN (vnode).create (2);
+  SLP_TREE_CHILDREN (vnode).quick_push (even);
+  SLP_TREE_CHILDREN (vnode).quick_push (odd);
+  SLP_TREE_REF_COUNT (even)++;
+  SLP_TREE_REF_COUNT (odd)++;
+  SLP_TREE_REF_COUNT (vnode) = 1;
+
+  SLP_TREE_LANES (vnode) = SLP_TREE_LANES (rep);
+  gcc_assert (perm.length () == SLP_TREE_LANES (vnode));
+  /* Representation is set to that of the current node as the vectorizer
+     can't deal with VEC_PERMs with no representation, as would be the
+     case with invariants.  */
+  SLP_TREE_REPRESENTATIVE (vnode) = SLP_TREE_REPRESENTATIVE (rep);
+  SLP_TREE_VECTYPE (vnode) = SLP_TREE_VECTYPE (rep);
+  return vnode;
+}
+
+class complex_mul_pattern : public complex_pattern
+{
+  protected:
+    complex_mul_pattern (slp_tree *node, vec<slp_tree> *m_ops, internal_fn ifn)
+      : complex_pattern (node, m_ops, ifn)
+    {
+      this->m_num_args = 2;
+    }
+
+  public:
+    void build (vec_info *);
+    static internal_fn
+    matches (complex_operation_t op, slp_tree_to_load_perm_map_t *, slp_tree *,
+	     vec<slp_tree> *);
+
+    static vect_pattern*
+    recognize (slp_tree_to_load_perm_map_t *, slp_tree *);
+
+    static vect_pattern*
+    mkInstance (slp_tree *node, vec<slp_tree> *m_ops, internal_fn ifn)
+    {
+      return new complex_mul_pattern (node, m_ops, ifn);
+    }
+
+};
+
+/* Pattern matcher for trying to match complex multiply pattern in SLP tree
+   If the operation matches then IFN is set to the operation it matched
+   and the arguments to the two replacement statements are put in m_ops.
+
+   If no match is found then IFN is set to IFN_LAST and m_ops is unchanged.
+
+   This function matches the patterns shaped as:
+
+   double ax = (b[i+1] * a[i]);
+   double bx = (a[i+1] * b[i]);
+
+   c[i] = c[i] - ax;
+   c[i+1] = c[i+1] + bx;
+
+   If a match occurred then TRUE is returned, else FALSE.  The initial match is
+   expected to be in OP1 and the initial match operands in args0.  */
+
+internal_fn
+complex_mul_pattern::matches (complex_operation_t op,
+			      slp_tree_to_load_perm_map_t *perm_cache,
+			      slp_tree *node, vec<slp_tree> *ops)
+{
+  internal_fn ifn = IFN_LAST;
+
+  if (op != MINUS_PLUS)
+    return IFN_LAST;
+
+  slp_tree root = *node;
+  /* First two nodes must be a multiply.  */
+  auto_vec<slp_tree> muls;
+  if (vect_match_call_complex_mla (root, 0) != MULT_MULT
+      || vect_match_call_complex_mla (root, 1, &muls) != MULT_MULT)
+    return IFN_LAST;
+
+  /* Now operand2+4 may lead to another expression.  */
+  auto_vec<slp_tree> left_op, right_op;
+  left_op.safe_splice (SLP_TREE_CHILDREN (muls[0]));
+  right_op.safe_splice (SLP_TREE_CHILDREN (muls[1]));
+
+  if (linear_loads_p (perm_cache, left_op[1]).first == PERM_ODDEVEN)
+    return IFN_LAST;
+
+  bool neg_first = false;
+  bool conj_first_operand = false;
+  bool is_neg = vect_normalize_conj_loc (right_op, &neg_first);
+
+  if (!is_neg)
+    {
+      /* A multiplication needs to multiply agains the real pair, otherwise
+	 the pattern matches that of FMS.   */
+      if (!vect_validate_multiplication (perm_cache, left_op, PERM_EVENEVEN)
+	  || vect_normalize_conj_loc (left_op))
+	return IFN_LAST;
+      ifn = IFN_COMPLEX_MUL;
+    }
+  else if (is_neg)
+    {
+      if (!vect_validate_multiplication (perm_cache, left_op, right_op,
+					 neg_first, &conj_first_operand,
+					 false))
+	return IFN_LAST;
+
+      ifn = IFN_COMPLEX_MUL_CONJ;
+    }
+
+  if (!vect_pattern_validate_optab (ifn, *node))
+    return IFN_LAST;
+
+  ops->truncate (0);
+  ops->create (3);
+
+  complex_perm_kinds_t kind = linear_loads_p (perm_cache, left_op[0]).first;
+  if (kind == PERM_EVENODD)
+    {
+      ops->quick_push (left_op[1]);
+      ops->quick_push (right_op[1]);
+      ops->quick_push (left_op[0]);
+    }
+  else if (kind == PERM_TOP)
+    {
+      ops->quick_push (left_op[1]);
+      ops->quick_push (right_op[1]);
+      ops->quick_push (left_op[0]);
+    }
+  else if (kind == PERM_EVENEVEN && !conj_first_operand)
+    {
+      ops->quick_push (left_op[0]);
+      ops->quick_push (right_op[0]);
+      ops->quick_push (left_op[1]);
+    }
+  else
+    {
+      ops->quick_push (left_op[0]);
+      ops->quick_push (right_op[1]);
+      ops->quick_push (left_op[1]);
+    }
+
+  return ifn;
+}
+
+/* Attempt to recognize a complex mul pattern.  */
+
+vect_pattern*
+complex_mul_pattern::recognize (slp_tree_to_load_perm_map_t *perm_cache,
+				slp_tree *node)
+{
+  auto_vec<slp_tree> ops;
+  complex_operation_t op
+    = vect_detect_pair_op (*node, true, &ops);
+  internal_fn ifn
+    = complex_mul_pattern::matches (op, perm_cache, node, &ops);
+  if (ifn == IFN_LAST)
+    return NULL;
+
+  return new complex_mul_pattern (node, &ops, ifn);
+}
+
+/* Perform a replacement of the detected complex mul pattern with the new
+   instruction sequences.  */
+
+void
+complex_mul_pattern::build (vec_info *vinfo)
+{
+  slp_tree node;
+  unsigned i;
+  FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (*this->m_node), i, node)
+    vect_free_slp_tree (node);
+
+  /* First re-arrange the children.  */
+  SLP_TREE_CHILDREN (*this->m_node).truncate (0);
+  SLP_TREE_CHILDREN (*this->m_node).create (2);
+  SLP_TREE_CHILDREN (*this->m_node).quick_push (this->m_ops[2]);
+  SLP_TREE_CHILDREN (*this->m_node).quick_push (
+    vect_build_combine_node (this->m_ops[0], this->m_ops[1], *this->m_node));
+  SLP_TREE_REF_COUNT (this->m_ops[2])++;
+
+  /* And then rewrite the node itself.  */
+  complex_pattern::build (vinfo);
+}
+
 /*******************************************************************************
  * Pattern matching definitions
  ******************************************************************************/

> -----Original Message-----
> From: Richard Biener <rguenther@suse.de>
> Sent: Friday, January 8, 2021 9:37 AM
> To: Tamar Christina <Tamar.Christina@arm.com>
> Cc: gcc-patches@gcc.gnu.org; nd <nd@arm.com>; ook@ucw.cz
> Subject: Re: [PATCH 5/8 v9]middle-end slp: support complex multiply and
> complex multiply conjugate
> 
> On Mon, 28 Dec 2020, Tamar Christina wrote:
> 
> > Hi All,
> >
> > This adds support for complex multiply and complex multiply and
> > accumulate to the vect pattern detector.
> >
> > Bootstrapped Regtested on aarch64-none-linux-gnu, x86_64-pc-linux-gnu
> > and no issues.
> >
> > Ok for master?
> >
> > Thanks,
> > Tamar
> >
> > gcc/ChangeLog:
> >
> > 	* internal-fn.def (COMPLEX_MUL, COMPLEX_MUL_CONJ): New.
> > 	* optabs.def (cmul_optab, cmul_conj_optab): New.
> > 	* doc/md.texi: Document them.
> > 	* tree-vect-slp-patterns.c (vect_match_call_complex_mla,
> > 	vect_normalize_conj_loc, is_eq_or_top, vect_validate_multiplication,
> > 	vect_build_combine_node, class complex_mul_pattern,
> > 	complex_mul_pattern::matches, complex_mul_pattern::recognize,
> > 	complex_mul_pattern::build): New.
> >
> > --- inline copy of patch --
> > diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi index
> >
> ec6ec180b91fcf9f481b6754c044483787fd923c..b8cc90e1a75e402abbf8a8cf2ef
> e
> > fc1a333f8b3a 100644
> > --- a/gcc/doc/md.texi
> > +++ b/gcc/doc/md.texi
> > @@ -6202,6 +6202,50 @@ The operation is only supported for vector
> modes @var{m}.
> >
> >  This pattern is not allowed to @code{FAIL}.
> >
> > +@cindex @code{cmul@var{m}4} instruction pattern @item
> > +@samp{cmul@var{m}4} Perform a vector multiply that is semantically
> > +the same as multiply of complex numbers.
> > +
> > +@smallexample
> > +  complex TYPE c[N];
> > +  complex TYPE a[N];
> > +  complex TYPE b[N];
> > +  for (int i = 0; i < N; i += 1)
> > +    @{
> > +      c[i] = a[i] * b[i];
> > +    @}
> > +@end smallexample
> > +
> > +In GCC lane ordering the real part of the number must be in the even
> > +lanes with the imaginary part in the odd lanes.
> > +
> > +The operation is only supported for vector modes @var{m}.
> > +
> > +This pattern is not allowed to @code{FAIL}.
> > +
> > +@cindex @code{cmul_conj@var{m}4} instruction pattern @item
> > +@samp{cmul_conj@var{m}4} Perform a vector multiply by conjugate that
> > +is semantically the same as a multiply of complex numbers where the
> > +second multiply arguments is conjugated.
> > +
> > +@smallexample
> > +  complex TYPE c[N];
> > +  complex TYPE a[N];
> > +  complex TYPE b[N];
> > +  for (int i = 0; i < N; i += 1)
> > +    @{
> > +      c[i] = a[i] * conj (b[i]);
> > +    @}
> > +@end smallexample
> > +
> > +In GCC lane ordering the real part of the number must be in the even
> > +lanes with the imaginary part in the odd lanes.
> > +
> > +The operation is only supported for vector modes @var{m}.
> > +
> > +This pattern is not allowed to @code{FAIL}.
> > +
> >  @cindex @code{ffs@var{m}2} instruction pattern  @item
> > @samp{ffs@var{m}2}  Store into operand 0 one plus the index of the
> > least significant 1-bit diff --git a/gcc/internal-fn.def
> > b/gcc/internal-fn.def index
> >
> 511fe70162b5d9db3a61a5285d31c008f6835487..5a0bbe3fe5dee591d54130e6
> 0f69
> > 96b28164ae38 100644
> > --- a/gcc/internal-fn.def
> > +++ b/gcc/internal-fn.def
> > @@ -279,6 +279,8 @@ DEF_INTERNAL_FLT_FLOATN_FN (FMAX,
> ECF_CONST, fmax,
> > binary)  DEF_INTERNAL_OPTAB_FN (XORSIGN, ECF_CONST, xorsign, binary)
> > DEF_INTERNAL_OPTAB_FN (COMPLEX_ADD_ROT90, ECF_CONST, cadd90,
> binary)
> > DEF_INTERNAL_OPTAB_FN (COMPLEX_ADD_ROT270, ECF_CONST,
> cadd270, binary)
> > +DEF_INTERNAL_OPTAB_FN (COMPLEX_MUL, ECF_CONST, cmul, binary)
> > +DEF_INTERNAL_OPTAB_FN (COMPLEX_MUL_CONJ, ECF_CONST,
> cmul_conj,
> > +binary)
> >
> >
> >  /* FP scales.  */
> > diff --git a/gcc/optabs.def b/gcc/optabs.def index
> >
> e9727def4dbf941bb9ac8b56f83f8ea0f52b262c..e82396bae1117c6de91304761
> a56
> > 0b7fbcb69ce1 100644
> > --- a/gcc/optabs.def
> > +++ b/gcc/optabs.def
> > @@ -292,6 +292,8 @@ OPTAB_D (copysign_optab, "copysign$F$a3")
> OPTAB_D
> > (xorsign_optab, "xorsign$F$a3")  OPTAB_D (cadd90_optab, "cadd90$a3")
> > OPTAB_D (cadd270_optab, "cadd270$a3")
> > +OPTAB_D (cmul_optab, "cmul$a3")
> > +OPTAB_D (cmul_conj_optab, "cmul_conj$a3")
> >  OPTAB_D (cos_optab, "cos$a2")
> >  OPTAB_D (cosh_optab, "cosh$a2")
> >  OPTAB_D (exp10_optab, "exp10$a2")
> > diff --git a/gcc/tree-vect-slp-patterns.c
> > b/gcc/tree-vect-slp-patterns.c index
> >
> dbc58f7c53868ed431fc67de1f0162eb0d3b2c24..82721acbab8cf81c4d6f9954c9
> 8f
> > b913a7bb6282 100644
> > --- a/gcc/tree-vect-slp-patterns.c
> > +++ b/gcc/tree-vect-slp-patterns.c
> > @@ -719,6 +719,368 @@ complex_add_pattern::recognize
> (slp_tree_to_load_perm_map_t *perm_cache,
> >    return new complex_add_pattern (node, &ops, ifn);  }
> >
> >
> +/*********************************************************
> ***********
> > +***********
> > + * complex_mul_pattern
> > +
> >
> +*********************************************************
> ************
> > +*********/
> > +
> > +/* Helper function of that looks for a match in the CHILDth child of NODE.
> The
> > +   child used is stored in RES.
> > +
> > +   If the match is successful then ARGS will contain the operands matched
> > +   and the complex_operation_t type is returned.  If match is not
> successful
> > +   then CMPLX_NONE is returned and ARGS is left unmodified.  */
> > +
> > +static inline complex_operation_t
> > +vect_match_call_complex_mla (slp_tree node, unsigned child,
> > +			     vec<slp_tree> *args = NULL, slp_tree *res = NULL)
> {
> > +  gcc_assert (child < SLP_TREE_CHILDREN (node).length ());
> > +
> > +  slp_tree data = SLP_TREE_CHILDREN (node)[child];
> > +
> > +  if (res)
> > +    *res = data;
> > +
> > +  return vect_detect_pair_op (data, false, args); }
> > +
> > +/* Check to see if either of the trees in ARGS are a NEGATE_EXPR.  If the
> first
> > +   child (args[0]) is a NEGATE_EXPR then NEG_FIRST_P is set to TRUE.
> > +
> > +   If a negate is found then the values in ARGS are reordered such that the
> > +   negate node is always the second one and the entry is replaced by the
> child
> > +   of the negate node.  */
> > +
> > +static inline bool
> > +vect_normalize_conj_loc (vec<slp_tree> args, bool *neg_first_p =
> > +NULL) {
> > +  gcc_assert (args.length () == 2);
> > +  bool neg_found = false;
> > +
> > +  if (vect_match_expression_p (args[0], NEGATE_EXPR))
> > +    {
> > +      std::swap (args[0], args[1]);
> > +      neg_found = true;
> > +      if (neg_first_p)
> > +	*neg_first_p = true;
> > +    }
> > +  else if (vect_match_expression_p (args[1], NEGATE_EXPR))
> > +    {
> > +      neg_found = true;
> > +      if (neg_first_p)
> > +	*neg_first_p = false;
> > +    }
> > +
> > +  if (neg_found)
> > +    args[1] = SLP_TREE_CHILDREN (args[1])[0];
> > +
> > +  return neg_found;
> > +}
> > +
> > +/* Helper function to check if PERM is KIND or PERM_TOP.  */
> > +
> > +static inline bool
> > +is_eq_or_top (complex_load_perm_t perm, complex_perm_kinds_t kind)
> {
> > +  return perm.first == kind || perm.first == PERM_TOP; }
> > +
> > +/* Helper function that checks to see if LEFT_OP and RIGHT_OP are both
> MULT_EXPR
> > +   nodes but also that they represent an operation that is either a complex
> > +   multiplication or a complex multiplication by conjugated value.
> > +
> > +   Of the negation is expected to be in the first half of the tree (As
> required
> > +   by an FMS pattern) then NEG_FIRST is true.  If the operation is a
> conjugate
> > +   operation then CONJ_FIRST_OPERAND is set to indicate whether the
> first or
> > +   second operand contains the conjugate operation.  */
> > +
> > +static inline bool
> > +vect_validate_multiplication (slp_tree_to_load_perm_map_t
> *perm_cache,
> > +			     vec<slp_tree> left_op, vec<slp_tree> right_op,
> > +			     bool neg_first, bool *conj_first_operand,
> > +			     bool fms)
> > +{
> > +  /* The presence of a negation indicates that we have either a conjugate
> or a
> > +     rotation.  We need to distinguish which one.  */
> > +  *conj_first_operand = false;
> > +  complex_perm_kinds_t kind;
> > +
> > +  /* Complex conjugates have the negation on the imaginary part of the
> > +     number where rotations affect the real component.  So check if the
> > +     negation is on a dup of lane 1.  */
> > +  if (fms)
> > +    {
> > +      /* Canonicalization for fms is not consistent. So have to test both
> > +	 variants to be sure.  This needs to be fixed in the mid-end so
> > +	 this part can be simpler.  */
> > +      kind = linear_loads_p (perm_cache, right_op[0]).first;
> > +      if (!((kind == PERM_ODDODD
> > +	   && is_eq_or_top (linear_loads_p (perm_cache, right_op[1]),
> > +			     PERM_ODDEVEN))
> > +	  || (kind == PERM_ODDEVEN
> > +	      && is_eq_or_top (linear_loads_p (perm_cache, right_op[1]),
> > +			     PERM_ODDODD))))
> > +	return false;
> > +    }
> > +  else
> > +    {
> > +      if (linear_loads_p (perm_cache, right_op[1]).first != PERM_ODDODD
> > +	  && !is_eq_or_top (linear_loads_p (perm_cache, right_op[0]),
> > +			    PERM_ODDEVEN))
> > +	return false;
> > +    }
> > +
> > +  /* Deal with differences in indexes.  */  int index1 = fms ? 1 : 0;
> > + int index2 = fms ? 0 : 1;
> > +
> > +  /* Check if the conjugate is on the second first or second operand.  The
> > +     order of the node with the conjugate value determines this, and the
> dup
> > +     node must be one of lane 0 of the same DR as the neg node.  */
> > +  kind = linear_loads_p (perm_cache, left_op[index1]).first;
> > +  if (kind == PERM_TOP)
> > +    {
> > +      if (linear_loads_p (perm_cache, left_op[index2]).first ==
> PERM_EVENODD)
> > +	return true;
> > +    }
> > +  else if (kind == PERM_EVENODD)
> > +    {
> > +      if ((kind = linear_loads_p (perm_cache, left_op[index2]).first) ==
> PERM_EVENODD)
> > +	return false;
> > +    }
> > +  else if (!neg_first)
> > +    *conj_first_operand = true;
> > +  else
> > +    return false;
> > +
> > +  if (kind != PERM_EVENEVEN)
> > +    return false;
> > +
> > +  return true;
> > +}
> > +
> > +/* Helper function to help distinguish between a conjugate and a rotation
> in a
> > +   complex multiplication.  The operations have similar shapes but the
> order of
> > +   the load permutes are different.  This function returns TRUE when the
> order
> > +   is consistent with a multiplication or multiplication by conjugated
> > +   operand but returns FALSE if it's a multiplication by rotated
> > +operand.  */
> > +
> > +static inline bool
> > +vect_validate_multiplication (slp_tree_to_load_perm_map_t
> *perm_cache,
> > +			     vec<slp_tree> op, complex_perm_kinds_t
> permKind) {
> > +  /* The left node is the more common case, test it first.  */
> > +  if (!is_eq_or_top (linear_loads_p (perm_cache, op[0]), permKind))
> > +    {
> > +      if (!is_eq_or_top (linear_loads_p (perm_cache, op[1]), permKind))
> > +	return false;
> > +    }
> > +  return true;
> > +}
> > +
> > +/* This function combines two nodes containing only even and only odd
> lanes
> > +   together into a single node which contains the nodes in even/odd order
> > +   by using a lane permute.  */
> > +
> > +static slp_tree
> > +vect_build_combine_node (slp_tree even, slp_tree odd, slp_tree rep) {
> > +  auto_vec<slp_tree> nodes;
> > +  nodes.create (2);
> > +  vec<std::pair<unsigned, unsigned> > perm;
> > +  perm.create (SLP_TREE_LANES (rep));
> > +
> > +  for (unsigned x = 0; x < SLP_TREE_LANES (rep); x+=2)
> > +    {
> > +      perm.quick_push (std::make_pair (0, x));
> > +      perm.quick_push (std::make_pair (1, x));
> > +    }
> 
> That looks wrong, it creates {0,0}, {1, 0}, {0, 2}, {1, 2} but you want {0, 0}, {1, 0},
> {0, 1}, {1, 1} AFAICS.  At least I assume SLP_TREE_LANES (odd/even) ==
> SLP_TREE_LANES (rep) / 2?
> 
> 'rep' isn't documented, I assume it's supoosed to be a "representative"
> for the result?
> 
> > +
> > +  nodes.quick_push (even);
> > +  nodes.quick_push (odd);
> 
> No need for this intermediate nodes array, just push to ...
> 
> > +  SLP_TREE_REF_COUNT (even)++;
> > +  SLP_TREE_REF_COUNT (odd)++;
> > +
> > +  slp_tree vnode = vect_create_new_slp_node (2, SLP_TREE_CODE
> > + (even));  SLP_TREE_CODE (vnode) = VEC_PERM_EXPR;
> > + SLP_TREE_LANE_PERMUTATION (vnode) = perm;  SLP_TREE_CHILDREN
> > + (vnode).safe_splice (nodes);
> 
> ... the children array directly (even with quick_push, we've already allocated
> 2 elements for the children).
> 
> > +  SLP_TREE_REF_COUNT (vnode) = 1;
> > +  SLP_TREE_LANES (vnode) = SLP_TREE_LANES (rep);  gcc_assert
> > + (perm.length () == SLP_TREE_LANES (vnode));
> > +  /* Representation is set to that of the current node as the vectorizer
> > +     can't deal with VEC_PERMs with no representation, as would be the
> > +     case with invariants.  */
> 
> Yeah, I need to fix this ...
> 
> > +  SLP_TREE_REPRESENTATIVE (vnode) = SLP_TREE_REPRESENTATIVE (rep);
> > +  SLP_TREE_VECTYPE (vnode) = SLP_TREE_VECTYPE (rep);
> > +  return vnode;
> > +}
> > +
> > +class complex_mul_pattern : public complex_pattern {
> > +  protected:
> > +    complex_mul_pattern (slp_tree *node, vec<slp_tree> *m_ops,
> internal_fn ifn)
> > +      : complex_pattern (node, m_ops, ifn)
> > +    {
> > +      this->m_num_args = 2;
> > +    }
> > +
> > +  public:
> > +    void build (vec_info *);
> > +    static internal_fn
> > +    matches (complex_operation_t op, slp_tree_to_load_perm_map_t *,
> slp_tree *,
> > +	     vec<slp_tree> *);
> > +
> > +    static vect_pattern*
> > +    recognize (slp_tree_to_load_perm_map_t *, slp_tree *);
> > +
> > +    static vect_pattern*
> > +    mkInstance (slp_tree *node, vec<slp_tree> *m_ops, internal_fn ifn)
> > +    {
> > +      return new complex_mul_pattern (node, m_ops, ifn);
> > +    }
> > +
> > +};
> > +
> > +/* Pattern matcher for trying to match complex multiply pattern in SLP
> tree
> > +   If the operation matches then IFN is set to the operation it matched
> > +   and the arguments to the two replacement statements are put in
> m_ops.
> > +
> > +   If no match is found then IFN is set to IFN_LAST and m_ops is unchanged.
> > +
> > +   This function matches the patterns shaped as:
> > +
> > +   double ax = (b[i+1] * a[i]);
> > +   double bx = (a[i+1] * b[i]);
> > +
> > +   c[i] = c[i] - ax;
> > +   c[i+1] = c[i+1] + bx;
> > +
> > +   If a match occurred then TRUE is returned, else FALSE.  The initial match
> is
> > +   expected to be in OP1 and the initial match operands in args0.  */
> > +
> > +internal_fn
> > +complex_mul_pattern::matches (complex_operation_t op,
> > +			      slp_tree_to_load_perm_map_t *perm_cache,
> > +			      slp_tree *node, vec<slp_tree> *ops) {
> > +  internal_fn ifn = IFN_LAST;
> > +
> > +  if (op != MINUS_PLUS)
> > +    return IFN_LAST;
> > +
> > +  slp_tree root = *node;
> > +  /* First two nodes must be a multiply.  */  auto_vec<slp_tree>
> > + muls;  if (vect_match_call_complex_mla (root, 0) != MULT_MULT
> > +      || vect_match_call_complex_mla (root, 1, &muls) != MULT_MULT)
> > +    return IFN_LAST;
> > +
> > +  /* Now operand2+4 may lead to another expression.  */
> > + auto_vec<slp_tree> left_op, right_op;  left_op.safe_splice
> > + (SLP_TREE_CHILDREN (muls[0]));  right_op.safe_splice
> > + (SLP_TREE_CHILDREN (muls[1]));
> > +
> > +  if (linear_loads_p (perm_cache, left_op[1]).first == PERM_ODDEVEN)
> > +    return IFN_LAST;
> > +
> > +  bool neg_first;
> > +  bool is_neg = vect_normalize_conj_loc (right_op, &neg_first);
> > +
> > +  if (!is_neg)
> > +    {
> > +      /* A multiplication needs to multiply agains the real pair, otherwise
> > +	 the pattern matches that of FMS.   */
> > +      if (!vect_validate_multiplication (perm_cache, left_op,
> PERM_EVENEVEN)
> > +	  || vect_normalize_conj_loc (left_op))
> > +	return IFN_LAST;
> > +      ifn = IFN_COMPLEX_MUL;
> > +    }
> > +  else if (is_neg)
> > +    {
> > +      bool conj_first_operand;
> > +      if (!vect_validate_multiplication (perm_cache, left_op, right_op,
> > +					 neg_first, &conj_first_operand,
> > +					 false))
> > +	return IFN_LAST;
> > +
> > +      ifn = IFN_COMPLEX_MUL_CONJ;
> > +    }
> > +
> > +  if (!vect_pattern_validate_optab (ifn, *node))
> > +    return IFN_LAST;
> > +
> > +  ops->truncate (0);
> > +  ops->create (3);
> > +
> > +  complex_perm_kinds_t kind = linear_loads_p (perm_cache,
> > + left_op[0]).first;  if (kind == PERM_EVENODD)
> > +    {
> > +      ops->quick_push (left_op[1]);
> > +      ops->quick_push (right_op[1]);
> > +      ops->quick_push (left_op[0]);
> > +    }
> > +  else if (kind == PERM_TOP)
> > +    {
> > +      ops->quick_push (left_op[1]);
> > +      ops->quick_push (right_op[1]);
> > +      ops->quick_push (left_op[0]);
> > +    }
> > +  else
> > +    {
> > +      ops->quick_push (left_op[0]);
> > +      ops->quick_push (right_op[0]);
> > +      ops->quick_push (left_op[1]);
> > +    }
> > +
> > +  return ifn;
> > +}
> > +
> > +/* Attempt to recognize a complex mul pattern.  */
> > +
> > +vect_pattern*
> > +complex_mul_pattern::recognize (slp_tree_to_load_perm_map_t
> *perm_cache,
> > +				slp_tree *node)
> > +{
> > +  auto_vec<slp_tree> ops;
> > +  complex_operation_t op
> > +    = vect_detect_pair_op (*node, true, &ops);
> > +  internal_fn ifn
> > +    = complex_mul_pattern::matches (op, perm_cache, node, &ops);
> > +  if (ifn == IFN_LAST)
> > +    return NULL;
> > +
> > +  return new complex_mul_pattern (node, &ops, ifn); }
> > +
> > +/* Perform a replacement of the detected complex mul pattern with the
> new
> > +   instruction sequences.  */
> > +
> > +void
> > +complex_mul_pattern::build (vec_info *vinfo) {
> > +  auto_vec<slp_tree> nodes;
> > +
> > +  /* First re-arrange the children.  */  nodes.create (2);
> > +
> > +  nodes.quick_push (this->m_ops[2]);
> > +  nodes.quick_push (
> > +    vect_build_combine_node (this->m_ops[0], this->m_ops[1],
> > + *this->m_node));  SLP_TREE_REF_COUNT (this->m_ops[2])++;
> > +
> > +  slp_tree node;
> > +  unsigned i;
> > +  FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (*this->m_node), i, node)
> > +    vect_free_slp_tree (node);
> > +
> > +  SLP_TREE_CHILDREN (*this->m_node).truncate (0);
> SLP_TREE_CHILDREN
> > + (*this->m_node).safe_splice (nodes);
> 
> please elide the nodes array.  *this->m_node now has a "wrong"
> representative but I guess
> 
> > +  complex_pattern::build (vinfo);
> 
> will fix that up?  I still find the structure of the pattern matching & transform
> hard to follow.  But well - I've settled with the idea of refactoring it for next
> stage1 after the fact ;)

Indeed it does, I can flip order if replacing them last is clearer.

For next stage1 I wonder if it's not easier to not have build_slp produce the two_operands
At all and have a generic expander that targets can override.  This of course would require
It to change the VF, but will have to to support LDn/STn in SLP anyway.

But this would simplify things a lot.  I have some ideas but will write them up to get a review on
the idea before I start implementing.

Thanks for allowing this version in!

Regards,
Tamar

> 
> Thanks,
> Richard.

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diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index ec6ec180b91fcf9f481b6754c044483787fd923c..b8cc90e1a75e402abbf8a8cf2efefc1a333f8b3a 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -6202,6 +6202,50 @@ The operation is only supported for vector modes @var{m}.
 
 This pattern is not allowed to @code{FAIL}.
 
+@cindex @code{cmul@var{m}4} instruction pattern
+@item @samp{cmul@var{m}4}
+Perform a vector multiply that is semantically the same as multiply of
+complex numbers.
+
+@smallexample
+  complex TYPE c[N];
+  complex TYPE a[N];
+  complex TYPE b[N];
+  for (int i = 0; i < N; i += 1)
+    @{
+      c[i] = a[i] * b[i];
+    @}
+@end smallexample
+
+In GCC lane ordering the real part of the number must be in the even lanes with
+the imaginary part in the odd lanes.
+
+The operation is only supported for vector modes @var{m}.
+
+This pattern is not allowed to @code{FAIL}.
+
+@cindex @code{cmul_conj@var{m}4} instruction pattern
+@item @samp{cmul_conj@var{m}4}
+Perform a vector multiply by conjugate that is semantically the same as a
+multiply of complex numbers where the second multiply arguments is conjugated.
+
+@smallexample
+  complex TYPE c[N];
+  complex TYPE a[N];
+  complex TYPE b[N];
+  for (int i = 0; i < N; i += 1)
+    @{
+      c[i] = a[i] * conj (b[i]);
+    @}
+@end smallexample
+
+In GCC lane ordering the real part of the number must be in the even lanes with
+the imaginary part in the odd lanes.
+
+The operation is only supported for vector modes @var{m}.
+
+This pattern is not allowed to @code{FAIL}.
+
 @cindex @code{ffs@var{m}2} instruction pattern
 @item @samp{ffs@var{m}2}
 Store into operand 0 one plus the index of the least significant 1-bit
diff --git a/gcc/internal-fn.def b/gcc/internal-fn.def
index 511fe70162b5d9db3a61a5285d31c008f6835487..5a0bbe3fe5dee591d54130e60f6996b28164ae38 100644
--- a/gcc/internal-fn.def
+++ b/gcc/internal-fn.def
@@ -279,6 +279,8 @@ DEF_INTERNAL_FLT_FLOATN_FN (FMAX, ECF_CONST, fmax, binary)
 DEF_INTERNAL_OPTAB_FN (XORSIGN, ECF_CONST, xorsign, binary)
 DEF_INTERNAL_OPTAB_FN (COMPLEX_ADD_ROT90, ECF_CONST, cadd90, binary)
 DEF_INTERNAL_OPTAB_FN (COMPLEX_ADD_ROT270, ECF_CONST, cadd270, binary)
+DEF_INTERNAL_OPTAB_FN (COMPLEX_MUL, ECF_CONST, cmul, binary)
+DEF_INTERNAL_OPTAB_FN (COMPLEX_MUL_CONJ, ECF_CONST, cmul_conj, binary)
 
 
 /* FP scales.  */
diff --git a/gcc/optabs.def b/gcc/optabs.def
index e9727def4dbf941bb9ac8b56f83f8ea0f52b262c..e82396bae1117c6de91304761a560b7fbcb69ce1 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -292,6 +292,8 @@ OPTAB_D (copysign_optab, "copysign$F$a3")
 OPTAB_D (xorsign_optab, "xorsign$F$a3")
 OPTAB_D (cadd90_optab, "cadd90$a3")
 OPTAB_D (cadd270_optab, "cadd270$a3")
+OPTAB_D (cmul_optab, "cmul$a3")
+OPTAB_D (cmul_conj_optab, "cmul_conj$a3")
 OPTAB_D (cos_optab, "cos$a2")
 OPTAB_D (cosh_optab, "cosh$a2")
 OPTAB_D (exp10_optab, "exp10$a2")
diff --git a/gcc/tree-vect-slp-patterns.c b/gcc/tree-vect-slp-patterns.c
index dbc58f7c53868ed431fc67de1f0162eb0d3b2c24..fb58b45602f00a440ef7c27853276945ba696522 100644
--- a/gcc/tree-vect-slp-patterns.c
+++ b/gcc/tree-vect-slp-patterns.c
@@ -719,6 +719,375 @@ complex_add_pattern::recognize (slp_tree_to_load_perm_map_t *perm_cache,
   return new complex_add_pattern (node, &ops, ifn);
 }
 
+/*******************************************************************************
+ * complex_mul_pattern
+ ******************************************************************************/
+
+/* Helper function of that looks for a match in the CHILDth child of NODE.  The
+   child used is stored in RES.
+
+   If the match is successful then ARGS will contain the operands matched
+   and the complex_operation_t type is returned.  If match is not successful
+   then CMPLX_NONE is returned and ARGS is left unmodified.  */
+
+static inline complex_operation_t
+vect_match_call_complex_mla (slp_tree node, unsigned child,
+			     vec<slp_tree> *args = NULL, slp_tree *res = NULL)
+{
+  gcc_assert (child < SLP_TREE_CHILDREN (node).length ());
+
+  slp_tree data = SLP_TREE_CHILDREN (node)[child];
+
+  if (res)
+    *res = data;
+
+  return vect_detect_pair_op (data, false, args);
+}
+
+/* Check to see if either of the trees in ARGS are a NEGATE_EXPR.  If the first
+   child (args[0]) is a NEGATE_EXPR then NEG_FIRST_P is set to TRUE.
+
+   If a negate is found then the values in ARGS are reordered such that the
+   negate node is always the second one and the entry is replaced by the child
+   of the negate node.  */
+
+static inline bool
+vect_normalize_conj_loc (vec<slp_tree> args, bool *neg_first_p = NULL)
+{
+  gcc_assert (args.length () == 2);
+  bool neg_found = false;
+
+  if (vect_match_expression_p (args[0], NEGATE_EXPR))
+    {
+      std::swap (args[0], args[1]);
+      neg_found = true;
+      if (neg_first_p)
+	*neg_first_p = true;
+    }
+  else if (vect_match_expression_p (args[1], NEGATE_EXPR))
+    {
+      neg_found = true;
+      if (neg_first_p)
+	*neg_first_p = false;
+    }
+
+  if (neg_found)
+    args[1] = SLP_TREE_CHILDREN (args[1])[0];
+
+  return neg_found;
+}
+
+/* Helper function to check if PERM is KIND or PERM_TOP.  */
+
+static inline bool
+is_eq_or_top (complex_load_perm_t perm, complex_perm_kinds_t kind)
+{
+  return perm.first == kind || perm.first == PERM_TOP;
+}
+
+/* Helper function that checks to see if LEFT_OP and RIGHT_OP are both MULT_EXPR
+   nodes but also that they represent an operation that is either a complex
+   multiplication or a complex multiplication by conjugated value.
+
+   Of the negation is expected to be in the first half of the tree (As required
+   by an FMS pattern) then NEG_FIRST is true.  If the operation is a conjugate
+   operation then CONJ_FIRST_OPERAND is set to indicate whether the first or
+   second operand contains the conjugate operation.  */
+
+static inline bool
+vect_validate_multiplication (slp_tree_to_load_perm_map_t *perm_cache,
+			     vec<slp_tree> left_op, vec<slp_tree> right_op,
+			     bool neg_first, bool *conj_first_operand,
+			     bool fms)
+{
+  /* The presence of a negation indicates that we have either a conjugate or a
+     rotation.  We need to distinguish which one.  */
+  *conj_first_operand = false;
+  complex_perm_kinds_t kind;
+
+  /* Complex conjugates have the negation on the imaginary part of the
+     number where rotations affect the real component.  So check if the
+     negation is on a dup of lane 1.  */
+  if (fms)
+    {
+      /* Canonicalization for fms is not consistent. So have to test both
+	 variants to be sure.  This needs to be fixed in the mid-end so
+	 this part can be simpler.  */
+      kind = linear_loads_p (perm_cache, right_op[0]).first;
+      if (!((kind == PERM_ODDODD
+	   && is_eq_or_top (linear_loads_p (perm_cache, right_op[1]),
+			     PERM_ODDEVEN))
+	  || (kind == PERM_ODDEVEN
+	      && is_eq_or_top (linear_loads_p (perm_cache, right_op[1]),
+			     PERM_ODDODD))))
+	return false;
+    }
+  else
+    {
+      if (linear_loads_p (perm_cache, right_op[1]).first != PERM_ODDODD
+	  && !is_eq_or_top (linear_loads_p (perm_cache, right_op[0]),
+			    PERM_ODDEVEN))
+	return false;
+    }
+
+  /* Deal with differences in indexes.  */
+  int index1 = fms ? 1 : 0;
+  int index2 = fms ? 0 : 1;
+
+  /* Check if the conjugate is on the second first or second operand.  The
+     order of the node with the conjugate value determines this, and the dup
+     node must be one of lane 0 of the same DR as the neg node.  */
+  kind = linear_loads_p (perm_cache, left_op[index1]).first;
+  if (kind == PERM_TOP)
+    {
+      if (linear_loads_p (perm_cache, left_op[index2]).first == PERM_EVENODD)
+	return true;
+    }
+  else if (kind == PERM_EVENODD)
+    {
+      if ((kind = linear_loads_p (perm_cache, left_op[index2]).first) == PERM_EVENODD)
+	return false;
+    }
+  else if (!neg_first)
+    *conj_first_operand = true;
+  else
+    return false;
+
+  if (kind != PERM_EVENEVEN)
+    return false;
+
+  return true;
+}
+
+/* Helper function to help distinguish between a conjugate and a rotation in a
+   complex multiplication.  The operations have similar shapes but the order of
+   the load permutes are different.  This function returns TRUE when the order
+   is consistent with a multiplication or multiplication by conjugated
+   operand but returns FALSE if it's a multiplication by rotated operand.  */
+
+static inline bool
+vect_validate_multiplication (slp_tree_to_load_perm_map_t *perm_cache,
+			     vec<slp_tree> op, complex_perm_kinds_t permKind)
+{
+  /* The left node is the more common case, test it first.  */
+  if (!is_eq_or_top (linear_loads_p (perm_cache, op[0]), permKind))
+    {
+      if (!is_eq_or_top (linear_loads_p (perm_cache, op[1]), permKind))
+	return false;
+    }
+  return true;
+}
+
+/* This function combines two nodes containing only even and only odd lanes
+   together into a single node which contains the nodes in even/odd order
+   by using a lane permute.
+
+   The lanes in EVEN and ODD are duplicated 2 times inside the vectors.
+   So for a lanes = 4 EVEN contains {EVEN1, EVEN1, EVEN2, EVEN2}.
+
+   The tree REPRESENTATION is taken from the supplied REP along with the
+   vectype which must be the same between all three nodes.
+*/
+
+static slp_tree
+vect_build_combine_node (slp_tree even, slp_tree odd, slp_tree rep)
+{
+  vec<std::pair<unsigned, unsigned> > perm;
+  perm.create (SLP_TREE_LANES (rep));
+
+  for (unsigned x = 0; x < SLP_TREE_LANES (rep); x+=2)
+    {
+      perm.quick_push (std::make_pair (0, x));
+      perm.quick_push (std::make_pair (1, x+1));
+    }
+
+  slp_tree vnode = vect_create_new_slp_node (2, SLP_TREE_CODE (even));
+  SLP_TREE_CODE (vnode) = VEC_PERM_EXPR;
+  SLP_TREE_LANE_PERMUTATION (vnode) = perm;
+
+  SLP_TREE_CHILDREN (vnode).create (2);
+  SLP_TREE_CHILDREN (vnode).quick_push (even);
+  SLP_TREE_CHILDREN (vnode).quick_push (odd);
+  SLP_TREE_REF_COUNT (even)++;
+  SLP_TREE_REF_COUNT (odd)++;
+  SLP_TREE_REF_COUNT (vnode) = 1;
+
+  SLP_TREE_LANES (vnode) = SLP_TREE_LANES (rep);
+  gcc_assert (perm.length () == SLP_TREE_LANES (vnode));
+  /* Representation is set to that of the current node as the vectorizer
+     can't deal with VEC_PERMs with no representation, as would be the
+     case with invariants.  */
+  SLP_TREE_REPRESENTATIVE (vnode) = SLP_TREE_REPRESENTATIVE (rep);
+  SLP_TREE_VECTYPE (vnode) = SLP_TREE_VECTYPE (rep);
+  return vnode;
+}
+
+class complex_mul_pattern : public complex_pattern
+{
+  protected:
+    complex_mul_pattern (slp_tree *node, vec<slp_tree> *m_ops, internal_fn ifn)
+      : complex_pattern (node, m_ops, ifn)
+    {
+      this->m_num_args = 2;
+    }
+
+  public:
+    void build (vec_info *);
+    static internal_fn
+    matches (complex_operation_t op, slp_tree_to_load_perm_map_t *, slp_tree *,
+	     vec<slp_tree> *);
+
+    static vect_pattern*
+    recognize (slp_tree_to_load_perm_map_t *, slp_tree *);
+
+    static vect_pattern*
+    mkInstance (slp_tree *node, vec<slp_tree> *m_ops, internal_fn ifn)
+    {
+      return new complex_mul_pattern (node, m_ops, ifn);
+    }
+
+};
+
+/* Pattern matcher for trying to match complex multiply pattern in SLP tree
+   If the operation matches then IFN is set to the operation it matched
+   and the arguments to the two replacement statements are put in m_ops.
+
+   If no match is found then IFN is set to IFN_LAST and m_ops is unchanged.
+
+   This function matches the patterns shaped as:
+
+   double ax = (b[i+1] * a[i]);
+   double bx = (a[i+1] * b[i]);
+
+   c[i] = c[i] - ax;
+   c[i+1] = c[i+1] + bx;
+
+   If a match occurred then TRUE is returned, else FALSE.  The initial match is
+   expected to be in OP1 and the initial match operands in args0.  */
+
+internal_fn
+complex_mul_pattern::matches (complex_operation_t op,
+			      slp_tree_to_load_perm_map_t *perm_cache,
+			      slp_tree *node, vec<slp_tree> *ops)
+{
+  internal_fn ifn = IFN_LAST;
+
+  if (op != MINUS_PLUS)
+    return IFN_LAST;
+
+  slp_tree root = *node;
+  /* First two nodes must be a multiply.  */
+  auto_vec<slp_tree> muls;
+  if (vect_match_call_complex_mla (root, 0) != MULT_MULT
+      || vect_match_call_complex_mla (root, 1, &muls) != MULT_MULT)
+    return IFN_LAST;
+
+  /* Now operand2+4 may lead to another expression.  */
+  auto_vec<slp_tree> left_op, right_op;
+  left_op.safe_splice (SLP_TREE_CHILDREN (muls[0]));
+  right_op.safe_splice (SLP_TREE_CHILDREN (muls[1]));
+
+  if (linear_loads_p (perm_cache, left_op[1]).first == PERM_ODDEVEN)
+    return IFN_LAST;
+
+  bool neg_first = false;
+  bool conj_first_operand = false;
+  bool is_neg = vect_normalize_conj_loc (right_op, &neg_first);
+
+  if (!is_neg)
+    {
+      /* A multiplication needs to multiply agains the real pair, otherwise
+	 the pattern matches that of FMS.   */
+      if (!vect_validate_multiplication (perm_cache, left_op, PERM_EVENEVEN)
+	  || vect_normalize_conj_loc (left_op))
+	return IFN_LAST;
+      ifn = IFN_COMPLEX_MUL;
+    }
+  else if (is_neg)
+    {
+      if (!vect_validate_multiplication (perm_cache, left_op, right_op,
+					 neg_first, &conj_first_operand,
+					 false))
+	return IFN_LAST;
+
+      ifn = IFN_COMPLEX_MUL_CONJ;
+    }
+
+  if (!vect_pattern_validate_optab (ifn, *node))
+    return IFN_LAST;
+
+  ops->truncate (0);
+  ops->create (3);
+
+  complex_perm_kinds_t kind = linear_loads_p (perm_cache, left_op[0]).first;
+  if (kind == PERM_EVENODD)
+    {
+      ops->quick_push (left_op[1]);
+      ops->quick_push (right_op[1]);
+      ops->quick_push (left_op[0]);
+    }
+  else if (kind == PERM_TOP)
+    {
+      ops->quick_push (left_op[1]);
+      ops->quick_push (right_op[1]);
+      ops->quick_push (left_op[0]);
+    }
+  else if (kind == PERM_EVENEVEN && !conj_first_operand)
+    {
+      ops->quick_push (left_op[0]);
+      ops->quick_push (right_op[0]);
+      ops->quick_push (left_op[1]);
+    }
+  else
+    {
+      ops->quick_push (left_op[0]);
+      ops->quick_push (right_op[1]);
+      ops->quick_push (left_op[1]);
+    }
+
+  return ifn;
+}
+
+/* Attempt to recognize a complex mul pattern.  */
+
+vect_pattern*
+complex_mul_pattern::recognize (slp_tree_to_load_perm_map_t *perm_cache,
+				slp_tree *node)
+{
+  auto_vec<slp_tree> ops;
+  complex_operation_t op
+    = vect_detect_pair_op (*node, true, &ops);
+  internal_fn ifn
+    = complex_mul_pattern::matches (op, perm_cache, node, &ops);
+  if (ifn == IFN_LAST)
+    return NULL;
+
+  return new complex_mul_pattern (node, &ops, ifn);
+}
+
+/* Perform a replacement of the detected complex mul pattern with the new
+   instruction sequences.  */
+
+void
+complex_mul_pattern::build (vec_info *vinfo)
+{
+  slp_tree node;
+  unsigned i;
+  FOR_EACH_VEC_ELT (SLP_TREE_CHILDREN (*this->m_node), i, node)
+    vect_free_slp_tree (node);
+
+  /* First re-arrange the children.  */
+  SLP_TREE_CHILDREN (*this->m_node).truncate (0);
+  SLP_TREE_CHILDREN (*this->m_node).create (2);
+  SLP_TREE_CHILDREN (*this->m_node).quick_push (this->m_ops[2]);
+  SLP_TREE_CHILDREN (*this->m_node).quick_push (
+    vect_build_combine_node (this->m_ops[0], this->m_ops[1], *this->m_node));
+  SLP_TREE_REF_COUNT (this->m_ops[2])++;
+
+  /* And then rewrite the node itself.  */
+  complex_pattern::build (vinfo);
+}
+
 /*******************************************************************************
  * Pattern matching definitions
  ******************************************************************************/