[gcc r14-9877] s390x: Optimize vector permute with constant indexes

[Juergen Christ <jchrist@gcc.gnu.org>]

https://gcc.gnu.org/g:1f719aa7c0d35b47f3d15a54f074718b78e92bb0

commit r14-9877-g1f719aa7c0d35b47f3d15a54f074718b78e92bb0
Author: Juergen Christ <jchrist@linux.ibm.com>
Date:   Mon Apr 1 13:34:37 2024 +0200

    s390x: Optimize vector permute with constant indexes
    
    Loop vectorizer can generate vector permutes with constant indexes
    where all indexes are equal.  Optimize this case to use vector
    replicate instead of vector permute.
    
    gcc/ChangeLog:
    
            * config/s390/s390.cc (expand_perm_as_replicate): Implement.
            (vectorize_vec_perm_const_1): Call new function.
            * config/s390/vx-builtins.md (vec_splat<mode>): Change to...
            (@vec_splat<mode>): ...this.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/s390/vector/vec-expand-replicate.c: New test.
    
    Signed-off-by: Juergen Christ <jchrist@linux.ibm.com>

Diff:
---
 gcc/config/s390/s390.cc                            | 33 ++++++++++++
 gcc/config/s390/vx-builtins.md                     |  2 +-
 .../gcc.target/s390/vector/vec-expand-replicate.c  | 60 ++++++++++++++++++++++
 3 files changed, 94 insertions(+), 1 deletion(-)

diff --git a/gcc/config/s390/s390.cc b/gcc/config/s390/s390.cc
index 3ee7ae7b8d4..bf46eab2d63 100644
--- a/gcc/config/s390/s390.cc
+++ b/gcc/config/s390/s390.cc
@@ -17933,6 +17933,36 @@ expand_perm_as_a_vlbr_vstbr_candidate (const struct expand_vec_perm_d &d)
   return false;
 }
 
+static bool
+expand_perm_as_replicate (const struct expand_vec_perm_d &d)
+{
+  unsigned char i;
+  unsigned char elem;
+  rtx base = d.op0;
+  rtx insn;
+  /* Needed to silence maybe-uninitialized warning.  */
+  gcc_assert (d.nelt > 0);
+  elem = d.perm[0];
+  for (i = 1; i < d.nelt; ++i)
+    if (d.perm[i] != elem)
+      return false;
+  if (!d.testing_p)
+    {
+      if (elem >= d.nelt)
+	{
+	  base = d.op1;
+	  elem -= d.nelt;
+	}
+      insn = maybe_gen_vec_splat (d.vmode, d.target, base, GEN_INT (elem));
+      if (insn == NULL_RTX)
+	return false;
+      emit_insn (insn);
+      return true;
+    }
+  else
+    return maybe_code_for_vec_splat (d.vmode) != CODE_FOR_nothing;
+}
+
 /* Try to find the best sequence for the vector permute operation
    described by D.  Return true if the operation could be
    expanded.  */
@@ -17951,6 +17981,9 @@ vectorize_vec_perm_const_1 (const struct expand_vec_perm_d &d)
   if (expand_perm_as_a_vlbr_vstbr_candidate (d))
     return true;
 
+  if (expand_perm_as_replicate (d))
+    return true;
+
   return false;
 }
 
diff --git a/gcc/config/s390/vx-builtins.md b/gcc/config/s390/vx-builtins.md
index 432d81a719f..93c0d408a43 100644
--- a/gcc/config/s390/vx-builtins.md
+++ b/gcc/config/s390/vx-builtins.md
@@ -424,7 +424,7 @@
 
 
 ; Replicate from vector element
-(define_expand "vec_splat<mode>"
+(define_expand "@vec_splat<mode>"
   [(set (match_operand:V_HW                      0 "register_operand"  "")
 	(vec_duplicate:V_HW (vec_select:<non_vec>
 			     (match_operand:V_HW 1 "register_operand"  "")
diff --git a/gcc/testsuite/gcc.target/s390/vector/vec-expand-replicate.c b/gcc/testsuite/gcc.target/s390/vector/vec-expand-replicate.c
new file mode 100644
index 00000000000..872b1c9321c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/s390/vector/vec-expand-replicate.c
@@ -0,0 +1,60 @@
+/* Check that the vectorize_vec_perm_const expander correctly deals with
+   replication.  Extracted from spec "nab".  */
+
+/* { dg-do compile } */
+/* { dg-options "-O3 -mzarch -march=z13 -fvect-cost-model=unlimited" } */
+
+typedef double POINT_T[3];
+typedef double MATRIX_T[][4];
+typedef struct {
+  POINT_T a_pos;
+} ATOM_T;
+typedef struct {
+  ATOM_T *r_atoms;
+} RESIDUE_T;
+typedef struct strand_t {
+  RESIDUE_T *s_residues;
+} STRAND_T;
+typedef struct strand_t MOLECULE_T;
+double xfm_xyz_oxyz4[4];
+MOLECULE_T add_he2o3transformmol_mol, add_he2o3transformmol_sp;
+RESIDUE_T add_he2o3transformmol_res;
+int add_he2o3transformmol_r, add_he2o3transformmol_a, add_he2o3transformmol_i;
+ATOM_T *add_he2o3transformmol_ap;
+POINT_T add_he2o3transformmol_xyz, add_he2o3transformmol_nxyz;
+static void xfm_xyz(POINT_T oxyz, MATRIX_T mat, POINT_T nxyz) {
+  int i, j;
+  double nxyz4[4];
+  for (i = 0; i < 3; i++)
+    xfm_xyz_oxyz4[i] = oxyz[i];
+  xfm_xyz_oxyz4[3] = 1.0;
+  for (i = 0; i < 4; i++) {
+    nxyz4[i] = 0.0;
+    for (j = 0; j < 4; j++)
+      nxyz4[i] += xfm_xyz_oxyz4[j] * mat[j][i];
+  }
+  for (i = 0; i < 3; i++)
+    nxyz[i] = nxyz4[i];
+}
+void add_he2o3transformmol(MATRIX_T mat, int n) {
+  for (add_he2o3transformmol_sp = add_he2o3transformmol_mol;;)
+    for (add_he2o3transformmol_r = 0;;) {
+      add_he2o3transformmol_res =
+          add_he2o3transformmol_sp.s_residues[add_he2o3transformmol_r];
+      for (add_he2o3transformmol_a = 0; add_he2o3transformmol_a < n; add_he2o3transformmol_a++) {
+        add_he2o3transformmol_ap =
+            &add_he2o3transformmol_res.r_atoms[add_he2o3transformmol_a];
+        for (add_he2o3transformmol_i = 0; add_he2o3transformmol_i < 3;
+             add_he2o3transformmol_i++)
+          add_he2o3transformmol_xyz[add_he2o3transformmol_i] =
+              add_he2o3transformmol_ap->a_pos[add_he2o3transformmol_i];
+        xfm_xyz(add_he2o3transformmol_xyz, mat, add_he2o3transformmol_nxyz);
+        for (add_he2o3transformmol_i = 0; add_he2o3transformmol_i < 3;
+             add_he2o3transformmol_i++)
+          add_he2o3transformmol_ap->a_pos[add_he2o3transformmol_i] =
+              add_he2o3transformmol_nxyz[add_he2o3transformmol_i];
+      }
+    }
+}
+
+/* { dg-final { scan-assembler-not "vperm" } } */