Re: [PATCH v1] LoongArch: Adjust cost of vector_stmt that match multiply-add pattern.

[chenglulu]

在 2024/1/24 下午5:36, Li Wei 写道:

We found that when only 128-bit vectorization was enabled, 549.fotonik3d_r
failed to vectorize effectively. For this reason, we adjust the cost of
128-bit vector_stmt that match the multiply-add pattern to facilitate 128-bit
vectorization.
The experimental results show that after the modification, 549.fotonik3d_r
performance can be improved by 9.77% under the 128-bit vectorization option.

gcc/ChangeLog:

        * config/loongarch/loongarch.cc (loongarch_multiply_add_p): New.
        (loongarch_vector_costs::add_stmt_cost): Adjust.

gcc/testsuite/ChangeLog:

        * gfortran.dg/vect/vect-10.f90: New test.
---
  gcc/config/loongarch/loongarch.cc          | 42 +++++++++++++
  gcc/testsuite/gfortran.dg/vect/vect-10.f90 | 71 ++++++++++++++++++++++
  2 files changed, 113 insertions(+)
  create mode 100644 gcc/testsuite/gfortran.dg/vect/vect-10.f90

diff --git a/gcc/config/loongarch/loongarch.cc 
b/gcc/config/loongarch/loongarch.cc
index 072c68d97e3..32a0b6f43e8 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -4096,6 +4096,36 @@ 
loongarch_vector_costs::determine_suggested_unroll_factor (loop_vec_info loop_vi
    return 1 << ceil_log2 (uf);
  }

+static bool

+loongarch_multiply_add_p (vec_info *vinfo, stmt_vec_info stmt_info)
+{
+  gassign *assign = dyn_cast<gassign *> (stmt_info->stmt);
+  if (!assign)
+    return false;
+  tree_code code = gimple_assign_rhs_code (assign);
+  if (code != PLUS_EXPR && code != MINUS_EXPR)
+    return false;
+
+  auto is_mul_result = [&](int i)
+    {
+      tree rhs = gimple_op (assign, i);
+      if (TREE_CODE (rhs) != SSA_NAME)
+       return false;
+
+      stmt_vec_info def_stmt_info = vinfo->lookup_def (rhs);
+      if (!def_stmt_info
+         || STMT_VINFO_DEF_TYPE (def_stmt_info) != vect_internal_def)
+       return false;
+      gassign *rhs_assign = dyn_cast<gassign *> (def_stmt_info->stmt);
+      if (!rhs_assign || gimple_assign_rhs_code (rhs_assign) != MULT_EXPR)
+       return false;
+
+      return true;
+    };
+
+  return is_mul_result (1) || is_mul_result (2);
+}
+
  unsigned
  loongarch_vector_costs::add_stmt_cost (int count, vect_cost_for_stmt kind,
                                       stmt_vec_info stmt_info, slp_tree,
@@ -4108,6 +4138,18 @@ loongarch_vector_costs::add_stmt_cost (int count, 
vect_cost_for_stmt kind,
      {
        int stmt_cost = loongarch_builtin_vectorization_cost (kind, vectype,
                                                            misalign);
+      if (vectype && stmt_info)
+       {
+         gassign *assign = dyn_cast<gassign *> (STMT_VINFO_STMT (stmt_info));
+         machine_mode mode = TYPE_MODE (vectype);

Hi, Liwei:

I think the code here needs to be commented.

Thanks.

+         if (kind == vector_stmt && GET_MODE_SIZE (mode) == 16 && assign)
+           {
+             if (!vect_is_reduction (stmt_info)
+                 && loongarch_multiply_add_p (m_vinfo, stmt_info))
+               stmt_cost = 0;
+           }
+       }
+
        retval = adjust_cost_for_freq (stmt_info, where, count * stmt_cost);
        m_costs[where] += retval;