From bb211ae35474a9fa1a8189f0a4c525ce3d8c280e Mon Sep 17 00:00:00 2001
From: Jiahao Xu <xujiahao@loongson.cn>
Date: Wed, 6 Dec 2023 15:04:53 +0800
Subject: [PATCH 063/188] LoongArch: Vectorized loop unrolling is disable for
 divf/sqrtf/rsqrtf when -mrecip is enabled.

Using -mrecip generates a sequence of instructions to replace divf, sqrtf and rsqrtf. The number
of generated instructions is close to or exceeds the maximum issue instructions per cycle of the
LoongArch, so vectorized loop unrolling is not performed on them.

gcc/ChangeLog:

	* config/loongarch/loongarch.cc (loongarch_vector_costs::determine_suggested_unroll_factor):
	If m_has_recip is true, uf return 1.
	(loongarch_vector_costs::add_stmt_cost): Detect the use of approximate instruction sequence.
---
 gcc/config/loongarch/loongarch.cc | 36 +++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/gcc/config/loongarch/loongarch.cc b/gcc/config/loongarch/loongarch.cc
index 18326ce47..d64777179 100644
--- a/gcc/config/loongarch/loongarch.cc
+++ b/gcc/config/loongarch/loongarch.cc
@@ -3970,7 +3970,9 @@ protected:
   /* Reduction factor for suggesting unroll factor.  */
   unsigned m_reduc_factor = 0;
   /* True if the loop contains an average operation. */
-  bool m_has_avg =false;
+  bool m_has_avg = false;
+  /* True if the loop uses approximation instruction sequence.  */
+  bool m_has_recip = false;
 };
 
 /* Implement TARGET_VECTORIZE_CREATE_COSTS.  */
@@ -4017,7 +4019,7 @@ loongarch_vector_costs::determine_suggested_unroll_factor (loop_vec_info loop_vi
 {
   class loop *loop = LOOP_VINFO_LOOP (loop_vinfo);
 
-  if (m_has_avg)
+  if (m_has_avg || m_has_recip)
     return 1;
 
   /* Don't unroll if it's specified explicitly not to be unrolled.  */
@@ -4077,6 +4079,36 @@ loongarch_vector_costs::add_stmt_cost (int count, vect_cost_for_stmt kind,
 	}
     }
 
+  combined_fn cfn;
+  if (kind == vector_stmt
+      && stmt_info
+      && stmt_info->stmt)
+    {
+      /* Detect the use of approximate instruction sequence.  */
+      if ((TARGET_RECIP_VEC_SQRT || TARGET_RECIP_VEC_RSQRT)
+	  && (cfn = gimple_call_combined_fn (stmt_info->stmt)) != CFN_LAST)
+	switch (cfn)
+	  {
+	  case CFN_BUILT_IN_SQRTF:
+	    m_has_recip = true;
+	  default:
+	    break;
+	  }
+      else if (TARGET_RECIP_VEC_DIV
+	       && gimple_code (stmt_info->stmt) == GIMPLE_ASSIGN)
+	{
+	  machine_mode mode = TYPE_MODE (vectype);
+	  switch (gimple_assign_rhs_code (stmt_info->stmt))
+	    {
+	    case RDIV_EXPR:
+	      if (GET_MODE_INNER (mode) == SFmode)
+		m_has_recip = true;
+	    default:
+	      break;
+	    }
+	}
+    }
+
   return retval;
 }
 
-- 
2.43.0