ARC: Table-driven ashlsi implementation for better code/rtx_costs.

One of the cool features of the H8 backend is its use of tables to select
optimal shift implementations for different CPU variants.  This patch
borrows (plagiarizes) that idiom for SImode left shifts in the ARC backend
(for CPUs without a barrel-shifter).  This provides a convenient mechanism
for both selecting the best implementation strategy (for speed vs. size),
and providing accurate rtx_costs [without duplicating a lot of logic].
Left shift RTX costs are especially important for use in synth_mult.

An example improvement is:

int foo(int x) { return 32768*x; }

which is now generated with -O2 -mcpu=em -mswap as:

foo:	bmsk_s  r0,r0,16
        swap    r0,r0
        j_s.d   [blink]
        ror     r0,r0

where previously the ARC backend would generate a loop:

foo:	mov     lp_count,15
        lp      2f
        add     r0,r0,r0
        nop
2:      # end single insn loop
        j_s     [blink]

2024-01-09  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	* config/arc/arc.cc (arc_shift_alg): New enumerated type for
	left shift implementation strategies.
	(arc_shift_info): Type for each entry of the shift strategy table.
	(arc_shift_context_idx): Return a integer value for each code
	generation context, used as an index
	(arc_ashl_alg): Table indexed by context and shifted bit count.
	(arc_split_ashl): Use the arc_ashl_alg table to select SImode
	left shift implementation.
	(arc_rtx_costs) <case ASHIFT>: Use the arc_ashl_alg table to
	provide accurate costs, when optimizing for speed or size.

1 files changed, 318 insertions, 32 deletions

diff --git a/gcc/config/arc/arc.cc b/gcc/config/arc/arc.cc
index 6a80442..179f11f 100644
--- a/gcc/config/arc/arc.cc
+++ b/gcc/config/arc/arc.cc
@@ -4222,6 +4222,253 @@ output_shift_loop (enum rtx_code code, rtx *operands)
   return "";
 }
 
+/* See below where shifts are handled for explanation of this enum.  */
+enum arc_shift_alg
+{
+  SHIFT_MOVE,		/* Register-to-register move.  */
+  SHIFT_LOOP,		/* Zero-overhead loop implementation.  */
+  SHIFT_INLINE,		/* Mmultiple LSHIFTs and LSHIFT-PLUSs.  */ 
+  SHIFT_AND_ROT,        /* Bitwise AND, then ROTATERTs.  */
+  SHIFT_SWAP,		/* SWAP then multiple LSHIFTs/LSHIFT-PLUSs.  */
+  SHIFT_AND_SWAP_ROT	/* Bitwise AND, then SWAP, then ROTATERTs.  */
+};
+
+struct arc_shift_info {
+  enum arc_shift_alg alg;
+  unsigned int cost;
+};
+
+/* Return shift algorithm context, an index into the following tables.
+ * 0 for -Os (optimize for size)	3 for -O2 (optimized for speed)
+ * 1 for -Os -mswap TARGET_V2		4 for -O2 -mswap TARGET_V2
+ * 2 for -Os -mswap !TARGET_V2		5 for -O2 -mswap !TARGET_V2  */
+static unsigned int
+arc_shift_context_idx ()
+{
+  if (optimize_function_for_size_p (cfun))
+    {
+      if (!TARGET_SWAP)
+	return 0;
+      if (TARGET_V2)
+	return 1;
+      return 2;
+    }
+  else
+    {
+      if (!TARGET_SWAP)
+	return 3;
+      if (TARGET_V2)
+	return 4;
+      return 5;
+    }
+}
+
+static const arc_shift_info arc_ashl_alg[6][32] = {
+  {  /* 0: -Os.  */
+    { SHIFT_MOVE,         COSTS_N_INSNS (1) },  /*  0 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (1) },  /*  1 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  2 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  3 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  4 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  5 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  6 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  7 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  8 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  9 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 10 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 11 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 12 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 13 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 14 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 15 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 16 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 17 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 18 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 19 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 20 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 21 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 22 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 23 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 24 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 25 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 26 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 27 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 28 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (4) },  /* 29 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (3) },  /* 30 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (2) }   /* 31 */
+  },
+  {  /* 1: -Os -mswap TARGET_V2.  */
+    { SHIFT_MOVE,         COSTS_N_INSNS (1) },  /*  0 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (1) },  /*  1 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  2 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  3 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  4 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  5 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  6 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  7 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  8 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  9 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 10 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 11 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 12 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 13 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (4) },  /* 14 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (3) },  /* 15 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (1) },  /* 16 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (2) },  /* 17 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (3) },  /* 18 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (3) },  /* 19 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 20 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 21 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 22 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 23 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 24 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 25 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 26 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 27 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 28 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (4) },  /* 29 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (3) },  /* 30 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (2) }   /* 31 */
+  },
+  {  /* 2: -Os -mswap !TARGET_V2.  */
+    { SHIFT_MOVE,         COSTS_N_INSNS (1) },  /*  0 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (1) },  /*  1 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  2 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  3 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  4 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  5 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  6 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  7 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  8 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  9 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 10 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 11 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 12 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 13 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (4) },  /* 14 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (3) },  /* 15 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (2) },  /* 16 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (3) },  /* 17 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 18 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 19 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 20 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 21 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 22 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 23 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 24 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 25 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 26 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 27 */
+    { SHIFT_LOOP,         COSTS_N_INSNS (4) },  /* 28 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (4) },  /* 29 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (3) },  /* 30 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (2) }   /* 31 */
+  },
+  {  /* 3: -O2.  */
+    { SHIFT_MOVE,         COSTS_N_INSNS (1) },  /*  0 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (1) },  /*  1 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  2 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  3 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  4 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  5 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  6 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  7 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  8 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  9 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 10 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 11 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 12 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (6) },  /* 13 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (6) },  /* 14 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (6) },  /* 15 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (7) },  /* 16 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (7) },  /* 17 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (7) },  /* 18 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (8) },  /* 19 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (8) },  /* 20 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (8) },  /* 21 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (9) },  /* 22 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (9) },  /* 23 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (9) },  /* 24 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (8) },  /* 25 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (7) },  /* 26 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (6) },  /* 27 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (5) },  /* 28 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (4) },  /* 29 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (3) },  /* 30 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (2) }   /* 31 */
+  },
+  {  /* 4: -O2 -mswap TARGET_V2.  */
+    { SHIFT_MOVE,         COSTS_N_INSNS (1) },  /*  0 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (1) },  /*  1 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  2 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  3 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  4 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  5 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  6 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  7 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  8 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  9 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 10 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 11 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 12 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (5) },  /* 13 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (4) },  /* 14 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (3) },  /* 15 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (1) },  /* 16 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (2) },  /* 17 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (3) },  /* 18 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (3) },  /* 19 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 20 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 21 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 22 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (5) },  /* 23 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (5) },  /* 24 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (5) },  /* 25 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (6) },  /* 26 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (6) },  /* 27 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (5) },  /* 28 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (4) },  /* 29 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (3) },  /* 30 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (2) }   /* 31 */
+  },
+  {  /* 5: -O2 -mswap !TARGET_V2.  */
+    { SHIFT_MOVE,         COSTS_N_INSNS (1) },  /*  0 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (1) },  /*  1 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  2 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (2) },  /*  3 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  4 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  5 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (3) },  /*  6 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  7 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  8 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (4) },  /*  9 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 10 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 11 */
+    { SHIFT_INLINE,       COSTS_N_INSNS (5) },  /* 12 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (5) },  /* 13 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (4) },  /* 14 */
+    { SHIFT_AND_SWAP_ROT, COSTS_N_INSNS (3) },  /* 15 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (2) },  /* 16 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (3) },  /* 17 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 18 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (4) },  /* 19 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (5) },  /* 20 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (5) },  /* 21 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (5) },  /* 22 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (6) },  /* 23 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (6) },  /* 24 */
+    { SHIFT_SWAP,         COSTS_N_INSNS (6) },  /* 25 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (7) },  /* 26 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (6) },  /* 27 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (5) },  /* 28 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (4) },  /* 29 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (3) },  /* 30 */
+    { SHIFT_AND_ROT,      COSTS_N_INSNS (2) }   /* 31 */
+  }
+};
 
 /* Split SImode left shift instruction.  */
 void
@@ -4230,11 +4477,29 @@ arc_split_ashl (rtx *operands)
   if (CONST_INT_P (operands[2]))
     {
       int n = INTVAL (operands[2]) & 0x1f;
-      if (n <= 9)
+      switch (arc_ashl_alg [arc_shift_context_idx ()][n].alg)
 	{
+	case SHIFT_MOVE:
+	  emit_move_insn (operands[0], operands[1]);
+	  return;
+
+	case SHIFT_SWAP:
+	  if (!TARGET_V2)
+	    {
+	      emit_insn (gen_andsi3_i (operands[0], operands[1],
+				       GEN_INT (0xffff)));
+	      emit_insn (gen_rotrsi2_cnt16 (operands[0], operands[0]));
+	    }
+	  else
+	    emit_insn (gen_ashlsi2_cnt16 (operands[0], operands[1]));
+	  n -= 16;
 	  if (n == 0)
-	    emit_move_insn (operands[0], operands[1]);
-	  else if (n <= 2)
+	    return;
+	  operands[1] = operands[0];
+	  /* FALL THRU */
+
+	case SHIFT_INLINE:
+	  if (n <= 2)
 	    {
 	      emit_insn (gen_ashlsi3_cnt1 (operands[0], operands[1]));
 	      if (n == 2)
@@ -4256,37 +4521,27 @@ arc_split_ashl (rtx *operands)
 		emit_insn (gen_ashlsi3_cnt1 (operands[0], operands[0]));
 	    }
 	  return;
-	}
-      else if (n >= 16 && n <= 22 && TARGET_SWAP && TARGET_V2)
-	{
-	  emit_insn (gen_ashlsi2_cnt16 (operands[0], operands[1]));
-	  if (n > 16)
-	    {
-	      operands[1] = operands[0];
-	      operands[2] = GEN_INT (n - 16);
-	      arc_split_ashl (operands);
-	    }
+
+	case SHIFT_AND_ROT:
+	  emit_insn (gen_andsi3_i (operands[0], operands[1],
+				   GEN_INT ((1 << (32 - n)) - 1)));
+	  for (; n < 32; n++)
+	    emit_insn (gen_rotrsi3_cnt1 (operands[0], operands[0]));
 	  return;
-	}
-      else if (n >= 29)
-	{
-	  if (n < 31)
-	    {
-	      if (n == 29)
-		{
-		  emit_insn (gen_andsi3_i (operands[0], operands[1],
-					   GEN_INT (7)));
-		  emit_insn (gen_rotrsi3_cnt1 (operands[0], operands[0]));
-		}
-	      else
-		emit_insn (gen_andsi3_i (operands[0], operands[1],
-					 GEN_INT (3)));
-	      emit_insn (gen_rotrsi3_cnt1 (operands[0], operands[0]));
-	    }
-	  else
-	    emit_insn (gen_andsi3_i (operands[0], operands[1], const1_rtx));
-	  emit_insn (gen_rotrsi3_cnt1 (operands[0], operands[0]));
+
+	case SHIFT_AND_SWAP_ROT:
+	  emit_insn (gen_andsi3_i (operands[0], operands[1],
+				   GEN_INT ((1 << (32 - n)) - 1)));
+	  emit_insn (gen_rotrsi2_cnt16 (operands[0], operands[0]));
+	  for (; n < 16; n++)
+	    emit_insn (gen_rotrsi3_cnt1 (operands[0], operands[0]));
 	  return;
+
+	case SHIFT_LOOP:
+	  break;
+
+	default:
+	  gcc_unreachable ();
 	}
     }
 
@@ -5568,6 +5823,37 @@ arc_rtx_costs (rtx x, machine_mode mode, int outer_code,
        If we need more than 12 insns to do a multiply, then go out-of-line,
        since the call overhead will be < 10% of the cost of the multiply.  */
     case ASHIFT:
+      if (mode == DImode)
+	{
+	  if (XEXP (x, 1) == const1_rtx)
+	    {
+	      *total += rtx_cost (XEXP (x, 0), mode, ASHIFT, 0, speed)
+			+ COSTS_N_INSNS (2);
+	      return true;
+	    }
+	  return false;
+	}
+      if (TARGET_BARREL_SHIFTER)
+	{
+	  *total = COSTS_N_INSNS (1);
+	  if (CONST_INT_P (XEXP (x, 1)))
+	    {
+	      *total += rtx_cost (XEXP (x, 0), mode, ASHIFT, 0, speed);
+	      return true;
+	    }
+	}
+      else if (CONST_INT_P (XEXP (x, 1)))
+	{
+	  unsigned int n = INTVAL (XEXP (x, 1)) & 0x1f;
+	  *total = arc_ashl_alg[arc_shift_context_idx ()][n].cost
+		   + rtx_cost (XEXP (x, 0), mode, ASHIFT, 0, speed);
+	  return true;
+	}
+      else
+	/* Variable shift loop takes 2 * n + 2 cycles.  */
+	*total = speed ? COSTS_N_INSNS (64) : COSTS_N_INSNS (4);
+      return false;
+
     case ASHIFTRT:
     case LSHIFTRT:
     case ROTATE: