Patchwork [AArch64,costs,1/18] Refactor aarch64_address_costs.

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Submitter James Greenhalgh
Date March 27, 2014, 5:33 p.m.
Message ID <1395941622-22926-2-git-send-email-james.greenhalgh@arm.com>
Download mbox | patch
Permalink /patch/334422/
State New
Headers show

Comments

James Greenhalgh - March 27, 2014, 5:33 p.m.
Hi,

The address cost function, as it stands, is fairly limited.

Rather than write a lot of new walking code, we would instead
like to reuse some of the existing infrastructure which can
categorize an address.

This patch therefore rewires aarch64_address_costs to use
aarch64_classify_address, which drastically simplifies the
function.

We can also take advantage of the higher level of detail
returned by address classification, allowing us to cost "fast"
and "slow" register shifts differently.

Tested in series on aarch64-none-elf with no regressions.

OK for stage 1?

Thanks,
James

---
gcc/

2014-03-27  James Greenhalgh  <james.greenhalgh@arm.com>

	* config/aarch64/aarch64-protos.h (scale_addr_mode_cost): New.
	(cpu_addrcost_table): Use it.
	* config/aarch64/aarch64.c (generic_addrcost_table): Initialize it.
	(aarch64_address_cost): Rewrite using aarch64_classify_address,
	move it.

Patch

diff --git a/gcc/config/aarch64/aarch64-protos.h b/gcc/config/aarch64/aarch64-protos.h
index 5542f02..cdea6a4 100644
--- a/gcc/config/aarch64/aarch64-protos.h
+++ b/gcc/config/aarch64/aarch64-protos.h
@@ -108,9 +108,22 @@  enum aarch64_symbol_type
    cost models and vectors for address cost calculations, register
    move costs and memory move costs.  */
 
+/* Scaled addressing modes can vary cost depending on the mode of the
+   value to be loaded/stored.  QImode values cannot use scaled
+   addressing modes.  */
+
+struct scale_addr_mode_cost
+{
+  const int hi;
+  const int si;
+  const int di;
+  const int ti;
+};
+
 /* Additional cost for addresses.  */
 struct cpu_addrcost_table
 {
+  const struct scale_addr_mode_cost addr_scale_costs;
   const int pre_modify;
   const int post_modify;
   const int register_offset;
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 3c06d92..2a2e2e9 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -171,11 +171,20 @@  __extension__
 #endif
 static const struct cpu_addrcost_table generic_addrcost_table =
 {
+#if HAVE_DESIGNATED_INITIALIZERS
+  .addr_scale_costs =
+#endif
+    {
+      NAMED_PARAM (qi, 0),
+      NAMED_PARAM (hi, 0),
+      NAMED_PARAM (si, 0),
+      NAMED_PARAM (ti, 0),
+    },
   NAMED_PARAM (pre_modify, 0),
   NAMED_PARAM (post_modify, 0),
   NAMED_PARAM (register_offset, 0),
   NAMED_PARAM (register_extend, 0),
-  NAMED_PARAM (imm_offset, 0)
+  NAMED_PARAM (imm_offset, 0),
 };
 
 #if HAVE_DESIGNATED_INITIALIZERS && GCC_VERSION >= 2007
@@ -4515,6 +4524,101 @@  aarch64_strip_shift_or_extend (rtx x)
   return aarch64_strip_shift (x);
 }
 
+static int
+aarch64_address_cost (rtx x,
+		      enum machine_mode mode,
+		      addr_space_t as ATTRIBUTE_UNUSED,
+		      bool speed)
+{
+  enum rtx_code c = GET_CODE (x);
+  const struct cpu_addrcost_table *addr_cost = aarch64_tune_params->addr_cost;
+  struct aarch64_address_info info;
+  int cost = 0;
+  info.shift = 0;
+
+  if (!aarch64_classify_address (&info, x, mode, c, false))
+    {
+      if (GET_CODE (x) == CONST || GET_CODE (x) == SYMBOL_REF)
+	{
+	  /* This is a CONST or SYMBOL ref which will be split
+	     in a different way depending on the code model in use.
+	     Cost it through the generic infrastructure.  */
+	  int cost_symbol_ref = rtx_cost (x, MEM, 1, speed);
+	  /* Divide through by the cost of one instruction to
+	     bring it to the same units as the address costs.  */
+	  cost_symbol_ref /= COSTS_N_INSNS (1);
+	  /* The cost is then the cost of preparing the address,
+	     followed by an immediate (possibly 0) offset.  */
+	  return cost_symbol_ref + addr_cost->imm_offset;
+	}
+      else
+	{
+	  /* This is most likely a jump table from a case
+	     statement.  */
+	  return addr_cost->register_offset;
+	}
+    }
+
+  switch (info.type)
+    {
+      case ADDRESS_LO_SUM:
+      case ADDRESS_SYMBOLIC:
+      case ADDRESS_REG_IMM:
+	cost += addr_cost->imm_offset;
+	break;
+
+      case ADDRESS_REG_WB:
+	if (c == PRE_INC || c == PRE_DEC || c == PRE_MODIFY)
+	  cost += addr_cost->pre_modify;
+	else if (c == POST_INC || c == POST_DEC || c == POST_MODIFY)
+	  cost += addr_cost->post_modify;
+	else
+	  gcc_unreachable ();
+
+	break;
+
+      case ADDRESS_REG_REG:
+	cost += addr_cost->register_offset;
+	break;
+
+      case ADDRESS_REG_UXTW:
+      case ADDRESS_REG_SXTW:
+	cost += addr_cost->register_extend;
+	break;
+
+      default:
+	gcc_unreachable ();
+    }
+
+
+  if (info.shift > 0)
+    {
+      /* For the sake of calculating the cost of the shifted register
+	 component, we can treat same sized modes in the same way.  */
+      switch (GET_MODE_BITSIZE (mode))
+	{
+	  case 16:
+	    cost += addr_cost->addr_scale_costs.hi;
+	    break;
+
+	  case 32:
+	    cost += addr_cost->addr_scale_costs.si;
+	    break;
+
+	  case 64:
+	    cost += addr_cost->addr_scale_costs.di;
+	    break;
+
+	  /* We can't tell, or this is a 128-bit vector.  */
+	  default:
+	    cost += addr_cost->addr_scale_costs.ti;
+	    break;
+	}
+    }
+
+  return cost;
+}
+
 /* Calculate the cost of calculating X, storing it in *COST.  Result
    is true if the total cost of the operation has now been calculated.  */
 static bool
@@ -4834,37 +4938,6 @@  aarch64_rtx_costs (rtx x, int code, int outer ATTRIBUTE_UNUSED,
 }
 
 static int
-aarch64_address_cost (rtx x ATTRIBUTE_UNUSED,
-		  enum machine_mode mode ATTRIBUTE_UNUSED,
-		  addr_space_t as ATTRIBUTE_UNUSED, bool speed ATTRIBUTE_UNUSED)
-{
-  enum rtx_code c  = GET_CODE (x);
-  const struct cpu_addrcost_table *addr_cost = aarch64_tune_params->addr_cost;
-
-  if (c == PRE_INC || c == PRE_DEC || c == PRE_MODIFY)
-    return addr_cost->pre_modify;
-
-  if (c == POST_INC || c == POST_DEC || c == POST_MODIFY)
-    return addr_cost->post_modify;
-
-  if (c == PLUS)
-    {
-      if (GET_CODE (XEXP (x, 1)) == CONST_INT)
-	return addr_cost->imm_offset;
-      else if (GET_CODE (XEXP (x, 0)) == MULT
-	       || GET_CODE (XEXP (x, 0)) == ZERO_EXTEND
-	       || GET_CODE (XEXP (x, 0)) == SIGN_EXTEND)
-	return addr_cost->register_extend;
-
-      return addr_cost->register_offset;
-    }
-  else if (c == MEM || c == LABEL_REF || c == SYMBOL_REF)
-    return addr_cost->imm_offset;
-
-  return 0;
-}
-
-static int
 aarch64_register_move_cost (enum machine_mode mode ATTRIBUTE_UNUSED,
 			    reg_class_t from, reg_class_t to)
 {