[PATCH] i386: Update SSE <-> integer move costs

[PATCH] i386: Update SSE <-> integer move costs

[H.J. Lu]

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Since inline_secondary_memory_needed has

  /* ??? This is a lie.  We do have moves between mmx/general, and for
     mmx/sse2.  But by saying we need secondary memory we discourage the
     register allocator from using the mmx registers unless needed.  */
  if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2))
    return true;

moves between MMX and non-MMX units require secondary memory.   There
is no need to check moves between MMX and integer units.

struct processor_costs has:

  const int mmxsse_to_integer;  /* cost of moving mmxsse register to
                                   integer.  */
  const int ssemmx_to_integer;  /* cost of moving integer to mmxsse register. */

This patch also renames mmxsse_to_integer to sse_to_integer and
ssemmx_to_integer to integer_to_sse.

Tested on Linux/x86-64.

OK for trunk?

Thanks.

PR target/90877
* config/i386/i386-features.c
(dimode_scalar_chain::compute_convert_gain): Replace
mmxsse_to_integer with sse_to_integer.
* config/i386/i386.c (ix86_register_move_cost): Verify that
moves between MMX and non-MMX units require secondary memory.
Correct costs of moves between SSE and integer units.
* config/i386/i386.h (processor_costs): Rename cost of moving
SSE register to integer to sse_to_integer.  Rename cost of
moving integer register to SSE to integer_to_sse.


-- 
H.J.

[-- Attachment #2: 0001-i386-Update-SSE-integer-move-costs.patch --]
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From c29a79197696bcd95714e22954e00935b683c209 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 13 Jun 2019 14:12:25 -0700
Subject: [PATCH] i386: Update SSE <-> integer move costs

Since inline_secondary_memory_needed has

  /* ??? This is a lie.  We do have moves between mmx/general, and for
     mmx/sse2.  But by saying we need secondary memory we discourage the
     register allocator from using the mmx registers unless needed.  */
  if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2))
    return true;

moves between MMX and non-MMX units require secondary memory.   There
is no need to check moves between MMX and integer units.

struct processor_costs has:

  const int mmxsse_to_integer;  /* cost of moving mmxsse register to
                                   integer.  */
  const int ssemmx_to_integer;  /* cost of moving integer to mmxsse register. */

This patch also renames mmxsse_to_integer to sse_to_integer and
ssemmx_to_integer to integer_to_sse.

Tested on Linux/x86-64.

	PR target/90877
	* config/i386/i386-features.c
	(dimode_scalar_chain::compute_convert_gain): Replace
	mmxsse_to_integer with sse_to_integer.
	* config/i386/i386.c (ix86_register_move_cost): Verify that
	moves between MMX and non-MMX units require secondary memory.
	Correct costs of moves between SSE and integer units.
	* config/i386/i386.h (processor_costs): Rename cost of moving
	SSE register to integer to sse_to_integer.  Rename cost of
	moving integer register to SSE to integer_to_sse.
---
 gcc/config/i386/i386-features.c |  2 +-
 gcc/config/i386/i386.c          | 17 ++++++++++-------
 gcc/config/i386/i386.h          |  5 ++---
 3 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/gcc/config/i386/i386-features.c b/gcc/config/i386/i386-features.c
index 51f88ae4d8a..2eac8f715bb 100644
--- a/gcc/config/i386/i386-features.c
+++ b/gcc/config/i386/i386-features.c
@@ -554,7 +554,7 @@ dimode_scalar_chain::compute_convert_gain ()
     fprintf (dump_file, "  Instruction conversion gain: %d\n", gain);
 
   EXECUTE_IF_SET_IN_BITMAP (defs_conv, 0, insn_uid, bi)
-    cost += DF_REG_DEF_COUNT (insn_uid) * ix86_cost->mmxsse_to_integer;
+    cost += DF_REG_DEF_COUNT (insn_uid) * ix86_cost->sse_to_integer;
 
   if (dump_file)
     fprintf (dump_file, "  Registers conversion cost: %d\n", cost);
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 2eddea56b2e..941e208bcf0 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -18633,18 +18633,21 @@ ix86_register_move_cost (machine_mode mode, reg_class_t class1_i,
       return cost;
     }
 
-  /* Moves between SSE/MMX and integer unit are expensive.  */
-  if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2)
-      || SSE_CLASS_P (class1) != SSE_CLASS_P (class2))
+  /* Moves between MMX and non-MMX units require secondary memory.  */
+  if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2))
+    gcc_unreachable ();
+
+  /* Moves between SSE and integer units are expensive.  */
+  if (SSE_CLASS_P (class1) != SSE_CLASS_P (class2))
 
     /* ??? By keeping returned value relatively high, we limit the number
-       of moves between integer and MMX/SSE registers for all targets.
+       of moves between integer and SSE registers for all targets.
        Additionally, high value prevents problem with x86_modes_tieable_p(),
-       where integer modes in MMX/SSE registers are not tieable
+       where integer modes in SSE registers are not tieable
        because of missing QImode and HImode moves to, from or between
        MMX/SSE registers.  */
-    return MAX (8, MMX_CLASS_P (class1) || MMX_CLASS_P (class2)
-		? ix86_cost->mmxsse_to_integer : ix86_cost->ssemmx_to_integer);
+    return MAX (8, SSE_CLASS_P (class1)
+		? ix86_cost->sse_to_integer : ix86_cost->integer_to_sse);
 
   if (MAYBE_FLOAT_CLASS_P (class1))
     return ix86_cost->fp_move;
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index 01213ccb82c..0ac5d651823 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -276,9 +276,8 @@ struct processor_costs {
   const int sse_store[5];	/* cost of storing SSE register
 				   in SImode, DImode and TImode.  */
   const int sse_unaligned_store[5];/* cost of unaligned store.  */
-  const int mmxsse_to_integer;	/* cost of moving mmxsse register to
-				   integer.  */
-  const int ssemmx_to_integer;  /* cost of moving integer to mmxsse register. */
+  const int sse_to_integer;	/* cost of moving SSE register to integer.  */
+  const int integer_to_sse;	/* cost of moving integer register to SSE. */
   const int gather_static, gather_per_elt; /* Cost of gather load is computed
 				   as static + per_item * nelts. */
   const int scatter_static, scatter_per_elt; /* Cost of gather store is
-- 
2.20.1

Re: [PATCH] i386: Update SSE <-> integer move costs

[Uros Bizjak]

On Fri, Jun 14, 2019 at 5:19 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> Since inline_secondary_memory_needed has
>
>   /* ??? This is a lie.  We do have moves between mmx/general, and for
>      mmx/sse2.  But by saying we need secondary memory we discourage the
>      register allocator from using the mmx registers unless needed.  */
>   if (MMX_CLASS_P (class1) != MMX_CLASS_P (class2))
>     return true;
>
> moves between MMX and non-MMX units require secondary memory.   There
> is no need to check moves between MMX and integer units.
>
> struct processor_costs has:
>
>   const int mmxsse_to_integer;  /* cost of moving mmxsse register to
>                                    integer.  */
>   const int ssemmx_to_integer;  /* cost of moving integer to mmxsse register. */
>
> This patch also renames mmxsse_to_integer to sse_to_integer and
> ssemmx_to_integer to integer_to_sse.
>
> Tested on Linux/x86-64.
>
> OK for trunk?
>
> Thanks.
>
> PR target/90877
> * config/i386/i386-features.c
> (dimode_scalar_chain::compute_convert_gain): Replace
> mmxsse_to_integer with sse_to_integer.
> * config/i386/i386.c (ix86_register_move_cost): Verify that
> moves between MMX and non-MMX units require secondary memory.
> Correct costs of moves between SSE and integer units.
> * config/i386/i386.h (processor_costs): Rename cost of moving
> SSE register to integer to sse_to_integer.  Rename cost of
> moving integer register to SSE to integer_to_sse.

OK.

Thanks,
Uros.