Re: [PATCH] Prefer mempcpy to memcpy on x86_64 target (PR middle-end/81657).

["Martin Liška" <mliska@suse.cz>]

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Hi.

I'm sending updated version of the patch.

Patch can bootstrap on ppc64le-redhat-linux and x86_64-linux and survives regression tests.

Martin

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From 6d19b1bf0c28a683e1458e16943e34bb547d36d6 Mon Sep 17 00:00:00 2001
From: marxin <mliska@suse.cz>
Date: Wed, 14 Mar 2018 09:44:18 +0100
Subject: [PATCH] Introduce new libc_func_speed target hook (PR
 middle-end/81657).

gcc/ChangeLog:

2018-03-14  Martin Liska  <mliska@suse.cz>

	PR middle-end/81657
	* builtins.c (expand_builtin_memory_copy_args): Handle situation
	when libc library provides a fast mempcpy implementation/
	* config/linux-protos.h (ix86_linux_libc_func_speed): New.
	(TARGET_LIBC_FUNC_SPEED): Likewise.
	* config/i386/linux64.h (SUBTARGET_LIBC_FUNC_SPEED): Define
	macro.
	* config/i386/linux.h (SUBTARGET_LIBC_FUNC_SPEED): Likewise.
	* config/i386/t-linux: Add x86-linux.o.
	* config.gcc: Likewise.
	* config/i386/x86-linux.c: New file.
	* coretypes.h (enum libc_speed): Likewise.
	* doc/tm.texi: Document new target hook.
	* doc/tm.texi.in: Likewise.
	* expr.c (emit_block_move_hints): Handle libc bail out argument.
	* expr.h (emit_block_move_hints): Add new parameters.
	* target.def: Add new hook.
	* targhooks.c (enum libc_speed): New enum.
	(default_libc_func_speed): Provide a default hook
	implementation.
	* targhooks.h (default_libc_func_speed): Likewise.

gcc/testsuite/ChangeLog:

2018-03-28  Martin Liska  <mliska@suse.cz>

	* gcc.dg/string-opt-1.c:

gcc/testsuite/ChangeLog:

2018-03-14  Martin Liska  <mliska@suse.cz>

	* gcc.dg/string-opt-1.c: Adjust scans for i386 and glibc target
	and others.
---
 gcc/builtins.c                      | 15 ++++++++++-
 gcc/config.gcc                      |  1 +
 gcc/config/i386/i386.c              |  5 ++++
 gcc/config/i386/linux.h             |  2 ++
 gcc/config/i386/linux64.h           |  2 ++
 gcc/config/i386/t-linux             |  6 +++++
 gcc/config/i386/x86-linux.c         | 54 +++++++++++++++++++++++++++++++++++++
 gcc/config/linux-protos.h           |  1 +
 gcc/coretypes.h                     |  7 +++++
 gcc/doc/tm.texi                     |  4 +++
 gcc/doc/tm.texi.in                  |  1 +
 gcc/expr.c                          | 11 +++++++-
 gcc/expr.h                          |  3 ++-
 gcc/target.def                      |  7 +++++
 gcc/targhooks.c                     |  9 +++++++
 gcc/targhooks.h                     |  1 +
 gcc/testsuite/gcc.dg/string-opt-1.c |  5 ++--
 17 files changed, 129 insertions(+), 5 deletions(-)
 create mode 100644 gcc/config/i386/x86-linux.c

diff --git a/gcc/builtins.c b/gcc/builtins.c
index 487d9d58db2..98ee3fb272d 100644
--- a/gcc/builtins.c
+++ b/gcc/builtins.c
@@ -3651,13 +3651,26 @@ expand_builtin_memory_copy_args (tree dest, tree src, tree len,
   src_mem = get_memory_rtx (src, len);
   set_mem_align (src_mem, src_align);
 
+  /* emit_block_move_hints can generate a library call to memcpy function.
+     In situations when a libc library provides fast implementation
+     of mempcpy, then it's better to call mempcpy directly.  */
+  bool avoid_libcall
+    = (endp == 1
+       && targetm.libc_func_speed ((int)BUILT_IN_MEMPCPY) == LIBC_FAST_SPEED
+       && target != const0_rtx);
+
   /* Copy word part most expediently.  */
+  bool libcall_avoided = false;
   dest_addr = emit_block_move_hints (dest_mem, src_mem, len_rtx,
 				     CALL_EXPR_TAILCALL (exp)
 				     && (endp == 0 || target == const0_rtx)
 				     ? BLOCK_OP_TAILCALL : BLOCK_OP_NORMAL,
 				     expected_align, expected_size,
-				     min_size, max_size, probable_max_size);
+				     min_size, max_size, probable_max_size,
+				     avoid_libcall ? &libcall_avoided : NULL);
+
+  if (libcall_avoided)
+    return NULL_RTX;
 
   if (dest_addr == 0)
     {
diff --git a/gcc/config.gcc b/gcc/config.gcc
index 1b58c060a92..6445ff569b3 100644
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -1607,6 +1607,7 @@ x86_64-*-linux* | x86_64-*-kfreebsd*-gnu)
 	x86_64-*-linux*)
 		tm_file="${tm_file} linux.h linux-android.h i386/linux-common.h i386/linux64.h"
 		extra_options="${extra_options} linux-android.opt"
+		extra_objs="${extra_objs} x86-linux.o"
 	  	;;
 	x86_64-*-kfreebsd*-gnu)
 		tm_file="${tm_file} kfreebsd-gnu.h i386/kfreebsd-gnu64.h"
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index b4f6aec1434..2471ff7b99a 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -52105,6 +52105,11 @@ ix86_run_selftests (void)
 #undef TARGET_WARN_PARAMETER_PASSING_ABI
 #define TARGET_WARN_PARAMETER_PASSING_ABI ix86_warn_parameter_passing_abi
 
+#ifdef SUBTARGET_LIBC_FUNC_SPEED
+#undef TARGET_LIBC_FUNC_SPEED
+#define TARGET_LIBC_FUNC_SPEED SUBTARGET_LIBC_FUNC_SPEED
+#endif
+
 #if CHECKING_P
 #undef TARGET_RUN_TARGET_SELFTESTS
 #define TARGET_RUN_TARGET_SELFTESTS selftest::ix86_run_selftests
diff --git a/gcc/config/i386/linux.h b/gcc/config/i386/linux.h
index 69f97f15b0d..6c59cbd6d62 100644
--- a/gcc/config/i386/linux.h
+++ b/gcc/config/i386/linux.h
@@ -24,3 +24,5 @@ along with GCC; see the file COPYING3.  If not see
 
 #undef MUSL_DYNAMIC_LINKER
 #define MUSL_DYNAMIC_LINKER "/lib/ld-musl-i386.so.1"
+
+#define SUBTARGET_LIBC_FUNC_SPEED ix86_linux_libc_func_speed
diff --git a/gcc/config/i386/linux64.h b/gcc/config/i386/linux64.h
index f2d913e30ac..d855f5cc239 100644
--- a/gcc/config/i386/linux64.h
+++ b/gcc/config/i386/linux64.h
@@ -37,3 +37,5 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define MUSL_DYNAMIC_LINKER64 "/lib/ld-musl-x86_64.so.1"
 #undef MUSL_DYNAMIC_LINKERX32
 #define MUSL_DYNAMIC_LINKERX32 "/lib/ld-musl-x32.so.1"
+
+#define SUBTARGET_LIBC_FUNC_SPEED ix86_linux_libc_func_speed
diff --git a/gcc/config/i386/t-linux b/gcc/config/i386/t-linux
index 155314c08a7..6e3ebe94fe8 100644
--- a/gcc/config/i386/t-linux
+++ b/gcc/config/i386/t-linux
@@ -1 +1,7 @@
 MULTIARCH_DIRNAME = $(call if_multiarch,i386-linux-gnu)
+
+x86-linux.o: $(srcdir)/config/i386/x86-linux.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
+  $(TM_H) $(RTL_H) $(REGS_H) hard-reg-set.h output.h $(TREE_H) flags.h \
+  $(TM_P_H) $(HASHTAB_H) $(GGC_H)
+	$(COMPILER) -c $(ALL_COMPILERFLAGS) $(ALL_CPPFLAGS) $(INCLUDES) \
+	$(srcdir)/config/i386/x86-linux.c
diff --git a/gcc/config/i386/x86-linux.c b/gcc/config/i386/x86-linux.c
new file mode 100644
index 00000000000..71291d18a71
--- /dev/null
+++ b/gcc/config/i386/x86-linux.c
@@ -0,0 +1,54 @@
+/* Implementation for linux-specific functions for i386 and x86-64 systems.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   Contributed by Martin Liska <mliska@suse.cz>.
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+Under Section 7 of GPL version 3, you are granted additional
+permissions described in the GCC Runtime Library Exception, version
+3.1, as published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License and
+a copy of the GCC Runtime Library Exception along with this program;
+see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+<http://www.gnu.org/licenses/>.  */
+
+#define IN_TARGET_CODE 1
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "cp/cp-tree.h" /* This is why we're a separate module.  */
+#include "stringpool.h"
+#include "attribs.h"
+
+/* This hook determines whether a function from libc has a fast implementation
+   FN is present at the runtime.  We override it for i386 and glibc C library
+   as this combination provides fast implementation of mempcpy function.  */
+
+enum libc_speed
+ix86_linux_libc_func_speed (int fn)
+{
+  enum built_in_function f = (built_in_function)fn;
+
+  if (!OPTION_GLIBC)
+    return LIBC_UNKNOWN_SPEED;
+
+  switch (f)
+    {
+      case BUILT_IN_MEMPCPY:
+	return LIBC_FAST_SPEED;
+      default:
+	return LIBC_UNKNOWN_SPEED;
+    }
+}
diff --git a/gcc/config/linux-protos.h b/gcc/config/linux-protos.h
index 9da8dd7ecaa..b7284735366 100644
--- a/gcc/config/linux-protos.h
+++ b/gcc/config/linux-protos.h
@@ -20,3 +20,4 @@ along with GCC; see the file COPYING3.  If not see
 extern bool linux_has_ifunc_p (void);
 
 extern bool linux_libc_has_function (enum function_class fn_class);
+extern enum libc_speed ix86_linux_libc_func_speed (int fn);
diff --git a/gcc/coretypes.h b/gcc/coretypes.h
index 283b4eb33fe..fe618f708f4 100644
--- a/gcc/coretypes.h
+++ b/gcc/coretypes.h
@@ -384,6 +384,13 @@ enum excess_precision_type
   EXCESS_PRECISION_TYPE_FAST
 };
 
+enum libc_speed
+{
+  LIBC_FAST_SPEED,
+  LIBC_SLOW_SPEED,
+  LIBC_UNKNOWN_SPEED
+};
+
 /* Support for user-provided GGC and PCH markers.  The first parameter
    is a pointer to a pointer, the second a cookie.  */
 typedef void (*gt_pointer_operator) (void *, void *);
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index bd8b917ba82..0f7c91a22c4 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -5501,6 +5501,10 @@ macro, a reasonable default is used.
 This hook determines whether a function from a class of functions
 @var{fn_class} is present at the runtime.
 @end deftypefn
+@deftypefn {Target Hook} libc_speed TARGET_LIBC_FUNC_SPEED (int @var{fn})
+This hook determines whether a function from libc has a fast implementation
+@var{fn} is present at the runtime.
+@end deftypefn
 
 @defmac NEXT_OBJC_RUNTIME
 Set this macro to 1 to use the "NeXT" Objective-C message sending conventions
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index b0207146e8c..4bb2998a8a1 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -3933,6 +3933,7 @@ macro, a reasonable default is used.
 @end defmac
 
 @hook TARGET_LIBC_HAS_FUNCTION
+@hook TARGET_LIBC_FUNC_SPEED
 
 @defmac NEXT_OBJC_RUNTIME
 Set this macro to 1 to use the "NeXT" Objective-C message sending conventions
diff --git a/gcc/expr.c b/gcc/expr.c
index 00660293f72..f3bd698bc4d 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -1554,6 +1554,8 @@ compare_by_pieces (rtx arg0, rtx arg1, unsigned HOST_WIDE_INT len,
    MIN_SIZE is the minimal size of block to move
    MAX_SIZE is the maximal size of block to move, if it can not be represented
    in unsigned HOST_WIDE_INT, than it is mask of all ones.
+   If BAIL_OUT_LIBCALL is non-null, do not emit library call and assign
+   true to the pointer when move is not done.
 
    Return the address of the new block, if memcpy is called and returns it,
    0 otherwise.  */
@@ -1563,7 +1565,8 @@ emit_block_move_hints (rtx x, rtx y, rtx size, enum block_op_methods method,
 		       unsigned int expected_align, HOST_WIDE_INT expected_size,
 		       unsigned HOST_WIDE_INT min_size,
 		       unsigned HOST_WIDE_INT max_size,
-		       unsigned HOST_WIDE_INT probable_max_size)
+		       unsigned HOST_WIDE_INT probable_max_size,
+		       bool *bail_out_libcall)
 {
   bool may_use_call;
   rtx retval = 0;
@@ -1625,6 +1628,12 @@ emit_block_move_hints (rtx x, rtx y, rtx size, enum block_op_methods method,
 	   && ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (x))
 	   && ADDR_SPACE_GENERIC_P (MEM_ADDR_SPACE (y)))
     {
+      if (bail_out_libcall)
+	{
+	  *bail_out_libcall = true;
+	  return retval;
+	}
+
       /* Since x and y are passed to a libcall, mark the corresponding
 	 tree EXPR as addressable.  */
       tree y_expr = MEM_EXPR (y);
diff --git a/gcc/expr.h b/gcc/expr.h
index b3d523bcb24..c2bf87fd14e 100644
--- a/gcc/expr.h
+++ b/gcc/expr.h
@@ -110,7 +110,8 @@ extern rtx emit_block_move_hints (rtx, rtx, rtx, enum block_op_methods,
 			          unsigned int, HOST_WIDE_INT,
 				  unsigned HOST_WIDE_INT,
 				  unsigned HOST_WIDE_INT,
-				  unsigned HOST_WIDE_INT);
+				  unsigned HOST_WIDE_INT,
+				  bool *bail_out_libcall = NULL);
 extern rtx emit_block_cmp_hints (rtx, rtx, rtx, tree, rtx, bool,
 				 by_pieces_constfn, void *);
 extern bool emit_storent_insn (rtx to, rtx from);
diff --git a/gcc/target.def b/gcc/target.def
index c5b2a1e7e71..3bbddc82776 100644
--- a/gcc/target.def
+++ b/gcc/target.def
@@ -2639,6 +2639,13 @@ DEFHOOK
  bool, (enum function_class fn_class),
  default_libc_has_function)
 
+DEFHOOK
+(libc_func_speed,
+ "This hook determines whether a function from libc has a fast implementation\n\
+@var{fn} is present at the runtime.",
+ libc_speed, (int fn),
+ default_libc_func_speed)
+
 /* True if new jumps cannot be created, to replace existing ones or
    not, at the current point in the compilation.  */
 DEFHOOK
diff --git a/gcc/targhooks.c b/gcc/targhooks.c
index fafcc6c5196..6e44f6f79cf 100644
--- a/gcc/targhooks.c
+++ b/gcc/targhooks.c
@@ -1642,6 +1642,15 @@ no_c99_libc_has_function (enum function_class fn_class ATTRIBUTE_UNUSED)
   return false;
 }
 
+/* This hook determines whether a function from libc has a fast implementation
+   FN is present at the runtime.  */
+
+enum libc_speed
+default_libc_func_speed (int)
+{
+  return LIBC_UNKNOWN_SPEED;
+}
+
 tree
 default_builtin_tm_load_store (tree ARG_UNUSED (type))
 {
diff --git a/gcc/targhooks.h b/gcc/targhooks.h
index 8a4393f2ba4..7508673ad0a 100644
--- a/gcc/targhooks.h
+++ b/gcc/targhooks.h
@@ -205,6 +205,7 @@ extern bool default_have_conditional_execution (void);
 extern bool default_libc_has_function (enum function_class);
 extern bool no_c99_libc_has_function (enum function_class);
 extern bool gnu_libc_has_function (enum function_class);
+extern enum libc_speed default_libc_func_speed (int);
 
 extern tree default_builtin_tm_load_store (tree);
 
diff --git a/gcc/testsuite/gcc.dg/string-opt-1.c b/gcc/testsuite/gcc.dg/string-opt-1.c
index 2f060732bf0..7faaadcbb1f 100644
--- a/gcc/testsuite/gcc.dg/string-opt-1.c
+++ b/gcc/testsuite/gcc.dg/string-opt-1.c
@@ -48,5 +48,6 @@ main (void)
   return 0;
 }
 
-/* { dg-final { scan-assembler-not "\<mempcpy\>" } } */
-/* { dg-final { scan-assembler "memcpy" } } */
+/* { dg-final { scan-assembler-not "\<mempcpy\>" { target { ! { i?86-*-gnu* x86_64-*-gnu* i?86-*-linux* x86_64-*-linux* } } } } } */
+/* { dg-final { scan-assembler "memcpy" { target  { ! { i?86-*-gnu* x86_64-*-gnu* i?86-*-linux* x86_64-*-linux* } } } } } */
+/* { dg-final { scan-assembler "mempcpy" { target  { i?86-*-gnu* x86_64-*-gnu* i?86-*-linux* x86_64-*-linux* } } } } */
-- 
2.16.3