diff mbox series

[v3,13/14] MIPS: Improve inlined memcpy

Message ID 20260717125453.74473-14-eldar.osmanovic@htecgroup.com
State New
Headers
Series Mips target improvements |

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Commit Message

Eldar Osmanovic July 17, 2026, 12:56 p.m. UTC 
  From: Matthew Fortune <matthew.fortune@imgtec.com>

Add -mblockmov-limit to control which constant-sized block moves are
eligible for inline expansion. Use straight-line code for larger
word-aligned copies when optimizing for speed, avoiding loop overhead.

gcc/ChangeLog:

	* config/mips/mips-protos.h (mips_expand_block_move): Add alignment
	argument.
	* config/mips/mips.cc (mips_expand_block_move): Add support to
	control size of inlined memcpy. A memcpy strictly less than the
	limit determined with an option -mblockmov-limit will be
	considered for inlining. Improve aligned straight line memcpy.
	* config/mips/mips.h (MIPS_MAX_MOVE_MEM_STRAIGHT): Define macro.
	* config/mips/mips.md (cpymemsi): Pass the alignment to
	mips_expand_block_move.
	* config/mips/mips.opt (mblockmov-limit): New option.

gcc/testsuite/ChangeLog:

	* gcc.target/mips/inline-memcpy-limit.c: New test.
	* gcc.target/mips/inline-memcpy-straight.c: New test.
	* gcc.target/mips/align-1-o32.c:
	* gcc.target/mips/mips.exp: Add blockmov-limit to the list of
	supported options.

Cherry-picked cf1e4960a4f80301e4c8f71a35cbbc8fef1ce6fd,
and 4194c529fade9b3106d118cac63b71bc8b13f7be
from https://github.com/MIPS/gcc

Signed-off-by: Matthew Fortune <matthew.fortune@imgtec.com>
Signed-off-by: Robert Suchanek <robert.suchanek@imgtec.com>
Signed-off-by: Faraz Shahbazker <fshahbazker@wavecomp.com>
Signed-off-by: Aleksandar Rakic <aleksandar.rakic@htecgroup.com>
Signed-off-by: Eldar Osmanovic <eldar.osmanovic@htecgroup.com>
---
 gcc/config/mips/mips-protos.h                 |  2 +-
 gcc/config/mips/mips.cc                       | 29 ++++++++++++-------
 gcc/config/mips/mips.h                        |  5 ++++
 gcc/config/mips/mips.md                       |  2 +-
 gcc/config/mips/mips.opt                      |  3 ++
 gcc/testsuite/gcc.target/mips/align-1-o32.c   |  2 +-
 .../gcc.target/mips/inline-memcpy-limit.c     | 17 +++++++++++
 .../gcc.target/mips/inline-memcpy-straight.c  | 18 ++++++++++++
 gcc/testsuite/gcc.target/mips/mips.exp        |  1 +
 9 files changed, 66 insertions(+), 13 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/mips/inline-memcpy-limit.c
 create mode 100644 gcc/testsuite/gcc.target/mips/inline-memcpy-straight.c
diff mbox series

Patch

diff --git a/gcc/config/mips/mips-protos.h b/gcc/config/mips/mips-protos.h
index 49ba91d88cb..64d80613e9e 100644
--- a/gcc/config/mips/mips-protos.h
+++ b/gcc/config/mips/mips-protos.h
@@ -242,7 +242,7 @@  extern bool mips_get_pic_call_symbol (rtx *, int);
 extern void mips_set_return_address (rtx, rtx);
 extern bool mips_move_by_pieces_p (unsigned HOST_WIDE_INT, unsigned int);
 extern bool mips_store_by_pieces_p (unsigned HOST_WIDE_INT, unsigned int);
-extern bool mips_expand_block_move (rtx, rtx, rtx);
+extern bool mips_expand_block_move (rtx, rtx, rtx, rtx);
 extern void mips_expand_synci_loop (rtx, rtx);
 
 extern void mips_init_cumulative_args (CUMULATIVE_ARGS *, tree);
diff --git a/gcc/config/mips/mips.cc b/gcc/config/mips/mips.cc
index c3be68c15f7..1c79d980790 100644
--- a/gcc/config/mips/mips.cc
+++ b/gcc/config/mips/mips.cc
@@ -9472,7 +9472,7 @@  mips_block_move_loop (rtx dest, rtx src, HOST_WIDE_INT length,
    memory reference SRC to memory reference DEST.  */
 
 bool
-mips_expand_block_move (rtx dest, rtx src, rtx length)
+mips_expand_block_move (rtx dest, rtx src, rtx length, rtx alignment)
 {
   if (!CONST_INT_P (length))
     return false;
@@ -9482,16 +9482,25 @@  mips_expand_block_move (rtx dest, rtx src, rtx length)
 	  || MEM_ALIGN (dest) < MIPS_MIN_MOVE_MEM_ALIGN))
     return false;
 
-  if (INTVAL (length) <= MIPS_MAX_MOVE_BYTES_PER_LOOP_ITER)
+  if (mips_movmem_limit == -1 || INTVAL (length) < mips_movmem_limit)
     {
-      mips_block_move_straight (dest, src, INTVAL (length));
-      return true;
-    }
-  else if (optimize)
-    {
-      mips_block_move_loop (dest, src, INTVAL (length),
-			    MIPS_MAX_MOVE_BYTES_PER_LOOP_ITER);
-      return true;
+      if (INTVAL (length) <= MIPS_MAX_MOVE_BYTES_PER_LOOP_ITER
+	       /* We increase slightly the maximum number of bytes in
+		  a straight-line block if the source and destination
+		  are aligned to the register width.  */
+	       || (!optimize_size
+		   && INTVAL (alignment) == UNITS_PER_WORD
+		   && INTVAL (length) <= MIPS_MAX_MOVE_MEM_STRAIGHT))
+	{
+	  mips_block_move_straight (dest, src, INTVAL (length));
+	  return true;
+	}
+      else if (optimize)
+	{
+	  mips_block_move_loop (dest, src, INTVAL (length),
+				MIPS_MAX_MOVE_BYTES_PER_LOOP_ITER);
+	  return true;
+	}
     }
 
   return false;
diff --git a/gcc/config/mips/mips.h b/gcc/config/mips/mips.h
index ae34159ed37..b43f4c4dbe3 100644
--- a/gcc/config/mips/mips.h
+++ b/gcc/config/mips/mips.h
@@ -3158,6 +3158,11 @@  while (0)
 #define MIPS_MAX_MOVE_BYTES_STRAIGHT \
   (MIPS_MAX_MOVE_BYTES_PER_LOOP_ITER * 2)
 
+/* The maximum number of bytes that can be copied by any expanded block move;
+   see mips_expand_block_move.  */
+#define MIPS_MAX_MOVE_MEM_STRAIGHT \
+  (MIPS_MAX_MOVE_BYTES_PER_LOOP_ITER * 3)
+
 /* The base cost of a memcpy call, for MOVE_RATIO and friends.  These
    values were determined experimentally by benchmarking with CSiBE.
    In theory, the call overhead is higher for TARGET_ABICALLS (especially
diff --git a/gcc/config/mips/mips.md b/gcc/config/mips/mips.md
index 62cb1c270af..27cac8ba932 100644
--- a/gcc/config/mips/mips.md
+++ b/gcc/config/mips/mips.md
@@ -5875,7 +5875,7 @@ 
 	      (use (match_operand:SI 3 "const_int_operand"))])]
   "!TARGET_MIPS16 && !TARGET_MEMCPY"
 {
-  if (mips_expand_block_move (operands[0], operands[1], operands[2]))
+  if (mips_expand_block_move (operands[0], operands[1], operands[2], operands[3]))
     DONE;
   else
     FAIL;
diff --git a/gcc/config/mips/mips.opt b/gcc/config/mips/mips.opt
index d2967aecd38..f48f22b53a6 100644
--- a/gcc/config/mips/mips.opt
+++ b/gcc/config/mips/mips.opt
@@ -550,6 +550,9 @@  mfunc-opt-list=
 Target RejectNegative Joined Var(mips_func_opt_list_file) Init(0) Defer
 mfunc-opt-list=FILE	Use to specify per function optimizations.
 
+mblockmov-limit=
+Target RejectNegative Undocumented Joined UInteger Var(mips_movmem_limit) Init(-1)
+
 minline-intermix
 Target Var(TARGET_INLINE_INTERMIX)
 Allow inlining even if the compression flags differ between caller and callee.
diff --git a/gcc/testsuite/gcc.target/mips/align-1-o32.c b/gcc/testsuite/gcc.target/mips/align-1-o32.c
index e043d6a3eca..965b192abfd 100644
--- a/gcc/testsuite/gcc.target/mips/align-1-o32.c
+++ b/gcc/testsuite/gcc.target/mips/align-1-o32.c
@@ -1,7 +1,7 @@ 
 /* Check that typedef alignment does not affect passing of function
    parameters for O32 ABI.  */
 /* { dg-do compile { target { "mips*-*-*" } } } */
-/* { dg-options "-mabi=32"  } */
+/* { dg-options "-mabi=32 -mblockmov-limit=0"  } */
 /* { dg-skip-if "" { *-*-* } { "-flto" } { "" } } */
 
 typedef struct ui8
diff --git a/gcc/testsuite/gcc.target/mips/inline-memcpy-limit.c b/gcc/testsuite/gcc.target/mips/inline-memcpy-limit.c
new file mode 100644
index 00000000000..4755e100dda
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/inline-memcpy-limit.c
@@ -0,0 +1,17 @@ 
+/* { dg-options "-mabi=32 -mblockmov-limit=16" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Os" } { "" } } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } } */
+
+/* -mblockmov-limit should prevent a constant-sized copy at the limit from
+   being expanded inline. */
+   
+unsigned int a[4];
+unsigned int b[4];
+
+NOCOMPRESSION void
+foo (void)
+{
+	__builtin_memcpy (a, b, sizeof (a));
+}
+
+/* { dg-final { scan-assembler "\tmemcpy" } } */
diff --git a/gcc/testsuite/gcc.target/mips/inline-memcpy-straight.c b/gcc/testsuite/gcc.target/mips/inline-memcpy-straight.c
new file mode 100644
index 00000000000..50093c64d9d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/mips/inline-memcpy-straight.c
@@ -0,0 +1,18 @@ 
+/* { dg-options "-mabi=32" } */
+/* { dg-skip-if "" { *-*-* } { "-O0" "-Os" } { "" } } */
+/* { dg-skip-if "" { *-*-* } { "-flto" } } */
+
+/* A word-aligned copy of up to MIPS_MAC_MOVE_MEM_STRAIGHT bytes should be
+   expanded as straight-line code rather than as block-move loop. */
+   
+unsigned int a[4];
+unsigned int b[4];
+
+NOCOMPRESSION void
+foo (void)
+{
+	__builtin_memcpy (a, b, sizeof (a));
+}
+
+/* { dg-final { scan-assembler-not "\tmemcpy" } } */
+/* { dg-final { scan-assembler-not "\tbne\t" } } */
diff --git a/gcc/testsuite/gcc.target/mips/mips.exp b/gcc/testsuite/gcc.target/mips/mips.exp
index 8a5a1fa3134..5993be2aa03 100644
--- a/gcc/testsuite/gcc.target/mips/mips.exp
+++ b/gcc/testsuite/gcc.target/mips/mips.exp
@@ -312,6 +312,7 @@  foreach option {
 # Add -mfoo= options to mips_option_groups.
 foreach option {
     abs
+    blockmov-limit
     branch-cost
     code-readable
     func-opt-list