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-rw-r--r--sysdeps/tile/tilegx/memset.c151
1 files changed, 151 insertions, 0 deletions
diff --git a/sysdeps/tile/tilegx/memset.c b/sysdeps/tile/tilegx/memset.c
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+++ b/sysdeps/tile/tilegx/memset.c
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+/* Copyright (C) 2011-2014 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library.  If not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <arch/chip.h>
+#include <string.h>
+#include <stdint.h>
+#include "string-endian.h"
+
+void *
+__memset (void *s, int c, size_t n)
+{
+  uint64_t *out64;
+  int n64, to_align64;
+  uint64_t v64;
+  uint8_t *out8 = s;
+
+  /* Experimentation shows that a trivial tight loop is a win up until
+     around a size of 20, where writing a word at a time starts to win.  */
+#define BYTE_CUTOFF 20
+
+#if BYTE_CUTOFF < 7
+  /* This must be at least at least this big, or some code later
+     on doesn't work.  */
+# error "BYTE_CUTOFF is too small."
+#endif
+
+  if (n < BYTE_CUTOFF)
+    {
+      /* Strangely, this turns out to be the tightest way to write
+         this loop.  */
+      if (n != 0)
+        {
+          do
+            {
+              /* Strangely, combining these into one line performs worse.  */
+              *out8 = c;
+              out8++;
+            }
+          while (--n != 0);
+        }
+
+      return s;
+    }
+
+  /* Align 'out8'. We know n >= 7 so this won't write past the end.  */
+  while (((uintptr_t) out8 & 7) != 0)
+    {
+      *out8++ = c;
+      --n;
+    }
+
+  /* Align 'n'. */
+  while (n & 7)
+    out8[--n] = c;
+
+  out64 = (uint64_t *) out8;
+  n64 = n >> 3;
+
+  /* Tile input byte out to 64 bits. */
+  v64 = copy_byte(c);
+
+  /* This must be at least 8 or the following loop doesn't work. */
+#define CACHE_LINE_SIZE_IN_DOUBLEWORDS (CHIP_L2_LINE_SIZE() / 8)
+
+  /* Determine how many words we need to emit before the 'out32'
+     pointer becomes aligned modulo the cache line size.  */
+  to_align64 = (-((uintptr_t) out64 >> 3)) &
+    (CACHE_LINE_SIZE_IN_DOUBLEWORDS - 1);
+
+  /* Only bother aligning and using wh64 if there is at least
+     one full cache line to process.  This check also prevents
+     overrunning the end of the buffer with alignment words.  */
+  if (to_align64 <= n64 - CACHE_LINE_SIZE_IN_DOUBLEWORDS)
+    {
+      int lines_left;
+
+      /* Align out64 mod the cache line size so we can use wh64. */
+      n64 -= to_align64;
+      for (; to_align64 != 0; to_align64--)
+        {
+          *out64 = v64;
+          out64++;
+        }
+
+      /* Use unsigned divide to turn this into a right shift. */
+      lines_left = (unsigned) n64 / CACHE_LINE_SIZE_IN_DOUBLEWORDS;
+
+      do
+        {
+          /* Only wh64 a few lines at a time, so we don't exceed the
+             maximum number of victim lines.  */
+          int x = ((lines_left < CHIP_MAX_OUTSTANDING_VICTIMS ()) ? lines_left
+                   : CHIP_MAX_OUTSTANDING_VICTIMS ());
+          uint64_t *wh = out64;
+          int i = x;
+          int j;
+
+          lines_left -= x;
+
+          do
+            {
+              __insn_wh64 (wh);
+              wh += CACHE_LINE_SIZE_IN_DOUBLEWORDS;
+            }
+          while (--i);
+
+          for (j = x * (CACHE_LINE_SIZE_IN_DOUBLEWORDS / 4); j != 0; j--)
+            {
+              *out64++ = v64;
+              *out64++ = v64;
+              *out64++ = v64;
+              *out64++ = v64;
+            }
+        }
+      while (lines_left != 0);
+
+      /* We processed all full lines above, so only this many
+         words remain to be processed.  */
+      n64 &= CACHE_LINE_SIZE_IN_DOUBLEWORDS - 1;
+    }
+
+  /* Now handle any leftover values. */
+  if (n64 != 0)
+    {
+      do
+        {
+          *out64 = v64;
+          out64++;
+        }
+      while (--n64 != 0);
+    }
+
+  return s;
+}
+weak_alias (__memset, memset)
+libc_hidden_builtin_def (memset)