compiler, runtime: Track fields with tag go:"track".

	* go-gcc.cc: Include "output.h".
	(global_variable): Add is_unique_section parameter.
	(global_variable_set_init): Adjust unique section if necessary.
	* Make-lang.in (go/go-gcc.o): Add dependency on output.h.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@193945 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 101 insertions, 0 deletions

diff --git a/libgo/runtime/go-fieldtrack.c b/libgo/runtime/go-fieldtrack.c
new file mode 100644
index 00000000000..62b36dc7bc0
--- /dev/null
+++ b/libgo/runtime/go-fieldtrack.c
@@ -0,0 +1,101 @@
+/* go-fieldtrack.c -- structure field data analysis.
+
+   Copyright 2012 The Go Authors. All rights reserved.
+   Use of this source code is governed by a BSD-style
+   license that can be found in the LICENSE file.  */
+
+#include "runtime.h"
+#include "go-type.h"
+#include "map.h"
+
+/* The compiler will track fields that have the tag go:"track".  Any
+   function that refers to such a field will call this function with a
+   string
+       fieldtrack "package.type.field"
+
+   This function does not actually do anything.  Instead, we gather
+   the field tracking information by looking for strings of that form
+   in the read-only data section.  This is, of course, a horrible
+   hack, but it's good enough for now.  We can improve it, e.g., by a
+   linker plugin, if this turns out to be useful.  */
+
+void
+__go_fieldtrack (byte *p __attribute__ ((unused)))
+{
+}
+
+/* A runtime function to add all the tracked fields to a
+   map[string]bool.  */
+
+extern const char _etext[] __attribute__ ((weak));
+extern const char __etext[] __attribute__ ((weak));
+extern const char __data_start[] __attribute__ ((weak));
+extern const char _edata[] __attribute__ ((weak));
+extern const char __edata[] __attribute__ ((weak));
+extern const char __bss_start[] __attribute__ ((weak));
+
+void runtime_Fieldtrack (struct __go_map *) __asm__ ("runtime.Fieldtrack");
+
+void
+runtime_Fieldtrack (struct __go_map *m)
+{
+  const char *p;
+  const char *pend;
+  const char *prefix;
+  size_t prefix_len;
+
+  p = __data_start;
+  if (p == NULL)
+    p = __etext;
+  if (p == NULL)
+    p = _etext;
+  if (p == NULL)
+    return;
+
+  pend = __edata;
+  if (pend == NULL)
+    pend = _edata;
+  if (pend == NULL)
+    pend = __bss_start;
+  if (pend == NULL)
+    return;
+
+  prefix = "fieldtrack ";
+  prefix_len = __builtin_strlen (prefix);
+
+  while (p < pend)
+    {
+      const char *q1;
+      const char *q2;
+
+      q1 = __builtin_memchr (p + prefix_len, '"', pend - (p + prefix_len));
+      if (q1 == NULL)
+	break;
+
+      if (__builtin_memcmp (q1 - prefix_len, prefix, prefix_len) != 0)
+	{
+	  p = q1 + 1;
+	  continue;
+	}
+
+      q1++;
+      q2 = __builtin_memchr (q1, '"', pend - q1);
+      if (q2 == NULL)
+	break;
+
+      if (__builtin_memchr (q1, '\0', q2 - q1) == NULL)
+	{
+	  String s;
+	  void *v;
+	  _Bool *pb;
+
+	  s.str = (const byte *) q1;
+	  s.len = q2 - q1;
+	  v = __go_map_index (m, &s, 1);
+	  pb = (_Bool *) v;
+	  *pb = 1;
+	}
+
+      p = q2;
+    }
+}