PATCH: Adds a __COUNTER__ macro.

PATCH: Adds a __COUNTER__ macro.

[Ollie Wild]

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This patch adds a builtin __COUNTER__ macro which expands to
incrementing integral values starting from 0.  In conjunction with the
'##' operator, this is useful for generating unique identifiers.  Per
my comments at http://gcc.gnu.org/ml/gcc-patches/2007-05/msg01488.html,
this does not include some additional logic to integrate with the
pending -fdirectives-only patch.

Tested with a full bootstrap and testsuite run on i686-pc-linux-gnu.

Ollie

:ADDPATCH libcpp:

2007-05-23  Ollie Wild <aaw@google.com>

       * macro.c (_cpp_builtin_macro_text): Handle BT_COUNTER.
       * pch.c (cpp_write_pch_deps): Save __COUNTER__ state.
       (cpp_write_pch_state): Save __COUNTER__ state.
       (cpp_valid_state): Check valid __COUNTER__ state.
       (cpp_read_state): Read new __COUNTER__ state.
       * include/cpplib.h (enum builtin_type): Add BT_COUNTER enumerator.
       * init.c (builtin_array): Add __COUNTER__/BT_COUNTER.
       * internal.h (struct cpp_reader): Add counter member.

2007-05-23  Ollie Wild  <aaw@google.com>

       * doc/cpp.texi (Common Predefined Macros): Add __COUNTER__
       description.

2007-05-23  Ollie Wild  <aaw@google.com>

       * gcc.dg/cpp/counter-1.c: New test.
       * gcc.dg/pch/counter-1.c: New test.
       * gcc.dg/pch/counter-1.hs: New file.
       * gcc.dg/pch/counter-2.c: New test.
       * gcc.dg/pch/counter-2.hs: New file.
       * gcc.dg/pch/counter-3.c: New test.
       * gcc.dg/pch/counter-3.hs: New file.

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diff --git a/gcc/doc/cpp.texi b/gcc/doc/cpp.texi
index e6786cf..54941a9 100644
--- a/gcc/doc/cpp.texi
+++ b/gcc/doc/cpp.texi
@@ -1917,6 +1917,13 @@ underscores.
 
 @table @code
 
+@item __COUNTER__
+This macro expands to sequential integral values starting from 0.  In
+conjuction with the @code{##} operator, this provides a convenient means to
+generate unique identifiers.  Care must be taken to ensure that
+@code{__COUNTER__} is not expanded prior to inclusion of precompiled headers
+which use it.  Otherwise, the precompiled headers will not be used.
+
 @item __GNUC__
 @itemx __GNUC_MINOR__
 @itemx __GNUC_PATCHLEVEL__
diff --git a/gcc/testsuite/gcc.dg/cpp/counter-1.c b/gcc/testsuite/gcc.dg/cpp/counter-1.c
new file mode 100644
index 0000000..80d8b78
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/counter-1.c
@@ -0,0 +1,20 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+/* { dg-do preprocess } */
+
+/* Tests __COUNTER__ macro is correctly expanded.  */
+
+#define counter __COUNTER__
+
+#if __COUNTER__ != 0
+#error __COUNTER__ != 0
+#endif
+
+#if counter != 1
+#error counter != 1
+#endif
+
+#if __COUNTER__ != 2
+#error __COUNTER__ != 2
+#endif
diff --git a/gcc/testsuite/gcc.dg/pch/counter-1.c b/gcc/testsuite/gcc.dg/pch/counter-1.c
new file mode 100644
index 0000000..79cea88
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pch/counter-1.c
@@ -0,0 +1,9 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+#include "counter-1.h"
+
+int main(void) 
+{
+  return __COUNTER__;
+}
diff --git a/gcc/testsuite/gcc.dg/pch/counter-1.hs b/gcc/testsuite/gcc.dg/pch/counter-1.hs
new file mode 100644
index 0000000..c3d2ce7
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pch/counter-1.hs
@@ -0,0 +1,5 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+static unsigned offset[] = {__COUNTER__, __COUNTER__, __COUNTER__};
+#define counter __COUNTER__
diff --git a/gcc/testsuite/gcc.dg/pch/counter-2.c b/gcc/testsuite/gcc.dg/pch/counter-2.c
new file mode 100644
index 0000000..7bbde23
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pch/counter-2.c
@@ -0,0 +1,15 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+/* { dg-options "-I. -Winvalid-pch" } */
+
+#if __COUNTER__ != 0
+#error __COUNTER__ != 0
+#endif
+
+#include "counter-2.h"/* { dg-error "`__COUNTER__' is invalid|No such file|they were invalid" } */
+
+int main(void) 
+{
+  return __COUNTER__;
+}
diff --git a/gcc/testsuite/gcc.dg/pch/counter-2.hs b/gcc/testsuite/gcc.dg/pch/counter-2.hs
new file mode 100644
index 0000000..63b8a2b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pch/counter-2.hs
@@ -0,0 +1,4 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+static int i = __COUNTER__;
diff --git a/gcc/testsuite/gcc.dg/pch/counter-3.c b/gcc/testsuite/gcc.dg/pch/counter-3.c
new file mode 100644
index 0000000..8279205
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pch/counter-3.c
@@ -0,0 +1,13 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+#if __COUNTER__ != 0
+#error __COUNTER__ != 0
+#endif
+
+#include "counter-3.h"
+
+int main(void) 
+{
+  return __COUNTER__;
+}
diff --git a/gcc/testsuite/gcc.dg/pch/counter-3.hs b/gcc/testsuite/gcc.dg/pch/counter-3.hs
new file mode 100644
index 0000000..19039c8
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pch/counter-3.hs
@@ -0,0 +1,4 @@
+/* Copyright (C) 2007 Free Software Foundation
+   Contributed by Ollie Wild <aaw@google.com> */
+
+#define counter __COUNTER__
diff --git a/libcpp/include/cpplib.h b/libcpp/include/cpplib.h
index b293998..ff5292e 100644
--- a/libcpp/include/cpplib.h
+++ b/libcpp/include/cpplib.h
@@ -555,7 +555,8 @@ enum builtin_type
   BT_TIME,			/* `__TIME__' */
   BT_STDC,			/* `__STDC__' */
   BT_PRAGMA,			/* `_Pragma' operator */
-  BT_TIMESTAMP			/* `__TIMESTAMP__' */
+  BT_TIMESTAMP,			/* `__TIMESTAMP__' */
+  BT_COUNTER			/* `__COUNTER__' */
 };
 
 #define CPP_HASHNODE(HNODE)	((cpp_hashnode *) (HNODE))
diff --git a/libcpp/init.c b/libcpp/init.c
index db697e9..71583df 100644
--- a/libcpp/init.c
+++ b/libcpp/init.c
@@ -310,6 +310,7 @@ static const struct builtin builtin_array[] =
   B("__BASE_FILE__",	 BT_BASE_FILE),
   B("__LINE__",		 BT_SPECLINE),
   B("__INCLUDE_LEVEL__", BT_INCLUDE_LEVEL),
+  B("__COUNTER__",	 BT_COUNTER),
   /* Keep builtins not used for -traditional-cpp at the end, and
      update init_builtins() if any more are added.  */
   B("_Pragma",		 BT_PRAGMA),
diff --git a/libcpp/internal.h b/libcpp/internal.h
index 9395f6a..d000cfd 100644
--- a/libcpp/internal.h
+++ b/libcpp/internal.h
@@ -452,6 +452,9 @@ struct cpp_reader
   /* A saved list of the defined macros, for dependency checking
      of precompiled headers.  */
   struct cpp_savedstate *savedstate;
+
+  /* Next value of __COUNTER__ macro. */
+  unsigned int counter;
 };
 
 /* Character classes.  Based on the more primitive macros in safe-ctype.h.
diff --git a/libcpp/macro.c b/libcpp/macro.c
index 748635f..cfdf595 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -263,6 +263,10 @@ _cpp_builtin_macro_text (cpp_reader *pfile, cpp_hashnode *node)
       else
 	result = pfile->time;
       break;
+
+    case BT_COUNTER:
+      number = pfile->counter++;
+      break;
     }
 
   if (result == NULL)
diff --git a/libcpp/pch.c b/libcpp/pch.c
index cc23b4e..09373a2 100644
--- a/libcpp/pch.c
+++ b/libcpp/pch.c
@@ -337,6 +337,14 @@ cpp_write_pch_deps (cpp_reader *r, FILE *f)
   /* Free the saved state.  */
   free (ss);
   r->savedstate = NULL;
+
+  /* Save the next value of __COUNTER__. */
+  if (fwrite (&r->counter, sizeof (r->counter), 1, f) != 1)
+    {
+      cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
+      return -1;
+    }
+
   return 0;
 }
 
@@ -361,6 +369,15 @@ cpp_write_pch_state (cpp_reader *r, FILE *f)
       return -1;
     }
 
+  /* Save the next __COUNTER__ value.  When we include a precompiled header,
+     we need to start at the offset we would have if the header had been
+     included normally. */
+  if (fwrite (&r->counter, sizeof (r->counter), 1, f) != 1)
+    {
+      cpp_errno (r, CPP_DL_ERROR, "while writing precompiled header");
+      return -1;
+    }
+
   return 0;
 }
 
@@ -423,6 +440,7 @@ cpp_valid_state (cpp_reader *r, const char *name, int fd)
   struct ht_node_list nl = { 0, 0, 0 };
   unsigned char *first, *last;
   unsigned int i;
+  unsigned int counter;
   
   /* Read in the list of identifiers that must be defined
      Check that they are defined in the same way.  */
@@ -524,7 +542,23 @@ cpp_valid_state (cpp_reader *r, const char *name, int fd)
     }
    
   free(nl.defs);
+  nl.defs = NULL;
   free (undeftab);
+  undeftab = NULL;
+
+  /* Read in the next value of __COUNTER__.
+     Check that (a) __COUNTER__ was not used in the pch or (b) __COUNTER__
+     has not been used in this translation unit. */
+  if (read (fd, &counter, sizeof (counter)) != sizeof (counter))
+    goto error;
+  if (counter && r->counter)
+    {
+      if (CPP_OPTION (r, warn_invalid_pch))
+	cpp_error (r, CPP_DL_WARNING_SYSHDR, 
+		   "%s: not used because `__COUNTER__' is invalid",
+		   name);
+	goto fail;
+    }
 
   /* We win!  */
   return 0;
@@ -631,6 +665,7 @@ cpp_read_state (cpp_reader *r, const char *name, FILE *f,
 {
   size_t i;
   struct lexer_state old_state;
+  unsigned int counter;
 
   /* Restore spec_nodes, which will be full of references to the old 
      hashtable entries and so will now be invalid.  */
@@ -690,6 +725,12 @@ cpp_read_state (cpp_reader *r, const char *name, FILE *f,
   if (! _cpp_read_file_entries (r, f))
     goto error;
 
+  if (fread (&counter, sizeof (counter), 1, f) != 1)
+    goto error;
+
+  if (!r->counter)
+    r->counter = counter;
+
   return 0;
   
  error:

Re: PATCH: Adds a __COUNTER__ macro.

[Tom Tromey]

>>>>> "Ollie" == Ollie Wild <aaw@google.com> writes:

Ollie> This patch adds a builtin __COUNTER__ macro which expands to
Ollie> incrementing integral values starting from 0.  In conjunction with the
Ollie> '##' operator, this is useful for generating unique identifiers.  Per
Ollie> my comments at http://gcc.gnu.org/ml/gcc-patches/2007-05/msg01488.html,
Ollie> this does not include some additional logic to integrate with the
Ollie> pending -fdirectives-only patch.

Ollie> Tested with a full bootstrap and testsuite run on i686-pc-linux-gnu.

Looks good to me.  Thanks.

Tom