Re: [RFC,PATCH] Builtin macros for sizes of standard types

[Andreas Krebbel <Andreas dot Krebbel at de dot ibm dot com>]

Hi Mark,

although mentioned in the cc line your email somehow didn't make it 
to the mailing list archive.  I've copied its contents manually:

>> +   builtin_define_with_int_value ("__SIZEOF_VOID_P__",
>> + 		 		  POINTER_SIZE / BITS_PER_UNIT);
>
>If we're going to do this, this should be "__SIZEOF_POINTER__".  The
>value is also valid for sizeof (int *).  Do we support machines with
>function pointers whose sizes are different from function pointers?  If
>so, then, maybe "__SIZEOF_DATA_POINTER__".

I've tried to mimic the macros defined by autoconf (plus double
underscores).  Autoconf defines a SIZEOF_VOID_P but I don't have a strong
preference for it so I changed it to __SIZEOF_POINTER__.

I'm not aware of gcc supporting targets where the size of a function
pointer differs from the size of a data pointer.  I thought that
all pointer types are based on POINTER_SIZE.  If nobody objects
I would stick to __SIZEOF_POINTER__.

>Why not also have macros for "float", "double", and "long double"?  In
>other words, if we're going to put these macros in, we should try to
>support all of the fundamental C types.

Agreed.  I've also added a __SIZEOF_SIZE_T__.

Bootstrapped on i686, s390 and s390x.
No testsuite regressions.

OK for mainline?

Bye,

-Andreas-

2007-01-23  Andreas Krebbel  <krebbel1@de.ibm.com>

	* c-cppbuiltin.c (builtin_define_type_sizeof): New function.
	(c_cpp_builtins): New builtin macros: __SIZEOF_INT__, __SIZEOF_LONG__,
	__SIZEOF_LONG_LONG__, __SIZEOF_SHORT__, __SIZEOF_POINTER__,
	__SIZEOF_SIZE_T__, __SIZEOF_FLOAT__, __SIZEOF_DOUBLE__ and
	__SIZEOF_LONG_DOUBLE__.
	* doc/cpp.texi: Documentation for the new builtin macros added.


2007-01-23  Andreas Krebbel  <krebbel1@de.ibm.com>

	* gcc.c-torture/compile/sizeof-macros-1.c: New testcase.


Index: gcc/c-cppbuiltin.c
===================================================================
*** gcc/c-cppbuiltin.c.orig	2007-01-23 12:06:15.000000000 +0100
--- gcc/c-cppbuiltin.c	2007-01-23 12:06:19.000000000 +0100
*************** static void builtin_define_with_hex_fp_v
*** 58,63 ****
--- 58,64 ----
  static void builtin_define_stdint_macros (void);
  static void builtin_define_type_max (const char *, tree, int);
  static void builtin_define_type_precision (const char *, tree);
+ static void builtin_define_type_sizeof (const char *, tree);
  static void builtin_define_float_constants (const char *, 
  					    const char *,
  					    const char *,
*************** builtin_define_type_precision (const cha
*** 71,76 ****
--- 72,85 ----
    builtin_define_with_int_value (name, TYPE_PRECISION (type));
  }
  
+ /* Define NAME with value TYPE size_unit.  */
+ static void
+ builtin_define_type_sizeof (const char *name, tree type)
+ {
+   builtin_define_with_int_value (name,
+ 				 TREE_INT_CST_LOW (TYPE_SIZE_UNIT (type)));
+ }
+ 
  /* Define the float.h constants for TYPE using NAME_PREFIX, FP_SUFFIX,
     and FP_CAST. */
  static void
*************** c_cpp_builtins (cpp_reader *pfile)
*** 549,554 ****
--- 558,577 ----
    if (flag_openmp)
      cpp_define (pfile, "_OPENMP=200505");
  
+   builtin_define_type_sizeof ("__SIZEOF_INT__", integer_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_LONG__", long_integer_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_LONG_LONG__",
+ 			      long_long_integer_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_SHORT__", short_integer_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_FLOAT__", float_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_DOUBLE__", double_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_LONG_DOUBLE__", long_double_type_node);
+   builtin_define_type_sizeof ("__SIZEOF_SIZE_T__", size_type_node);
+   /* ptr_type_node can't be used here since ptr_mode is only set when
+      toplev calls backend_init which is not done with -E switch.  */
+   builtin_define_with_int_value ("__SIZEOF_POINTER__",
+ 				 POINTER_SIZE / BITS_PER_UNIT);
+ 
    /* A straightforward target hook doesn't work, because of problems
       linking that hook's body when part of non-C front ends.  */
  # define preprocessing_asm_p() (cpp_get_options (pfile)->lang == CLK_ASM)
Index: gcc/doc/cpp.texi
===================================================================
*** gcc/doc/cpp.texi.orig	2007-01-23 12:06:15.000000000 +0100
--- gcc/doc/cpp.texi	2007-01-23 12:06:19.000000000 +0100
*************** respectively.  They exist to make the st
*** 2079,2084 ****
--- 2079,2097 ----
  work correctly.  You should not use these macros directly; instead, include
  the appropriate headers.
  
+ @item __SIZEOF_INT__
+ @itemx __SIZEOF_LONG__
+ @itemx __SIZEOF_LONG_LONG__
+ @itemx __SIZEOF_SHORT__
+ @itemx __SIZEOF_POINTER__
+ @itemx __SIZEOF_SIZE_T__
+ @itemx __SIZEOF_FLOAT__
+ @itemx __SIZEOF_DOUBLE__
+ @itemx __SIZEOF_LONG_DOUBLE__
+ Defined to the number of bytes of the C standard data types: @code{int},
+ @code{long}, @code{long long}, @code{short}, @code{void *}, @code{size_t},
+ @code{float}, @code{double} and @code{long double}.
+ 
  @item __DEPRECATED
  This macro is defined, with value 1, when compiling a C++ source file
  with warnings about deprecated constructs enabled.  These warnings are
Index: gcc/testsuite/gcc.c-torture/compile/sizeof-macros-1.c
===================================================================
*** /dev/null	1970-01-01 00:00:00.000000000 +0000
--- gcc/testsuite/gcc.c-torture/compile/sizeof-macros-1.c	2007-01-23 13:57:32.000000000 +0100
***************
*** 0 ****
--- 1,12 ----
+ /* This checks the gcc builtin macros defined to the byte
+    sizes of C standard types.  */
+ 
+ int a[sizeof(int) == __SIZEOF_INT__ ? 1 : -1];
+ int b[sizeof(long) == __SIZEOF_LONG__ ? 1 : -1];
+ int c[sizeof(long long) == __SIZEOF_LONG_LONG__ ? 1 : -1];
+ int d[sizeof(short) == __SIZEOF_SHORT__ ? 1 : -1];
+ int e[sizeof(void *) == __SIZEOF_POINTER__ ? 1 : -1];
+ int f[sizeof(__SIZE_TYPE__) == __SIZEOF_SIZE_T__ ? 1 : -1];
+ int g[sizeof(float) == __SIZEOF_FLOAT__ ? 1 : -1];
+ int h[sizeof(double) == __SIZEOF_DOUBLE__ ? 1 : -1];
+ int i[sizeof(long double) == __SIZEOF_LONG_DOUBLE__ ? 1 : -1];