Hi,
this patch has some impacts to the C front-end, and I'd like to know wether my
approach is correct before finalizing it. So comments are welcome.
It implements the VMS 'pragma pointer_size 32/64/short/long', which change the
default size of a pointer. This feature allows to use a 32 bits or a 64 bits
ABI with only one C library (there are other weirdness to make this possible,
but the main feature is this one).
This feature was already supported by Ada (using pragma size), and by the
__attribute__(mode (XX)), so the back-end stuff is already present.
The patch is simple: the C front-end will now calls c_build_pointer_type
(instead of build_pointer_type), which in turn calls
build_pointer_type_for_mode using the right mode.
The handling of the pragma pointer_size simply change the pointer mode for C.
I haven't tried to change other C++ or Obj-C front-ends, because I haven't yet
investigated how they deal with this option on VMS.
This patch was tested on ia64 OpenVMS and also by bootstrapping gcc on x86-64
Darwin.
Tristan.
2012-03-06 Tristan Gingold <ging...@adacore.com>
* c-tree.h (c_default_pointer_mode): New variable.
* c-decl.c (c_default_pointer_mode): New variable.
(c_build_pointer_type): New function.
(grokdeclarator): Call c_build_pointer_type instead
of build_pointer_type.
* config/vms/vms-c.c: Include c-tree.h
(saved_pointer_mode): New variable.
(handle_pragma_pointer_size): New function.
(vms_pragma_pointer_size, vms_pragma_required_pointer_size): Likewise.
(vms_c_register_pragma): Register __pointer_size and
__required_pointer_size pragmas.
diff --git a/gcc/c-decl.c b/gcc/c-decl.c
index de46578..160d393 100644
--- a/gcc/c-decl.c
+++ b/gcc/c-decl.c
@@ -146,6 +146,10 @@ static int warn_about_return_type;
static bool undef_nested_function;
+/* Mode used to build pointers (VOIDmode means ptr_mode). */
+
+enum machine_mode c_default_pointer_mode = VOIDmode;
+
/* Each c_binding structure describes one binding of an identifier to
a decl. All the decls in a scope - irrespective of namespace - are
@@ -558,6 +562,23 @@ add_stmt (tree t)
return t;
}
+/* Build a pointer type using the default pointer mode. */
+
+static tree
+c_build_pointer_type (tree to_type)
+{
+ addr_space_t as = to_type == error_mark_node? ADDR_SPACE_GENERIC
+ : TYPE_ADDR_SPACE (to_type);
+ enum machine_mode pointer_mode;
+
+ if (as != ADDR_SPACE_GENERIC || c_default_pointer_mode == VOIDmode)
+ pointer_mode = targetm.addr_space.pointer_mode (as);
+ else
+ pointer_mode = c_default_pointer_mode;
+ return build_pointer_type_for_mode (to_type, pointer_mode, false);
+}
+
+
/* Return true if we will want to say something if a goto statement
crosses DECL. */
@@ -5683,7 +5704,7 @@ grokdeclarator (const struct c_declarator *declarator,
TYPE_NAME (type) = decl;
}
- type = build_pointer_type (type);
+ type = c_build_pointer_type (type);
/* Process type qualifiers (such as const or volatile)
that were given inside the `*'. */
@@ -5918,7 +5939,7 @@ grokdeclarator (const struct c_declarator *declarator,
type = TREE_TYPE (type);
if (type_quals)
type = c_build_qualified_type (type, type_quals);
- type = build_pointer_type (type);
+ type = c_build_pointer_type (type);
type_quals = array_ptr_quals;
if (type_quals)
type = c_build_qualified_type (type, type_quals);
@@ -5937,7 +5958,7 @@ grokdeclarator (const struct c_declarator *declarator,
"ISO C forbids qualified function types");
if (type_quals)
type = c_build_qualified_type (type, type_quals);
- type = build_pointer_type (type);
+ type = c_build_pointer_type (type);
type_quals = TYPE_UNQUALIFIED;
}
else if (type_quals)
diff --git a/gcc/c-tree.h b/gcc/c-tree.h
index 51c660c..db60935 100644
--- a/gcc/c-tree.h
+++ b/gcc/c-tree.h
@@ -625,6 +625,10 @@ extern int current_function_returns_abnormally;
extern int system_header_p;
+/* Mode used to build pointers (VOIDmode means ptr_mode). */
+
+extern enum machine_mode c_default_pointer_mode;
+
/* In c-decl.c */
extern void c_finish_incomplete_decl (tree);
extern void c_write_global_declarations (void);
diff --git a/gcc/config/vms/vms-c.c b/gcc/config/vms/vms-c.c
index 4a2d19c..e4f8493 100644
--- a/gcc/config/vms/vms-c.c
+++ b/gcc/config/vms/vms-c.c
@@ -27,6 +27,7 @@ along with GCC; see the file COPYING3. If not see
#include "tree.h"
#include "c-family/c-pragma.h"
#include "c-family/c-common.h"
+#include "c-tree.h"
#include "toplev.h"
#include "ggc.h"
#include "tm_p.h"
@@ -283,6 +284,70 @@ vms_pragma_extern_prefix (cpp_reader * ARG_UNUSED (dummy))
}
}
+/* #pragma __pointer_size */
+
+static enum machine_mode saved_pointer_mode;
+
+static void
+handle_pragma_pointer_size (const char *pragma_name)
+{
+ enum cpp_ttype tok;
+ tree x;
+
+ tok = pragma_lex (&x);
+ if (tok == CPP_NAME)
+ {
+ const char *op = IDENTIFIER_POINTER (x);
+
+ if (!strcmp (op, "__save"))
+ saved_pointer_mode = c_default_pointer_mode;
+ else if (!strcmp (op, "__restore"))
+ c_default_pointer_mode = saved_pointer_mode;
+ else if (!strcmp (op, "__short"))
+ c_default_pointer_mode = SImode;
+ else if (!strcmp (op, "__long"))
+ c_default_pointer_mode = DImode;
+ else
+ error ("malformed %<#pragma %s%>, ignoring", pragma_name);
+ }
+ else if (tok == CPP_NUMBER)
+ {
+ int val;
+
+ if (TREE_CODE (x) == INTEGER_CST)
+ val = TREE_INT_CST_LOW (x);
+ else
+ val = -1;
+
+ if (val == 32)
+ c_default_pointer_mode = SImode;
+ else if (val == 64)
+ c_default_pointer_mode = DImode;
+ else
+ error ("invalid constant in %<#pragma %s%>", pragma_name);
+ }
+ else
+ {
+ error ("malformed %<#pragma %s%>, ignoring", pragma_name);
+ }
+}
+
+static void
+vms_pragma_pointer_size (cpp_reader * ARG_UNUSED (dummy))
+{
+ /* Ignore if no -mpointer-size option. */
+ if (flag_vms_pointer_size == VMS_POINTER_SIZE_NONE)
+ return;
+
+ handle_pragma_pointer_size ("pointer_size");
+}
+
+static void
+vms_pragma_required_pointer_size (cpp_reader * ARG_UNUSED (dummy))
+{
+ handle_pragma_pointer_size ("required_pointer_size");
+}
+
/* Add vms-specific pragma. */
void
@@ -298,6 +363,10 @@ vms_c_register_pragma (void)
vms_pragma_nomember_alignment);
c_register_pragma_with_expansion (NULL, "nomember_alignment",
vms_pragma_nomember_alignment);
+ c_register_pragma (NULL, "__pointer_size",
+ vms_pragma_pointer_size);
+ c_register_pragma (NULL, "__required_pointer_size",
+ vms_pragma_required_pointer_size);
c_register_pragma (NULL, "__extern_model", vms_pragma_extern_model);
c_register_pragma (NULL, "extern_model", vms_pragma_extern_model);
c_register_pragma (NULL, "__message", vms_pragma_message);
