[PATCH] Target hook for rewriting inline asm constraints
Andreas Krebbel
Andreas.Krebbel@de.ibm.com
Wed Oct 24 16:01:00 GMT 2007
Hello,
if a back end wants to support new memory operands it has to extend
the GO_IF_LEGITIMATE_ADDRESS target hook. Unfortunately this also
changes the semantics of the 'm' constraint possibly breaking every
existing inline assembly out there.
The attached patch introduces a new target hook which can be defined
in the back end to rewrite constraints used in inline assemblies. If
a back end supports new memory operands it usually also has to provide
a new constraint letter defining what the former 'm' constraint would
have accepted. The intention of that target hook is to provide a
mechanism allowing the back end to replace the 'm' contraint with that
new constraint letter.
I know that this is not perfectly appropriate for stage 3. But since
it is a nop for all targets not defining that target hook and since I
need it for S/390 back end patches I'm working on I hope that can
nevertheless go in.
Bootstrapping on s390x and x86_64.
OK for mainline given no testsuite regressions occur?
Bye,
-Andreas-
2007-10-24 Andreas Krebbel <krebbel1@de.ibm.com>
* target-def.h (TARGET_REPLACE_INLINE_ASM_CONSTRAINT): New
macro. Added to TARGET_INITIALIZER definition.
* target.h (replace_inline_asm_constraint): Function pointer added.
* targhooks.c (default_replace_inline_asm_constraint): New function.
* targhooks.h (default_replace_inline_asm_constraint): Prototype added.
* c-parser.c (c_parser_asm_operands): Invoke new target hook.
* doc/tm.texi (TARGET_REPLACE_INLINE_ASM_CONSTRAINT):
Documenation added.
Index: gcc/target-def.h
===================================================================
*** gcc/target-def.h.orig 2007-10-19 16:34:27.000000000 +0200
--- gcc/target-def.h 2007-10-19 16:56:47.000000000 +0200
***************
*** 603,608 ****
--- 603,612 ----
#define TARGET_SECONDARY_RELOAD default_secondary_reload
#endif
+ #ifndef TARGET_REPLACE_INLINE_ASM_CONSTRAINT
+ #define TARGET_REPLACE_INLINE_ASM_CONSTRAINT default_replace_inline_asm_constraint
+ #endif
+
/* C specific. */
#ifndef TARGET_C_MODE_FOR_SUFFIX
#define TARGET_C_MODE_FOR_SUFFIX default_mode_for_suffix
***************
*** 769,774 ****
--- 773,779 ----
TARGET_INVALID_UNARY_OP, \
TARGET_INVALID_BINARY_OP, \
TARGET_SECONDARY_RELOAD, \
+ TARGET_REPLACE_INLINE_ASM_CONSTRAINT, \
TARGET_C, \
TARGET_CXX, \
TARGET_EXTRA_LIVE_ON_ENTRY, \
Index: gcc/target.h
===================================================================
*** gcc/target.h.orig 2007-10-19 16:34:27.000000000 +0200
--- gcc/target.h 2007-10-19 16:55:27.000000000 +0200
*************** struct gcc_target
*** 846,851 ****
--- 846,855 ----
enum machine_mode,
struct secondary_reload_info *);
+ /* Return a replacement for constraint c when used for an inline
+ assembly operand. */
+ const char *(*replace_inline_asm_constraint) (const char *c);
+
/* Functions specific to the C family of frontends. */
struct c {
/* Return machine mode for non-standard suffix
Index: gcc/targhooks.c
===================================================================
*** gcc/targhooks.c.orig 2007-10-19 16:34:27.000000000 +0200
--- gcc/targhooks.c 2007-10-19 16:53:38.000000000 +0200
*************** default_secondary_reload (bool in_p ATTR
*** 661,666 ****
--- 661,672 ----
return class;
}
+ const char *
+ default_replace_inline_asm_constraint (const char *c)
+ {
+ return c;
+ }
+
bool
default_handle_c_option (size_t code ATTRIBUTE_UNUSED,
const char *arg ATTRIBUTE_UNUSED,
Index: gcc/targhooks.h
===================================================================
*** gcc/targhooks.h.orig 2007-10-19 16:34:27.000000000 +0200
--- gcc/targhooks.h 2007-10-19 16:56:00.000000000 +0200
*************** extern rtx default_internal_arg_pointer
*** 90,95 ****
--- 90,96 ----
extern enum reg_class default_secondary_reload (bool, rtx, enum reg_class,
enum machine_mode,
secondary_reload_info *);
+ extern const char * default_replace_inline_asm_constraint (const char *c);
extern void hook_void_bitmap (bitmap);
extern bool default_handle_c_option (size_t, const char *, int);
extern int default_reloc_rw_mask (void);
Index: gcc/c-parser.c
===================================================================
*** gcc/c-parser.c.orig 2007-10-19 14:36:57.000000000 +0200
--- gcc/c-parser.c 2007-10-24 16:37:43.000000000 +0200
*************** along with GCC; see the file COPYING3.
*** 42,47 ****
--- 42,48 ----
#include "tm.h"
#include "tree.h"
#include "rtl.h"
+ #include "tm_p.h"
#include "langhooks.h"
#include "input.h"
#include "cpplib.h"
*************** c_parser_asm_operands (c_parser *parser,
*** 4262,4267 ****
--- 4263,4300 ----
str = c_parser_asm_string_literal (parser);
if (str == NULL_TREE)
return NULL_TREE;
+ {
+ const char *p = TREE_STRING_POINTER (str);
+ char result[255], tmp[255];
+ char c;
+ int len;
+
+ result[0] = '\0';
+
+ do
+ switch (c = *p, len = CONSTRAINT_LEN (c, p), c)
+ {
+ case '\0':
+ len = 0;
+ break;
+ case ',':
+ c = '\0';
+ break;
+ case '=': case '+': case '*': case '%': case '?':
+ case '!': case '#':
+ case '0': case '1': case '2': case '3': case '4':
+ case '5': case '6': case '7': case '8': case '9':
+ result[strlen (result) + 1] = '\0';
+ result[strlen (result)] = c;
+ break;
+ default:
+ memcpy (tmp, p, len);
+ tmp[len] = '\0';
+ strcat (result, targetm.replace_inline_asm_constraint (tmp));
+ }
+ while ((p += len), c);
+ str = build_string (strlen (result), result);
+ }
parser->lex_untranslated_string = false;
if (!c_parser_require (parser, CPP_OPEN_PAREN, "expected %<(%>"))
{
Index: gcc/doc/tm.texi
===================================================================
*** gcc/doc/tm.texi.orig 2007-10-19 16:33:25.000000000 +0200
--- gcc/doc/tm.texi 2007-10-24 16:50:29.000000000 +0200
*************** to the functions in @file{libgcc} that p
*** 10355,10357 ****
--- 10355,10367 ----
call stack unwinding. It is used in declarations in @file{unwind-generic.h}
and the associated definitions of those functions.
@end defmac
+
+ @deftypefn {Target Hook} {const char *} TARGET_REPLACE_INLINE_ASM_CONSTRAINT (const char *@var{str})
+ Define this target hook to return a constraint string which should be
+ used instead of @var{str} in inline assembly operands.
+
+ One case where this target hook needs to be defined is when the back
+ end target hook @code{GO_IF_LEGITIMATE_ADDRESS} has to be extended to
+ support new memory operands while keeping the semantics of the ``m''
+ constraint.
+ @end deftypefn
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