Hi!
As discussed in the PR, this patch attempts to change multiversioning
so that backwards compatibility with the previous target attribute behavior
is preserved. In particular, e.g. for
void foo () __attribute__((target ("avx")));
void foo ()
{
}
the foo definition was just merged with the previous declaration and
used the avx target attribute. The patch introduces
target ("default")
which should be used if a default multiversion variant is desirable.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
I've mentioned a bunch of other issues with multiversioning in the PR
(including missing documentation for the feature), hope those can be
resolved incrementally.
2013-01-18 Jakub Jelinek <ja...@redhat.com>
PR c++/55742
* config/i386/i386.c (ix86_valid_target_attribute_inner_p): Diagnose
invalid args instead of ICEing on it.
(ix86_valid_target_attribute_p): Allow target("default") attribute.
(sorted_attr_string): Formatting fix.
(ix86_mangle_function_version_assembler_n): Mangle target("default")
as if no target attribute is present.
(ix86_function_versions): Don't return true if one of the decls
doesn't have target attribute. If they don't and one of the decls
is DECL_FUNCTION_VERSIONED, report an error.
(is_function_default_version): Return true if there is
target("default") attribute rather than no target attribute at all.
* g++.dg/mv1.C: Adjust test.
* g++.dg/mv2.C: Likewise.
* g++.dg/mv5.C: Likewise.
* g++.dg/mv6.C: Likewise.
--- gcc/config/i386/i386.c.jj 2013-01-18 17:59:41.692943971 +0100
+++ gcc/config/i386/i386.c 2013-01-18 18:43:21.105326012 +0100
@@ -4223,7 +4223,10 @@ ix86_valid_target_attribute_inner_p (tre
}
else if (TREE_CODE (args) != STRING_CST)
- gcc_unreachable ();
+ {
+ error ("invalid %<target%> attribute value");
+ return false;
+ }
/* Handle multiple arguments separated by commas. */
next_optstr = ASTRDUP (TREE_STRING_POINTER (args));
@@ -4433,6 +4436,15 @@ ix86_valid_target_attribute_p (tree fnde
{
struct cl_target_option cur_target;
bool ret = true;
+
+ /* attribute((target("default"))) does nothing, beyond
+ affecting multi-versioning. */
+ if (TREE_VALUE (args)
+ && TREE_CODE (TREE_VALUE (args)) == STRING_CST
+ && TREE_CHAIN (args) == NULL_TREE
+ && strcmp (TREE_STRING_POINTER (TREE_VALUE (args)), "default") == 0)
+ return true;
+
tree old_optimize = build_optimization_node ();
tree new_target, new_optimize;
tree func_optimize = DECL_FUNCTION_SPECIFIC_OPTIMIZATION (fndecl);
@@ -28964,7 +28976,7 @@ sorted_attr_string (const char *str)
if (str[i] == ',')
argnum++;
- attr_str = (char *)xmalloc (strlen (str) + 1);
+ attr_str = (char *) xmalloc (strlen (str) + 1);
strcpy (attr_str, str);
/* Replace "=,-" with "_". */
@@ -29034,6 +29046,9 @@ ix86_mangle_function_version_assembler_n
version_string
= TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (version_attr)));
+ if (strcmp (version_string, "default") == 0)
+ return id;
+
attr_str = sorted_attr_string (version_string);
assembler_name = (char *) xmalloc (strlen (orig_name)
+ strlen (attr_str) + 2);
@@ -29058,7 +29073,7 @@ ix86_function_versions (tree fn1, tree f
const char *attr_str1, *attr_str2;
char *target1, *target2;
bool result;
-
+
if (TREE_CODE (fn1) != FUNCTION_DECL
|| TREE_CODE (fn2) != FUNCTION_DECL)
return false;
@@ -29070,12 +29085,35 @@ ix86_function_versions (tree fn1, tree f
if (attr1 == NULL_TREE && attr2 == NULL_TREE)
return false;
- /* If one function does not have a target attribute, these are versions. */
+ /* Diagnose missing target attribute if one of the decls is already
+ multi-versioned. */
if (attr1 == NULL_TREE || attr2 == NULL_TREE)
- return true;
+ {
+ if (DECL_FUNCTION_VERSIONED (fn1) || DECL_FUNCTION_VERSIONED (fn2))
+ {
+ if (attr2 != NULL_TREE)
+ {
+ tree tem = fn1;
+ fn1 = fn2;
+ fn2 = tem;
+ attr1 = attr2;
+ }
+ error_at (DECL_SOURCE_LOCATION (fn2),
+ "missing %<target%> attribute for multi-versioned %D",
+ fn2);
+ error_at (DECL_SOURCE_LOCATION (fn1),
+ "previous declaration of %D", fn1);
+ /* Prevent diagnosing of the same error multiple times. */
+ DECL_ATTRIBUTES (fn2)
+ = tree_cons (get_identifier ("target"),
+ copy_node (TREE_VALUE (attr1)),
+ DECL_ATTRIBUTES (fn2));
+ }
+ return false;
+ }
- attr_str1 = TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (attr1)));
- attr_str2 = TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (attr2)));
+ attr_str1 = TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (attr1)));
+ attr_str2 = TREE_STRING_POINTER (TREE_VALUE (TREE_VALUE (attr2)));
target1 = sorted_attr_string (attr_str1);
target2 = sorted_attr_string (attr_str2);
@@ -29196,9 +29234,14 @@ make_dispatcher_decl (const tree decl)
static bool
is_function_default_version (const tree decl)
{
- return (TREE_CODE (decl) == FUNCTION_DECL
- && DECL_FUNCTION_VERSIONED (decl)
- && lookup_attribute ("target", DECL_ATTRIBUTES (decl)) == NULL_TREE);
+ if (TREE_CODE (decl) != FUNCTION_DECL
+ || !DECL_FUNCTION_VERSIONED (decl))
+ return false;
+ tree attr = lookup_attribute ("target", DECL_ATTRIBUTES (decl));
+ gcc_assert (attr);
+ attr = TREE_VALUE (TREE_VALUE (attr));
+ return (TREE_CODE (attr) == STRING_CST
+ && strcmp (TREE_STRING_POINTER (attr), "default") == 0);
}
/* Make a dispatcher declaration for the multi-versioned function DECL.
--- gcc/testsuite/g++.dg/mv1.C.jj 2013-01-18 17:59:41.567944606 +0100
+++ gcc/testsuite/g++.dg/mv1.C 2013-01-18 18:31:36.223533556 +0100
@@ -6,7 +6,7 @@
#include <assert.h>
/* Default version. */
-int foo ();
+int foo () __attribute__ ((target("default")));
/* The other versions of foo. Mix up the ordering and
check if the dispatching does it in the order of priority. */
/* Check combination of target attributes. */
@@ -65,7 +65,8 @@ int main ()
return 0;
}
-int foo ()
+int __attribute__ ((target("default")))
+foo ()
{
return 0;
}
--- gcc/testsuite/g++.dg/mv2.C.jj 2013-01-18 17:59:41.456945279 +0100
+++ gcc/testsuite/g++.dg/mv2.C 2013-01-18 18:31:36.224533535 +0100
@@ -7,7 +7,7 @@
#include <assert.h>
/* Default version. */
-int foo ();
+int foo () __attribute__ ((target ("default")));
/* The dispatch checks should be in the exact reverse order of the
declarations below. */
int foo () __attribute__ ((target ("mmx")));
@@ -51,7 +51,7 @@ int main ()
return 0;
}
-int
+int __attribute__ ((target("default")))
foo ()
{
return 0;
--- gcc/testsuite/g++.dg/mv5.C.jj 2013-01-18 17:59:41.587944512 +0100
+++ gcc/testsuite/g++.dg/mv5.C 2013-01-18 18:31:36.224533535 +0100
@@ -7,7 +7,7 @@
/* Default version. */
-inline int
+inline int __attribute__ ((target ("default")))
foo ()
{
return 0;
--- gcc/testsuite/g++.dg/mv6.C.jj 2013-01-18 17:59:41.507944953 +0100
+++ gcc/testsuite/g++.dg/mv6.C 2013-01-18 18:31:36.224533535 +0100
@@ -8,6 +8,7 @@ class Foo
{
public:
/* Default version of foo. */
+ __attribute__ ((target("default")))
int foo ()
{
return 0;
Jakub
