On 02 Apr 22:45, Jan Hubicka wrote:
> > Hi,
> >
> > Current in LTO static const bounds are created as external symbol. It
> > doesn't work in case original symbols were removed and privatized. This
> > patch introduces a separate comdat symbol to be used in LTO. Bootstrapped
> > and tested on x86_64-unknown-linux-gnu. Does this approach look OK?
>
> As I understand it, you want to create a static variables, like
> __chkp_zero_bounds
> which should be shared across translation units. Currently the function does:
> static tree
> chkp_make_static_const_bounds (HOST_WIDE_INT lb,
> HOST_WIDE_INT ub,
> const char *name)
> {
> tree var;
>
> /* With LTO we may have constant bounds already in varpool.
> Try to find it. */
> var = chkp_find_const_bounds_var (lb, ub);
>
> if (var)
> return var;
>
> var = build_decl (UNKNOWN_LOCATION, VAR_DECL,
> get_identifier (name), pointer_bounds_type_node);
>
> TREE_PUBLIC (var) = 1;
> TREE_USED (var) = 1;
> TREE_READONLY (var) = 1;
> TREE_STATIC (var) = 1;
> TREE_ADDRESSABLE (var) = 0;
> DECL_ARTIFICIAL (var) = 1;
> DECL_READ_P (var) = 1;
> /* We may use this symbol during ctors generation in chkp_finish_file
> when all symbols are emitted. Force output to avoid undefined
> symbols in ctors. */
> if (!in_lto_p)
> {
> DECL_INITIAL (var) = targetm.chkp_make_bounds_constant (lb, ub);
> DECL_COMDAT (var) = 1;
> varpool_node::get_create (var)->set_comdat_group (DECL_ASSEMBLER_NAME
> (var));
> varpool_node::get_create (var)->force_output = 1;
> }
> else
> DECL_EXTERNAL (var) = 1;
> varpool_node::finalize_decl (var);
> }
>
> You should not set comdat group by hand, or we get into troubles on non-ELF
> targets. Just call make_decl_one_only (var, DECL_ASSEMBLER_NAME (var));
>
> Now in LTO I guess you want to check if the symbol is provided by the source
> compilation unit, i.e. call symtab_node::get_for_asmname (DECL_ASSEMBLER_NAME
> (var)) and if it is there, check it have proper type and fatal_error otherwise
> and if it does, discar var and use existing variable
>
> This avoid a duplicate declaration of a symbol that is invalid in symtab.
> (once we solve the transparent alias thing, I will add verification for that)
> Because you already set force_output, the symbol should not be privatized and
> renamed in any way.
>
> If there are cases the symbol can get legally optimized out, I guess you
> can also avoid setting force_output and we can stream references to the
> decls into optimization summary in a case we want ot bind for it in WPA,
> but that can wait for next stage1.
>
> Honza
Thanks a lot for looking into it! Seems originally I mostly got problems due
to no DECL_WEAK for generated var, make_decl_one_only seems to work for my
tests. Will run more testing to make sure it's OK. Here is a new patch
version. Is it OK?
Thanks,
Ilya
--
gcc/
2015-04-03 Ilya Enkovich <ilya.enkov...@intel.com>
* tree-chkp.c (chkp_find_const_bounds_var): Search
by assembler name.
(chkp_make_static_const_bounds): Use make_decl_one_only.
gcc/testsuite/
2015-04-03 Ilya Enkovich <ilya.enkov...@intel.com>
* gcc.dg/lto/chkp-static-bounds_0.c: New.
diff --git a/gcc/testsuite/gcc.dg/lto/chkp-static-bounds_0.c
b/gcc/testsuite/gcc.dg/lto/chkp-static-bounds_0.c
new file mode 100644
index 0000000..596e551
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/lto/chkp-static-bounds_0.c
@@ -0,0 +1,26 @@
+/* { dg-lto-do link } */
+/* { dg-require-effective-target mpx } */
+/* { dg-lto-options { { -flto -flto-partition=max -fcheck-pointer-bounds -mmpx
} } } */
+
+const char *cc;
+
+int test1 (const char *c)
+{
+ c = __builtin___bnd_init_ptr_bounds (c);
+ cc = c;
+ return c[0] * 2;
+}
+
+struct S
+{
+ int (*fnptr) (const char *);
+} S;
+
+struct S s1 = {test1};
+struct S s2 = {test1};
+struct S s3 = {test1};
+
+int main (int argc, const char **argv)
+{
+ return s1.fnptr (argv[0]) + s2.fnptr (argv[1]);
+}
diff --git a/gcc/tree-chkp.c b/gcc/tree-chkp.c
index 03f75b3..4daeab6 100644
--- a/gcc/tree-chkp.c
+++ b/gcc/tree-chkp.c
@@ -1876,26 +1876,17 @@ chkp_add_bounds_to_call_stmt (gimple_stmt_iterator *gsi)
/* Return constant static bounds var with specified LB and UB
if such var exists in varpool. Return NULL otherwise. */
static tree
-chkp_find_const_bounds_var (HOST_WIDE_INT lb,
- HOST_WIDE_INT ub)
+chkp_find_const_bounds_var (tree id)
{
- tree val = targetm.chkp_make_bounds_constant (lb, ub);
- struct varpool_node *node;
-
- /* We expect bounds constant is represented as a complex value
- of two pointer sized integers. */
- gcc_assert (TREE_CODE (val) == COMPLEX_CST);
+ struct symtab_node *node = symtab_node::get_for_asmname (id);
- FOR_EACH_VARIABLE (node)
- if (POINTER_BOUNDS_P (node->decl)
- && TREE_READONLY (node->decl)
- && DECL_INITIAL (node->decl)
- && TREE_CODE (DECL_INITIAL (node->decl)) == COMPLEX_CST
- && tree_int_cst_equal (TREE_REALPART (DECL_INITIAL (node->decl)),
- TREE_REALPART (val))
- && tree_int_cst_equal (TREE_IMAGPART (DECL_INITIAL (node->decl)),
- TREE_IMAGPART (val)))
+ if (node)
+ {
+ /* We don't allow this symbol usage for non bounds. */
+ gcc_assert (node->type == SYMTAB_VARIABLE);
+ gcc_assert (POINTER_BOUNDS_P (node->decl));
return node->decl;
+ }
return NULL;
}
@@ -1907,37 +1898,34 @@ chkp_make_static_const_bounds (HOST_WIDE_INT lb,
HOST_WIDE_INT ub,
const char *name)
{
+ tree id = get_identifier (name);
tree var;
+ varpool_node *node;
/* With LTO we may have constant bounds already in varpool.
Try to find it. */
- var = chkp_find_const_bounds_var (lb, ub);
+ var = chkp_find_const_bounds_var (id);
if (var)
return var;
- var = build_decl (UNKNOWN_LOCATION, VAR_DECL,
- get_identifier (name), pointer_bounds_type_node);
+ var = build_decl (UNKNOWN_LOCATION, VAR_DECL, id,
+ pointer_bounds_type_node);
- TREE_PUBLIC (var) = 1;
TREE_USED (var) = 1;
TREE_READONLY (var) = 1;
TREE_STATIC (var) = 1;
TREE_ADDRESSABLE (var) = 0;
DECL_ARTIFICIAL (var) = 1;
DECL_READ_P (var) = 1;
+ DECL_INITIAL (var) = targetm.chkp_make_bounds_constant (lb, ub);
+ make_decl_one_only (var, DECL_ASSEMBLER_NAME (var));
/* We may use this symbol during ctors generation in chkp_finish_file
when all symbols are emitted. Force output to avoid undefined
symbols in ctors. */
- if (!in_lto_p)
- {
- DECL_INITIAL (var) = targetm.chkp_make_bounds_constant (lb, ub);
- DECL_COMDAT (var) = 1;
- varpool_node::get_create (var)->set_comdat_group (DECL_ASSEMBLER_NAME
(var));
- varpool_node::get_create (var)->force_output = 1;
- }
- else
- DECL_EXTERNAL (var) = 1;
+ node = varpool_node::get_create (var);
+ node->force_output = 1;
+
varpool_node::finalize_decl (var);
return var;
