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re PR ipa/88936 (-fipa-pta breaks bash (incorrect optimisation of recursive static function))

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2019-04-15  Richard Biener  <rguenther@suse.de>

	PR ipa/88936
	* tree.h (auto_var_p): Declare.
	* tree.c (auto_var_p): New function, split out from ...
	(auto_var_in_fn_p): ... here.
	* tree-ssa-structalias.c (struct variable_info): Add shadow_var_uid
	member.
	(new_var_info): Initialize it.
	(set_uids_in_ptset): Also set the shadow variable uid if required.
	(ipa_pta_execute): Postprocess points-to solutions assigning
	shadow variable uids for locals that may reach their containing
	function recursively.
	* tree-ssa-ccp.c (fold_builtin_alloca_with_align): Do not
	assert but instead check whether the points-to solution is
	a singleton.

	* gcc.dg/torture/pr88936-1.c: New testcase.
	* gcc.dg/torture/pr88936-2.c: Likewise.
	* gcc.dg/torture/pr88936-3.c: Likewise.

From-SVN: r270366
This commit is contained in:
Richard Biener 2019-04-15 10:09:08 +00:00 committed by Richard Biener
parent 79a1870200
commit 869032b176
9 changed files with 194 additions and 16 deletions
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17
gcc/ChangeLog
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@ -1,3 +1,20 @@
2019-04-15 Richard Biener <rguenther@suse.de>
PR ipa/88936
* tree.h (auto_var_p): Declare.
* tree.c (auto_var_p): New function, split out from ...
(auto_var_in_fn_p): ... here.
* tree-ssa-structalias.c (struct variable_info): Add shadow_var_uid
member.
(new_var_info): Initialize it.
(set_uids_in_ptset): Also set the shadow variable uid if required.
(ipa_pta_execute): Postprocess points-to solutions assigning
shadow variable uids for locals that may reach their containing
function recursively.
* tree-ssa-ccp.c (fold_builtin_alloca_with_align): Do not
assert but instead check whether the points-to solution is
a singleton.
2019-04-15 Martin Jambor <mjambor@suse.cz>
PR ipa/pr89693

7
gcc/testsuite/ChangeLog
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@ -1,3 +1,10 @@
2019-04-15 Richard Biener <rguenther@suse.de>
PR ipa/88936
* gcc.dg/torture/pr88936-1.c: New testcase.
* gcc.dg/torture/pr88936-2.c: Likewise.
* gcc.dg/torture/pr88936-3.c: Likewise.
2019-04-15 Martin Jambor <mjambor@suse.cz>
PR ipa/pr89693

27
gcc/testsuite/gcc.dg/torture/pr88936-1.c Normal file
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@ -0,0 +1,27 @@
/* { dg-do run } */
/* { dg-additional-options "-fipa-pta" } */
static long bug (long depth, long * v)
{
if (depth == 0)
{
*v = 0;
return 1;
}
long r = 1;
long val = bug(depth - 1, &r);
return 2 * r + val;
}
static long ff (long depth)
{
return bug(depth, (long*)0);
}
int main()
{
if (ff(1) != 1)
__builtin_abort ();
return 0;
}

22
gcc/testsuite/gcc.dg/torture/pr88936-2.c Normal file
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@ -0,0 +1,22 @@
/* { dg-do run } */
/* { dg-additional-options "-fipa-pta" } */
static int *p;
void bar(int cnt)
{
int i = 0;
if (cnt == 0)
{
p = &i;
bar (1);
if (i != 1)
__builtin_abort ();
}
else if (cnt == 1)
*p = 1;
}
int main()
{
bar (0);
return 0;
}

21
gcc/testsuite/gcc.dg/torture/pr88936-3.c Normal file
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@ -0,0 +1,21 @@
/* { dg-do run } */
/* { dg-additional-options "-fipa-pta" } */
static int *p;
void bar(int cnt)
{
if (cnt == 0)
{
p = &cnt;
bar (1);
if (cnt != 1)
__builtin_abort ();
}
else if (cnt == 1)
*p = 1;
}
int main()
{
bar (0);
return 0;
}

25
gcc/tree-ssa-ccp.c
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@ -2170,23 +2170,26 @@ fold_builtin_alloca_with_align (gimple *stmt)
if (size > threshold)
return NULL_TREE;
/* We have to be able to move points-to info. We used to assert
that we can but IPA PTA might end up with two UIDs here
as it might need to handle more than one instance being
live at the same time. Instead of trying to detect this case
(using the first UID would be OK) just give up for now. */
struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs);
unsigned uid = 0;
if (pi != NULL
&& !pi->pt.anything
&& !pt_solution_singleton_or_null_p (&pi->pt, &uid))
return NULL_TREE;
/* Declare array. */
elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1);
n_elem = size * 8 / BITS_PER_UNIT;
array_type = build_array_type_nelts (elem_type, n_elem);
var = create_tmp_var (array_type);
SET_DECL_ALIGN (var, TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)));
{
struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs);
if (pi != NULL && !pi->pt.anything)
{
bool singleton_p;
unsigned uid;
singleton_p = pt_solution_singleton_or_null_p (&pi->pt, &uid);
gcc_assert (singleton_p);
SET_DECL_PT_UID (var, uid);
}
}
if (uid != 0)
SET_DECL_PT_UID (var, uid);
/* Fold alloca to the address of the array. */
return fold_convert (TREE_TYPE (lhs), build_fold_addr_expr (var));

72
gcc/tree-ssa-structalias.c
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@ -299,6 +299,11 @@ struct variable_info
/* Full size of the base variable, in bits. */
unsigned HOST_WIDE_INT fullsize;
/* In IPA mode the shadow UID in case the variable needs to be duplicated in
the final points-to solution because it reaches its containing
function recursively. Zero if none is needed. */
unsigned int shadow_var_uid;
/* Name of this variable */
const char *name;
@ -397,6 +402,7 @@ new_var_info (tree t, const char *name, bool add_id)
ret->solution = BITMAP_ALLOC (&pta_obstack);
ret->oldsolution = NULL;
ret->next = 0;
ret->shadow_var_uid = 0;
ret->head = ret->id;
stats.total_vars++;
@ -6452,6 +6458,16 @@ set_uids_in_ptset (bitmap into, bitmap from, struct pt_solution *pt,
&& (TREE_STATIC (vi->decl) || DECL_EXTERNAL (vi->decl))
&& ! decl_binds_to_current_def_p (vi->decl))
pt->vars_contains_interposable = true;
/* If this is a local variable we can have overlapping lifetime
of different function invocations through recursion duplicate
it with its shadow variable. */
if (in_ipa_mode
&& vi->shadow_var_uid != 0)
{
bitmap_set_bit (into, vi->shadow_var_uid);
pt->vars_contains_nonlocal = true;
}
}
else if (TREE_CODE (vi->decl) == FUNCTION_DECL
@ -8076,6 +8092,62 @@ ipa_pta_execute (void)
/* From the constraints compute the points-to sets. */
solve_constraints ();
/* Now post-process solutions to handle locals from different
runtime instantiations coming in through recursive invocations. */
unsigned shadow_var_cnt = 0;
for (unsigned i = 1; i < varmap.length (); ++i)
{
varinfo_t fi = get_varinfo (i);
if (fi->is_fn_info
&& fi->decl)
/* Automatic variables pointed to by their containing functions
parameters need this treatment. */
for (varinfo_t ai = first_vi_for_offset (fi, fi_parm_base);
ai; ai = vi_next (ai))
{
varinfo_t vi = get_varinfo (find (ai->id));
bitmap_iterator bi;
unsigned j;
EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, j, bi)
{
varinfo_t pt = get_varinfo (j);
if (pt->shadow_var_uid == 0
&& pt->decl
&& auto_var_in_fn_p (pt->decl, fi->decl))
{
pt->shadow_var_uid = allocate_decl_uid ();
shadow_var_cnt++;
}
}
}
/* As well as global variables which are another way of passing
arguments to recursive invocations. */
else if (fi->is_global_var)
{
for (varinfo_t ai = fi; ai; ai = vi_next (ai))
{
varinfo_t vi = get_varinfo (find (ai->id));
bitmap_iterator bi;
unsigned j;
EXECUTE_IF_SET_IN_BITMAP (vi->solution, 0, j, bi)
{
varinfo_t pt = get_varinfo (j);
if (pt->shadow_var_uid == 0
&& pt->decl
&& auto_var_p (pt->decl))
{
pt->shadow_var_uid = allocate_decl_uid ();
shadow_var_cnt++;
}
}
}
}
}
if (shadow_var_cnt && dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file, "Allocated %u shadow variables for locals "
"maybe leaking into recursive invocations of their containing "
"functions\n", shadow_var_cnt);
/* Compute the global points-to sets for ESCAPED.
??? Note that the computed escape set is not correct
for the whole unit as we fail to consider graph edges to

18
gcc/tree.c
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@ -9268,17 +9268,25 @@ get_type_static_bounds (const_tree type, mpz_t min, mpz_t max)
}
}
/* Return true if VAR is an automatic variable. */
bool
auto_var_p (const_tree var)
{
return ((((VAR_P (var) && ! DECL_EXTERNAL (var))
|| TREE_CODE (var) == PARM_DECL)
&& ! TREE_STATIC (var))
|| TREE_CODE (var) == RESULT_DECL);
}
/* Return true if VAR is an automatic variable defined in function FN. */
bool
auto_var_in_fn_p (const_tree var, const_tree fn)
{
return (DECL_P (var) && DECL_CONTEXT (var) == fn
&& ((((VAR_P (var) && ! DECL_EXTERNAL (var))
|| TREE_CODE (var) == PARM_DECL)
&& ! TREE_STATIC (var))
|| TREE_CODE (var) == LABEL_DECL
|| TREE_CODE (var) == RESULT_DECL));
&& (auto_var_p (var)
|| TREE_CODE (var) == LABEL_DECL));
}
/* Subprogram of following function. Called by walk_tree.

1
gcc/tree.h
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@ -4893,6 +4893,7 @@ extern bool stdarg_p (const_tree);
extern bool prototype_p (const_tree);
extern bool is_typedef_decl (const_tree x);
extern bool typedef_variant_p (const_tree);
extern bool auto_var_p (const_tree);
extern bool auto_var_in_fn_p (const_tree, const_tree);
extern tree build_low_bits_mask (tree, unsigned);
extern bool tree_nop_conversion_p (const_tree, const_tree);