The following fixes a wrong-code bug caused by loop invariant motion
hoisting an expression using an uninitialized value outside of its
controlling condition causing IVOPTs to use that to rewrite a defined
value. PR107839 is a similar case involving a bogus uninit diagnostic.
PR tree-optimization/107833
PR tree-optimization/107839
* cfghooks.cc: Include tree.h.
* tree-ssa-loop-im.cc (movement_possibility): Wrap and
make stmts using any ssa_name_maybe_undef_p operand
to preserve execution.
(loop_invariant_motion_in_fun): Call mark_ssa_maybe_undefs
to init maybe-undefined status.
* tree-ssa-loop-ivopts.cc (ssa_name_maybe_undef_p,
ssa_name_set_maybe_undef, ssa_name_any_use_dominates_bb_p,
mark_ssa_maybe_undefs): Move ...
* tree-ssa.cc: ... here.
* tree-ssa.h (ssa_name_any_use_dominates_bb_p,
mark_ssa_maybe_undefs): Declare.
(ssa_name_maybe_undef_p, ssa_name_set_maybe_undef): Define.
* gcc.dg/torture/pr107833.c: New testcase.
* gcc.dg/uninit-pr107839.c: Likewise.
(cherry picked from commit
44c8402d35160515b3c09fd2bc239587e0c32a2b)
#include "diagnostic-core.h"
#include "dumpfile.h"
#include "cfganal.h"
+#include "tree.h"
#include "tree-ssa.h"
#include "cfgloop.h"
#include "sreal.h"
--- /dev/null
+/* { dg-do run } */
+
+int a, b[1] = { 0 }, c, *d = b, e, *f, g;
+
+__attribute__((noipa)) int
+foo (const char *x)
+{
+ (void) x;
+ return 0;
+}
+
+int
+main ()
+{
+ for (int h = 0; a < 2; a++)
+ {
+ int i;
+ for (g = 0; g < 2; g++)
+ if (a < h)
+ {
+ e = i % 2;
+ c = *f;
+ }
+ for (h = 0; h < 3; h++)
+ {
+ if (d)
+ break;
+ i--;
+ foo ("0");
+ }
+ }
+ return 0;
+}
--- /dev/null
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wuninitialized" } */
+
+int f (int);
+void g (int c)
+{
+ int v;
+ if (c)
+ v = f(0);
+ while (1)
+ if (c)
+ f(v + v); /* { dg-bogus "uninitialized" } */
+}
#include "alias.h"
#include "builtins.h"
#include "tree-dfa.h"
+#include "tree-ssa.h"
#include "dbgcnt.h"
/* TODO: Support for predicated code motion. I.e.
because it may trap), return MOVE_PRESERVE_EXECUTION.
Otherwise return MOVE_IMPOSSIBLE. */
-enum move_pos
-movement_possibility (gimple *stmt)
+static enum move_pos
+movement_possibility_1 (gimple *stmt)
{
tree lhs;
enum move_pos ret = MOVE_POSSIBLE;
return ret;
}
+static enum move_pos
+movement_possibility (gimple *stmt)
+{
+ enum move_pos pos = movement_possibility_1 (stmt);
+ if (pos == MOVE_POSSIBLE)
+ {
+ use_operand_p use_p;
+ ssa_op_iter ssa_iter;
+ FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, ssa_iter, SSA_OP_USE)
+ if (TREE_CODE (USE_FROM_PTR (use_p)) == SSA_NAME
+ && ssa_name_maybe_undef_p (USE_FROM_PTR (use_p)))
+ return MOVE_PRESERVE_EXECUTION;
+ }
+ return pos;
+}
+
+
/* Compare the profile count inequality of bb and loop's preheader, it is
three-state as stated in profile-count.h, FALSE is returned if inequality
cannot be decided. */
tree_ssa_lim_initialize (store_motion);
+ mark_ssa_maybe_undefs ();
+
/* Gathers information about memory accesses in the loops. */
analyze_memory_references (store_motion);
return *slot;
}
-/* Return TRUE iff VAR is marked as maybe-undefined. See
- mark_ssa_maybe_undefs. */
-
-static inline bool
-ssa_name_maybe_undef_p (tree var)
-{
- gcc_checking_assert (TREE_CODE (var) == SSA_NAME);
- return TREE_VISITED (var);
-}
-
-/* Set (or clear, depending on VALUE) VAR's maybe-undefined mark. */
-
-static inline void
-ssa_name_set_maybe_undef (tree var, bool value = true)
-{
- gcc_checking_assert (TREE_CODE (var) == SSA_NAME);
- TREE_VISITED (var) = value;
-}
-
-/* Return TRUE iff there are any non-PHI uses of VAR that dominate the
- end of BB. If we return TRUE and BB is a loop header, then VAR we
- be assumed to be defined within the loop, even if it is marked as
- maybe-undefined. */
-
-static inline bool
-ssa_name_any_use_dominates_bb_p (tree var, basic_block bb)
-{
- imm_use_iterator iter;
- use_operand_p use_p;
- FOR_EACH_IMM_USE_FAST (use_p, iter, var)
- {
- if (is_a <gphi *> (USE_STMT (use_p))
- || is_gimple_debug (USE_STMT (use_p)))
- continue;
- basic_block dombb = gimple_bb (USE_STMT (use_p));
- if (dominated_by_p (CDI_DOMINATORS, bb, dombb))
- return true;
- }
-
- return false;
-}
-
-/* Mark as maybe_undef any SSA_NAMEs that are unsuitable as ivopts
- candidates for potentially involving undefined behavior. */
-
-static void
-mark_ssa_maybe_undefs (void)
-{
- auto_vec<tree> queue;
-
- /* Scan all SSA_NAMEs, marking the definitely-undefined ones as
- maybe-undefined and queuing them for propagation, while clearing
- the mark on others. */
- unsigned int i;
- tree var;
- FOR_EACH_SSA_NAME (i, var, cfun)
- {
- if (SSA_NAME_IS_VIRTUAL_OPERAND (var)
- || !ssa_undefined_value_p (var, false))
- ssa_name_set_maybe_undef (var, false);
- else
- {
- ssa_name_set_maybe_undef (var);
- queue.safe_push (var);
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "marking _%i as maybe-undef\n",
- SSA_NAME_VERSION (var));
- }
- }
-
- /* Now propagate maybe-undefined from a DEF to any other PHI that
- uses it, as long as there isn't any intervening use of DEF. */
- while (!queue.is_empty ())
- {
- var = queue.pop ();
- imm_use_iterator iter;
- use_operand_p use_p;
- FOR_EACH_IMM_USE_FAST (use_p, iter, var)
- {
- /* Any uses of VAR that aren't PHI args imply VAR must be
- defined, otherwise undefined behavior would have been
- definitely invoked. Only PHI args may hold
- maybe-undefined values without invoking undefined
- behavior for that reason alone. */
- if (!is_a <gphi *> (USE_STMT (use_p)))
- continue;
- gphi *phi = as_a <gphi *> (USE_STMT (use_p));
-
- tree def = gimple_phi_result (phi);
- if (ssa_name_maybe_undef_p (def))
- continue;
-
- /* Look for any uses of the maybe-unused SSA_NAME that
- dominates the block that reaches the incoming block
- corresponding to the PHI arg in which it is mentioned.
- That means we can assume the SSA_NAME is defined in that
- path, so we only mark a PHI result as maybe-undef if we
- find an unused reaching SSA_NAME. */
- int idx = phi_arg_index_from_use (use_p);
- basic_block bb = gimple_phi_arg_edge (phi, idx)->src;
- if (ssa_name_any_use_dominates_bb_p (var, bb))
- continue;
-
- ssa_name_set_maybe_undef (def);
- queue.safe_push (def);
- if (dump_file && (dump_flags & TDF_DETAILS))
- fprintf (dump_file, "marking _%i as maybe-undef because of _%i\n",
- SSA_NAME_VERSION (def), SSA_NAME_VERSION (var));
- }
- }
-}
/* Return *TP if it is an SSA_NAME marked with TREE_VISITED, i.e., as
unsuitable as ivopts candidates for potentially involving undefined
}
+/* Return TRUE iff there are any non-PHI uses of VAR that dominate the
+ end of BB. If we return TRUE and BB is a loop header, then VAR we
+ be assumed to be defined within the loop, even if it is marked as
+ maybe-undefined. */
+
+bool
+ssa_name_any_use_dominates_bb_p (tree var, basic_block bb)
+{
+ imm_use_iterator iter;
+ use_operand_p use_p;
+ FOR_EACH_IMM_USE_FAST (use_p, iter, var)
+ {
+ if (is_a <gphi *> (USE_STMT (use_p))
+ || is_gimple_debug (USE_STMT (use_p)))
+ continue;
+ basic_block dombb = gimple_bb (USE_STMT (use_p));
+ if (dominated_by_p (CDI_DOMINATORS, bb, dombb))
+ return true;
+ }
+
+ return false;
+}
+
+/* Mark as maybe_undef any SSA_NAMEs that are unsuitable as ivopts
+ candidates for potentially involving undefined behavior. */
+
+void
+mark_ssa_maybe_undefs (void)
+{
+ auto_vec<tree> queue;
+
+ /* Scan all SSA_NAMEs, marking the definitely-undefined ones as
+ maybe-undefined and queuing them for propagation, while clearing
+ the mark on others. */
+ unsigned int i;
+ tree var;
+ FOR_EACH_SSA_NAME (i, var, cfun)
+ {
+ if (SSA_NAME_IS_VIRTUAL_OPERAND (var)
+ || !ssa_undefined_value_p (var, false))
+ ssa_name_set_maybe_undef (var, false);
+ else
+ {
+ ssa_name_set_maybe_undef (var);
+ queue.safe_push (var);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "marking _%i as maybe-undef\n",
+ SSA_NAME_VERSION (var));
+ }
+ }
+
+ /* Now propagate maybe-undefined from a DEF to any other PHI that
+ uses it, as long as there isn't any intervening use of DEF. */
+ while (!queue.is_empty ())
+ {
+ var = queue.pop ();
+ imm_use_iterator iter;
+ use_operand_p use_p;
+ FOR_EACH_IMM_USE_FAST (use_p, iter, var)
+ {
+ /* Any uses of VAR that aren't PHI args imply VAR must be
+ defined, otherwise undefined behavior would have been
+ definitely invoked. Only PHI args may hold
+ maybe-undefined values without invoking undefined
+ behavior for that reason alone. */
+ if (!is_a <gphi *> (USE_STMT (use_p)))
+ continue;
+ gphi *phi = as_a <gphi *> (USE_STMT (use_p));
+
+ tree def = gimple_phi_result (phi);
+ if (ssa_name_maybe_undef_p (def))
+ continue;
+
+ /* Look for any uses of the maybe-unused SSA_NAME that
+ dominates the block that reaches the incoming block
+ corresponding to the PHI arg in which it is mentioned.
+ That means we can assume the SSA_NAME is defined in that
+ path, so we only mark a PHI result as maybe-undef if we
+ find an unused reaching SSA_NAME. */
+ int idx = phi_arg_index_from_use (use_p);
+ basic_block bb = gimple_phi_arg_edge (phi, idx)->src;
+ if (ssa_name_any_use_dominates_bb_p (var, bb))
+ continue;
+
+ ssa_name_set_maybe_undef (def);
+ queue.safe_push (def);
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ fprintf (dump_file, "marking _%i as maybe-undef because of _%i\n",
+ SSA_NAME_VERSION (def), SSA_NAME_VERSION (var));
+ }
+ }
+}
+
/* If necessary, rewrite the base of the reference tree *TP from
a MEM_REF to a plain or converted symbol. */
extern bool ssa_defined_default_def_p (tree t);
extern bool ssa_undefined_value_p (tree, bool = true);
extern bool gimple_uses_undefined_value_p (gimple *);
+
+
+bool ssa_name_any_use_dominates_bb_p (tree var, basic_block bb);
+extern void mark_ssa_maybe_undefs (void);
+
+/* Return TRUE iff VAR is marked as maybe-undefined. See
+ mark_ssa_maybe_undefs. */
+
+static inline bool
+ssa_name_maybe_undef_p (tree var)
+{
+ gcc_checking_assert (TREE_CODE (var) == SSA_NAME);
+ return TREE_VISITED (var);
+}
+
+/* Set (or clear, depending on VALUE) VAR's maybe-undefined mark. */
+
+static inline void
+ssa_name_set_maybe_undef (tree var, bool value = true)
+{
+ gcc_checking_assert (TREE_CODE (var) == SSA_NAME);
+ TREE_VISITED (var) = value;
+}
+
+
extern void execute_update_addresses_taken (void);
/* Given an edge_var_map V, return the PHI arg definition. */
git://gcc.gnu.org / gcc.git / commitdiff