ipa-sra: Do not remove statements necessary because of non-call EH (PR 95113)

PR 95113 revealed that when reasoning about which parameters are dead,
IPA-SRA does not perform the same check related to non-call exceptions
as tree DCE.  It most certainly should and so this patch moves the
condition used in tree-ssa-dce.c into a separate predicate (in
tree-eh.c) and uses it from both places.

gcc/ChangeLog:

2020-05-27  Martin Jambor  <mjambor@suse.cz>

	PR ipa/95113
	* tree-ssa-dce.c (mark_stmt_if_obviously_necessary): Move non-call
	exceptions check to...
	* tree-eh.c (stmt_unremovable_because_of_non_call_eh_p): ...this
	new function.
	* tree-eh.h (stmt_unremovable_because_of_non_call_eh_p): Declare it.
	* ipa-sra.c (isra_track_scalar_value_uses): Use it.  New parameter
	fun.

gcc/testsuite/ChangeLog:

2020-05-27  Martin Jambor  <mjambor@suse.cz>

	PR ipa/95113
	* gcc.dg/ipa/pr95113.c: New test.

diff --git a/gcc/ipa-sra.c b/gcc/ipa-sra.c
index 7c922e40a4e70f69962f02e16f195a91b5ce62ca..c81e8869e7a273b5c750d6f22ef404038f3bc5ed 100644 (file)
--- a/gcc/ipa-sra.c
+++ b/gcc/ipa-sra.c
@@ -795,17 +795,17 @@ get_single_param_flow_source (const isra_param_flow *param_flow)
 }
 
 /* Inspect all uses of NAME and simple arithmetic calculations involving NAME
-   in NODE and return a negative number if any of them is used for something
-   else than either an actual call argument, simple arithmetic operation or
-   debug statement.  If there are no such uses, return the number of actual
-   arguments that this parameter eventually feeds to (or zero if there is none).
-   For any such parameter, mark PARM_NUM as one of its sources.  ANALYZED is a
-   bitmap that tracks which SSA names we have already started
-   investigating.  */
+   in FUN represented with NODE and return a negative number if any of them is
+   used for something else than either an actual call argument, simple
+   arithmetic operation or debug statement.  If there are no such uses, return
+   the number of actual arguments that this parameter eventually feeds to (or
+   zero if there is none).  For any such parameter, mark PARM_NUM as one of its
+   sources.  ANALYZED is a bitmap that tracks which SSA names we have already
+   started investigating.  */
 
 static int
-isra_track_scalar_value_uses (cgraph_node *node, tree name, int parm_num,
-                             bitmap analyzed)
+isra_track_scalar_value_uses (function *fun, cgraph_node *node, tree name,
+                             int parm_num, bitmap analyzed)
 {
   int res = 0;
   imm_use_iterator imm_iter;
@@ -859,8 +859,9 @@ isra_track_scalar_value_uses (cgraph_node *node, tree name, int parm_num,
            }
          res += all_uses;
        }
-      else if ((is_gimple_assign (stmt) && !gimple_has_volatile_ops (stmt))
-              || gimple_code (stmt) == GIMPLE_PHI)
+      else if (!stmt_unremovable_because_of_non_call_eh_p (fun, stmt)
+              && ((is_gimple_assign (stmt) && !gimple_has_volatile_ops (stmt))
+                  || gimple_code (stmt) == GIMPLE_PHI))
        {
          tree lhs;
          if (gimple_code (stmt) == GIMPLE_PHI)
@@ -876,7 +877,7 @@ isra_track_scalar_value_uses (cgraph_node *node, tree name, int parm_num,
          gcc_assert (!gimple_vdef (stmt));
          if (bitmap_set_bit (analyzed, SSA_NAME_VERSION (lhs)))
            {
-             int tmp = isra_track_scalar_value_uses (node, lhs, parm_num,
+             int tmp = isra_track_scalar_value_uses (fun, node, lhs, parm_num,
                                                      analyzed);
              if (tmp < 0)
                {
@@ -927,7 +928,8 @@ isra_track_scalar_param_local_uses (function *fun, cgraph_node *node, tree parm,
     return true;
 
   bitmap analyzed = BITMAP_ALLOC (NULL);
-  int call_uses = isra_track_scalar_value_uses (node, name, parm_num, analyzed);
+  int call_uses = isra_track_scalar_value_uses (fun, node, name, parm_num,
+                                               analyzed);
   BITMAP_FREE (analyzed);
   if (call_uses < 0)
     return true;

diff --git a/gcc/testsuite/gcc.dg/ipa/pr95113.c b/gcc/testsuite/gcc.dg/ipa/pr95113.c
new file mode 100644 (file)
index 0000000..a8f8c90
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/ipa/pr95113.c
@@ -0,0 +1,33 @@
+/* { dg-do run } */
+/* { dg-options "-O2 -fexceptions -fnon-call-exceptions" } */
+/* { dg-require-effective-target exceptions } */
+
+int a, b;
+
+static inline long int
+foo (long int x, int y)
+{
+  if (y == 0)
+    return 0;
+
+  if (x == -1 && y == -1)
+    return 0;
+
+  return x / y;
+}
+
+static inline int
+bar (int *p)
+{
+  int c = foo (a, 1) + *p;
+  return b;
+}
+
+int
+main ()
+{
+  int d = 0;
+  b = foo (1, 1);
+  bar (&d);
+  return 0;
+}

diff --git a/gcc/tree-eh.c b/gcc/tree-eh.c
index 10ef2e3157c04523d9188e7c8fe1068d3341b568..4246dca8806b2f39417ffb086df5827e56e36d0c 100644 (file)
--- a/gcc/tree-eh.c
+++ b/gcc/tree-eh.c
@@ -2936,6 +2936,16 @@ stmt_could_throw_p (function *fun, gimple *stmt)
     }
 }
 
+/* Return true if STMT in function FUN must be assumed necessary because of
+   non-call exceptions.  */
+
+bool
+stmt_unremovable_because_of_non_call_eh_p (function *fun, gimple *stmt)
+{
+  return (fun->can_throw_non_call_exceptions
+         && !fun->can_delete_dead_exceptions
+         && stmt_could_throw_p (fun, stmt));
+}
 
 /* Return true if expression T could throw an exception.  */
 

diff --git a/gcc/tree-eh.h b/gcc/tree-eh.h
index cb1019e0d87e9729e716b6c95e78aa21578fcf09..ba911cadbe797beab0317b45245cf881ef8642c5 100644 (file)
--- a/gcc/tree-eh.h
+++ b/gcc/tree-eh.h
@@ -39,6 +39,7 @@ extern bool operation_could_trap_p (enum tree_code, bool, bool, tree);
 extern bool tree_could_trap_p (tree);
 extern tree rewrite_to_non_trapping_overflow (tree);
 extern bool stmt_could_throw_p (function *, gimple *);
+extern bool stmt_unremovable_because_of_non_call_eh_p (function *, gimple *);
 extern bool tree_could_throw_p (tree);
 extern bool stmt_can_throw_external (function *, gimple *);
 extern bool stmt_can_throw_internal (function *, gimple *);

diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 757cfad5b5e18da3c4b6ca75a19235c0a648bb40..fae5ae7234034f8b768f4b26d331f7204159924f 100644 (file)
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -201,9 +201,7 @@ mark_stmt_if_obviously_necessary (gimple *stmt, bool aggressive)
 {
   /* With non-call exceptions, we have to assume that all statements could
      throw.  If a statement could throw, it can be deemed necessary.  */
-  if (cfun->can_throw_non_call_exceptions
-      && !cfun->can_delete_dead_exceptions
-      && stmt_could_throw_p (cfun, stmt))
+  if (stmt_unremovable_because_of_non_call_eh_p (cfun, stmt))
     {
       mark_stmt_necessary (stmt, true);
       return;