[PATCH, PR tree-optimization/65002] Disable SRA for functions wrongly marked as read-only

[Ilya Enkovich]

Hi,

PR65002 is the second issue caused by SRA for functions wrongly marked as read-only.  Previous fix for PR64353 doesn't work for this case because SSA update happens too late.  Here is a patch to disable SRA for such functions to avoid inconsistent SSA issues.

Bootstrapped and tested on x86_64-unknown-linux-gnu.  OK for trunk?

Thanks,
Ilya
--
gcc/

2015-02-12  Ilya Enkovich  <ilya.enkovich@intel.com>

	PR tree-optimization/65002
	* tree-cfg.c (pass_data_fixup_cfg): Don't update
	SSA on start.
	* tree-sra.c (some_callers_have_no_vuse_p): New.
	(ipa_early_sra): Reject functions whose callers
	assume funciton is read only.

gcc/testsuite/

2015-02-12  Ilya Enkovich  <ilya.enkovich@intel.com>

	PR tree-optimization/65002
	* gcc.dg/pr65002.C: New.


diff --git a/gcc/testsuite/gcc.dg/pr65002.C b/gcc/testsuite/gcc.dg/pr65002.C
new file mode 100644
index 0000000..ac7c66b
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr65002.C
@@ -0,0 +1,26 @@
+/* PR tree-optimization/65002 */
+/* { dg-do compile } */
+/* { dg-options "-O2" } */
+
+namespace fastmath {
+  template <typename T> float floor(const T &) __attribute__((const));
+  template <typename T> float floor(const T &p1) { return p1; }
+}
+using fastmath::floor;
+class A {
+public:
+  A(int, int);
+  virtual int m_fn1(float) const;
+};
+class B : A {
+public:
+  B(int, int p2) : A(entity, p2) {}
+  int m_fn1(float p1) const { long b(floor(p1)); }
+  int entity;
+};
+
+int a;
+void Convert() {
+  if (int *c = 0)
+    B(*c, a);
+}
diff --git a/gcc/tree-cfg.c b/gcc/tree-cfg.c
index 2e23553..006bc08 100644
--- a/gcc/tree-cfg.c
+++ b/gcc/tree-cfg.c
@@ -8754,7 +8754,7 @@ const pass_data pass_data_fixup_cfg =
   PROP_cfg, /* properties_required */
   0, /* properties_provided */
   0, /* properties_destroyed */
-  TODO_update_ssa_only_virtuals, /* todo_flags_start */
+  0, /* todo_flags_start */
   0, /* todo_flags_finish */
 };
 
diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index ad9584e..7f78e68 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -4890,6 +4890,20 @@ some_callers_have_mismatched_arguments_p (struct cgraph_node *node,
   return false;
 }
 
+/* Return false if all callers have vuse attached to a call statement.  */
+
+static bool
+some_callers_have_no_vuse_p (struct cgraph_node *node,
+			     void *data ATTRIBUTE_UNUSED)
+{
+  struct cgraph_edge *cs;
+  for (cs = node->callers; cs; cs = cs->next_caller)
+    if (!cs->call_stmt || !gimple_vuse (cs->call_stmt))
+      return true;
+
+  return false;
+}
+
 /* Convert all callers of NODE.  */
 
 static bool
@@ -5116,6 +5130,15 @@ ipa_early_sra (void)
       goto simple_out;
     }
 
+  if (node->call_for_symbol_thunks_and_aliases
+       (some_callers_have_no_vuse_p, NULL, true))
+    {
+      if (dump_file)
+	fprintf (dump_file, "There are callers with no VUSE attached "
+		 "to a call stmt.\n");
+      goto simple_out;
+    }
+
   bb_dereferences = XCNEWVEC (HOST_WIDE_INT,
 				 func_param_count
 				 * last_basic_block_for_fn (cfun));