re PR tree-optimization/63748 (wrong may be used uninitialized warning (abnormal edges))

2014-11-10  Patrick Palka  <ppalka@gcc.gnu.org>

gcc/
	PR middle-end/63748
	* tree-ssa-propagate.c (may_propagate_copy): Allow propagating
	SSA copies whose source and destination names both occur in
	abnormal PHIs.

gcc/testsuite/
	PR middle-end/63748
	* gcc.dg/pr63748.c: New testcase.

From-SVN: r217317

4 files changed, 63 insertions, 12 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 6ad4342..8a32922 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2014-11-10  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR middle-end/63748
+	* tree-ssa-propagate.c (may_propagate_copy): Allow propagating
+	SSA copies whose source and destination names both occur in
+	abnormal PHIs.
+
 2014-11-10 Roman Gareev  <gareevroman@gmail.com>
 
 	* Makefile.in: Remove the compilation of graphite-clast-to-gimple.o.
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index a9cb2d0..812696d 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-10  Patrick Palka  <ppalka@gcc.gnu.org>
+
+	PR middle-end/63748
+	* gcc.dg/pr63748.c: New testcase.
+
 2014-11-10  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* gcc.dg/pr44194-1.c (dg-do): Add missing braces.
diff --git a/gcc/testsuite/gcc.dg/pr63748.c b/gcc/testsuite/gcc.dg/pr63748.c
new file mode 100644
index 0000000..2e50445
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr63748.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -Wall" } */
+
+#include <setjmp.h>
+
+jmp_buf *alloc_jmp_buf ();
+int foo (void *);
+
+int
+test (int op, int noside)
+{
+  void *argvec = 0;
+
+  if (op)
+    {
+      jmp_buf *buf = alloc_jmp_buf (); /* { dg-bogus "uninitialized" } */
+      setjmp (*buf);
+
+      if (noside)
+        goto nosideret;
+
+    do_call_it:
+
+      if (noside)
+        goto nosideret;
+
+      return foo (argvec);
+    }
+
+  argvec = __builtin_alloca (1);
+  goto do_call_it;
+
+nosideret:
+  return 1;
+}
+
diff --git a/gcc/tree-ssa-propagate.c b/gcc/tree-ssa-propagate.c
index 9f4d381..0195afa 100644
--- a/gcc/tree-ssa-propagate.c
+++ b/gcc/tree-ssa-propagate.c
@@ -1275,21 +1275,24 @@ may_propagate_copy (tree dest, tree orig)
   tree type_d = TREE_TYPE (dest);
   tree type_o = TREE_TYPE (orig);
 
-  /* If ORIG flows in from an abnormal edge, it cannot be propagated.  */
+  /* If ORIG is a default definition which flows in from an abnormal edge
+     then the copy can be propagated.  It is important that we do so to avoid
+     uninitialized copies.  */
   if (TREE_CODE (orig) == SSA_NAME
       && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig)
-      /* If it is the default definition and an automatic variable then
-         we can though and it is important that we do to avoid
-	 uninitialized regular copies.  */
-      && !(SSA_NAME_IS_DEFAULT_DEF (orig)
-	   && (SSA_NAME_VAR (orig) == NULL_TREE
-	       || TREE_CODE (SSA_NAME_VAR (orig)) == VAR_DECL)))
+      && SSA_NAME_IS_DEFAULT_DEF (orig)
+      && (SSA_NAME_VAR (orig) == NULL_TREE
+	  || TREE_CODE (SSA_NAME_VAR (orig)) == VAR_DECL))
+    ;
+  /* Otherwise if ORIG just flows in from an abnormal edge then the copy cannot
+     be propagated.  */
+  else if (TREE_CODE (orig) == SSA_NAME
+	   && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (orig))
     return false;
-
-  /* If DEST is an SSA_NAME that flows from an abnormal edge, then it
-     cannot be replaced.  */
-  if (TREE_CODE (dest) == SSA_NAME
-      && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
+  /* Similarly if DEST flows in from an abnormal edge then the copy cannot be
+     propagated.  */
+  else if (TREE_CODE (dest) == SSA_NAME
+	   && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (dest))
     return false;
 
   /* Do not copy between types for which we *do* need a conversion.  */