re PR middle-end/38851 (Compiler warns about uninitialized variable that is an object...

2009-01-26  Richard Guenther  <rguenther@suse.de>

	PR middle-end/38851
	* Makefile.in (tree-ssa-dse.o): Add langhooks.h.
	* tree-ssa-dse.c: Include langhooks.h
	(execute_simple_dse): Remove stores with zero size.

	* g++.dg/warn/Wuninitialized-1.C: New testcase.

From-SVN: r143672

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ecf9e46..f9ca880 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2009-01-26  Richard Guenther  <rguenther@suse.de>
+
+       PR middle-end/38851
+       * Makefile.in (tree-ssa-dse.o): Add langhooks.h.
+       * tree-ssa-dse.c: Include langhooks.h
+       (execute_simple_dse): Remove stores with zero size.
+
 2009-01-24  Jakub Jelinek  <jakub@redhat.com>
 
        PR c/38957

diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 8b214b9..ab461e7 100644 (file)
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -2110,7 +2110,7 @@ tree-outof-ssa.o : tree-outof-ssa.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
 tree-ssa-dse.o : tree-ssa-dse.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
    $(TM_H) $(GGC_H) $(TREE_H) $(RTL_H) $(TM_P_H) $(BASIC_BLOCK_H) \
    $(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) domwalk.h $(FLAGS_H) \
-   $(DIAGNOSTIC_H) $(TIMEVAR_H)
+   $(DIAGNOSTIC_H) $(TIMEVAR_H) langhooks.h
 tree-ssa-forwprop.o : tree-ssa-forwprop.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
    $(TM_H) $(GGC_H) $(TREE_H) $(RTL_H) $(TM_P_H) $(BASIC_BLOCK_H) \
    $(TREE_FLOW_H) tree-pass.h $(TREE_DUMP_H) $(DIAGNOSTIC_H) $(TIMEVAR_H) \

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index d079da9..ea1493a 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2009-01-26  Richard Guenther  <rguenther@suse.de>
+
+       PR middle-end/38851
+       * g++.dg/warn/Wuninitialized-1.C: New testcase.
+
 2009-01-25  Hans-Peter Nilsson  <hp@axis.com>
 
        * gcc.dg/bitfld-15.c: Gate warning on target

diff --git a/gcc/testsuite/g++.dg/warn/Wuninitialized-1.C b/gcc/testsuite/g++.dg/warn/Wuninitialized-1.C
new file mode 100644 (file)
index 0000000..7b1b90b
--- /dev/null
+++ b/gcc/testsuite/g++.dg/warn/Wuninitialized-1.C
@@ -0,0 +1,15 @@
+/* { dg-options "-O2 -Wuninitialized" } */
+
+struct Empty { Empty() {} }; /* { dg-bogus "uninitialized" } */
+struct Other {
+    Other(const Empty& e_) : e(e_) {}
+    Empty e;
+};
+void bar(Other&);
+void foo()
+{
+  Empty e;
+  Other o(e);
+  bar(o);
+}
+

diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index b4be514..8a72495 100644 (file)
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-dump.h"
 #include "domwalk.h"
 #include "flags.h"
+#include "langhooks.h"
 
 /* This file implements dead store elimination.
 
@@ -660,20 +661,35 @@ execute_simple_dse (void)
         tree op;
        bool removed = false;
         ssa_op_iter iter;
+       tree size;
 
-       if (gimple_stored_syms (stmt)
-           && !bitmap_empty_p (gimple_stored_syms (stmt))
-            && (is_gimple_assign (stmt)
-               || (is_gimple_call (stmt)
-                    && gimple_call_lhs (stmt)))
-           && !bitmap_intersect_p (gimple_stored_syms (stmt), variables_loaded))
+       if (is_gimple_assign (stmt)
+           && AGGREGATE_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt)))
+           && (size = lang_hooks.expr_size (gimple_assign_lhs (stmt)))
+           && integer_zerop (size))
+         {
+           if (dump_file && (dump_flags & TDF_DETAILS))
+             {
+               fprintf (dump_file, "  Deleted zero-sized store '");
+               print_gimple_stmt (dump_file, stmt, 0, dump_flags);
+               fprintf (dump_file, "'\n");
+             }
+           removed = true;
+           gsi_remove (&gsi, true);
+           todo |= TODO_cleanup_cfg;
+         }
+       else if (gimple_stored_syms (stmt)
+                && !bitmap_empty_p (gimple_stored_syms (stmt))
+                && (is_gimple_assign (stmt)
+                    || (is_gimple_call (stmt)
+                        && gimple_call_lhs (stmt)))
+                && !bitmap_intersect_p (gimple_stored_syms (stmt),
+                                        variables_loaded))
          {
            unsigned int i;
            bitmap_iterator bi;
            bool dead = true;
 
-
-
            /* See if STMT only stores to write-only variables and
               verify that there are no volatile operands.  tree-ssa-operands
               sets has_volatile_ops flag for all statements involving