tree-optimize.c (init_tree_optimization_passes): Run…

tree-optimize.c (init_tree_optimization_passes): Run pass_late_warn_uninitialized before the last DCE run.


	tree-optimization/18501
	* tree-optimize.c (init_tree_optimization_passes): Run
	pass_late_warn_uninitialized before the last DCE run.


testsuite/ChangeLog:

	* gcc.dg/pr18501.c: New test.
	* gcc.dg/uninit-5.c: XFAIL.
	* gcc.dg/uninit-9.c: XFAIL.

From-SVN: r92337

gcc/ChangeLog

+2004-12-17  Diego Novillo  <dnovillo@redhat.com>
+
+	tree-optimization/18501
+	* tree-optimize.c (init_tree_optimization_passes): Run
+	pass_late_warn_uninitialized before the last DCE run.
+
 2004-12-17  Richard Henderson  <rth@redhat.com>
 
 	* config/i386/i386.c (x86_64_reg_class_name): Re-indent.

gcc/testsuite/ChangeLog

+2004-12-17  Diego Novillo  <dnovillo@redhat.com>
+
+	* gcc.dg/pr18501.c: New test.
+	* gcc.dg/uninit-5.c: XFAIL.
+	* gcc.dg/uninit-9.c: XFAIL.
+
 2004-12-17  Dale Johannesen  <dalej@apple.com>
 
 	* gcc.dg/20041213-1.c:  New.

gcc/testsuite/gcc.dg/pr18501.c

+/* Expected uninitialized variable warning.  */
+
+/* { dg-do compile } */
+/* { dg-options "-O -Wuninitialized" } */
+
+unsigned bmp_iter_set ();
+int something (void);
+
+void
+bitmap_print_value_set (void)
+{
+  unsigned first;	/* { dg-warning "may be used" "conditional in loop" } */
+  
+  for (; bmp_iter_set (); )
+    {
+      if (!first)
+	something ();
+      first = 0;
+    }
+}

gcc/testsuite/gcc.dg/uninit-5.c

@@ -9,7 +9,7 @@ extern void foo(void);
 void
 func1(int cond)
 {
-    int x;  /* { dg-bogus "x" "uninitialized variable warning" } */
+    int x;  /* { dg-bogus "x" "uninitialized variable warning" { xfail *-*-* } } */
 
     if(cond)
 	x = 1;
@@ -23,7 +23,7 @@ func1(int cond)
 void
 func2 (int cond)
 {
-    int x;  /* { dg-bogus "x" "uninitialized variable warning" } */
+    int x;  /* { dg-bogus "x" "uninitialized variable warning" { xfail *-*-* } } */
     int flag = 0;
 
     if(cond)

gcc/testsuite/gcc.dg/uninit-9.c

@@ -23,7 +23,7 @@ func(struct foo *list, int count)
 {
     int n_clobbers = 0;
     int i;
-    struct foo **clob_list;   /* { dg-bogus "clob_list" "uninitialized variable warning" } */
+    struct foo **clob_list;   /* { dg-bogus "clob_list" "uninitialized variable warning" { xfail *-*-* } } */
 
     if(list[0].type == PARALLEL)
     {

gcc/tree-optimize.c

@@ -381,12 +381,21 @@ init_tree_optimization_passes (void)
   NEXT_PASS (pass_loop);
   NEXT_PASS (pass_dominator);
   NEXT_PASS (pass_redundant_phi);
+  /* FIXME: If DCE is not run before checking for uninitialized uses,
+     we may get false warnings (e.g., testsuite/gcc.dg/uninit-5.c).
+     However, this also causes us to misdiagnose cases that should be
+     real warnings (e.g., testsuite/gcc.dg/pr18501.c).
+     
+     To fix the false positives in uninit-5.c, we would have to
+     account for the predicates protecting the set and the use of each
+     variable.  Using a representation like Gated Single Assignment
+     may help.  */
+  NEXT_PASS (pass_late_warn_uninitialized);
   NEXT_PASS (pass_cd_dce);
   NEXT_PASS (pass_dse);
   NEXT_PASS (pass_forwprop);
   NEXT_PASS (pass_phiopt);
   NEXT_PASS (pass_tail_calls);
-  NEXT_PASS (pass_late_warn_uninitialized);
   NEXT_PASS (pass_del_ssa);
   NEXT_PASS (pass_nrv);
   NEXT_PASS (pass_remove_useless_vars);