re PR c/43007 (No longer folds (unsigned int) ((long long unsigned int) spi_bias / 1008))

2010-02-10  Richard Guenther  <rguenther@suse.de>

	PR c/43007
	* tree.c (get_unwidened): Handle constants.
	* convert.c (convert_to_integer): Handle TRUNC_DIV_EXPR.

	* gcc.c-torture/execute/20100209-1.c: New testcase.
	* gcc.dg/fold-div-3.c: Likewise.

From-SVN: r156653

6 files changed, 72 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ecda788..ce3d086 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2010-02-10  Richard Guenther  <rguenther@suse.de>
+
+	PR c/43007
+	* tree.c (get_unwidened): Handle constants.
+	* convert.c (convert_to_integer): Handle TRUNC_DIV_EXPR.
+
 2010-02-10  Martin Jambor  <mjambor@suse.cz>
 
 	PR lto/42985
diff --git a/gcc/convert.c b/gcc/convert.c
index 4fe95ce..39fbd4d 100644
--- a/gcc/convert.c
+++ b/gcc/convert.c
@@ -673,6 +673,31 @@ convert_to_integer (tree type, tree expr)
 	    }
 	  break;
 
+	case TRUNC_DIV_EXPR:
+	  {
+	    tree arg0 = get_unwidened (TREE_OPERAND (expr, 0), type);
+	    tree arg1 = get_unwidened (TREE_OPERAND (expr, 1), type);
+
+	    /* Don't distribute unless the output precision is at least as big
+	       as the actual inputs and it has the same signedness.  */
+	    if (outprec >= TYPE_PRECISION (TREE_TYPE (arg0))
+		&& outprec >= TYPE_PRECISION (TREE_TYPE (arg1))
+		/* If signedness of arg0 and arg1 don't match,
+		   we can't necessarily find a type to compare them in.  */
+		&& (TYPE_UNSIGNED (TREE_TYPE (arg0))
+		    == TYPE_UNSIGNED (TREE_TYPE (arg1)))
+		/* Do not change the sign of the division.  */
+		&& (TYPE_UNSIGNED (TREE_TYPE (expr))
+		    == TYPE_UNSIGNED (TREE_TYPE (arg0)))
+		/* Either require unsigned division or a division by
+		   a constant that is not -1.  */
+		&& (TYPE_UNSIGNED (TREE_TYPE (arg0))
+		    || (TREE_CODE (arg1) == INTEGER_CST
+			&& !integer_all_onesp (arg1))))
+	      goto trunc1;
+	    break;
+	  }
+
 	case MAX_EXPR:
 	case MIN_EXPR:
 	case MULT_EXPR:
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 59181d7..273636c 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2010-02-10  Richard Guenther  <rguenther@suse.de>
+
+	PR c/43007
+	* gcc.c-torture/execute/20100209-1.c: New testcase.
+	* gcc.dg/fold-div-3.c: Likewise.
+
 2010-02-10  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcc.dg/builtin-ffs-1.c: New test.
diff --git a/gcc/testsuite/gcc.c-torture/execute/20100209-1.c b/gcc/testsuite/gcc.c-torture/execute/20100209-1.c
new file mode 100644
index 0000000..bf0597b
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/20100209-1.c
@@ -0,0 +1,12 @@
+int bar(int foo)
+{
+  return (int)(((unsigned long long)(long long)foo) / 8);
+}
+extern void abort (void);
+int main()
+{
+  if (sizeof (long long) > sizeof (int)
+      && bar(-1) != -1)
+    abort ();
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/fold-div-3.c b/gcc/testsuite/gcc.dg/fold-div-3.c
new file mode 100644
index 0000000..2e78757
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/fold-div-3.c
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-original" } */
+
+unsigned int
+apply_frontend_param (unsigned int spi_bias)
+{
+  static const int ppm = 8000;
+  spi_bias /= 1000ULL + ppm/1000;
+  return spi_bias;
+}
+
+/* Make sure we perform the division in the narrower type.  */
+
+/* { dg-final { scan-tree-dump "spi_bias = spi_bias / 1008;" "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */
diff --git a/gcc/tree.c b/gcc/tree.c
index 5d44841..c51cca7 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -7623,6 +7623,14 @@ get_unwidened (tree op, tree for_type)
 	}
     }
 
+  /* If we finally reach a constant see if it fits in for_type and
+     in that case convert it.  */
+  if (for_type
+      && TREE_CODE (win) == INTEGER_CST
+      && TREE_TYPE (win) != for_type
+      && int_fits_type_p (win, for_type))
+    win = fold_convert (for_type, win);
+
   return win;
 }