re PR c/4389 (Improper constant folding)

	PR c/4389
	* tree.c (host_integerp): Ensure that the constant integer is
	representable in a HOST_WIDE_INT or an unsigned HOST_WIDE_INT
	when pos is zero or non-zero respectively.  Clarify comment.
	* c-format.c (check_format_info_recurse): Fix host_integerp
	usage; the pos argument should be zero when assigning to a
	signed HOST_WIDE_INT.

	* gcc.dg/20020219-1.c: New test.

From-SVN: r49914

5 files changed, 52 insertions, 10 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index bbcf0f1..235f625 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2002-02-20  Roger Sayle  <roger@eyesopen.com>
+	    Jakub Jelinek  <jakub@redhat.com>
+
+	PR c/4389
+	* tree.c (host_integerp): Ensure that the constant integer is
+	representable in a HOST_WIDE_INT or an unsigned HOST_WIDE_INT
+	when pos is zero or non-zero respectively.  Clarify comment.
+	* c-format.c (check_format_info_recurse): Fix host_integerp
+	usage; the pos argument should be zero when assigning to a
+	signed HOST_WIDE_INT.
+
 2002-02-20  Richard Henderson  <rth@redhat.com>
 
 	* config/i386/i386.c (ix86_expand_vector_move): Use the mode
diff --git a/gcc/c-format.c b/gcc/c-format.c
index b15b630..d52cfba 100644
--- a/gcc/c-format.c
+++ b/gcc/c-format.c
@@ -1,6 +1,6 @@
 /* Check calls to formatted I/O functions (-Wformat).
-   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2001
-   Free Software Foundation, Inc.
+   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000,
+   2001, 2002 Free Software Foundation, Inc.
 
 This file is part of GCC.
 
@@ -1516,13 +1516,12 @@ check_format_info_recurse (status, res, info, format_tree, params, arg_num)
 	  res->number_non_literal++;
 	  return;
 	}
-      if (!host_integerp (arg1, 1))
+      if (!host_integerp (arg1, 0)
+	  || (offset = tree_low_cst (arg1, 0)) < 0)
 	{
 	  res->number_non_literal++;
 	  return;
 	}
-
-      offset = TREE_INT_CST_LOW (arg1);
     }
   if (TREE_CODE (format_tree) != ADDR_EXPR)
     {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index fb55f89..90b39b2 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -2,6 +2,8 @@
 
 	* gcc.c-torture/execute/20020219-1.c: New test.
 
+	* gcc.dg/20020219-1.c: New test.
+
 2002-02-17  Jakub Jelinek  <jakub@redhat.com>
 
 	* gcc.c-torture/execute/20020216-1.c: New test.
diff --git a/gcc/testsuite/gcc.dg/20020219-1.c b/gcc/testsuite/gcc.dg/20020219-1.c
new file mode 100644
index 0000000..c879f23
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/20020219-1.c
@@ -0,0 +1,28 @@
+/* PR c/4389
+   This testcase failed because host_integerp (x, 0) was returning
+   1 even for constants bigger than 2^31.  */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+
+extern void abort (void);
+extern void exit (int);
+struct A {
+  int a[10000][10000];
+};
+int b[2] = { 213151, 0 };
+
+void foo (struct A *x, int y)
+{
+  if (x->a[9999][9999] != x->a[y][y])
+    abort ();
+  if (x->a[9999][9999] != 213151)
+    abort ();
+}
+
+int main (void)
+{
+  struct A *x;
+  asm ("" : "=r" (x) : "0" (&b[1]));
+  foo (x - 1, 9999);
+  exit (0);
+}
diff --git a/gcc/tree.c b/gcc/tree.c
index 764aa79..5e0210b 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -3436,8 +3436,10 @@ tree_int_cst_compare (t1, t2)
     return 0;
 }
 
-/* Return 1 if T is an INTEGER_CST that can be represented in a single
-   HOST_WIDE_INT value.  If POS is nonzero, the result must be positive.  */
+/* Return 1 if T is an INTEGER_CST that can be manipulated efficiently on
+   the host.  If POS is zero, the value can be represented in a single
+   HOST_WIDE_INT.  If POS is nonzero, the value must be positive and can
+   be represented in a single unsigned HOST_WIDE_INT.  */
 
 int
 host_integerp (t, pos)
@@ -3449,9 +3451,9 @@ host_integerp (t, pos)
 	  && ((TREE_INT_CST_HIGH (t) == 0
 	       && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) >= 0)
 	      || (! pos && TREE_INT_CST_HIGH (t) == -1
-		  && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) < 0)
-	      || (! pos && TREE_INT_CST_HIGH (t) == 0
-		  && TREE_UNSIGNED (TREE_TYPE (t)))));
+		  && (HOST_WIDE_INT) TREE_INT_CST_LOW (t) < 0
+		  && ! TREE_UNSIGNED (TREE_TYPE (t)))
+	      || (pos && TREE_INT_CST_HIGH (t) == 0)));
 }
 
 /* Return the HOST_WIDE_INT least significant bits of T if it is an