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gcc/gcc47-pr55137.patch

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2012-11-07 Jakub Jelinek <jakub@redhat.com>
PR c++/55137
* fold-const.c (fold_binary_loc) <associate>: Don't introduce
TREE_OVERFLOW through reassociation. If type doesn't have defined
overflow, but one or both of the operands do, use the wrapping type
for reassociation and only convert to type at the end.
* g++.dg/opt/pr55137.C: New test.
* gcc.c-torture/execute/pr55137.c: New test.
--- gcc/fold-const.c.jj 2012-11-07 09:16:41.929494183 +0100
+++ gcc/fold-const.c 2012-11-07 09:47:12.227710542 +0100
@@ -10309,6 +10309,7 @@ fold_binary_loc (location_t loc,
{
tree var0, con0, lit0, minus_lit0;
tree var1, con1, lit1, minus_lit1;
+ tree atype = type;
bool ok = true;
/* Split both trees into variables, constants, and literals. Then
@@ -10324,11 +10325,25 @@ fold_binary_loc (location_t loc,
if (code == MINUS_EXPR)
code = PLUS_EXPR;
- /* With undefined overflow we can only associate constants with one
- variable, and constants whose association doesn't overflow. */
+ /* With undefined overflow prefer doing association in a type
+ which wraps on overflow, if that is one of the operand types. */
if ((POINTER_TYPE_P (type) && POINTER_TYPE_OVERFLOW_UNDEFINED)
|| (INTEGRAL_TYPE_P (type) && !TYPE_OVERFLOW_WRAPS (type)))
{
+ if (INTEGRAL_TYPE_P (TREE_TYPE (arg0))
+ && TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg0)))
+ atype = TREE_TYPE (arg0);
+ else if (INTEGRAL_TYPE_P (TREE_TYPE (arg1))
+ && TYPE_OVERFLOW_WRAPS (TREE_TYPE (arg1)))
+ atype = TREE_TYPE (arg1);
+ gcc_assert (TYPE_PRECISION (atype) == TYPE_PRECISION (type));
+ }
+
+ /* With undefined overflow we can only associate constants with one
+ variable, and constants whose association doesn't overflow. */
+ if ((POINTER_TYPE_P (atype) && POINTER_TYPE_OVERFLOW_UNDEFINED)
+ || (INTEGRAL_TYPE_P (atype) && !TYPE_OVERFLOW_WRAPS (atype)))
+ {
if (var0 && var1)
{
tree tmp0 = var0;
@@ -10343,16 +10358,6 @@ fold_binary_loc (location_t loc,
if (!operand_equal_p (tmp0, tmp1, 0))
ok = false;
}
-
- if (ok && lit0 && lit1)
- {
- tree tmp0 = fold_convert (type, lit0);
- tree tmp1 = fold_convert (type, lit1);
-
- if (!TREE_OVERFLOW (tmp0) && !TREE_OVERFLOW (tmp1)
- && TREE_OVERFLOW (fold_build2 (code, type, tmp0, tmp1)))
- ok = false;
- }
}
/* Only do something if we found more than two objects. Otherwise,
@@ -10363,10 +10368,16 @@ fold_binary_loc (location_t loc,
+ (lit0 != 0) + (lit1 != 0)
+ (minus_lit0 != 0) + (minus_lit1 != 0))))
{
- var0 = associate_trees (loc, var0, var1, code, type);
- con0 = associate_trees (loc, con0, con1, code, type);
- lit0 = associate_trees (loc, lit0, lit1, code, type);
- minus_lit0 = associate_trees (loc, minus_lit0, minus_lit1, code, type);
+ bool any_overflows = false;
+ if (lit0) any_overflows |= TREE_OVERFLOW (lit0);
+ if (lit1) any_overflows |= TREE_OVERFLOW (lit1);
+ if (minus_lit0) any_overflows |= TREE_OVERFLOW (minus_lit0);
+ if (minus_lit1) any_overflows |= TREE_OVERFLOW (minus_lit1);
+ var0 = associate_trees (loc, var0, var1, code, atype);
+ con0 = associate_trees (loc, con0, con1, code, atype);
+ lit0 = associate_trees (loc, lit0, lit1, code, atype);
+ minus_lit0 = associate_trees (loc, minus_lit0, minus_lit1,
+ code, atype);
/* Preserve the MINUS_EXPR if the negative part of the literal is
greater than the positive part. Otherwise, the multiplicative
@@ -10380,38 +10391,45 @@ fold_binary_loc (location_t loc,
&& tree_int_cst_lt (lit0, minus_lit0))
{
minus_lit0 = associate_trees (loc, minus_lit0, lit0,
- MINUS_EXPR, type);
+ MINUS_EXPR, atype);
lit0 = 0;
}
else
{
lit0 = associate_trees (loc, lit0, minus_lit0,
- MINUS_EXPR, type);
+ MINUS_EXPR, atype);
minus_lit0 = 0;
}
}
+
+ /* Don't introduce overflows through reassociation. */
+ if (!any_overflows
+ && ((lit0 && TREE_OVERFLOW (lit0))
+ || (minus_lit0 && TREE_OVERFLOW (minus_lit0))))
+ return NULL_TREE;
+
if (minus_lit0)
{
if (con0 == 0)
return
fold_convert_loc (loc, type,
associate_trees (loc, var0, minus_lit0,
- MINUS_EXPR, type));
+ MINUS_EXPR, atype));
else
{
con0 = associate_trees (loc, con0, minus_lit0,
- MINUS_EXPR, type);
+ MINUS_EXPR, atype);
return
fold_convert_loc (loc, type,
associate_trees (loc, var0, con0,
- PLUS_EXPR, type));
+ PLUS_EXPR, atype));
}
}
- con0 = associate_trees (loc, con0, lit0, code, type);
+ con0 = associate_trees (loc, con0, lit0, code, atype);
return
fold_convert_loc (loc, type, associate_trees (loc, var0, con0,
- code, type));
+ code, atype));
}
}
--- gcc/testsuite/g++.dg/opt/pr55137.C.jj 2012-11-07 09:31:45.027160654 +0100
+++ gcc/testsuite/g++.dg/opt/pr55137.C 2012-11-07 09:31:45.028160649 +0100
@@ -0,0 +1,4 @@
+// PR c++/55137
+// { dg-do compile }
+
+enum E { F = -1 + (int) (sizeof (int) - 1) };
--- gcc/testsuite/gcc.c-torture/execute/pr55137.c.jj 2012-11-07 09:44:11.226768063 +0100
+++ gcc/testsuite/gcc.c-torture/execute/pr55137.c 2012-11-07 09:44:24.380691303 +0100
@@ -0,0 +1,30 @@
+/* PR c++/55137 */
+
+extern void abort (void);
+
+int
+foo (unsigned int x)
+{
+ return ((int) (x + 1U) + 1) < (int) x;
+}
+
+int
+bar (unsigned int x)
+{
+ return (int) (x + 1U) + 1;
+}
+
+int
+baz (unsigned int x)
+{
+ return x + 1U;
+}
+
+int
+main ()
+{
+ if (foo (__INT_MAX__) != (bar (__INT_MAX__) < __INT_MAX__)
+ || foo (__INT_MAX__) != ((int) baz (__INT_MAX__) + 1 < __INT_MAX__))
+ abort ();
+ return 0;
+}
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