In the following testcase generic_simplify folded A - (-B) -> A + B,
which means we didn't detect an overflow. So I've tweaked match.pd.
But fold-const.c still can do such a transformation as well, so I had
to tweak it there as well in the same way.
Bootstrapped/regtested on x86_64-linux, ok for trunk?
2014-11-12 Marek Polacek <pola...@redhat.com>
* match.pd (A - (-B) -> A + B): Check for TYPE_OVERFLOW_WRAPS
and SANITIZE_SI_OVERFLOW.
* fold-const.c (fold_binary_loc): Likewise.
* c-c++-common/ubsan/overflow-sub-4.c: New test.
* c-c++-common/ubsan/overflow-sub-2.c: Adjust dg-output.
* c-c++-common/ubsan/overflow-int128.c: Likewise.
diff --git gcc/fold-const.c gcc/fold-const.c
index 756f469..504e1b6 100644
--- gcc/fold-const.c
+++ gcc/fold-const.c
@@ -10544,6 +10544,8 @@ fold_binary_loc (location_t loc,
/* A - B -> A + (-B) if B is easily negatable. */
if (negate_expr_p (arg1)
+ && (TYPE_OVERFLOW_WRAPS (type)
+ || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0)
&& ((FLOAT_TYPE_P (type)
/* Avoid this transformation if B is a positive REAL_CST. */
&& (TREE_CODE (arg1) != REAL_CST
diff --git gcc/match.pd gcc/match.pd
index 29b5ab2..5a485f3 100644
--- gcc/match.pd
+++ gcc/match.pd
@@ -291,7 +291,9 @@ along with GCC; see the file COPYING3. If not see
(simplify
(minus (convert1? @0) (convert2? (negate @1)))
(if (tree_nop_conversion_p (type, TREE_TYPE (@0))
- && tree_nop_conversion_p (type, TREE_TYPE (@1)))
+ && tree_nop_conversion_p (type, TREE_TYPE (@1))
+ && (TYPE_OVERFLOW_WRAPS (type)
+ || (flag_sanitize & SANITIZE_SI_OVERFLOW) == 0))
(plus (convert @0) (convert @1))))
/* -(-A) -> A */
(simplify
diff --git gcc/testsuite/c-c++-common/ubsan/overflow-sub-2.c
gcc/testsuite/c-c++-common/ubsan/overflow-sub-2.c
index daf6a54..88c4762 100644
--- gcc/testsuite/c-c++-common/ubsan/overflow-sub-2.c
+++ gcc/testsuite/c-c++-common/ubsan/overflow-sub-2.c
@@ -43,12 +43,12 @@ main (void)
}
/* { dg-output "signed integer overflow: -2147483648 - 1 cannot be represented
in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -2147483648 \\+ -1 cannot be
represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -2147483548 \\+ -1024 cannot
be represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -2147483648 \\+ -1 cannot be
represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -2147482648 \\+ -1048576
cannot be represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -2147483548 - 1024 cannot be
represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -2147483648 - 1 cannot be
represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -2147482648 - 1048576 cannot
be represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* - 1 cannot be
represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* \\+ -1 cannot be
represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* \\+ -1024 cannot
be represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* \\+ -1 cannot be
represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* \\+ -1048576
cannot be represented in type 'long int'\[^\n\r]*" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* - 1 cannot be
represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* - 1024 cannot be
represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* - 1 cannot be
represented in type 'long int'\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: -\[^\n\r]* - 1048576 cannot
be represented in type 'long int'\[^\n\r]*" } */
diff --git gcc/testsuite/c-c++-common/ubsan/overflow-int128.c
gcc/testsuite/c-c++-common/ubsan/overflow-int128.c
index 125d6bf..4384d7c 100644
--- gcc/testsuite/c-c++-common/ubsan/overflow-int128.c
+++ gcc/testsuite/c-c++-common/ubsan/overflow-int128.c
@@ -41,7 +41,7 @@ main (void)
/* { dg-output "\[^\n\r]*signed integer overflow:
0x7fffffffffffffffffffffffffffff9b \\+ 1024 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
/* { dg-output "\[^\n\r]*signed integer overflow: -1 \\+
0x80000000000000000000000000000000 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
/* { dg-output "\[^\n\r]*signed integer overflow:
0x80000000000000000000000000000000 \\+ -1 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
-/* { dg-output "\[^\n\r]*signed integer overflow:
0x80000000000000000000000000000000 \\+ -1 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow:
0x80000000000000000000000000000000 - 1 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
/* { dg-output "\[^\n\r]*signed integer overflow:
0x80000000000000000000000000000064 \\+ -1024 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
/* { dg-output "\[^\n\r]*signed integer overflow:
0x7fffffffffffffffffffffffffffffff \\* 2 cannot be represented in type
'__int128'(\n|\r\n|\r)" } */
/* { dg-output "\[^\n\r]*negation of 0x80000000000000000000000000000000 cannot
be represented in type '__int128'; cast to an unsigned type to negate this
value to itself\[^\n\r]*(\n|\r\n|\r)" } */
diff --git gcc/testsuite/c-c++-common/ubsan/overflow-sub-4.c
gcc/testsuite/c-c++-common/ubsan/overflow-sub-4.c
index e69de29..519b7ba 100644
--- gcc/testsuite/c-c++-common/ubsan/overflow-sub-4.c
+++ gcc/testsuite/c-c++-common/ubsan/overflow-sub-4.c
@@ -0,0 +1,19 @@
+/* { dg-do run } */
+/* { dg-options "-fsanitize=signed-integer-overflow" } */
+
+#define INT_MIN (-__INT_MAX__ - 1)
+
+int
+main ()
+{
+ int x = INT_MIN;
+ int y = 0;
+ int z;
+ asm ("" : "+g" (y));
+ asm ("" : "+g" (x));
+ z = y - (-x);
+ asm ("" : "+g" (z));
+}
+
+/* { dg-output "negation of -2147483648 cannot be represented in type
'int'\[^\n\r]*; cast to an unsigned type to negate this value to
itself\[^\n\r]*(\n|\r\n|\r)" } */
+/* { dg-output "\[^\n\r]*signed integer overflow: 0 - -2147483648 cannot be
represented in type 'int'\[^\n\r]*(\n|\r\n|\r)" } */
Marek
