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re PR sanitizer/81065 (UBSAN: false positive as a result of distribution involving different types) 

2017-06-13  Richard Biener  <rguenther@suse.de>

	PR middle-end/81065
	* fold-const.c (extract_muldiv_1): Remove bogus distribution
	case of C * (x * C2 + C3).
	(fold_addr_of_array_ref_difference): Properly fold index difference.

	* c-c++-common/ubsan/pr81065.c: New testcase.

From-SVN: r249144
This commit is contained in:
Richard Biener 2017-06-13 07:07:08 +00:00 committed by Richard Biener
parent cd34e54306
commit 4f2c198d76
4 changed files with 26 additions and 6 deletions
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7
gcc/ChangeLog
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@ -1,3 +1,10 @@
2017-06-13 Richard Biener <rguenther@suse.de>
PR middle-end/81065
* fold-const.c (extract_muldiv_1): Remove bogus distribution
case of C * (x * C2 + C3).
(fold_addr_of_array_ref_difference): Properly fold index difference.
2017-06-12 David S. Miller <davem@davemloft.net>
PR target/80968

7
gcc/fold-const.c
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@ -6241,11 +6241,6 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type,
if (TYPE_UNSIGNED (ctype) && ctype != type)
break;
/* If we were able to eliminate our operation from the first side,
apply our operation to the second side and reform the PLUS. */
if (t1 != 0 && (TREE_CODE (t1) != code || code == MULT_EXPR))
return fold_build2 (tcode, ctype, fold_convert (ctype, t1), op1);
/* The last case is if we are a multiply. In that case, we can
apply the distributive law to commute the multiply and addition
if the multiplication of the constants doesn't overflow
@ -8908,7 +8903,7 @@ fold_addr_of_array_ref_difference (location_t loc, tree type,
tree op0 = fold_convert_loc (loc, type, TREE_OPERAND (aref0, 1));
tree op1 = fold_convert_loc (loc, type, TREE_OPERAND (aref1, 1));
tree esz = fold_convert_loc (loc, type, array_ref_element_size (aref0));
tree diff = build2 (MINUS_EXPR, type, op0, op1);
tree diff = fold_build2_loc (loc, MINUS_EXPR, type, op0, op1);
return fold_build2_loc (loc, PLUS_EXPR, type,
base_offset,
fold_build2_loc (loc, MULT_EXPR, type,

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-06-13 Richard Biener <rguenther@suse.de>
PR middle-end/81065
* c-c++-common/ubsan/pr81065.c: New testcase.
2017-06-12 Ian Lance Taylor <iant@golang.org>
* gcc.dg/tree-prof/split-1.c: Require split_stack, don't require

13
gcc/testsuite/c-c++-common/ubsan/pr81065.c Normal file
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@ -0,0 +1,13 @@
/* { dg-do run } */
/* { dg-options "-fsanitize=undefined -fsanitize-undefined-trap-on-error" } */
unsigned char x = 154;
int foo() {
// 8575 * (254408 - 9057) = 8575 * 245351 = 2103884825 = 0x7d66bc19
return 8575 * (1652 * x - 9057);
}
int main() {
foo();
return 0;
}