The following plugs one place in extract_muldiv where it should avoid folding when sanitizing overflow.
I'm unsure about the testcase, I didn't find any that tests for a runtime sanitizer error ... Bootstrapped and tested on x86_64-unknown-linux-gnu. OK? PR middle-end/108995 * fold-const.cc (extract_muldiv_1): Avoid folding (CST * b) / CST2 when sanitizing overflow and we rely on overflow being undefined. * gcc.dg/ubsan/pr108995.c: New testcase. --- gcc/fold-const.cc | 7 +++---- gcc/testsuite/gcc.dg/ubsan/pr108995.c | 15 +++++++++++++++ 2 files changed, 18 insertions(+), 4 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/ubsan/pr108995.c diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc index 99882ef820a..02a24c5fe65 100644 --- a/gcc/fold-const.cc +++ b/gcc/fold-const.cc @@ -7093,6 +7093,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type, If we have an unsigned type, we cannot do this since it will change the result if the original computation overflowed. */ if (TYPE_OVERFLOW_UNDEFINED (ctype) + && !TYPE_OVERFLOW_SANITIZED (ctype) && ((code == MULT_EXPR && tcode == EXACT_DIV_EXPR) || (tcode == MULT_EXPR && code != TRUNC_MOD_EXPR && code != CEIL_MOD_EXPR @@ -7102,8 +7103,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type, if (wi::multiple_of_p (wi::to_wide (op1), wi::to_wide (c), TYPE_SIGN (type))) { - if (TYPE_OVERFLOW_UNDEFINED (ctype)) - *strict_overflow_p = true; + *strict_overflow_p = true; return fold_build2 (tcode, ctype, fold_convert (ctype, op0), fold_convert (ctype, const_binop (TRUNC_DIV_EXPR, @@ -7112,8 +7112,7 @@ extract_muldiv_1 (tree t, tree c, enum tree_code code, tree wide_type, else if (wi::multiple_of_p (wi::to_wide (c), wi::to_wide (op1), TYPE_SIGN (type))) { - if (TYPE_OVERFLOW_UNDEFINED (ctype)) - *strict_overflow_p = true; + *strict_overflow_p = true; return fold_build2 (code, ctype, fold_convert (ctype, op0), fold_convert (ctype, const_binop (TRUNC_DIV_EXPR, diff --git a/gcc/testsuite/gcc.dg/ubsan/pr108995.c b/gcc/testsuite/gcc.dg/ubsan/pr108995.c new file mode 100644 index 00000000000..79a178c6751 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ubsan/pr108995.c @@ -0,0 +1,15 @@ +/* { dg-do run { xfail *-*-* } } */ +/* With optimization we constant fold and diagnose the overflow and do + not sanitize anything. */ +/* { dg-skip-if "" { *-*-* } { "*" } { ! "-O0" } } */ +/* { dg-options "-fsanitize=undefined -fno-sanitize-recover=undefined" } */ + +int a; +const int b = 44514; +int *c = &a; + +int main () +{ + *c = 65526 * b / 6; + return 0; +} -- 2.35.3