From ec459469f8a75d96a9b26694554efcc900d411de Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 19 Dec 2022 14:55:45 +0100 Subject: [PATCH] tree-optimization/108164 - undefined overflow with IV vectorization vect_update_ivs_after_vectorizer can end up emitting a signed IV update when the loop body performed an unsigned computation. The following makes sure to perform that update in the type of the loop update type to avoid undefined behavior on overflow. PR tree-optimization/108164 * tree-vect-loop-manip.cc (vect_update_ivs_after_vectorizer): Perform vect_step_op_add update in the appropriate type. * gcc.dg/pr108164.c: New testcase. --- gcc/testsuite/gcc.dg/pr108164.c | 19 +++++++++++++++++++ gcc/tree-vect-loop-manip.cc | 12 +++++++----- 2 files changed, 26 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/pr108164.c diff --git a/gcc/testsuite/gcc.dg/pr108164.c b/gcc/testsuite/gcc.dg/pr108164.c new file mode 100644 index 000000000000..d76d557876ef --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr108164.c @@ -0,0 +1,19 @@ +/* { dg-do run } */ +/* { dg-options "-O3 -fno-tree-dce" } */ + +int a, b, c; +int main() +{ + int e = -1; + short f = -1; + for (; c < 1; c++) + while (f >= e) + f++; + for (; a < 2; a++) { + short g = ~(~b | ~f); + int h = -g; + int i = (3 / ~h) / ~b; + b = i; + } + return 0; +} diff --git a/gcc/tree-vect-loop-manip.cc b/gcc/tree-vect-loop-manip.cc index 1d96130c985e..5ec739ed2181 100644 --- a/gcc/tree-vect-loop-manip.cc +++ b/gcc/tree-vect-loop-manip.cc @@ -1576,14 +1576,16 @@ vect_update_ivs_after_vectorizer (loop_vec_info loop_vinfo, if (induction_type == vect_step_op_add) { - off = fold_build2 (MULT_EXPR, TREE_TYPE (step_expr), - fold_convert (TREE_TYPE (step_expr), niters), - step_expr); + tree stype = TREE_TYPE (step_expr); + off = fold_build2 (MULT_EXPR, stype, + fold_convert (stype, niters), step_expr); if (POINTER_TYPE_P (type)) ni = fold_build_pointer_plus (init_expr, off); else - ni = fold_build2 (PLUS_EXPR, type, - init_expr, fold_convert (type, off)); + ni = fold_convert (type, + fold_build2 (PLUS_EXPR, stype, + fold_convert (stype, init_expr), + off)); } /* Don't bother call vect_peel_nonlinear_iv_init. */ else if (induction_type == vect_step_op_neg) -- 2.47.3