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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-4405] tree-chrec: Fix up ICE on pointer multiplication [PR107835] Date: Wed, 30 Nov 2022 10:46:19 +0000 (GMT) [thread overview] Message-ID: <20221130104619.76A033858D37@sourceware.org> (raw) https://gcc.gnu.org/g:7716ee1e90412f785cba20acffd59fc7461302cb commit r13-4405-g7716ee1e90412f785cba20acffd59fc7461302cb Author: Jakub Jelinek <jakub@redhat.com> Date: Wed Nov 30 11:44:27 2022 +0100 tree-chrec: Fix up ICE on pointer multiplication [PR107835] r13-254-gdd3c7873a61019e9 added an optimization for {a, +, a} (x-1), but as can be seen on the following testcase, the way it is written where chrec_fold_multiply is called with type doesn't work for pointers: res = build_int_cst (TREE_TYPE (x), 1); res = chrec_fold_plus (TREE_TYPE (x), x, res); res = chrec_convert_rhs (type, res, NULL); res = chrec_fold_multiply (type, chrecr, res); while what we were doing before and what is still used if the condition doesn't match is fine: res = chrec_convert_rhs (TREE_TYPE (chrecr), x, NULL); res = chrec_fold_multiply (TREE_TYPE (chrecr), chrecr, res); res = chrec_fold_plus (type, CHREC_LEFT (chrec), res); because it performs chrec_fold_multiply on TREE_TYPE (chrecr) and converts only afterwards. I think the easiest fix is to ignore the new path for pointer types. 2022-11-30 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/107835 * tree-chrec.cc (chrec_apply): Don't handle "{a, +, a} (x-1)" as "a*x" if type is a pointer type. * gcc.c-torture/compile/pr107835.c: New test. Diff: --- gcc/testsuite/gcc.c-torture/compile/pr107835.c | 11 +++++++++++ gcc/tree-chrec.cc | 3 ++- 2 files changed, 13 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/gcc.c-torture/compile/pr107835.c b/gcc/testsuite/gcc.c-torture/compile/pr107835.c new file mode 100644 index 00000000000..122beff2f11 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr107835.c @@ -0,0 +1,11 @@ +/* PR tree-optimization/107835 */ + +int * +foo (void) +{ + int *x = 0; + unsigned n = n; + for (; n; --n, ++x) + ; + return x; +} diff --git a/gcc/tree-chrec.cc b/gcc/tree-chrec.cc index 7321fb9d282..dcf26cbae84 100644 --- a/gcc/tree-chrec.cc +++ b/gcc/tree-chrec.cc @@ -622,7 +622,8 @@ chrec_apply (unsigned var, /* "{a, +, b} (x)" -> "a + b*x". */ else if (operand_equal_p (CHREC_LEFT (chrec), chrecr) && TREE_CODE (x) == PLUS_EXPR - && integer_all_onesp (TREE_OPERAND (x, 1))) + && integer_all_onesp (TREE_OPERAND (x, 1)) + && !POINTER_TYPE_P (type)) { /* We know the number of iterations can't be negative. So {a, +, a} (x-1) -> "a*x". */
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