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From: Richard Biener <rguenth@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r14-4790] tree-optimization/111445 - simple_iv simplification fault Date: Fri, 20 Oct 2023 13:53:54 +0000 (GMT) [thread overview] Message-ID: <20231020135354.5D6793858D20@sourceware.org> (raw) https://gcc.gnu.org/g:9692309ed6b625f0fb358c0e230404b5603f69a6 commit r14-4790-g9692309ed6b625f0fb358c0e230404b5603f69a6 Author: Richard Biener <rguenther@suse.de> Date: Fri Oct 20 15:08:49 2023 +0200 tree-optimization/111445 - simple_iv simplification fault The following fixes a missed check in the simple_iv attempt to simplify (signed T)((unsigned T) base + step) where it allows a truncating inner conversion leading to wrong code. PR tree-optimization/111445 * tree-scalar-evolution.cc (simple_iv_with_niters): Add missing check for a sign-conversion. * gcc.dg/torture/pr111445.c: New testcase. Diff: --- gcc/testsuite/gcc.dg/torture/pr111445.c | 29 +++++++++++++++++++++++++++++ gcc/tree-scalar-evolution.cc | 3 ++- 2 files changed, 31 insertions(+), 1 deletion(-) diff --git a/gcc/testsuite/gcc.dg/torture/pr111445.c b/gcc/testsuite/gcc.dg/torture/pr111445.c new file mode 100644 index 000000000000..320e0b906754 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr111445.c @@ -0,0 +1,29 @@ +/* { dg-do run } */ + +extern void abort (void); +short a, b; +unsigned char c = 255; +unsigned cnt; +void __attribute__((noipa)) +check (int x) +{ + if (x != 0) + abort (); + cnt++; +} +int main() +{ + int d; + unsigned char e; + d = 0; + for (; a >= 0; a--) { + int *f = &d; + *f = c; + } + e = 0; + for (; (unsigned char)(d - 255) + e <= 1; e++) + check (b); + if (cnt != 2) + abort (); + return 0; +} diff --git a/gcc/tree-scalar-evolution.cc b/gcc/tree-scalar-evolution.cc index 7cafe5ce5760..95a15fe09881 100644 --- a/gcc/tree-scalar-evolution.cc +++ b/gcc/tree-scalar-evolution.cc @@ -3286,7 +3286,8 @@ simple_iv_with_niters (class loop *wrto_loop, class loop *use_loop, type = TREE_TYPE (iv->base); e = TREE_OPERAND (iv->base, 0); - if (TREE_CODE (e) != PLUS_EXPR + if (!tree_nop_conversion_p (type, TREE_TYPE (e)) + || TREE_CODE (e) != PLUS_EXPR || TREE_CODE (TREE_OPERAND (e, 1)) != INTEGER_CST || !tree_int_cst_equal (iv->step, fold_convert (type, TREE_OPERAND (e, 1))))
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