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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-4990] vrp: Handle pointers in maybe_set_nonzero_bits [PR108253] Date: Wed, 4 Jan 2023 11:17:07 +0000 (GMT) [thread overview] Message-ID: <20230104111707.3F5643858D1E@sourceware.org> (raw) https://gcc.gnu.org/g:ebc449119442501c927ede0e83697eaece72223e commit r13-4990-gebc449119442501c927ede0e83697eaece72223e Author: Jakub Jelinek <jakub@redhat.com> Date: Wed Jan 4 12:16:22 2023 +0100 vrp: Handle pointers in maybe_set_nonzero_bits [PR108253] maybe_set_nonzero_bits calls set_nonzero_bits which asserts that var doesn't have pointer type. While we could punt for those cases, I think we can handle at least some easy cases. Earlier in maybe_set_nonzero_bits we've checked this is on (var & cst) == 0 edge and the other edge is __builtin_unreachable, so if cst is say 3 as in the testcase, we want to turn it into 4 byte alignment of the pointer. 2023-01-04 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/108253 * tree-vrp.cc (maybe_set_nonzero_bits): Handle var with pointer types. * g++.dg/opt/pr108253.C: New test. Diff: --- gcc/testsuite/g++.dg/opt/pr108253.C | 48 +++++++++++++++++++++++++++++++++++++ gcc/tree-vrp.cc | 18 ++++++++++++-- 2 files changed, 64 insertions(+), 2 deletions(-) diff --git a/gcc/testsuite/g++.dg/opt/pr108253.C b/gcc/testsuite/g++.dg/opt/pr108253.C new file mode 100644 index 00000000000..0409121f2c7 --- /dev/null +++ b/gcc/testsuite/g++.dg/opt/pr108253.C @@ -0,0 +1,48 @@ +// PR tree-optimization/108253 +// { dg-do compile { target c++11 } } +// { dg-options "-O2" } + +struct S +{ + int *s; + S () : s (new int) {} + S (const S &r) noexcept : s (r.s) { __atomic_fetch_add (r.s, 1, 4); } +}; +struct T +{ + explicit T (const S &x) : t (x) {} + const S t; +}; +struct U +{ + operator int () const { new T (u); return 0; } + S u; +}; +bool foo (int matcher); +unsigned long bar (unsigned long pos, unsigned long end_pos); +struct V +{ + alignas (4) char v[4]; +}; +struct W +{ + void baz () + { + if (!w) __builtin_abort (); + if (reinterpret_cast <__UINTPTR_TYPE__> (w->v) % 4 != 0) __builtin_abort (); + __builtin_unreachable (); + } + [[gnu::noinline]] void qux (unsigned long) { if (!w) bar (0, x); } + V *w = nullptr; + unsigned x = 0; +}; + +void +test () +{ + W w; + U t; + if (!foo (t)) + w.baz (); + w.qux (0); +} diff --git a/gcc/tree-vrp.cc b/gcc/tree-vrp.cc index 0dfea5ace06..3c431760a16 100644 --- a/gcc/tree-vrp.cc +++ b/gcc/tree-vrp.cc @@ -789,8 +789,22 @@ maybe_set_nonzero_bits (edge e, tree var) return; } cst = gimple_assign_rhs2 (stmt); - set_nonzero_bits (var, wi::bit_and_not (get_nonzero_bits (var), - wi::to_wide (cst))); + if (POINTER_TYPE_P (TREE_TYPE (var))) + { + struct ptr_info_def *pi = SSA_NAME_PTR_INFO (var); + if (pi && pi->misalign) + return; + wide_int w = wi::bit_not (wi::to_wide (cst)); + unsigned int bits = wi::ctz (w); + if (bits == 0 || bits >= HOST_BITS_PER_INT) + return; + unsigned int align = 1U << bits; + if (pi == NULL || pi->align < align) + set_ptr_info_alignment (get_ptr_info (var), align, 0); + } + else + set_nonzero_bits (var, wi::bit_and_not (get_nonzero_bits (var), + wi::to_wide (cst))); } /* Searches the case label vector VEC for the index *IDX of the CASE_LABEL
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