From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2140) id 7738038582A6; Sun, 19 Nov 2023 06:31:16 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7738038582A6 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1700375476; bh=j7qyacbxklHIvKx0PdXlRAnRJIiBLDORukm26PFBnZI=; h=From:To:Subject:Date:From; b=hkDpjBNE6f8ybrC0SRAtqjk2H6zipkCyC8dEyvOoaKHTbuRhM3asuSmD3Bpq/UXR3 kEzOBDr9BKvCKPtCe4IOBBz4jSz1rk5FPfYcXwR+AfkIhS+wez0buPpudqNTN7rjqv igY3+IQNUNfkOFSXnm8HTYBoGvmEIgHWYunvH1nE= Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Alexandre Oliva To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/users/aoliva/heads/testme)] warn on cast of pointer to packed plus constant X-Act-Checkin: gcc X-Git-Author: Alexandre Oliva X-Git-Refname: refs/users/aoliva/heads/testme X-Git-Oldrev: 48dece46f1b5ea2fa7b3bf8c8165047484073a7c X-Git-Newrev: c50d78d2eb189e6cdcf5b2c341f9cf76e3fb7dc1 Message-Id: <20231119063116.7738038582A6@sourceware.org> Date: Sun, 19 Nov 2023 06:31:16 +0000 (GMT) List-Id: https://gcc.gnu.org/g:c50d78d2eb189e6cdcf5b2c341f9cf76e3fb7dc1 commit c50d78d2eb189e6cdcf5b2c341f9cf76e3fb7dc1 Author: Alexandre Oliva Date: Sun Nov 19 01:25:01 2023 -0300 warn on cast of pointer to packed plus constant gcc.dg/analyzer/null-deref-pr108251-smp-fetch_ssl_fc_has_early.c gets an unaligned pointer value warning on -fshort-enums targets in C, but not in C++. The former simplifies the offset-and-cast expression enough that check_and_warn_address_or_pointer_of_packed_member finds no more than a type cast of the base pointer, but in C++, the entire expression, with cast, constant offsetting, and cast again, is retained, and that's too much for the warning code. Or rather it was. It's easy enough to take the base pointer from PLUS_POINTER_EXPR, and a constant offset can't possibly increase alignment for just any pointer of laxer alignment, so we can safely disregard the offset. for gcc/c-family/ChangeLog * c-warn.cc (check_and_warn_address_or_pointer_of_packed_member): Take the base pointer from PLUS_POINTER_EXPR when the addend is constant. Diff: --- gcc/c-family/c-warn.cc | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/gcc/c-family/c-warn.cc b/gcc/c-family/c-warn.cc index d2938b91043..c705f43e5c3 100644 --- a/gcc/c-family/c-warn.cc +++ b/gcc/c-family/c-warn.cc @@ -3108,9 +3108,17 @@ check_and_warn_address_or_pointer_of_packed_member (tree type, tree rhs) do { - while (TREE_CODE (rhs) == COMPOUND_EXPR) - rhs = TREE_OPERAND (rhs, 1); - orig_rhs = rhs; + do + { + orig_rhs = rhs; + while (TREE_CODE (rhs) == COMPOUND_EXPR) + rhs = TREE_OPERAND (rhs, 1); + /* Constants can't increase the alignment. */ + while (TREE_CODE (rhs) == POINTER_PLUS_EXPR + && CONSTANT_CLASS_P (TREE_OPERAND (rhs, 1))) + rhs = TREE_OPERAND (rhs, 0); + } + while (orig_rhs != rhs); STRIP_NOPS (rhs); nop_p |= orig_rhs != rhs; }