From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id 712173858D20 for ; Thu, 13 Apr 2023 16:00:07 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 712173858D20 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 906E2D75; Thu, 13 Apr 2023 09:00:51 -0700 (PDT) Received: from localhost (e121540-lin.manchester.arm.com [10.32.110.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 9D4043F6C4; Thu, 13 Apr 2023 09:00:06 -0700 (PDT) From: Richard Sandiford To: gcc-patches@gcc.gnu.org Mail-Followup-To: gcc-patches@gcc.gnu.org,jakub@redhat.com, richard.sandiford@arm.com Cc: jakub@redhat.com Subject: [PATCH] aarch64: Don't trust TYPE_ALIGN for pointers [PR108910] Date: Thu, 13 Apr 2023 17:00:05 +0100 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-31.1 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_NONE,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,SPF_HELO_NONE,SPF_NONE,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: The aarch64 PCS rules ignore user alignment for scalars and vectors and use the "natural" alignment of the type. GCC tried to calculate that natural alignment using: TYPE_ALIGN (TYPE_MAIN_VARIANT (type)) But as discussed in the PR, it's possible that the main variant of a pointer type is an overaligned type (although that's usually accidental). This isn't known to be a problem for other types, so this patch changes the bare minimum. It might be that we need to ignore TYPE_ALIGN in other cases too. Tested on aarch64-linux-gnu & pushed to trunk so far. Will backport to GCC 12 soon. Richard gcc/ PR target/108910 * config/aarch64/aarch64.cc (aarch64_function_arg_alignment): Do not trust TYPE_ALIGN for pointer types; use POINTER_SIZE instead. gcc/testsuite/ PR target/108910 * gcc.dg/torture/pr108910.c: New test. --- gcc/config/aarch64/aarch64.cc | 15 ++++++++++++++- gcc/testsuite/gcc.dg/torture/pr108910.c | 8 ++++++++ 2 files changed, 22 insertions(+), 1 deletion(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr108910.c diff --git a/gcc/config/aarch64/aarch64.cc b/gcc/config/aarch64/aarch64.cc index 42617ced73a..f4ef22ce02f 100644 --- a/gcc/config/aarch64/aarch64.cc +++ b/gcc/config/aarch64/aarch64.cc @@ -7484,7 +7484,20 @@ aarch64_function_arg_alignment (machine_mode mode, const_tree type, gcc_assert (TYPE_MODE (type) == mode); if (!AGGREGATE_TYPE_P (type)) - return TYPE_ALIGN (TYPE_MAIN_VARIANT (type)); + { + /* The ABI alignment is the natural alignment of the type, without + any attributes applied. Normally this is the alignment of the + TYPE_MAIN_VARIANT, but not always; see PR108910 for a counterexample. + For now we just handle the known exceptions explicitly. */ + type = TYPE_MAIN_VARIANT (type); + if (POINTER_TYPE_P (type)) + { + gcc_assert (known_eq (POINTER_SIZE, GET_MODE_BITSIZE (mode))); + return POINTER_SIZE; + } + gcc_assert (!TYPE_USER_ALIGN (type)); + return TYPE_ALIGN (type); + } if (TREE_CODE (type) == ARRAY_TYPE) return TYPE_ALIGN (TREE_TYPE (type)); diff --git a/gcc/testsuite/gcc.dg/torture/pr108910.c b/gcc/testsuite/gcc.dg/torture/pr108910.c new file mode 100644 index 00000000000..59735488c2e --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr108910.c @@ -0,0 +1,8 @@ +extern void foo (float, float *, float *); + +void +bar (void *p) +{ + float *__attribute__((aligned (64))) q = __builtin_assume_aligned (p, 64); + foo (0.0f, q, q); +} -- 2.25.1