From 95decac3ce8c8c7c5302cd6fac005a10463de165 Mon Sep 17 00:00:00 2001
From: Andre Vieira <andre.simoesdiasvieira@arm.com>
Date: Fri, 28 Oct 2022 15:05:11 +0100
Subject: [PATCH] vect: Reject non-byte offsets for gather/scatters [PR107346]
The ada failure reported in the PR was being caused by vect_check_gather_scatter
failing to deal with bit offsets that weren't multiples of BITS_PER_UNIT. This
patch makes vect_check_gather_scatter reject memory accesses with such offsets.
gcc/ChangeLog:
PR tree-optimization/107346
* tree-vect-data-refs.cc (vect_check_gather_scatter): Reject offsets
that aren't multiples of BITS_PER_UNIT.
---
gcc/tree-vect-data-refs.cc | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/gcc/tree-vect-data-refs.cc b/gcc/tree-vect-data-refs.cc
index 4a23d6172aaa..6c892791bd4c 100644
--- a/gcc/tree-vect-data-refs.cc
+++ b/gcc/tree-vect-data-refs.cc
@@ -4016,6 +4016,11 @@ vect_check_gather_scatter (stmt_vec_info stmt_info, loop_vec_info loop_vinfo,
if (reversep)
return false;
+ /* PR 107346. Packed structs can have fields at offsets that are not
+ multiples of BITS_PER_UNIT. Do not use gather/scatters in such cases. */
+ if (!multiple_p (pbitpos, BITS_PER_UNIT))
+ return false;
+
poly_int64 pbytepos = exact_div (pbitpos, BITS_PER_UNIT);
if (TREE_CODE (base) == MEM_REF)
--
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