From 9032d2b2414ed22e53a9980a51b835d3caf83c48 Mon Sep 17 00:00:00 2001 From: Jakub Jelinek Date: Sat, 19 Dec 2020 12:46:40 +0100 Subject: [PATCH] bswap: Fix up a thinko with empty CONSTRUCTORs [PR98378] The code I've added recently in find_bswap_or_nop for VECTOR CONSTRUCTORs is missing punt on an important case - namely empty CONSTRUCTORs, because in that case the loop will not initialize *n and the code after the loop will then use the uninitialized structure. 2020-12-19 Jakub Jelinek PR tree-optimization/98378 * gimple-ssa-store-merging.c (find_bswap_or_nop): Punt if CONSTRUCTOR has no elements. --- gcc/gimple-ssa-store-merging.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/gcc/gimple-ssa-store-merging.c b/gcc/gimple-ssa-store-merging.c index 2894205fa3c..2ab51e23c07 100644 --- a/gcc/gimple-ssa-store-merging.c +++ b/gcc/gimple-ssa-store-merging.c @@ -873,6 +873,8 @@ find_bswap_or_nop (gimple *stmt, struct symbolic_number *n, bool *bswap) if (sz != 16 && sz != 32 && sz != 64) return NULL; tree rhs = gimple_assign_rhs1 (stmt); + if (CONSTRUCTOR_NELTS (rhs) == 0) + return NULL; tree eltype = TREE_TYPE (TREE_TYPE (rhs)); unsigned HOST_WIDE_INT eltsz = int_size_in_bytes (eltype) * BITS_PER_UNIT; -- 2.30.2