@@ -1383,6 +1383,20 @@ aarch64_gimple_fold_builtin (gimple_stmt_iterator *gsi)
tree call = gimple_call_fn (stmt);
tree fndecl;
gimple new_stmt = NULL;
+
+ /* The operations folded below are reduction operations. These are
+ defined to leave their result in the 0'th element (from the perspective
+ of GCC). The architectural instruction we are folding will leave the
+ result in the 0'th element (from the perspective of the architecture).
+ For big-endian systems, these perspectives are not aligned.
+
+ It is therefore wrong to perform this fold on big-endian. There
+ are some tricks we could play with shuffling, but the mid-end is
+ inconsistent in the way it treats reduction operations, so we will
+ end up in difficulty. Until we fix the ambiguity - just bail out. */
+ if (BYTES_BIG_ENDIAN)
+ return false;
+
if (call)
{
fndecl = gimple_call_fndecl (stmt);