From 6a19dea7f68eaf44003008d284270933ad9d3177 Mon Sep 17 00:00:00 2001 From: Alexander Date: Tue, 29 Jun 2021 16:26:11 +0200 Subject: [PATCH] module/zfs: simplify ddt_stat_add() loop LLVM's Polly (ISL to be precise) is unhappy with the loop from ddt_stat_add(): CC [M] fs/zfs/zfs/ddt.o ../lib/External/isl/isl_schedule_node.c:2470: cannot insert node between set or sequence node and its filter children (building with the custom patch which adds Polly support to Kbuild) The mentioned loop is rather suboptimal. All that we need is to just treat ddt_stat_t as an array of u64 and perform 1:1 addition or substraction. This can be done in simpler for-loop with the determined index and bounds. Compiler will expand d_end - d into a number of ddt_stat_t fields at compile time. This prevents Polly from failing on this file. Reviewed-by: Matthew Ahrens Reviewed-by: Brian Behlendorf Signed-off-by: Alexander Lobakin Closes #12253 --- module/zfs/ddt.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/module/zfs/ddt.c b/module/zfs/ddt.c index b94a9f54ec..7b0b1d8967 100644 --- a/module/zfs/ddt.c +++ b/module/zfs/ddt.c @@ -423,8 +423,8 @@ ddt_stat_add(ddt_stat_t *dst, const ddt_stat_t *src, uint64_t neg) ASSERT(neg == 0 || neg == -1ULL); /* add or subtract */ - while (d < d_end) - *d++ += (*s++ ^ neg) - neg; + for (int i = 0; i < d_end - d; i++) + d[i] += (s[i] ^ neg) - neg; } static void