From 857f4517965b282234e12f6bca0c21ef10eec09b Mon Sep 17 00:00:00 2001 From: Yu-Chun Lin Date: Thu, 10 Apr 2025 01:11:16 +0800 Subject: [PATCH] ARC: unwind: Use built-in sort swap to reduce code size and improve performance The custom swap function used in sort() was identical to the default built-in sort swap. Remove the custom swap function and passes NULL to sort(), allowing it to use the default swap function. This change reduces code size and improves performance, particularly when CONFIG_MITIGATION_RETPOLINE is enabled. With RETPOLINE mitigation, indirect function calls incur significant overhead, and using the default swap function avoids this cost. $ ./scripts/bloat-o-meter ./unwind.o.old ./unwind.o.new add/remove: 0/1 grow/shrink: 0/1 up/down: 0/-22 (-22) Function old new delta init_unwind_hdr.constprop 544 540 -4 swap_eh_frame_hdr_table_entries 18 - -18 Total: Before=4410, After=4388, chg -0.50% Signed-off-by: Yu-Chun Lin Signed-off-by: Vineet Gupta --- arch/arc/kernel/unwind.c | 11 +---------- 1 file changed, 1 insertion(+), 10 deletions(-) diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c index d8969dab12d4..789cfb9ea14e 100644 --- a/arch/arc/kernel/unwind.c +++ b/arch/arc/kernel/unwind.c @@ -241,15 +241,6 @@ static int cmp_eh_frame_hdr_table_entries(const void *p1, const void *p2) return (e1->start > e2->start) - (e1->start < e2->start); } -static void swap_eh_frame_hdr_table_entries(void *p1, void *p2, int size) -{ - struct eh_frame_hdr_table_entry *e1 = p1; - struct eh_frame_hdr_table_entry *e2 = p2; - - swap(e1->start, e2->start); - swap(e1->fde, e2->fde); -} - static void init_unwind_hdr(struct unwind_table *table, void *(*alloc) (unsigned long)) { @@ -345,7 +336,7 @@ static void init_unwind_hdr(struct unwind_table *table, sort(header->table, n, sizeof(*header->table), - cmp_eh_frame_hdr_table_entries, swap_eh_frame_hdr_table_entries); + cmp_eh_frame_hdr_table_entries, NULL); table->hdrsz = hdrSize; smp_wmb(); -- 2.25.1