From 2c2d405829ebb18de5357cc6319614035b420519 Mon Sep 17 00:00:00 2001 From: Hans-Peter Nilsson Date: Mon, 10 Feb 2020 04:03:43 +0100 Subject: [PATCH] dbr: Filter-out TARGET_FLAGS_REGNUM from end_of_function_needs. Compared to the cc0 version, I noticed a regression in delay-slot-filling for CRIS for several functions in libgcc with a similar layout, one being lshrdi3, where with cc0 all delay-slots were filled, as exposed by the test-case in gcc.target/cris/pr93372-1.c. There's one slot that fails to be filled for the decc0rated CRIS port. A gdb session shows it is because of the automatic inclusion of TARGET_FLAGS_REGNUM in "registers needed at the end of the function" because there are insns in the epilogue that clobber the condition-code register. I'm not trying to tell a clobber from a set, as parallels with set instead of clobber seems likely to happen too, for targets with TARGET_FLAGS_REGNUM set. Other targets with delay-slots and one dedicated often-clobbered condition-code-register should consider defining TARGET_FLAGS_REGNUM. I noticed it improved delay-slot-filling also in other situations than this. (Previously approved by Jeff Law.) gcc: * resource.c (init_resource_info): Filter-out TARGET_FLAGS_REGNUM from end_of_function_needs. --- gcc/ChangeLog | 5 +++++ gcc/resource.c | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 75cc642b5a0..39330ba0515 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2020-05-09 Hans-Peter Nilsson + + * resource.c (init_resource_info): Filter-out TARGET_FLAGS_REGNUM + from end_of_function_needs. + 2020-05-08 Vladimir Makarov * ira-color.c (update_costs_from_allocno): Remove diff --git a/gcc/resource.c b/gcc/resource.c index 32faa73fd5f..0a9d5943abc 100644 --- a/gcc/resource.c +++ b/gcc/resource.c @@ -21,6 +21,7 @@ along with GCC; see the file COPYING3. If not see #include "system.h" #include "coretypes.h" #include "backend.h" +#include "target.h" #include "rtl.h" #include "df.h" #include "memmodel.h" @@ -1215,6 +1216,11 @@ init_resource_info (rtx_insn *epilogue_insn) break; } + /* Filter-out the flags register from those additionally required + registers. */ + if (targetm.flags_regnum != INVALID_REGNUM) + CLEAR_HARD_REG_BIT (end_of_function_needs.regs, targetm.flags_regnum); + /* Allocate and initialize the tables used by mark_target_live_regs. */ target_hash_table = XCNEWVEC (struct target_info *, TARGET_HASH_PRIME); bb_ticks = XCNEWVEC (int, last_basic_block_for_fn (cfun)); -- 2.30.2