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From: Daniel Hellstrom <danielh@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r11-9005] sparc: Prevent atomic instructions in beginning of functions for UT700 Date: Thu, 16 Sep 2021 11:44:28 +0000 (GMT) [thread overview] Message-ID: <20210916114428.200EA3858413@sourceware.org> (raw) https://gcc.gnu.org/g:7b30a12edf7a3a461bbfc9cbb29b3050c7164032 commit r11-9005-g7b30a12edf7a3a461bbfc9cbb29b3050c7164032 Author: Daniel Cederman <cederman@gaisler.com> Date: Mon Oct 12 08:50:35 2020 +0200 sparc: Prevent atomic instructions in beginning of functions for UT700 A call to the function might have a load instruction in the delay slot and a load followed by an atomic function could cause a deadlock. gcc/ChangeLog: * config/sparc/sparc.c (sparc_do_work_around_errata): Do not begin functions with atomic instruction in the UT700 errata workaround. Diff: --- gcc/config/sparc/sparc.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c index 2487caf72da..6f419f6fd58 100644 --- a/gcc/config/sparc/sparc.c +++ b/gcc/config/sparc/sparc.c @@ -1124,6 +1124,7 @@ static unsigned int sparc_do_work_around_errata (void) { rtx_insn *insn, *next; + bool find_first_useful = true; /* Force all instructions to be split into their final form. */ split_all_insns_noflow (); @@ -1148,6 +1149,16 @@ sparc_do_work_around_errata (void) else jump = NULL; + /* Do not begin function with atomic instruction. */ + if (sparc_fix_ut700 + && find_first_useful + && USEFUL_INSN_P (insn)) + { + find_first_useful = false; + if (atomic_insn_for_leon3_p (insn)) + emit_insn_before (gen_nop (), insn); + } + /* Place a NOP at the branch target of an integer branch if it is a floating-point operation or a floating-point branch. */ if (sparc_fix_gr712rc
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