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 --git a/gcc/config/sparc/sparc.c b/gcc/config/sparc/sparc.c
index 94061e1..7c9b347 100644 (file)
--- a/gcc/config/sparc/sparc.c
+++ b/gcc/config/sparc/sparc.c
@@ -1116,6 +1116,7 @@ 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 ();
@@ -1140,6 +1141,16 @@ 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