[gcc r12-3576] sparc: Add NOP in stack_protect_set32 if sparc_fix_b2bst enabled

[Daniel Hellstrom <danielh@gcc.gnu.org>]

https://gcc.gnu.org/g:a053dab90e69c2a8289c95caec236f239a2a764b

commit r12-3576-ga053dab90e69c2a8289c95caec236f239a2a764b
Author: Daniel Cederman <cederman@gaisler.com>
Date:   Thu Oct 1 09:11:38 2020 +0200

    sparc: Add NOP in stack_protect_set32 if sparc_fix_b2bst enabled
    
    This is needed to prevent the Store -> (Non-store or load) -> Store
    sequence.
    
    gcc/ChangeLog:
    
            * config/sparc/sparc.md (stack_protect_set32): Add NOP to prevent
            sensitive sequence for B2BST errata workaround.

Diff:
---
 gcc/config/sparc/sparc.md | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/gcc/config/sparc/sparc.md b/gcc/config/sparc/sparc.md
index 24b76e0cacd..3ac074a244d 100644
--- a/gcc/config/sparc/sparc.md
+++ b/gcc/config/sparc/sparc.md
@@ -8353,9 +8353,15 @@ visl")
 	(unspec:SI [(match_operand:SI 1 "memory_operand" "m")] UNSPEC_SP_SET))
    (set (match_scratch:SI 2 "=&r") (const_int 0))]
   "TARGET_ARCH32"
-  "ld\t%1, %2\;st\t%2, %0\;mov\t0, %2"
+{
+  if (sparc_fix_b2bst)
+    return "ld\t%1, %2\;st\t%2, %0\;mov\t0, %2\;nop";
+  else
+    return "ld\t%1, %2\;st\t%2, %0\;mov\t0, %2";
+}
   [(set_attr "type" "multi")
-   (set_attr "length" "3")])
+   (set (attr "length") (if_then_else (eq_attr "fix_b2bst" "true")
+		      (const_int 4) (const_int 3)))])
 
 (define_insn "stack_protect_set64"
   [(set (match_operand:DI 0 "memory_operand" "=m")