* reg-stack.c (straighten_stack): Do nothing if the virtual stack is

        empty or has a single entry.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@22376 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 7 insertions, 0 deletions

diff --git a/gcc/reg-stack.c b/gcc/reg-stack.c
index ab400c51f1d..a7a5fb7cd90 100644
--- a/gcc/reg-stack.c
+++ b/gcc/reg-stack.c
@@ -309,6 +309,13 @@ straighten_stack (insn, regstack)
   struct stack_def temp_stack;
   int top;
 
+  /* If there is only a single register on the stack, then the stack is
+     already in increasing order and no reorganization is needed.
+
+     Similarly if the stack is empty.  */
+  if (regstack->top <= 0)
+    return;
+
   temp_stack.reg_set = regstack->reg_set;
 
   for (top = temp_stack.top = regstack->top; top >= 0; top--)