flow.c: Update comment.

        * flow.c: Update comment.
        (notice_stack_pointer_modification): New static function.
        (record_volatile_insns): Use it.
        (mark_regs_live_at_end): Mark the stack pointer as alive
        at the end of the function if current_function_sp_is_unchanging
        is set.
        (life_analysis_1): Set current_function_sp_is_unchanging.
        * function.c: Define it.
        (init_function_start): Initialize it.
        * output.h: Declare it.
        * reorg.c (fill_simple_delay_slots, dbr_schedule): Mark
        the stack pointer as alive at the end of the function if
        current_function_sp_is_unchanging is set.
        * i386.c (ix86_epilogue): Optimize the restoring
        of the stack pointer.

From-SVN: r23009

1 files changed, 7 insertions, 0 deletions

diff --git a/gcc/function.c b/gcc/function.c
index 4645f5a..48018cf 100644
--- a/gcc/function.c
+++ b/gcc/function.c
@@ -138,6 +138,12 @@ int current_function_has_computed_jump;
 
 int current_function_contains_functions;
 
+/* Nonzero if function being compiled doesn't modify the stack pointer
+   (ignoring the prologue and epilogue).  This is only valid after
+   life_analysis has run. */
+
+int current_function_sp_is_unchanging;
+
 /* Nonzero if the current function is a thunk (a lightweight function that
    just adjusts one of its arguments and forwards to another function), so
    we should try to cut corners where we can.  */
@@ -5426,6 +5432,7 @@ init_function_start (subr, filename, line)
   current_function_has_nonlocal_label = 0;
   current_function_has_nonlocal_goto = 0;
   current_function_contains_functions = 0;
+  current_function_sp_is_unchanging = 0;
   current_function_is_thunk = 0;
 
   current_function_returns_pcc_struct = 0;