This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]

[C++] RFC: fix inlining logic


Hi!

g++ from the branch (and probably mainline) would not inline function
foo in the following small example:

void f2 (int);

static void
foo (float xx, int type)
{
  f1 (xx);
  f2 (type);
}

void
bar (void)
{
  foo (3.5, 6);
}

when compiled with g++ -O3 
g++ 2.95.2 will inline it just fine. 

(BTW this small example crashes the branch and mainline C compiler on
SPARC, see http://gcc.gnu.org/ml/gcc/2001-05/msg00030.html)

The problem is that init_decl_processing in cp/decl.c messes with the
inlining flags and manages to turn off flag_inline_functions 

Like this:
  if (!flag_no_inline)
    {
      flag_inline_trees = 1;
      flag_no_inline = 1;
    }

and later: 
  if (flag_no_inline)      
    {
      flag_inline_functions = 0;
    }

So flag_inline_functions is turned off all the time. Not good. 

One way to fix it is shown below. With this the foo function in the
above example is inlined. 

I have a few questions concerning inlining:
1. The code always sets flag_no_inline to 1, is that correct? 

2. Is this sequence in inlinable_function_p from cp/optimize.c 

 /* If the function was not declared `inline', then we don't inline
     it.  */
  else  if (!DECL_INLINE (fn))

correct? Why not inline functions not declared inline? Is the comment
innacurate? With my patch it inlines the "foo" just fine....


2001-05-02  Dan Nicolaescu  <dann@ics.uci.edu>

	* decl.c (init_decl_processing): Only reset
	flag_inline_functions if flag_no_inline is set.


*** decl.c.~1.747.2.22.~	Tue May  1 23:14:11 2001
--- decl.c	Wed May  2 11:10:52 2001
***************
*** 6354,6360 ****
--- 6354,6365 ----
        flag_inline_trees = 1;
        flag_no_inline = 1;
      }
+   else
+     {
+       flag_inline_functions = 0;
+     }
  
+   
    /* Initially, C.  */
    current_lang_name = lang_name_c;
  
***************
*** 6534,6543 ****
  
    if (flag_exceptions)
      init_exception_processing ();
-   if (flag_no_inline)
-     {
-       flag_inline_functions = 0;
-     }
  
    if (! supports_one_only ())
      flag_weak = 0;
--- 6539,6544 ----


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]