Optimize attribute and inlining

["Selvaraj, Senthil_Kumar" <Senthil_Kumar dot Selvaraj at atmel dot com>]

Declaring a function with __attribute__((optimize("O0")) turns off inlining for the translation unit (atleast) containing the function (see output at the end). Is this expected behavior?

I tracked this down to the fact that when processing the optimize attribute with O0, flag_no_inline is set to 1 and is not restored back. The early_inliner pass in ipa-inline.c (obviously) skips processing if flag_no_inline is set, and therefore inlining does not occur. I did see that handle_optimize_attribute in c-family/c-common.c saves and restores whatever options have corresponding fields in struct cl_optimization, but inlining is not one of them. That I guess is happening because inline is not described as an "Optimization" option in common.opt.

Test output
----------------
$ cat test.c
static void callee() { static int a; a++; }
void caller() { callee(); }
$ 
$ ~/Code/gcc/repo/native_install/bin/gcc -O1 -fdump-tree-all -S test.c
$ 
$ cat test.c.*.optimized

;; Function caller (caller, funcdef_no=1, decl_uid=1358, cgraph_uid=1)

caller ()
{
  int a.0;
  int a.1;
  static int a;
  static int a;

<bb 2>:
  a.0_3 = a;
  a.1_4 = a.0_3 + 1;
  a = a.1_4;
  return;

}

$ cat test.c
static void callee() { static int a; a++; }
void caller() { callee(); }
static void somefunc() __attribute__((optimize("O0")));
$ 
$ ~/Code/gcc/repo/native_install/bin/gcc -O1 -fdump-tree-all -S test.c
$ 
$ cat test.c.*.optimized

;; Function callee (callee, funcdef_no=0, decl_uid=1355, cgraph_uid=0)
callee ()
{
  static int a;
  int a.1;
  int a.0;

<bb 2>:
  a.0_1 = a;
  a.1_2 = a.0_1 + 1;
  a = a.1_2;
  return;

}

;; Function caller (caller, funcdef_no=1, decl_uid=1358, cgraph_uid=1)
caller ()
{
<bb 2>:
  callee ();
  return;

}

Regards
Senthil