optimization/9566: Inline function produces much worse code than manual inlining.

[Andrew Pinski]

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit- 
trail&database=gcc&pr=9566

The problem is because inlining causes a temporary variable which  
causes this and causes it to spill to the stack.

struct A {
   char const* src;
   char* dest;
   void copy() { *++dest = *++src; }
};

void g1() {
   A a;
   for(int i = 0; i < 10; ++i)
     a.copy();
}

void g2() {
   A a;
   for(int i = 0; i < 10; ++i)
       *++a.dest = *++a.src;
}

void g3() {
   A a;
   for(int i = 0; i < 10; ++i)
   {
     struct A b = a;
     {
       *++b.dest = *++b.src;
     }
     a = b;
   }
}

Note here g3 and g1 produce the same asm on PPC.

Thanks,
Andrew Pinski