branch_target_register_class - receipt for a crash

[Marcin Dalecki <martin at dalecki dot de>]

Inside gcc/target.h we have the declaration of
struct gcc_target { struct asm_out { struct sched { ...
there is a function refernce field named

 	int (* branch_target_register_class) (void);

The only place where this is referenced is in gcc/bt-load.c
and in esp the global branch_target_load_optimize() function.
Right away at the start. However there is no initialization of
brnach_target_register_class at all anywhere.
This of course will let the compiler crash on *every* call
to branch_target_load_optimize().

Again:

ejb227:~/gcc dalecki$ svngrep branch_target_register_class
.//gcc/bt-load.c:  enum reg_class class = (enum reg_class)  
targetm.branch_target_register_class ();
.//gcc/ChangeLog-2003:  * target.h (branch_target_register_class):  
Change return type to int.
.//gcc/ChangeLog-2003:  * target.h (struct gcc_target): Add  
branch_target_register_class
.//gcc/target.h:  int (* branch_target_register_class) (void);

Let's check who calls branch_target_load_optmize()...
We can see that all calls are guarded by

	flag_branch_target_load_optimize

and a corresponding report option:

gcc/common.opt:Common Report Var(flag_branch_target_load_optimize)

Enabing this option is going to crash the compiler miserable.

Looking at the use of flag_brnach_target_load_optmize2 I think all of  
the
associated code should be simply deleted.

Marcin Dalecki