Hello all,
I have an issue with optimization -funroll_loops in my custom backend.
> blueproc-blueice-none-gcc -O3 -dump-all -funroll-loops -S test3.c
(This is the command)
Between files test3.c.254r.loop2_done and test3.c.255r.web, there are
optimizations done that seems very dubious.
- There is a parallel operation that sets 4 subregs of regsiter SI 131
in the '254 file, and in the '255 file, additional registers
are introduced in a way:
a. It is not necessary. Not possible to optimize anything like this.
b. It breaks the functionality. It is not correct any more.
Q.
- Why ?. On what basis is this decided ?.
- Is it possible to turn the optimization off ?.
Best regards,
Henri.
+++++++++++++++++++ test3.c.c254r.loop2_done: +++++++++++++++++++++++++++
(insn 24 23 25 2 (parallel [
(set (subreg:QI (reg:SI 131) 0)
(if_then_else:QI (lt (reg:SI 78 [ d.7_7 ])
(const_int 1 [0x1]))
(const_int 1 [0x1])
(const_int 0 [0])))
(set (subreg:QI (reg:SI 131) 1)
(if_then_else:QI (gt (reg:SI 78 [ d.7_7 ])
(const_int 1 [0x1]))
(const_int 1 [0x1])
(const_int 0 [0])))
(set (subreg:QI (reg:SI 131) 2)
(if_then_else:QI (eq (reg:SI 78 [ d.7_7 ])
(const_int 1 [0x1]))
(const_int 1 [0x1])
(const_int 0 [0])))
(set (subreg:QI (reg:SI 131) 3)
(const_int 1 [0x1]))
]) 32 {comparison_internal_signed}
(expr_list:REG_UNUSED (reg:SI 131)
(expr_list:REG_UNUSED (reg:SI 131)
(expr_list:REG_UNUSED (reg:SI 131)
(nil)))))
(jump_insn 25 24 26 2 (set (pc)
(if_then_else (eq (subreg:QI (reg:SI 131) 2)
(const_int 1 [0x1]))
(label_ref 100)
(pc))) 34 {branch_internal_novec}
(expr_list:REG_DEAD (reg:SI 131)
(int_list:REG_BR_PROB 858993468 (nil)))
++++++++++++++++++++++++++++ test3.c.255r.web
+++++++++++++++++++++++++++++++++++++
(insn 24 23 25 2 (parallel [
(set (subreg:QI (reg:SI 131) 0)
(if_then_else:QI (lt (reg:SI 78 [ d.7_7 ])
(const_int 1 [0x1]))
(const_int 1 [0x1])
(const_int 0 [0])))
(set (subreg:QI (reg:SI 189) 1)
(if_then_else:QI (gt (reg:SI 78 [ d.7_7 ])
(const_int 1 [0x1]))
(const_int 1 [0x1])
(const_int 0 [0])))
(set (subreg:QI (reg:SI 190) 2)
(if_then_else:QI (eq (reg:SI 78 [ d.7_7 ])
(const_int 1 [0x1]))
(const_int 1 [0x1])
(const_int 0 [0])))
(set (subreg:QI (reg:SI 191) 3)
(const_int 1 [0x1]))
]) 32 {comparison_internal_signed}
(expr_list:REG_UNUSED (reg:SI 131)
(expr_list:REG_UNUSED (reg:SI 131)
(expr_list:REG_UNUSED (reg:SI 131)
(nil)))))
(jump_insn 25 24 26 2 (set (pc)
(if_then_else (eq (subreg:QI (reg:SI 191) 2)
(const_int 1 [0x1]))
(label_ref 100)
(pc))) 34 {branch_internal_novec}
(expr_list:REG_DEAD (reg:SI 131)
(int_list:REG_BR_PROB 858993468 (nil)))
