------- Comment #1 from rguenth at gcc dot gnu dot org 2010-05-19 09:38 -------
Confirmed.
We already expand it that way:
;; s = foo ();
(insn 5 4 6 t.c:7 (set (reg:QI 0 ax)
(const_int 0 [0x0])) -1 (nil))
(call_insn 6 5 7 t.c:7 (set (parallel:BLK [
(expr_list:REG_DEP_TRUE (reg:DI 0 ax)
(const_int 0 [0x0]))
(expr_list:REG_DEP_TRUE (reg:DI 1 dx)
(const_int 8 [0x8]))
])
(call (mem:QI (symbol_ref:DI ("foo") [flags 0x41] <function_decl
0x7ffff5aed500 foo>) [0 S1 A8])
(const_int 0 [0x0]))) -1 (nil)
(expr_list:REG_DEP_TRUE (use (reg:QI 0 ax))
(nil)))
(insn 7 6 8 t.c:7 (set (reg:DI 60)
(reg:DI 0 ax)) -1 (nil))
(insn 8 7 9 t.c:7 (set (reg:DI 61)
(reg:DI 1 dx)) -1 (nil))
(insn 9 8 10 t.c:7 (set (mem/s/c:DI (plus:DI (reg/f:DI 54 virtual-stack-vars)
(const_int -32 [0xffffffffffffffe0])) [2 S8 A128])
(reg:DI 60)) -1 (nil))
(insn 10 9 11 t.c:7 (set (mem/s/c:DI (plus:DI (reg/f:DI 54 virtual-stack-vars)
(const_int -24 [0xffffffffffffffe8])) [2 S8 A64])
(reg:DI 61)) -1 (nil))
(insn 11 10 12 t.c:7 (set (reg:DI 62)
(mem/s/c:DI (plus:DI (reg/f:DI 54 virtual-stack-vars)
(const_int -32 [0xffffffffffffffe0])) [2 S8 A128])) -1 (nil))
(insn 12 11 13 t.c:7 (set (mem/s/c:DI (plus:DI (reg/f:DI 54 virtual-stack-vars)
(const_int -16 [0xfffffffffffffff0])) [2 s+0 S8 A128])
(reg:DI 62)) -1 (nil))
(insn 13 12 14 t.c:7 (set (reg:DI 63)
(mem/s/c:DI (plus:DI (reg/f:DI 54 virtual-stack-vars)
(const_int -24 [0xffffffffffffffe8])) [2 S8 A64])) -1 (nil))
(insn 14 13 0 t.c:7 (set (mem/s/c:DI (plus:DI (reg/f:DI 54 virtual-stack-vars)
(const_int -8 [0xfffffffffffffff8])) [2 s+8 S8 A64])
(reg:DI 63)) -1 (nil))
So we create a stack representation to copy it to the stack temporary
(which both are unneeded). We should see that we can avoid the
temporary at all as there is no aggregate use of the struct left.
At least we should avoid the 2nd temporary.
I'm very sure there is a duplicate for this bug somewhere.
Also I wonder why RTL DSE cannot remove all the stores to the stack.
--
rguenth at gcc dot gnu dot org changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |matz at gcc dot gnu dot org
Severity|normal |enhancement
Status|UNCONFIRMED |NEW
Ever Confirmed|0 |1
Keywords| |missed-optimization
Last reconfirmed|0000-00-00 00:00:00 |2010-05-19 09:38:49
date| |
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44194
