On 09/15/14 08:33, Jiong Wang wrote:
Jeff,
thanks, I partially understand your meaning here.
take the function "ira_implicitly_set_insn_hard_regs" in ira-lives.c
for example,
when generating address rtl, gcc will automatically generate "const"
operator to prefix
the address expression, like the following. so a simple CONSTANT_P
check is enough in
case there is no embedded register.
(insn 309 310 308 3 (set (reg:DI 44 r15 [orig:94 ivtmp.674 ] [94])
(const:DI (plus:DI (symbol_ref:DI ("recog_data") [flags 0x40]
<var_decl 0x2b2c2ff91510 recog_data>)
(const_int 480 [0x1e0])))) -1
but for architecture like aarch64, the following instruction
sequences to forming address
may be generated
(insn 73 14 74 4 (set (reg/f:DI 20 x20 [99])
(high:DI (symbol_ref:DI ("global_a") [flags 0xc0] <var_decl
0x7ff755a60900 stats>))) 35 {*movdi_aarch64}
(expr_list:REG_EQUIV (high:DI (symbol_ref:DI ("global_a") [flags
0xc0] <var_decl 0x7ff755a60900 stats>))
(nil)))
(insn 17 30 25 5 (set (reg/f:DI 4 x4 [83])
(lo_sum:DI (reg/f:DI 20 x20 [99])
(symbol_ref:DI ("global_a") [flags 0xc0] <var_decl
0x7ff755a60900 stats>))) {add_losym_di}
(expr_list:REG_EQUIV (symbol_ref:DI ("global_a") [flags 0xc0]
<var_decl 0x7ff755a60900 stats>)
(nil)))
while CONSTANT_P could not catch the latter lo_sum case, as the
RTX_CLASS of lo_sum is RTX_OBJ not RTX_CONST_OBJ,
Hmm, it's been ~15 years since I regularly worked on a target that uses
HIGH/LO_SUM, I thought we wrapped the LO_SUM expression inside a CONST
as well, but reading the docs for CONST, that clearly isn't the case.
Sorry for that. Can you (re) send your current patch for this for review?
Jeff
