https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89676
Jakub Jelinek <jakub at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2019-03-12
CC| |jakub at gcc dot gnu.org,
| |vmakarov at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Indeed, we have:
(insn 14 3 6 2 (set (reg/v:DI 83 [ i ])
(mem/c:DI (reg/f:SI 16 argp) [1 i+0 S8 A32])) "pr89676.c":4:12 66
{*movdi_internal}
(expr_list:REG_EQUIV (mem/c:DI (reg/f:SI 16 argp) [1 i+0 S8 A32])
(nil)))
(insn 6 14 11 2 (parallel [
(set (reg:DI 84)
(ashift:DI (reg/v:DI 83 [ i ])
(const_int 3 [0x3])))
(clobber (reg:CC 17 flags))
]) "pr89676.c":4:12 509 {*ashldi3_doubleword}
(expr_list:REG_DEAD (reg/v:DI 83 [ i ])
(expr_list:REG_UNUSED (reg:CC 17 flags)
(nil))))
(insn 11 6 12 2 (set (reg/i:DI 0 ax)
(reg:DI 84)) "pr89676.c":5:1 66 {*movdi_internal}
(expr_list:REG_DEAD (reg:DI 84)
(nil)))
and the important insn has:
(define_insn "*ashl<mode>3_doubleword"
[(set (match_operand:DWI 0 "register_operand" "=&r")
(ashift:DWI (match_operand:DWI 1 "reg_or_pm1_operand" "0n")
(match_operand:QI 2 "nonmemory_operand" "<S>c")))
(clobber (reg:CC FLAGS_REG))]
constraints, IRA decides:
Pass 0 for finding pseudo/allocno costs
a0 (r84,l0) best AD_REGS, allocno AD_REGS
a1 (r83,l0) best GENERAL_REGS, allocno GENERAL_REGS
a0(r84,l0) costs: AD_REGS:-1000,-1000 CLOBBERED_REGS:2000,2000
Q_REGS:2000,2000 NON_Q_REGS:2000,2000 TLS_GOTBASE_REGS:2000,2000
GENERAL_REGS:2000
,2000 MEM:24000,24000
a1(r83,l0) costs: AD_REGS:0,0 CLOBBERED_REGS:0,0 Q_REGS:0,0 NON_Q_REGS:0,0
TLS_GOTBASE_REGS:0,0 GENERAL_REGS:0,0 MEM:0,0
Pass 1 for finding pseudo/allocno costs
r84: preferred AD_REGS, alternative GENERAL_REGS, allocno GENERAL_REGS
r83: preferred GENERAL_REGS, alternative NO_REGS, allocno GENERAL_REGS
a0(r84,l0) costs: AD_REGS:2000,-1000 CLOBBERED_REGS:2000,2000
Q_REGS:2000,2000 NON_Q_REGS:4000,4000 TLS_GOTBASE_REGS:2000,2000
GENERAL_REGS:2000,
2000 MEM:36000,36000
a1(r83,l0) costs: GENERAL_REGS:0,0 MEM:0,0
Disposition:
1:r83 l0 0 0:r84 l0 0
which I believe is to put both pseudo 83 and 84 into DImode eax.
LRA dump has:
********** Assignment #1: **********
Spill r83 after risky transformations
Reassigning non-reload pseudos
Assign 2 to r83 (freq=2000)
is that when it decides to put pseudo 83 into DImode %ecx instead?
If yes, what kind of risky transformation was here and why?
Vlad, can you please have a look? Thanks.
