https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106265
--- Comment #1 from Vineet Gupta <vineet.gupta at linux dot dev> ---
Analyzed a section of -dP dump where reg a2 is setup with exact same value
while being live.
rhs-cred.cc:42: (*(double *)((char *)&ao)[k] + *(double *)((char *)0)[12] +
#(insn 2662 1711 76 (set (reg:DI 12 a2 [2816])
# (const_int 4096 [0x1000])) "rhs-cred.cc":42:47 139 {*movdi_64bit}
# (nil))
li a2,4096 # tmp2816, # 2662 [c=4 l=4]
*movdi_64bit/1
rhs-cred.cc:39: bg = (&ao[az])[0] * *(&ao)[av] + *(&ao)[2];
#(insn 76 2662 2663 (set (reg/f:DI 20 s4 [orig:193 _239 ] [193])
# (plus:DI (reg:DI 13 a3 [1865])
# (reg:DI 20 s4 [orig:181 _224 ] [181]))) "rhs-cred.cc":39:40 4
{adddi3}
# (expr_list:REG_DEAD (reg:DI 13 a3 [1865])
# (nil)))
add s4,a3,s4 # _224, _239, tmp1865 # 76 [c=4 l=4]
adddi3/0
rhs-cred.cc:42: (*(double *)((char *)&ao)[k] + *(double *)((char *)0)[12] +
#(insn 2663 76 2660 (set (reg:DI 13 a3 [2815])
# (plus:DI (reg:DI 12 a2 [2816])
# (const_int -2024 [0xfffffffffffff818]))) "rhs-cred.cc":42:47 4
{adddi3}
# (expr_list:REG_DEAD (reg:DI 12 a2 [2816])
# (expr_list:REG_EQUAL (const_int 2072 [0x818])
# (nil))))
addi a3,a2,-2024 #, tmp2815, tmp2816 # 2663 [c=4 l=4]
adddi3/1
rhs-cred.cc:44: *(&ao)[av * 2] - *(&ao)[k] - (&ao[az])[2] +
#(insn 2660 2663 1710 (set (reg:DI 12 a2 [2814])
# (const_int 4096 [0x1000])) "rhs-cred.cc":44:29 139 {*movdi_64bit}
# (nil))
li a2,4096 # tmp2814, # 2660 [c=4 l=4]
*movdi_64bit/1
