https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101260
--- Comment #8 from Stefan Schulze Frielinghaus <stefansf at linux dot ibm.com>
---
Pass split2 transforms
(insn 218 222 114 15 (set (reg/v:TI 10 %r10 [orig:87 a ] [87])
(reg/v:TI 18 %f4 [orig:87 a ] [87])) 1466 {movti}
(nil))
into
(insn 234 222 235 15 (set (reg:DI 10 %r10 [ a ])
(reg:DI 18 %f4)) 1467 {*movdi_64}
(nil))
(insn 235 234 114 15 (set (reg:DI 11 %r11 [orig:87 a+8 ] [87])
(unspec:DI [
(reg:V2DI 18 %f4)
(const_int 1 [0x1])
] UNSPEC_VEC_EXTRACT)) 495 {*vec_extractv2di}
(nil))
which is then transformed by cprop_hardreg into
(insn 234 222 235 14 (set (reg:DI 10 %r10 [ a ])
(reg:DI 11 %r11 [18])) 1467 {*movdi_64}
(expr_list:REG_DEAD (reg:DI 11 %r11 [18])
(nil)))
(insn 235 234 114 14 (set (reg:DI 11 %r11 [orig:87 a+8 ] [87])
(unspec:DI [
(reg:V2DI 18 %f4)
(const_int 1 [0x1])
] UNSPEC_VEC_EXTRACT)) 495 {*vec_extractv2di}
(expr_list:REG_DEAD (reg:V2DI 18 %f4)
(nil)))
where in insn 234 register f4 is substituted by r11 which is wrong. This can
also be observed in the final assembler output:
vlvgp %v4,%r10,%r11
l %r2,12(%r1)
ahi %r2,-1
st %r2,12(%r1)
cijhe %r2,0,.L13
lgr %r10,%r11 // (*)
vlgvg %r11,%v4,1
Registers r10 and r11 are moved into v4. The inverse move from v4 into r10 and
r11 is broken since cprop_hardreg wrongly substitutes f4 by r11. Thus the
expected output for (*) is:
lgdr %r10,%f4
