https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67573
--- Comment #2 from Kazumoto Kojima <kkojima at gcc dot gnu.org> ---
It seems that LRA allocates r7 for the scratch reg at
(define_insn_and_split "call_value_pcrel"
[(set (match_operand 0 "" "=rf")
(call (mem:SI (match_operand:SI 1 "symbol_ref_operand" ""))
(match_operand 2 "" "")))
(use (reg:SI FPSCR_MODES_REG))
(use (reg:SI PIC_REG))
(clobber (reg:SI PR_REG))
(use (match_scratch:SI 3 "=r"))]
in the problematic case and the insn
(call_insn 208 207 209 22 (parallel [
(set (reg:SI 0 r0)
(call (mem:SI (symbol_ref:SI
("_ZNKSt7__cxx1112basic_stringIwSt11char_traitsIwESaIwEE4copyEPwjj") [flags
0x41] <function_decl 0xb72c0280 copy>) [0 copy S4 A32])
(const_int 0 [0])))
(use (reg:SI 154 fpscr0))
(use (reg:SI 12 r12))
(clobber (reg:SI 146 pr))
(clobber (reg:SI 7 r7 [357]))
]) fa.cc:484 322 {call_value_pcrel}
(expr_list:REG_EH_REGION (const_int 4 [0x4])
(expr_list:REG_CALL_DECL (symbol_ref:SI
("_ZNKSt7__cxx1112basic_stringIwSt11char_traitsIwESaIwEE4copyEPwjj") [flags
0x41] <function_decl 0xb72c0280 copy>)
(nil)))
(expr_list:SI (use (reg:SI 4 r4))
(expr_list:SI (use (reg:SI 5 r5))
(expr_list:SI (use (reg:SI 6 r6))
(expr_list:SI (use (reg:SI 7 r7))
(nil))))))
made the following passes confused.
