http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55597
--- Comment #7 from H.J. Lu <hjl.tools at gmail dot com> 2012-12-05 17:28:11
UTC ---
It is generated by
(gdb) bt
#0 set_unique_reg_note (insn=0x7ffff19a07e0, kind=REG_EQUAL,
datum=0x7ffff1ab4460) at /export/gnu/import/git/gcc/gcc/emit-rtl.c:4958
#1 0x0000000000726f1b in set_dst_reg_note (insn=0x7ffff19a07e0,
kind=REG_EQUAL, datum=0x7ffff1ab4460, dst=0x7ffff1ab44c0)
at /export/gnu/import/git/gcc/gcc/emit-rtl.c:5018
#2 0x0000000000949cbb in emit_libcall_block_1 (insns=0x7ffff1ab2730,
target=0x7ffff1ab44c0, result=0x7ffff1ab4500, equiv=0x7ffff1ab4460,
equiv_may_trap=false) at /export/gnu/import/git/gcc/gcc/optabs.c:3936
#3 0x0000000000949d10 in emit_libcall_block (insns=0x7ffff1ab2730,
target=0x7ffff1ab44c0, result=0x7ffff1ab4500, equiv=0x7ffff1ab4460)
at /export/gnu/import/git/gcc/gcc/optabs.c:3945
#4 0x0000000000d082fa in legitimize_tls_address (x=0x7ffff1ab4460,
model=TLS_MODEL_REAL, for_mov=true)
at /export/gnu/import/git/gcc/gcc/config/i386/i386.c:12805
#5 0x0000000000d0f4bb in ix86_expand_move (mode=SImode,
operands=0x7fffffffc920)
at /export/gnu/import/git/gcc/gcc/config/i386/i386.c:15936
#6 0x0000000000dc1b60 in gen_movsi (operand0=0x7ffff1ab44a0,
operand1=0x7ffff1aac2f0)
at /export/gnu/import/git/gcc/gcc/config/i386/i386.md:1701
#7 0x0000000000750380 in emit_move_insn_1 (x=0x7ffff1ab44a0, y=0x7ffff1aac2f0)
at /export/gnu/import/git/gcc/gcc/expr.c:3417
#8 0x00000000007507cd in emit_move_insn (x=0x7ffff1ab44a0, y=0x7ffff1aac2f0)
---Type <return> to continue, or q <return> to quit---
at /export/gnu/import/git/gcc/gcc/expr.c:3511
#9 0x0000000000733def in copy_to_mode_reg (mode=SImode, x=0x7ffff1aac2f0)
at /export/gnu/import/git/gcc/gcc/explow.c:645
#10 0x00000000009537f9 in maybe_legitimize_operand (
icode=CODE_FOR_zero_extendsidi2, opno=1, op=0x7fffffffcad0)
at /export/gnu/import/git/gcc/gcc/optabs.c:8069
#11 0x0000000000953ac8 in maybe_legitimize_operands (
icode=CODE_FOR_zero_extendsidi2, opno=0, nops=2, ops=0x7fffffffcac0)
at /export/gnu/import/git/gcc/gcc/optabs.c:8131
#12 0x0000000000953b5b in maybe_gen_insn (icode=CODE_FOR_zero_extendsidi2,
nops=2, ops=0x7fffffffcac0) at /export/gnu/import/git/gcc/gcc/optabs.c:8149
#13 0x0000000000949697 in maybe_emit_unop_insn (
icode=CODE_FOR_zero_extendsidi2, target=0x7ffff1ab4480,
op0=0x7ffff1aac2f0, code=ZERO_EXTEND)
at /export/gnu/import/git/gcc/gcc/optabs.c:3765
#14 0x000000000094976b in emit_unop_insn (icode=CODE_FOR_zero_extendsidi2,
target=0x7ffff1ab4480, op0=0x7ffff1aac2f0, code=ZERO_EXTEND)
at /export/gnu/import/git/gcc/gcc/optabs.c:3787
#15 0x0000000000748f7a in convert_move (to=0x7ffff1ab4480,
from=0x7ffff1aac2f0, unsignedp=1)
at /export/gnu/import/git/gcc/gcc/expr.c:607
(gdb) f 2
#2 0x0000000000949cbb in emit_libcall_block_1 (insns=0x7ffff1ab2730,
target=0x7ffff1ab44c0, result=0x7ffff1ab4500, equiv=0x7ffff1ab4460,
equiv_may_trap=false) at /export/gnu/import/git/gcc/gcc/optabs.c:3936
3936 set_dst_reg_note (last, REG_EQUAL, copy_rtx (equiv), target);
(gdb) call debug_rtx (last)
(insn 6 5 0 (set (reg:DI 61)
(reg:DI 0 ax)) x.i:8 -1
(nil))
(gdb) call debug_rtx (equiv)
(symbol_ref:SI ("__morestack_initial_sp") [flags 0x10] <var_decl 0x7ffff19bf390
__morestack_initial_sp>)
(gdb)
