https://gcc.gnu.org/bugzilla/show_bug.cgi?id=116953
Bug ID: 116953
Summary: [avr] error: operands to %T/%t must be reg + const_int
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: gjl at gcc dot gnu.org
Target Milestone: ---
unsigned foo (unsigned x, unsigned y)
{
int i;
for (i = 8; i--; x <<= 1)
y ^= (x ^ y) & 0x80 ? 79U : 0U;
return y;
}
$ avr-gcc -S -O2 -mmcu=atmega128 ...
bug.c: In function 'foo':
bug.c:7:1: error: operands to %T/%t must be reg + const_int:
7 | }
| ^
(const_int 79 [0x4f])
during RTL pass: final
bug.c:7:1: internal compiler error: in avr_print_operand, at
config/avr/avr.cc:2593
0xdec976 avr_print_operand
../../../source/gcc-master/gcc/config/avr/avr.cc:2593
0x6edc19 output_operand(rtx_def*, int)
../../../source/gcc-master/gcc/final.cc:3632
0x6ed73c output_asm_insn(char const*, rtx_def**)
../../../source/gcc-master/gcc/final.cc:3525
0xe058ad avr_out_sbxx_branch(rtx_insn*, rtx_def**)
../../../source/gcc-master/gcc/config/avr/avr.cc:13651
0x6ea2f6 get_insn_template(int, rtx_insn*)
../../../source/gcc-master/gcc/final.cc:2027
0x6ebea9 final_scan_insn_1
The bug works as follows:
avr.cc::avr_out_sbxx_branch() calls jump_over_one_insn_p() to determine whether
the current insn may skip the next instruction. jump_over_one_insn_p() uses
avr_2word_insn_p() on the NEXT insn, in particular it might compute insn
attributes to determine whether the next insn is a single instruction.
Computing insn attributes may run extract, which sets recog_data.operand
according to the next insn, but avr_out_sbxx_branch() assumes that operands
still holds operands for the current insn.
The probability for this bug increased with r15-3634, but it may also occur
without it.
Depending on the (operands of) the next insn, the ICE diagnostic may be
different, or wrong code may be generated, or a different ICE may trigger like
a segmentation fault.
