py/parse: Work around xtensa esp-2020r3 compiler bug.
This commit works around a bug in xtensa-esp32-elf-gcc version esp-2020r3.
The bug is in generation of loop constructs. The below code is generated
by the xtensa-esp32 compiler. The first extract is the buggy machine code
and the second extract is the corrected machine code. The test
`basics/logic_constfolding.py` fails with the first code and succeeds with
the second.
Disassembly of section .text.push_result_rule:
00000000 <push_result_rule>:
...
d6: 209770 or a9, a7, a7
d9: 178976 loop a9, f4 <push_result_rule+0xf4>
d9: R_XTENSA_SLOT0_OP .text.push_result_rule+0xf4
dc: 030190 rsr.lend a9
df: 130090 wsr.lbeg a9
e2: a8c992 addi a9, a9, -88
e5: 06d992 addmi a9, a9, 0x600
e8: 130190 wsr.lend a9
eb: 002000 isync
ee: 030290 rsr.lcount a9
f1: 01c992 addi a9, a9, 1
f4: 1494e7 bne a4, a14, 10c <push_result_rule+0x10c>
f4: R_XTENSA_SLOT0_OP .text.push_result_rule+0x10c
Disassembly of section .text.push_result_rule:
00000000 <push_result_rule>:
...
d6: 209770 or a9, a7, a7
d9: 178976 loop a9, f4 <push_result_rule+0xf4>
d9: R_XTENSA_SLOT0_OP .text.push_result_rule+0xf4
dc: 030190 rsr.lend a9
df: 130090 wsr.lbeg a9
e2: 000091 l32r a9, fffc00e4 <push_result_rule+0xfffc00e4>
e2: R_XTENSA_SLOT0_OP .literal.push_result_rule+0x18
e5: 0020f0 nop
e8: 130190 wsr.lend a9
eb: 002000 isync
ee: 030290 rsr.lcount a9
f1: 01c992 addi a9, a9, 1
f4: 1494e7 bne a4, a14, 10c <push_result_rule+0x10c>
f4: R_XTENSA_SLOT0_OP .text.push_result_rule+0x10c
Work done in collaboration with @jimmo.
Signed-off-by: Damien George <damien@micropython.org>
f63b4f85aa