Add rules for 8-byte integers to m68020 ncg. Add 8-byte long long to
ACK C on linux68k. Enable long-long tests for linux68k. The tests
pass in our emulator using musahi; I don't have a real 68k processor
and haven't tried other emulators.
Still missing are conversions between 8-byte integers and any size of
floats. The long-long tests don't cover these conversions, and our
emulator can't do floating-point.
Our build always enables TBL68020 and uses word size 4. Without
TBL68020, 8-byte multiply and divide are missing. With word size 2,
some conversions between 2-byte and 8-byte integers are missing.
Fix .cii in libem, which didn't work when converting from 1-byte or
2-byte integers. Now .cii and .cuu work, but also add some rules to
skip .cii and .cuu when converting 8-byte integers. The new rule for
loc 4 loc 8 cii `with test_set4` exposes a bug: the table may believe
that the condition codes test a 4-byte register when they only test a
word or byte, and this incorrect test may describe an unsigned word or
byte as negative. Another rule `with exact test_set1+test_set2` works
around the bug by ignoring the negative flag, because a zero-extended
word or byte is never negative.
The old rules for comparison and logic do work with 8-byte integers
and bitsets, but add some specific 8-byte rules to skip libem calls or
loops. There were no rules for 8-byte arithmetic, shift, or rotate;
so add some. There is a register shortage, because the table requires
preserving d3 to d7, leaving only 3 data registers (d0, d1, d2) for
8-byte operations. Because of the shortage, the code may move data to
an address register, or read a memory location more than once.
The multiplication and division code are translations of the i386
code. They pass the tests, but might not give the best performance on
a real 68k processor.
Skip the long-long test set on other platforms, because they don't
have long long. Each platform would need to implement 8-byte
operations like `adi 8` in its code generator, and set long long to
8 bytes in its descr file.
The first test is for negation, addition, and subtraction. It also
requires comparison for equality.
