edge splitting can cause new basic blocks to be added to the graph, but while
the graph itself gets properly rewritten the descriptor tables can't be updated
to take these into account, so they end up pointing at the wrong blocks. This
causes really hard-to-debug problems.
The new approach is to parse the descriptor blocks and then generate a
comparison chain. Brute force, but much easier for the compiler to reason
about.
need flt_arith any more. (And also generates them correctly on little-endian
systems.) as now parses numbers properly, doesn't trash memory all over the
place, and can handle negative numbers.
Using '-' might fail on platforms like FreeBSD. Commit 50a7031
stopped using '-' in the B compiler and ego. I now stop using '-' in
mcg, because I can now check that mcg still works.
Tests pass if one edits the top build.lua to uncomment "qemuppc" from
both vars.plats and vars.plats_with_tests, and one leaves mcg in
plat/qemuppc/descr.
Add or correct some EM instructions in treebuilder.c:
- "lof", "stf": handle negative offsets in load() and store().
- "cuu": add using IR_FROMUI.
- "lim", "sim": keep an entire word in ".ignmask", to be compatible
with mach/powerpc/libem/trp.s and ncg. We also keep a word in
".ignmask" in ncg for both i386 and m68020.
- "trp": pass trap number in register. See comment in
helper_function_with_arg().
- "sig": push the old value of .trppc on the stack.
- "and ?", "ior ?", "xor ?", "com ?", "cms ?", "set ?", "inn ?":
connect to helper functions in libem.
- "blm", "bls": drop call to memmove() and use new helper ".bls4",
because tests/plat/structcopy_e.c can't call memmove().
- "xor s", "cms s": if s is large, fall back on helper function.
- "rol", "ror": add by decomposing each rotate into 4 IR ops.
- "rck s", "bls s": make fatal unless s is word size.
- "loi": push multiple loads in the correct order.
- "dup s", "exg s": if s is large, fall back on helper.
- "dus": add using new helper ".dus4".
- "lxl", "lxa": follow the static chain, not the dynamic chain.
- "lor 1": materialise the stack before pushing the stack pointer.
- "lor 2", "str 2": make fatal.
- "los", "sts": drop calls to memcpy() and use helpers ".los4" and
and ".sts4", so lang/m2/libm2/LtoUset.e starts working.
- "gto": correctly read descriptor.
Change mach/powerpc/mcg/table:
- ANY.L: add for "asp -8".
- LOAD.L: work around register corruption.
- COMPAREUL.I: add for "cms 8".
possible values. Add the PowerPC ncg and mcg backend support to let the test
actually run, including modifying a bunch of PowrePC libem functions so that
they can be called from both ncg and mcg.
corresponding invocation in the ncg table so the same helpers can be used for
both mcg and ncg. Add a new IR opcode, FARJUMP, which jumps to a helper
function but saves volatile registers.
occasionally the first hop of a block would try to rearrange its registers (due
to evicted throughs), resulting in the phi moves copying values into the wrong
registers.
