* introduce a dump() function on Module.Fn which helpfully prints to
stderr the ZIR representation of a function (can be called before
attempting to codegen it). This is a debugging tool.
* implement x86 codegen for loops
* liveness: fix analysis of conditional branches. The logic was buggy
in a couple ways:
- it never actually saved the results into the IR instruction (fixed now)
- it incorrectly labeled operands as dying when their true death was
after the conditional branch ended (fixed now)
* zir rendering is enhanced to show liveness analysis results. this
helps when debugging liveness analysis.
* fix bug in zir rendering not numbering instructions correctly
closes#6021
`std.builtin.StackTrace` gains a `format` function.
GeneralPurposeAllocator uses `std.log.err` instead of directly printing
to stderr. Some errors are recoverable.
The test runner is modified to fail the test run if any log messages of
"err" or worse severity are encountered.
self-hosted is modified to always print log messages of "err" severity
or worse even if they have not been explicitly enabled.
This makes GeneralPurposeAllocator available on the freestanding target.
* std.Mutex API is improved to not have init() deinit(). This API is
designed to support static initialization and does not require any
resource cleanup. This also happens to work around some kind of
stage1 behavior that wasn't letting the new allocator mutex code
get compiled.
* the general purpose allocator now returns a bool from deinit()
which tells if there were any leaks. This value is used by the test
runner to fail the tests if there are any.
* self-hosted compiler is updated to use the general purpose allocator
when not linking against libc.
I made two mistakes in the previous commit; it was not actually using
the argv that we built, and also the qemu logic was unconditionally
skipping the test.
Now I have verified that when mangling the RISC-V "hello world" test and
then using -Denable-qemu, we get a test failure.
