* Sema: resolve type fully when emitting an alloc AIR instruction to
avoid tripping assertion for checking struct field alignment.
* LLVM backend: keep a reference to the LLVM target data alive during
lowering so that we can ask LLVM what it thinks the ABI alignment
and size of LLVM types are. We need this in order to lower tuples and
structs so that we can put in extra padding bytes when Zig disagrees
with LLVM about the size or alignment of something.
* LLVM backend: make the LLVM struct type packed that contains the most
aligned union field and the padding. This prevents the struct from
being too big according to LLVM. In the future, we may want to
consider instead emitting unions in a "flat" manner; putting the tag,
most aligned union field, and padding all in the same struct field
space.
* LLVM backend: make structs with 2 or fewer fields return isByRef=false.
This results in more efficient codegen. This required lowering of
bitcast to sometimes store the struct into an alloca, ptrcast, and
then load because LLVM does not allow bitcasting structs.
* enable more passing behavior tests.
The ensureUnusedCapacity did not reserve a big enough number. I changed
it to no longer guess the capacity because I saw that the number of
possible items was not determinable ahead of time and this can therefore
avoid allocating more memory than necessary.
Companion commit to 61a53a587558ff1fe1b0ec98bb424022885edccf.
This commit also moves over a bunch of behavior test cases to the
passing-for-stage2 section.
Before, the system to replace a result location pointer with a
traditional break instruction did not notice the case when one of the
bodies was unreachable. Now, the emitted ZIR code is improved and
simplified in this case, resulting in a new passing behavior test.
* Value: rename `error_union` to `eu_payload` and clarify the intended
usage in the doc comments. The way error unions is represented with
Value is fixed to not have ambiguous values.
* Fix codegen for error union constants in all the backends.
* Implement the AIR instructions having to do with error unions in the
LLVM backend.
Conflicts:
* doc/langref.html.in
* lib/std/enums.zig
* lib/std/fmt.zig
* lib/std/hash/auto_hash.zig
* lib/std/math.zig
* lib/std/mem.zig
* lib/std/meta.zig
* test/behavior/alignof.zig
* test/behavior/bitcast.zig
* test/behavior/bugs/1421.zig
* test/behavior/cast.zig
* test/behavior/ptrcast.zig
* test/behavior/type_info.zig
* test/behavior/vector.zig
Master branch added `try` to a bunch of testing function calls, and some
lines also had changed how to refer to the native architecture and other
`@import("builtin")` stuff.
