Commit 5393e56500d499753dbc39704c0161b47d1e4d5c has a flaw pointed out
by @mlugg: the `ty` field of pointer values changes when comptime values
are pointer-casted. This commit introduces a new encoding which
additionally stores the "original pointer type" which is used to store
the alignment of the anonymous decl, and potentially other information
in the future such as section and pointer address space. However, this
new encoding is only used when the original pointer type differs from
the casted pointer type in a meaningful way.
I was able to make the LLVM backend and the C backend lower anonymous
decls with the appropriate alignment, however I will need some help
figuring out how to do this for the backends that lower anonymous decls
via src/codegen.zig and the wasm backend.
Instead of creating Module.Decl objects, directly create InternPool
pointer values using the anon_decl Addr encoding.
The LLVM backend needed code to notice the alignment of the pointer and
lower accordingly. The other backends likely need a similar change.
This completes the migration from spv.ptrType to self.ptrType.
Unfortunately this requires us to pass a list of types to
constructStruct, which also requires some extra allocations
here and there.
This removes the strategy where union with different active
fields would be generated, and instead simply pointer casts
the active field type where required. This also allows removing
spv.ptrType and using self.ptrType instead, and allows caching
all union types (because there is only the canonical one).
This struct is used to configure the load, such as to make
it volatile. Previously this was done using a single bool, but
this struct makes it shorter to write non-volatile loads (the
usual) and more clear whats going on when a volatile load is
required.
To support self-referential pointers, in the future we will
need to pass the Zig type to any pointer that is created. This
lays some ground work for that by replacing most uses of
spv.ptrType with a new ptrType function that also accepts the
Zig type. This function's contents will soon be replaced by
a version that also supports self-referential pointers.
Also fixed some bugs regarding the use of direct/indirect.
The Khronos SPIRV-LLVM translator does not parse OpSource correctly. This
was causing tests to fail and other mysterious issues.
These are resolved by only generating a single OpSource instruction for now,
which does not have the source file locations also.
See https://github.com/KhronosGroup/SPIRV-LLVM-Translator/issues/2188
The previous code incorrectly added `sub_path` twice.
Also for the compilation unit, it was passing empty string to realpath,
resulting in the error handling codepath being used.
closes#17482
