This updates the C backend to use proper array types.
In order to do that, this commit also:
- fixes up elem_ptr and field_ptr handling
- adds `renderTypecast` (renders in C typecast format, e.g. "int* [10]")
- adds a bit special handling for undefined pointers, which is necessary
to support slice/elem_ptr to undefined decls
Get rid of `std.math.F80Repr`. Instead of trying to match the memory
layout of f80, we treat it as a value, same as the other floating point
types. The functions `make_f80` and `break_f80` are introduced to
compose an f80 value out of its parts, and the inverse operation.
stage2 LLVM backend: fix pointer to zero length array tripping LLVM
assertion. It now checks for when the element type is a zero-bit type
and lowers such thing the same way that pointers to other zero-bit types
are lowered.
Both stage1 and stage2 LLVM backends are adjusted so that f80 is lowered
as x86_fp80 on x86_64 and i386 architectures, and identical to a u80 on
others. LLVM constants are lowered in a less hacky way now that #10860
is fixed, by using the expression `(exp << 64) | fraction` using llvm
constants.
Sema is improved to handle c_longdouble by recursively handling it
correctly for whatever the float bit width is. In both stage1 and
stage2.
This moves the single bugs behavior tests to the outer branch and disables the test cases
for all non-passing backends.
For the larger files, we move it up a single branch and disable it for the c backend.
All test cases that do pass for the c backend however, are enabled.
LLVM union globals have to be lowered as unnamed structs if the
non-most-aligned field is the active tag. In this case it bubbles up so
that structs containing unions have the same restriction.
This fix needs to be applied to optionals and other callsites of
createNamedStruct.
The bug fixed in this commit was revealed in searching for
the cause of #10837.
`const` declarations inside comptime blocks were not getting properly
evaluated at compile-time. To accomplish this there is a new ZIR
instruction, `alloc_inferred_comptime`. Actually we already had one
named that, but it got renamed to `alloc_inferred_comptime_mut` to match
the naming convention with the other similar instructions.
