The following, from the documentation as of the time of writing, illustrates
the problem:
```zig
// Compile time coercion of float to int
test "implicit cast to comptime_int" {
var f: f32 = 54.0 / 5;
_ = f;
}
```
It is not clear how to unify the types of 54.0 and 5 to perform the
division. We can either
- cast 54.0 to comptime_int resulting in @as(comptime_int, 10), which is
casted to @as(f32, 10), or
- cast 5 to comptime_float resulting in @as(comptime_float, 10.8), which
is casted to @as(f32, 10.8)
Since the two resulting values are different, a compiler error is appropriate.
If we know that casting to either type will result in the same value we
don't need to error. For instance, 10.0 / 2 is okay, as is 10 / 2.0.
Fixes: #12364
Rather than lowering float negation as `0.0 - x`.
* Add AIR instruction for float negation.
* Add compiler-rt functions for f128, f80 negation
closes#11853
This shuffles some tests do ensure the new instructions are tested for the wasm backend,
by moving vectors into their own tests as well as move the f16 test cases as those require
special operating also.
Detect if we are storing an array operand to a bitcasted vector pointer.
If so, we instead reach through the bitcasted pointer to the vector pointer,
bitcast the array operand to a vector, and then lower this as a store of
a vector value to a vector pointer. This generally results in better code,
as well as working around an LLVM bug.
See #11154
Adds 2 new AIR instructions:
* dbg_var_ptr
* dbg_var_val
Sema no longer emits dbg_stmt AIR instructions when strip=true.
LLVM backend: fixed lowerPtrToVoid when calling ptrAlignment on
the element type is problematic.
LLVM backend: fixed alloca instructions improperly getting debug
location annotated, causing chaotic debug info behavior.
zig_llvm.cpp: fixed incorrect bindings for a function that should use
unsigned integers for line and column.
A bunch of C test cases regressed because the new dbg_var AIR
instructions caused their operands to be alive, exposing latent bugs.
Mostly it's just a problem that the C backend lowers mutable
and const slices to the same C type, so we need to represent that in the
C backend instead of printing two duplicate typedefs.
The checks detecting such no-op branches (essentially instructions
that branch to the instruction immediately following the branch) were
tightened to catch more of these occurrences.
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.
Support for f128, comptime_float, and c_longdouble require improvements
to compiler_rt and will implemented in a later PR. Some of the code in
this commit could be made more generic, for instance `llvm.airSqrt`
could probably be `llvm.airUnaryMath`, but let's cross that
bridge when we get to it.
