The LLVM intrinsics that live under `llvm.x86` are not actual functions,
so trying to invoke them as such using the platform's native C
calling convention causes incorrect types to be emitted in the IR.
Thanks to laytanl for assistance in testing.
`llvm_features` being empty is the default state, and implies the
presence of certain features.
Previously if any target features were explicitly enabled by the
`enable_target_feature` attribute, they were added comma separated
to `llvm_features`.
For example: `lzcnt,popcnt,...,sse4.2,sse`
This was causing LLVM to try to target a CPU that *ONLY* has the
explicitly enabled features. This now will prefix explicitly enabled
features with a `+`, and preserve the existing `llvm_features` string
by appending to it if it is set.
```
package example
import "core:dynlib"
import "core:fmt"
Symbols :: struct {
// `foo_` is prefixed, so we look for the symbol `foo_add`.
add: proc "c" (int, int) -> int,
// We use the tag here to override the symbol to look for, namely `bar_sub`.
sub: proc "c" (int, int) -> int `dynlib:"bar_sub"`,
// Exported global (if exporting an i32, the type must be ^i32 because the symbol is a pointer to the export.)
// If it's not a pointer or procedure type, we'll skip the struct field.
hellope: ^i32,
// Handle to free library.
// We can have more than one of these so we can match symbols for more than one DLL with one struct.
_my_lib_handle: dynlib.Library,
}
main :: proc() {
sym: Symbols
// Load symbols from `lib.dll` into Symbols struct.
// Each struct field is prefixed with `foo_` before lookup in the DLL's symbol table.
// The library's Handle (to unload) will be stored in `sym._my_lib_handle`. This way you can load multiple DLLs in one struct.
count := dynlib.initialize_symbols(&sym, "lib.dll", "foo_", "_my_lib_handle")
defer dynlib.unload_library(sym._my_lib_handle)
fmt.printf("%v symbols loaded from lib.dll (%p).\n", count, sym._my_lib_handle)
if count > 0 {
fmt.println("42 + 42 =", sym.add(42, 42))
fmt.println("84 - 13 =", sym.sub(84, 13))
fmt.println("hellope =", sym.hellope^)
}
}
```
