Custom type-checking (in WebAssemblyAsmTypeCheck.cpp) is used to
workaround the fact that separate variants of the instruction are
defined for externref and funcref.
Based on an initial patch by Paulo Matos <pmatos@igalia.com>.
Differential Revision: https://reviews.llvm.org/D123484
This patch implements the intrinsic for ref.null.
In the process of implementing int_wasm_ref_null_func() and
int_wasm_ref_null_extern() intrinsics, it removes the redundant
HeapType.
This also causes the textual assembler syntax for ref.null to
change. Instead of receiving an argument: `func` or `extern`, the
instruction mnemonic is either ref.null_func or ref.null_extern,
without the need for a further operand.
Reviewed By: tlively
Differential Revision: https://reviews.llvm.org/D114979
Alex Bradbury