Cranelift AArch64: Improve the type checks for IR operations

There were cases where the AArch64 backend assumed that an IR
operation would always operate on certain types (the most likely
reason being that the corresponding WebAssembly instruction did
not cover anything else), even though the definition of the IR
operation imposed no constraints like that.

Copyright (c) 2021, Arm Limited.

cranelift/codegen/src/isa/aarch64/lower.rs

@@ -1098,10 +1098,7 @@ pub(crate) fn lower_vector_compare<C: LowerCtx<I = Inst>>(
     ty: Type,
     cond: Cond,
 ) -> CodegenResult<()> {
-    let is_float = match ty {
-        F32X4 | F64X2 => true,
-        _ => false,
-    };
+    let is_float = ty.lane_type().is_float();
     let size = VectorSize::from_ty(ty);
 
     if is_float && (cond == Cond::Vc || cond == Cond::Vs) {
@@ -1831,14 +1828,14 @@ fn load_op_to_ty(op: Opcode) -> Option<Type> {
 /// a load can sometimes be merged into another operation.
 pub(crate) fn lower_load<
     C: LowerCtx<I = Inst>,
-    F: FnMut(&mut C, ValueRegs<Writable<Reg>>, Type, AMode),
+    F: FnMut(&mut C, ValueRegs<Writable<Reg>>, Type, AMode) -> CodegenResult<()>,
 >(
     ctx: &mut C,
     ir_inst: IRInst,
     inputs: &[InsnInput],
     output: InsnOutput,
     mut f: F,
-) {
+) -> CodegenResult<()> {
     let op = ctx.data(ir_inst).opcode();
 
     let elem_ty = load_op_to_ty(op).unwrap_or_else(|| ctx.output_ty(ir_inst, 0));
@@ -1847,7 +1844,7 @@ pub(crate) fn lower_load<
     let mem = lower_address(ctx, elem_ty, &inputs[..], off);
     let rd = get_output_reg(ctx, output);
 
-    f(ctx, rd, elem_ty, mem);
+    f(ctx, rd, elem_ty, mem)
 }
 
 pub(crate) fn emit_shl_i128<C: LowerCtx<I = Inst>>(