C backend: less branching

Author: andrewrk

src/codegen/c.zig

@@ -3348,8 +3348,8 @@ fn genBodyInner(f: *Function, body: []const Air.Inst.Index) error{ AnalysisFail,
  .atomic_load => try airAtomicLoad(f, inst),
  .memset => try airMemset(f, inst, false),
  .memset_safe => try airMemset(f, inst, true),
- .memcpy => try airMemcpy(f, inst),
- .memmove => try airMemmove(f, inst),
+ .memcpy => try airMemcpy(f, inst, "memcpy("),
+ .memmove => try airMemcpy(f, inst, "memmove("),
  .set_union_tag => try airSetUnionTag(f, inst),
  .get_union_tag => try airGetUnionTag(f, inst),
  .clz => try airUnBuiltinCall(f, inst, air_datas[@intFromEnum(inst)].ty_op.operand, "clz", .bits),
@@ -6976,15 +6976,7 @@ fn airMemset(f: *Function, inst: Air.Inst.Index, safety: bool) !CValue {
  return .none;
 }
 
-fn airMemcpy(f: *Function, inst: Air.Inst.Index) !CValue {
- return copyOp(f, inst, .memcpy);
-}
-
-fn airMemmove(f: *Function, inst: Air.Inst.Index) !CValue {
- return copyOp(f, inst, .memmove);
-}
-
-fn copyOp(f: *Function, inst: Air.Inst.Index, op: enum { memcpy, memmove }) !CValue {
+fn airMemcpy(f: *Function, inst: Air.Inst.Index, function_paren: []const u8) !CValue {
  const pt = f.object.dg.pt;
  const zcu = pt.zcu;
  const bin_op = f.air.instructions.items(.data)[@intFromEnum(inst)].bin_op;
@@ -6999,10 +6991,6 @@ fn copyOp(f: *Function, inst: Air.Inst.Index, op: enum { memcpy, memmove }) !CVa
  try writeArrayLen(f, writer, dest_ptr, dest_ty);
  try writer.writeAll(" != 0) ");
  }
- const function_paren = switch (op) {
- .memcpy => "memcpy(",
- .memmove => "memmove(",
- };
  try writer.writeAll(function_paren);
  try writeSliceOrPtr(f, writer, dest_ptr, dest_ty);
  try writer.writeAll(", ");