diff --git a/ir.c b/ir.c
index 48e4a1e..010474e 100644
--- a/ir.c
+++ b/ir.c
@@ -990,7 +990,7 @@ void ir_build_def_use_lists(ir_ctx *ctx)
 				lists[def].count++;
 			}
 		}
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_inputs_to_len(n);
 		i += n;
 		insn += n;
 	}
@@ -1012,7 +1012,7 @@ void ir_build_def_use_lists(ir_ctx *ctx)
 				edges[use_list->refs + use_list->count++] = i;
 			}
 		}
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_inputs_to_len(n);
 		i += n;
 		insn += n;
 	}
diff --git a/ir_aarch64.dasc b/ir_aarch64.dasc
index be56619..e652636 100644
--- a/ir_aarch64.dasc
+++ b/ir_aarch64.dasc
@@ -4670,8 +4670,7 @@ static void ir_allocate_unique_spill_slots(ir_ctx *ctx)
 					}
 					break;
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 			rule += n;
@@ -4735,8 +4734,7 @@ static void ir_preallocate_call_stack(ir_ctx *ctx, ir_backend_data *data)
 				peak_call_stack_size = call_stack_size;
 			}
 		}
-		n = ir_operands_count(ctx, insn);
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_len(insn);
 		i += n;
 		insn += n;
 	}
@@ -4911,8 +4909,7 @@ void *ir_emit_code(ir_ctx *ctx, size_t *size_ptr)
 		}
 
 		/* skip first instruction */
-		n = ir_operands_count(ctx, insn);
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_len(insn);
 		i += n;
 		insn += n;
 		rule = ctx->rules + i;
@@ -5107,8 +5104,7 @@ void *ir_emit_code(ir_ctx *ctx, size_t *size_ptr)
 					IR_ASSERT(0 && "NIY rule/insruction");
 					break;
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 			rule += n;
diff --git a/ir_check.c b/ir_check.c
index 35b3355..90748e5 100644
--- a/ir_check.c
+++ b/ir_check.c
@@ -339,7 +339,7 @@ bool ir_check(const ir_ctx *ctx)
 				}
 			}
 		}
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_inputs_to_len(n);
 		i += n;
 		insn += n;
 	}
diff --git a/ir_dump.c b/ir_dump.c
index 5ab56a1..1438fe8 100644
--- a/ir_dump.c
+++ b/ir_dump.c
@@ -132,7 +132,7 @@ void ir_dump_dot(const ir_ctx *ctx, FILE *f)
 				}
 			}
 		}
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_inputs_to_len(n);
 		i += n;
 		insn += n;
 	}
diff --git a/ir_emit_c.c b/ir_emit_c.c
index 911d874..6fb9b7d 100644
--- a/ir_emit_c.c
+++ b/ir_emit_c.c
@@ -756,8 +756,7 @@ static int ir_emit_func(ir_ctx *ctx, FILE *f)
 					return 0;
 				}
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 		}
@@ -955,8 +954,7 @@ static int ir_emit_func(ir_ctx *ctx, FILE *f)
 				default:
 					IR_ASSERT(0 && "NIY instruction");
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 		}
diff --git a/ir_gcm.c b/ir_gcm.c
index 865e445..f0d93a1 100644
--- a/ir_gcm.c
+++ b/ir_gcm.c
@@ -529,7 +529,7 @@ int ir_schedule(ir_ctx *ctx)
 			consts_count += ir_count_constant(used, insn->op2);
 		}
 		n = ir_input_edges_count(ctx, insn);
-		insns_count += 1 + (n >> 2); // support for multi-word instructions like MERGE
+		insns_count += ir_insn_inputs_to_len(n);
 		i = _next[i];
 		insn = &ctx->ir_base[i];
 		/* Schedule PARAM, VAR, PI */
@@ -547,7 +547,7 @@ int ir_schedule(ir_ctx *ctx)
 			ir_bitset_incl(scheduled, i);
 			_xlat[i] = insns_count;
 			/* Reuse "n" from MERGE and skip first input */
-			insns_count += 1 + ((n + 1) >> 2); // support for multi-word instructions like PHI
+			insns_count += ir_insn_inputs_to_len(n + 1);
 			for (j = n, p = insn->ops + 2; j > 0; p++, j--) {
 				input = *p;
 				if (input < IR_TRUE) {
@@ -591,7 +591,7 @@ restart:
 			}
 			ir_bitset_incl(scheduled, i);
 			_xlat[i] = insns_count;
-			insns_count += 1 + (n >> 2); // support for multi-word instructions like CALL
+			insns_count += ir_insn_inputs_to_len(n);
 			i = _next[i];
 			insn = &ctx->ir_base[i];
 		}
@@ -830,8 +830,7 @@ void ir_build_prev_refs(ir_ctx *ctx)
 		IR_ASSERT(!(bb->flags & IR_BB_UNREACHABLE));
 		for (i = bb->start, insn = ctx->ir_base + i; i < bb->end;) {
 			ctx->prev_ref[i] = prev;
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			prev = i;
 			i += n;
 			insn += n;
diff --git a/ir_private.h b/ir_private.h
index 2a5263d..fd0d1bd 100644
--- a/ir_private.h
+++ b/ir_private.h
@@ -842,6 +842,22 @@ IR_ALWAYS_INLINE ir_ref ir_input_edges_count(const ir_ctx *ctx, const ir_insn *i
 	return n;
 }
 
+IR_ALWAYS_INLINE uint32_t ir_insn_inputs_to_len(uint32_t inputs_count)
+{
+	return 1 + (inputs_count >> 2);
+}
+
+IR_ALWAYS_INLINE uint32_t ir_insn_len(const ir_insn *insn)
+{
+	uint32_t flags = ir_op_flags[insn->op];
+	uint32_t n = 1;
+	if (UNEXPECTED(IR_OP_HAS_VAR_INPUTS(flags))) {
+		/* MERGE, PHI, CALL, etc */
+		n = ir_insn_inputs_to_len(insn->inputs_count);
+	}
+	return n;
+}
+
 /*** IR Binding ***/
 IR_ALWAYS_INLINE ir_ref ir_binding_find(const ir_ctx *ctx, ir_ref ref)
 {
diff --git a/ir_ra.c b/ir_ra.c
index c7c2142..73433e7 100644
--- a/ir_ra.c
+++ b/ir_ra.c
@@ -57,8 +57,7 @@ static int ir_assign_virtual_registers_slow(ir_ctx *ctx)
 
 		/* skip first instruction */
 		insn = ctx->ir_base + i;
-		n = ir_operands_count(ctx, insn);
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_len(insn);
 		i += n;
 		insn += n;
 		while (i < bb->end) {
@@ -69,8 +68,7 @@ static int ir_assign_virtual_registers_slow(ir_ctx *ctx)
 					vregs[i] = ++vregs_count;
 				}
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 		}
diff --git a/ir_save.c b/ir_save.c
index 3e73a79..1df488f 100644
--- a/ir_save.c
+++ b/ir_save.c
@@ -123,7 +123,7 @@ void ir_save(const ir_ctx *ctx, FILE *f)
 			}
 		}
 		fprintf(f, "\n");
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_inputs_to_len(n);
 		i += n;
 		insn += n;
 	}
diff --git a/ir_x86.dasc b/ir_x86.dasc
index bc0de86..08e4d51 100644
--- a/ir_x86.dasc
+++ b/ir_x86.dasc
@@ -7716,8 +7716,7 @@ static void ir_allocate_unique_spill_slots(ir_ctx *ctx)
 					}
 					break;
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 			rule += n;
@@ -7778,8 +7777,7 @@ static void ir_preallocate_call_stack(ir_ctx *ctx, ir_backend_data *data)
 				peak_call_stack_size = call_stack_size;
 			}
 		}
-		n = ir_operands_count(ctx, insn);
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_len(insn);
 		i += n;
 		insn += n;
 	}
@@ -7984,8 +7982,7 @@ void *ir_emit_code(ir_ctx *ctx, size_t *size_ptr)
 		}
 
 		/* skip first instruction */
-		n = ir_operands_count(ctx, insn);
-		n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+		n = ir_insn_len(insn);
 		i += n;
 		insn += n;
 		rule = ctx->rules + i;
@@ -8515,8 +8512,7 @@ void *ir_emit_code(ir_ctx *ctx, size_t *size_ptr)
 					IR_ASSERT(0 && "NIY rule/insruction");
 					break;
 			}
-			n = ir_operands_count(ctx, insn);
-			n = 1 + (n >> 2); // support for multi-word instructions like MERGE and PHI
+			n = ir_insn_len(insn);
 			i += n;
 			insn += n;
 			rule += n;