The document describes the steps taken to compile the Clojure function fact into Java bytecode. It shows the Clojure definition, the macro expansion, analysis, and emission steps, and ultimately the generated Java bytecode with instructions for recursively calculating the factorial of a number.

2. 2

3. public java.lang.Object invoke(java.lang.Object);
Code:
Stack=8, Locals=8, Args_size=2
0: aload_1
1: aconst_null
2: astore_1
3: invokestatic #65; //Method clojure/lang
6: lstore_2
7: lconst_1
8: lstore 4
10: lload_2
11: lconst_0
12: lcmp
13: ifne 25
16: lload 4
18: invokestatic #71; //Method clojure/lang
21: goto 38
24: pop
25: lload_2
26: lconst_1
27: lsub
28: lload_2
29: lload 4
(defn fact [n] 31: lmul
(loop [n (long n), a 1] 32: lstore 4
(if (== n 0) 34: lstore_2
a 35: goto 10
(recur (dec n) (* n a))))) 38: areturn
3

4. (def fact
(fn-iasm [n]
(aload_1)
(checkcast Integer)
(invokevirtual ^int Integer/intValue [])
(istore_2)
(iconst_1)
(istore_3)
:loop
(iload_2)
(ifeq :end)
(ilaod_2)
(iload_3)
(imul)
(istore_3)
(iinc 2 -1)
(goto :loop)
:end
(iload_3)
(invokestatic ^Integer Integer/valueOf [int])
(areturn)))
4

5. (def fact public final java.lang.Object invoke(java.lang.
(fn-iasm [n] Code:
(aload_1) Stack=2, Locals=6, Args_size=2
(checkcast Integer) 0: aload_1
(invokevirtual ^int Integer/intValue []) 1: checkcast #25; //class java/lang/I
(istore_2) 4: invokevirtual #29; //Method java/lang/
(iconst_1) 7: istore_2
(istore_3) 8: iconst_1
:loop 9: istore_3
(iload_2) 10: iload_2
(ifeq :end) 11: ifeq 24
(ilaod_2) 14: iload_2
(iload_3) 15: iload_3
(imul) 16: imul
(istore_3) 17: istore_3
(iinc 2 -1) 18: iinc 2, -1
(goto :loop) 21: goto 10
:end 24: iload_3
(iload_3) 25: invokestatic #33; //Method java/lang/
(invokestatic ^Integer Integer/valueOf [int]) 28: areturn
(areturn)))
4

6. public java.lang.Object invoke(java.lang.Object);
Code:
Stack=8, Locals=8, Args_size=2
0: aload_1
1: aconst_null
2: astore_1
3: invokestatic #65; //Method clojure/lang
6: lstore_2
7: lconst_1
8: lstore 4
macro 10: lload_2
11: lconst_0
(defn fact [n]
(loop [n (long n), a 1] expand analyze emit 12: lcmp
13: ifne 25
(if (== n 0)
16: lload 4
a
18: invokestatic #71; //Method clojure/lang
(recur (dec n) (* n a)))))
21: goto 38
24: pop
25: lload_2
26: lconst_1
27: lsub
28: lload_2
29: lload 4
31: lmul
32: lstore 4
34: lstore_2
35: goto 10
38: areturn
5

7. public java.lang.Object invoke(java.lang.Object);
Code:
Stack=8, Locals=8, Args_size=2
0: aload_1
1: aconst_null
2: astore_1
3: invokestatic #65; //Method clojure/lang
6: lstore_2
7: lconst_1
8: lstore 4
macro 10: lload_2
11: lconst_0
(defn fact [n]
(loop [n (long n), a 1] expand analyze emit 12: lcmp
13: ifne 25
(if (== n 0)
16: lload 4
a
18: invokestatic #71; //Method clojure/lang
(recur (dec n) (* n a)))))
21: goto 38
24: pop
25: lload_2
26: lconst_1
27: lsub
28: lload_2
29: lload 4
31: lmul
32: lstore 4
34: lstore_2
35: goto 10
38: areturn
5

8. public java.lang.Object invoke(java.lang.Object);
Code:
Stack=8, Locals=8, Args_size=2
0: aload_1
1: aconst_null
2: astore_1
3: invokestatic #65; //Method clojure/lang
6: lstore_2
7: lconst_1
8: lstore 4
macro 10: lload_2
11: lconst_0
(defn fact [n]
(loop [n (long n), a 1] expand analyze emit 12: lcmp
13: ifne 25
(if (== n 0)
16: lload 4
a
18: invokestatic #71; //Method clojure/lang
(recur (dec n) (* n a)))))
21: goto 38
24: pop
25: lload_2
26: lconst_1
27: lsub
28: lload_2
29: lload 4
31: lmul
32: lstore 4
34: lstore_2
35: goto 10
38: areturn
5

9. public java.lang.Object invoke(java.lang.Object);
Code:
Stack=8, Locals=8, Args_size=2
0: aload_1
1: aconst_null
2: astore_1
3: invokestatic #65; //Method clojure/lang
6: lstore_2
7: lconst_1
8: lstore 4
macro 10: lload_2
11: lconst_0
(defn fact [n]
(loop [n (long n), a 1] expand analyze emit 12: lcmp
13: ifne 25
(if (== n 0)
16: lload 4
a
18: invokestatic #71; //Method clojure/lang
(recur (dec n) (* n a)))))
21: goto 38
24: pop
25: lload_2
public java.lang.Object invoke(java.lang.Object); 26: lconst_1
Code: 27: lsub
Stack=8, Locals=8, Args_size=2 28: lload_2
0: aload_1 29: lload 4
1: aconst_null 31: lmul
2: astore_1 32: lstore 4
3: invokestatic #65; //Method clojure/lang 34: lstore_2
6: lstore_2 35: goto 10
7: lconst_1 38: areturn
8: lstore 4
10: lload_2
11: lconst_0
12: lcmp
13: ifne 25
16: lload 4
18: invokestatic #71; //Method clojure/lang
21: goto 38
24: pop
25: lload_2
26: lconst_1
27: lsub
28: lload_2
29: lload 4
31: lmul
32: lstore 4
34: lstore_2
35: goto 10
38: areturn
5

10. 6

11. 7

15. 0.60
Clojure 1.2.1
iasm
0.45
0.30
0.15
0
100 200 300 400
9

16. 10