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Build 3.3M6 Following code could be slightly better generated: public class X { public static void main(String[] args) { while (args.length > 0) { System.out.println(); break; } for (int i = 0; i < args.length; i++) { System.out.println(i); break; } for (String s : args) { System.out.println(s); break; } do { System.out.println(); break; } while (args.length > 0); } } The 2 for-loops are not reversed, like the while does (due to no continuation point).
// Method descriptor #15 ([Ljava/lang/String;)V // Stack: 2, Locals: 5 public static void main(String[] args); 0 aload_0 [args] 1 arraylength 2 ifle 11 5 getstatic System.out : PrintStream [16] 8 invokevirtual PrintStream.println() : void [22] 11 iconst_0 12 istore_1 [i] 13 goto 26 16 getstatic System.out : PrintStream [16] 19 iload_1 [i] 20 invokevirtual PrintStream.println(int) : void [27] 23 goto 32 26 iload_1 [i] 27 aload_0 [args] 28 arraylength 29 if_icmplt 16 32 aload_0 [args] 33 astore 4 35 iconst_0 36 istore_2 37 aload 4 39 arraylength 40 istore_3 41 goto 59 44 aload 4 46 iload_2 47 aaload 48 astore_1 [s] 49 getstatic System.out : PrintStream [16] 52 aload_1 [s] 53 invokevirtual PrintStream.println(String) : void [30] 56 goto 64 59 iload_2 60 iload_3 61 if_icmplt 44 64 getstatic System.out : PrintStream [16] 67 invokevirtual PrintStream.println() : void [22] 70 return
The do statement looks suspicious too.
Actually do loops are fine. public class X { void foo1(int[] array) { while (array.length > 0) { System.out.println(); break; } } void foo2(int[] array) { for (int i = 0; i < array.length; i++) { System.out.println(i); break; } } void foo3(int[] array) { for (int i : array) { System.out.println(i); break; } } void foo4(int[] array) { do { System.out.println(); break; } while (array.length > 0); } } produces: // Method descriptor #15 ([I)V // Stack: 1, Locals: 2 void foo1(int[] array); 0 aload_1 [array] 1 arraylength 2 ifle 11 5 getstatic System.out : PrintStream [16] 8 invokevirtual PrintStream.println() : void [22] 11 return Line numbers: [pc: 0, line: 3] [pc: 5, line: 4] [pc: 11, line: 7] Local variable table: [pc: 0, pc: 12] local: this index: 0 type: X [pc: 0, pc: 12] local: array index: 1 type: int[] // Method descriptor #15 ([I)V // Stack: 2, Locals: 3 void foo2(int[] array); 0 iconst_0 1 istore_2 [i] 2 goto 15 5 getstatic System.out : PrintStream [16] 8 iload_2 [i] 9 invokevirtual PrintStream.println(int) : void [30] 12 goto 21 15 iload_2 [i] 16 aload_1 [array] 17 arraylength 18 if_icmplt 5 21 return Line numbers: [pc: 0, line: 9] [pc: 5, line: 10] [pc: 12, line: 11] [pc: 15, line: 9] [pc: 21, line: 13] Local variable table: [pc: 0, pc: 22] local: this index: 0 type: X [pc: 0, pc: 22] local: array index: 1 type: int[] [pc: 2, pc: 21] local: i index: 2 type: int // Method descriptor #15 ([I)V // Stack: 2, Locals: 6 void foo3(int[] array); 0 aload_1 [array] 1 astore 5 3 iconst_0 4 istore_3 5 aload 5 7 arraylength 8 istore 4 10 goto 28 13 aload 5 15 iload_3 16 iaload 17 istore_2 [i] 18 getstatic System.out : PrintStream [16] 21 iload_2 [i] 22 invokevirtual PrintStream.println(int) : void [30] 25 goto 34 28 iload_3 29 iload 4 31 if_icmplt 13 34 return Line numbers: [pc: 0, line: 15] [pc: 18, line: 16] [pc: 25, line: 17] [pc: 28, line: 15] [pc: 34, line: 19] Local variable table: [pc: 0, pc: 35] local: this index: 0 type: X [pc: 0, pc: 35] local: array index: 1 type: int[] [pc: 18, pc: 28] local: i index: 2 type: int // Method descriptor #15 ([I)V // Stack: 1, Locals: 2 void foo4(int[] array); 0 getstatic System.out : PrintStream [16] 3 invokevirtual PrintStream.println() : void [22] 6 return Line numbers: [pc: 0, line: 22] [pc: 6, line: 25] Local variable table: [pc: 0, pc: 7] local: this index: 0 type: X [pc: 0, pc: 7] local: array index: 1 type: int[]
Added ForeachStatementTests#test047 + updated other existing ones. Added ForStatementTest#test002-test004. Updated TryStementTest.
With changes, we now generate: // Method descriptor #6 ()V // Stack: 1, Locals: 1 public X(); 0 aload_0 [this] 1 invokespecial Object() [8] 4 return Line numbers: [pc: 0, line: 1] Local variable table: [pc: 0, pc: 5] local: this index: 0 type: X // Method descriptor #15 ([I)V // Stack: 1, Locals: 2 void foo1(int[] array); 0 aload_1 [array] 1 arraylength 2 ifle 11 5 getstatic System.out : PrintStream [16] 8 invokevirtual PrintStream.println() : void [22] 11 return Line numbers: [pc: 0, line: 3] [pc: 5, line: 4] [pc: 11, line: 7] Local variable table: [pc: 0, pc: 12] local: this index: 0 type: X [pc: 0, pc: 12] local: array index: 1 type: int[] // Method descriptor #15 ([I)V // Stack: 2, Locals: 3 void foo2(int[] array); 0 iconst_0 1 istore_2 [i] 2 iload_2 [i] 3 aload_1 [array] 4 arraylength 5 if_icmpge 15 8 getstatic System.out : PrintStream [16] 11 iload_2 [i] 12 invokevirtual PrintStream.println(int) : void [30] 15 return Line numbers: [pc: 0, line: 9] [pc: 8, line: 10] [pc: 15, line: 13] Local variable table: [pc: 0, pc: 16] local: this index: 0 type: X [pc: 0, pc: 16] local: array index: 1 type: int[] [pc: 2, pc: 15] local: i index: 2 type: int // Method descriptor #15 ([I)V // Stack: 2, Locals: 4 void foo3(int[] array); 0 aload_1 [array] 1 dup 2 astore_3 3 arraylength 4 ifeq 18 7 aload_3 8 iconst_0 9 iaload 10 istore_2 [i] 11 getstatic System.out : PrintStream [16] 14 iload_2 [i] 15 invokevirtual PrintStream.println(int) : void [30] 18 return Line numbers: [pc: 0, line: 15] [pc: 11, line: 16] [pc: 18, line: 19] Local variable table: [pc: 0, pc: 19] local: this index: 0 type: X [pc: 0, pc: 19] local: array index: 1 type: int[] [pc: 11, pc: 18] local: i index: 2 type: int // Method descriptor #15 ([I)V // Stack: 1, Locals: 2 void foo4(int[] array); 0 getstatic System.out : PrintStream [16] 3 invokevirtual PrintStream.println() : void [22] 6 return Line numbers: [pc: 0, line: 22] [pc: 6, line: 25] Local variable table: [pc: 0, pc: 7] local: this index: 0 type: X [pc: 0, pc: 7] local: array index: 1 type: int[]
Created attachment 62672 [details] Proposed patch
Created attachment 62706 [details] Better patch
Released for 3.3M7 Fixed
fyi - javac generates 31 bytecodes for #foo3, where we only issue 18. // Method descriptor #12 ([I)V // Stack: 2, Locals: 6 void foo3(int[] arg0); 0 aload_1 1 astore_2 2 aload_2 3 arraylength 4 istore_3 5 iconst_0 6 istore 4 8 iload 4 10 iload_3 11 if_icmpge 31 14 aload_2 15 iload 4 17 iaload 18 istore 5 20 getstatic System.out : PrintStream [2] 23 iload 5 25 invokevirtual PrintStream.println(int) : void [4] 28 goto 31 31 return Line numbers: [pc: 0, line: 15] [pc: 20, line: 16] [pc: 28, line: 17] [pc: 31, line: 19] Stack map table: number of frames 2 [pc: 8, append: {int[], int, int}] [pc: 31, chop 3 local(s)]
Verified for 3.3M7 with I20070427-0010
