fixed dead code patching in StackMapGenerator::removeRangeFromExcTable and added test (openjdk#10)

Author: asotona

src/java.base/share/classes/jdk/classfile/impl/StackMapGenerator.java

@@ -360,7 +360,7 @@ private void removeRangeFromExcTable(int rangeStart, int rangeEnd) {
             int handlerEnd = labelContext.labelToBci(e.tryEnd());
             if (rangeStart >= handlerEnd || rangeEnd <= handlerStart) {
                 //out of range
-                return;
+                continue;
             }
             if (trace) System.out.println("      Removing dead code range from exception handler start: " + handlerStart + " end: " + handlerEnd);
             if (rangeStart <= handlerStart) {

test/jdk/jdk/classfile/StackMapsTest.java

@@ -55,10 +55,36 @@ private byte[] buildDeadCode() {
                 ClassDesc.of("DeadCodePattern"),
                 List.of(Classfile.Option.generateStackmap(false), Classfile.Option.patchDeadCode(false)),
                 clb -> clb.withMethodBody(
-                        "twoReturns",
-                        MethodTypeDesc.of(ConstantDescs.CD_void),
-                        0,
-                        cob -> cob.return_().return_()));
+                                "twoReturns",
+                                MethodTypeDesc.of(ConstantDescs.CD_void),
+                                0,
+                                cob -> cob.return_().return_())
+                        .withMethodBody(
+                                "deadJumpInExceptionBlocks",
+                                MethodTypeDesc.of(ConstantDescs.CD_void),
+                                0,
+                                cob -> {
+                                    var deadEnd = cob.newLabel();
+                                    cob.goto_(deadEnd);
+                                    var deadStart = cob.newBoundLabel();
+                                    cob.return_(); //dead code
+                                    cob.labelBinding(deadEnd);
+                                    cob.return_();
+                                    var handler = cob.newBoundLabel();
+                                    cob.athrow();
+                                    //exception block before dead code to stay untouched
+                                    cob.exceptionCatch(cob.startLabel(), deadStart, handler, ConstantDescs.CD_Throwable);
+                                    //exception block after dead code to stay untouched
+                                    cob.exceptionCatch(deadEnd, handler, handler, ConstantDescs.CD_Throwable);
+                                     //exception block overlapping dead code to cut from right
+                                    cob.exceptionCatch(cob.startLabel(), deadEnd, handler, ConstantDescs.CD_Throwable);
+                                    //exception block overlapping dead code to from left
+                                    cob.exceptionCatch(deadStart, handler, handler, ConstantDescs.CD_Throwable);
+                                    //exception block matching dead code to remove
+                                    cob.exceptionCatch(deadStart, deadEnd, handler, ConstantDescs.CD_Throwable);
+                                    //exception block around dead code to split
+                                    cob.exceptionCatch(cob.startLabel(), handler, handler, ConstantDescs.CD_Throwable);
+                                }));
     }
 
     @Test