Re: ASM 4.0 RC2: Revisiting the NOP ATHROW bug

Eric Bruneton <[email protected]>
Newsgroups gmane.comp.java.objectweb.asm
Message-ID <[email protected]> 
> The python program:
>
>     def addsitedir(sitedir, known_paths=None):
>          if known_paths is None:
>              reset = 1
>          try:
>              names = os.listdir(sitedir)
>          except os.error:
>              return
>          return known_paths
>
>     if __name__ == '__main__':
>          _test()
>
>
> Gives an error:
>
>     Exception in thread "main" java.lang.VerifyError: Stack map does not
>     match the one at exception handler 103 in method
>     site$py._addsitedir$1(Lorg/python/core/PyFrame;Lorg/python/core/ThreadState;Lorg/python/core/PyObject;Lorg/python/core/PyObject;Lorg/python/core/PyObject;)Lorg/python/core/PyObject;
>     at offset 88
>
> The generated class file is here:
> http://pylonshq.com/pasties/1a43b011ac411cba6cc9fcb88ef5254a
> The method of interest is _addsitedir which starts at line 442.
>
> The ASM generated code is at:
> http://pylonshq.com/pasties/378d9ad2bc539623fb08d510f4da81cf and again
> the method begins at line 93.

ok, thanks. This time I have all the information I need :-) The problem 
has nothing to do with deadcode and NOP ATHROW. I think you were 
confused because you often have generated deadcode. The problem comes 
from the fact that you don't call visitTryCatchBlock *before* you visit 
the labels passed as arguments, as described in the Javadoc of 
visitTryCatchBlock. This is required for COMPUTE_FRAMES to work 
properly. You could have found this with a CheckClassAdapter in your 
generation chain (which also detects that you don't call visitCode, as 
required). See attached code.

Eric
Test.java (text/x-java, 6.7 KB) 
import java.io.PrintWriter;

import org.objectweb.asm.ClassReader;
import org.objectweb.asm.ClassVisitor;
import org.objectweb.asm.ClassWriter;
import org.objectweb.asm.Handle;
import org.objectweb.asm.Label;
import org.objectweb.asm.MethodVisitor;
import static org.objectweb.asm.Opcodes.*;

import org.objectweb.asm.util.CheckClassAdapter;
import org.objectweb.asm.util.TraceClassVisitor;

public class Test {

    public static void main(String[] args) throws Exception {
        ClassWriter cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES);
        CheckClassAdapter ca = new CheckClassAdapter(cw, false);
        ClassVisitor cv = new TraceClassVisitor(ca, new PrintWriter(System.out, true));
        cv.visit(V1_7, ACC_PUBLIC, "C", null, "java/lang/Object", null);
        MethodVisitor mv = cv.visitMethod(ACC_PUBLIC, "_addsitedir$1", "(Lorg/python/core/PyFrame;Lorg/python/core/ThreadState;Lorg/python/core/PyObject;Lorg/python/core/PyObject;Lorg/python/core/PyObject;)Lorg/python/core/PyObject;", null, null);
        mv.visitCode();
        Label l0 = new Label();
        mv.visitLabel(l0);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitInsn(ICONST_4);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setline", "(I)V");
        mv.visitFieldInsn(GETSTATIC, "site$py", "_1", "Lorg/python/core/PyString;");
        mv.visitInsn(POP);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitInsn(ICONST_5);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setline", "(I)V");
        mv.visitVarInsn(ALOAD, 5);
        mv.visitVarInsn(ASTORE, 6);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitLdcInsn("None");
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "getglobal", "(Ljava/lang/String;)Lorg/python/core/PyObject;");
        mv.visitVarInsn(ALOAD, 6);
        mv.visitInsn(SWAP);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyObject", "_is", "(Lorg/python/core/PyObject;)Lorg/python/core/PyObject;");
        mv.visitInsn(ACONST_NULL);
        mv.visitVarInsn(ASTORE, 6);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyObject", "__nonzero__", "()Z");
        Label l1 = new Label();
        mv.visitJumpInsn(IFEQ, l1);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitIntInsn(BIPUSH, 6);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setline", "(I)V");
        mv.visitFieldInsn(GETSTATIC, "site$py", "_2", "Lorg/python/core/PyInteger;");
        mv.visitVarInsn(ASTORE, 6);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitInsn(ICONST_2);
        mv.visitVarInsn(ALOAD, 6);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setlocal", "(ILorg/python/core/PyObject;)V");
        mv.visitInsn(ACONST_NULL);
        mv.visitVarInsn(ASTORE, 6);
        Label l2 = new Label();
        mv.visitJumpInsn(GOTO, l2);
        mv.visitLabel(l1);
        mv.visitLabel(l2);
        Label l3 = new Label();
        Label l4 = new Label();
        Label l6 = new Label();
        // mv.visitTryCatchBlock(l3, l4, l6, "java/lang/Throwable"); // uncomment this line (and comment the same line below) to make this code work
        mv.visitLabel(l3);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitIntInsn(BIPUSH, 8);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setline", "(I)V");
        mv.visitVarInsn(ALOAD, 2);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitLdcInsn("os");
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "getglobal", "(Ljava/lang/String;)Lorg/python/core/PyObject;");
        mv.visitLdcInsn("listdir");
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyObject", "__getattr__", "(Ljava/lang/String;)Lorg/python/core/PyObject;");
        mv.visitVarInsn(ALOAD, 4);
        mv.visitInvokeDynamicInsn("_", "(Lorg/python/core/ThreadState;Lorg/python/core/PyObject;Lorg/python/core/PyObject;)Lorg/python/core/PyObject;", new Handle(H_INVOKESTATIC, "org/python/core/opt/SpecializeCallSite", "bootstrap", "(Ljava/lang/invoke/MethodHandles$Lookup;Ljava/lang/String;Ljava/lang/invoke/MethodType;)Ljava/lang/invoke/CallSite;"), new Object[]{});
        mv.visitVarInsn(ASTORE, 6);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitInsn(ICONST_3);
        mv.visitVarInsn(ALOAD, 6);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setlocal", "(ILorg/python/core/PyObject;)V");
        mv.visitInsn(ACONST_NULL);
        mv.visitVarInsn(ASTORE, 6);
        mv.visitLabel(l4);
        Label l5 = new Label();
        mv.visitJumpInsn(GOTO, l5);
        mv.visitLabel(l6);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitMethodInsn(INVOKESTATIC, "org/python/core/Py", "setException", "(Ljava/lang/Throwable;Lorg/python/core/PyFrame;)Lorg/python/core/PyException;");
        mv.visitVarInsn(ASTORE, 6);
        mv.visitVarInsn(ALOAD, 6);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitLdcInsn("os");
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "getglobal", "(Ljava/lang/String;)Lorg/python/core/PyObject;");
        mv.visitLdcInsn("error");
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyObject", "__getattr__", "(Ljava/lang/String;)Lorg/python/core/PyObject;");
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyException", "match", "(Lorg/python/core/PyObject;)Z");
        Label l7 = new Label();
        mv.visitJumpInsn(IFEQ, l7);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitIntInsn(BIPUSH, 10);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setline", "(I)V");
        mv.visitVarInsn(ALOAD, 1);
        mv.visitInsn(ICONST_M1);
        mv.visitFieldInsn(PUTFIELD, "org/python/core/PyFrame", "f_lasti", "I");
        mv.visitFieldInsn(GETSTATIC, "org/python/core/Py", "None", "Lorg/python/core/PyObject;");
        mv.visitInsn(ARETURN);
        Label l8 = new Label();
        mv.visitJumpInsn(GOTO, l8);
        mv.visitLabel(l7);
        mv.visitVarInsn(ALOAD, 6);
        mv.visitInsn(ATHROW);
        mv.visitLabel(l5);
        mv.visitLabel(l8);
        mv.visitTryCatchBlock(l3, l4, l6, "java/lang/Throwable");
        mv.visitVarInsn(ALOAD, 1);
        mv.visitIntInsn(BIPUSH, 11);
        mv.visitMethodInsn(INVOKEVIRTUAL, "org/python/core/PyFrame", "setline", "(I)V");
        mv.visitVarInsn(ALOAD, 5);
        mv.visitVarInsn(ASTORE, 6);
        mv.visitVarInsn(ALOAD, 1);
        mv.visitInsn(ICONST_M1);
        mv.visitFieldInsn(PUTFIELD, "org/python/core/PyFrame", "f_lasti", "I");
        mv.visitVarInsn(ALOAD, 6);
        mv.visitInsn(ARETURN);
        mv.visitMaxs(0, 0);
        mv.visitEnd();
        cv.visitEnd();

        byte[] b = cw.toByteArray();
        ClassReader cr = new ClassReader(b);
        cr.accept(new TraceClassVisitor(new PrintWriter(System.out, true)), 0);
    }
}
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