Branch instructions were marked as invalid in code attributes if swit…

…ch instructions were present in between the branch instruction and the target instruction
ingokegel · Feb 25, 2018 · cfd5660 · cfd5660
1 parent 4c0c944
commit cfd5660
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Showing 3 changed files with 13 additions and 20 deletions.
diff --git a/...wser/src/main/kotlin/org/gjt/jclasslib/browser/detail/attributes/code/ByteCodeDocument.kt b/...wser/src/main/kotlin/org/gjt/jclasslib/browser/detail/attributes/code/ByteCodeDocument.kt
@@ -41,25 +41,10 @@ class ByteCodeDocument(styles: StyleContext, private val attribute: CodeAttribut
     }
 
     private fun verifyOffsets(instructions: ArrayList<Instruction>) {
-        instructions.forEachIndexed { i, instruction ->
-            if (instruction is AbstractBranchInstruction) {
-                var branchOffset = instruction.branchOffset
-                var targetDistance = 0
-                if (branchOffset > 0) {
-                    branchOffset -= instruction.size
-                    while (branchOffset > 0 && i + targetDistance + 1 < instructions.size) {
-                        ++targetDistance
-                        branchOffset -= instructions[i + targetDistance].size
-                    }
-                } else {
-                    while (branchOffset < 0 && i + targetDistance > 0) {
-                        --targetDistance
-                        branchOffset += instructions[i + targetDistance].size
-                    }
-                }
-                if (branchOffset != 0) {
-                    invalidBranches.add(instruction)
-                }
+        instructions.filterIsInstance<AbstractBranchInstruction>().forEach { instruction ->
+            val targetOffset = instruction.branchOffset + instruction.offset
+            if (instructions.none { it.offset == targetOffset }) {
+                invalidBranches.add(instruction)
             }
         }
     }

diff --git a/modules/data/src/main/kotlin/org/gjt/jclasslib/bytecode/Instruction.kt b/modules/data/src/main/kotlin/org/gjt/jclasslib/bytecode/Instruction.kt
@@ -27,6 +27,14 @@ open class Instruction(val opcode: Opcode) {
     open val size: Int
         get() = 1
 
+    /**
+     * Get the padded size in bytes of this instruction. This will be the same as
+     * `size` except for instances of [PaddedInstruction].
+     * @param offset the offset at which this instruction is found.
+     * @return the padded size in bytes
+     */
+    open fun getPaddedSize(offset: Int): Int = size
+
     /**
      * Read this instruction from the given ByteCodeInput.
      * Expects ByteCodeInput to be in JVM class file format and just

diff --git a/modules/data/src/main/kotlin/org/gjt/jclasslib/bytecode/PaddedInstruction.kt b/modules/data/src/main/kotlin/org/gjt/jclasslib/bytecode/PaddedInstruction.kt
@@ -22,7 +22,7 @@ open class PaddedInstruction(opcode: Opcode) : Instruction(opcode) {
      * @param offset the offset at which this instruction is found.
      * @return the padded size in bytes
      */
-    fun getPaddedSize(offset: Int): Int = size + paddingBytes(offset + 1)
+    override fun getPaddedSize(offset: Int): Int = size + paddingBytes(offset + 1)
 
     override fun read(input: ByteCodeInput) {
         super.read(input)