SI-7518 Better positioning for inlined code

retronym · retronym · commit 178c37bddede · 2013-05-29T11:31:12.000+02:00
The inliner was positioning all inlined instructions
at the method call (`targetPos). This makes debugging
of code compiled under `-optimize` difficult.

This commit retains the original position of the
inlined instruction if it is in the same source file
as the method call. In other cases, we have to fall
back to the `targetPos`; line number information in
classfiles can only index into current source file.
diff --git a/src/compiler/scala/tools/nsc/backend/opt/Inliners.scala b/src/compiler/scala/tools/nsc/backend/opt/Inliners.scala
@@ -878,6 +878,7 @@ abstract class Inliners extends SubComponent {
           }
           // check any pending NEW's
           pending remove i foreach (_.init = newInstr.asInstanceOf[CALL_METHOD])
+          newInstr.setPos(i.pos)
           newInstr
         }
 
@@ -909,7 +910,8 @@ abstract class Inliners extends SubComponent {
         val calleeLin = inc.m.linearizedBlocks()
         calleeLin foreach { bb =>
           var info = if(hasRETURN) (a in bb) else null
-          def emitInlined(i: Instruction) = inlinedBlock(bb).emit(i, targetPos)
+          def sameSource(p1: Position, p2: Position) = p1 != NoPosition && p2 != NoPosition && p1.source == p2.source
+          def emitInlined(i: Instruction) = inlinedBlock(bb).emit(i, if (sameSource(targetPos, i.pos)) i.pos else targetPos)
           def emitDrops(toDrop: Int)      = info.stack.types drop toDrop foreach (t => emitInlined(DROP(t)))
 
           for (i <- bb) {
diff --git a/test/files/run/t7518.check b/test/files/run/t7518.check
@@ -0,0 +1,14 @@
+class scala.tools.asm.tree.MethodNode
+   L0
+    LINENUMBER 6 L0
+    LDC "LINE 6"
+    INVOKEVIRTUAL java/lang/String.toString ()Ljava/lang/String;
+   L1
+    LINENUMBER 5 L1
+    POP
+    RETURN
+   L2
+    LOCALVARIABLE this LInlinePosition; L0 L2 0
+    MAXSTACK = 1
+    MAXLOCALS = 1
+
diff --git a/test/files/run/t7518/BytecodeSrc_1.flags b/test/files/run/t7518/BytecodeSrc_1.flags
@@ -0,0 +1 @@
+-optimize
diff --git a/test/files/run/t7518/BytecodeSrc_1.scala b/test/files/run/t7518/BytecodeSrc_1.scala
@@ -0,0 +1,9 @@
+class InlinePosition {
+  @inline final def foo[A](a: => A) = a
+
+  def client {
+    foo {
+      "LINE 6".toString
+    }
+  }
+}
diff --git a/test/files/run/t7518/Test.scala b/test/files/run/t7518/Test.scala
@@ -0,0 +1,12 @@
+import scala.tools.partest.BytecodeTest
+import scala.tools.asm.util._
+import java.io._
+
+object Test extends BytecodeTest {
+  def show {
+    val classNode = loadClassNode("InlinePosition", skipDebugInfo = false)
+    val meth = getMethod(classNode, "client")
+    val textifier = new Textifier()
+    meth.accept(new TraceMethodVisitor(textifier))
+  }
+}
diff --git a/test/files/run/t7518/Test_2.scala b/test/files/run/t7518/Test_2.scala
@@ -0,0 +1,15 @@
+import scala.tools.partest.BytecodeTest
+import scala.tools.asm.util._
+import scala.tools.nsc.util.stringFromWriter
+
+object Test extends BytecodeTest {
+  def show {
+    // your code that inspect ASM trees and prints values
+    val classNode = loadClassNode("InlinePosition", skipDebugInfo = false)
+    val meth = getMethod(classNode, "client")
+    println(meth.getClass)
+    val textifier = new Textifier()
+    meth.accept(new TraceMethodVisitor(textifier))
+    println(stringFromWriter(w => textifier.print(w)))
+  }
+}
