Fix #5138. jruby > 9.1.13.0 crashing on bundler when certain jvm flag…

…s are enabled. Better title would be CFG merges and deletes a BB other BBs still think they are pointing to. This seems reasonable to me at the moment and I want to land so if someone is enterprising they can try and find more problems. I will have people look at this.
jruby · Apr 14, 2018 · 3c599d4 · 3c599d4
1 parent f25b8be
commit 3c599d4
Showing 5 changed files with 26 additions and 1 deletion.
diff --git a/core/src/main/java/org/jruby/ir/instructions/JumpInstr.java b/core/src/main/java/org/jruby/ir/instructions/JumpInstr.java
@@ -16,6 +16,10 @@ public Label getJumpTarget() {
         return (Label) getOperand1();
     }
 
+    public void setJumpTarget(Label target) {
+        setOperand1(target);
+    }
+
     @Override
     public Instr clone(CloneInfo ii) {
         return new JumpInstr(ii.getRenamedLabel(getJumpTarget()));

diff --git a/core/src/main/java/org/jruby/ir/instructions/JumpTargetInstr.java b/core/src/main/java/org/jruby/ir/instructions/JumpTargetInstr.java
@@ -7,4 +7,5 @@
  */
 public interface JumpTargetInstr {
     Label getJumpTarget();
+    void setJumpTarget(Label target);
 }
diff --git a/core/src/main/java/org/jruby/ir/instructions/OneOperandBranchInstr.java b/core/src/main/java/org/jruby/ir/instructions/OneOperandBranchInstr.java
@@ -34,6 +34,10 @@ public void setOperand(int i, Operand operand) {
         }
     }
 
+    public void setJumpTarget(Label target) {
+        this.jumpTarget = target;
+    }
+
     public Label getJumpTarget() {
         return jumpTarget;
     }

diff --git a/core/src/main/java/org/jruby/ir/instructions/TwoOperandBranchInstr.java b/core/src/main/java/org/jruby/ir/instructions/TwoOperandBranchInstr.java
@@ -38,6 +38,10 @@ public void setOperand(int i, Operand operand) {
         }
     }
 
+    public void setJumpTarget(Label target) {
+        this.jumpTarget = target;
+    }
+
     public Label getJumpTarget() {
         return jumpTarget;
     }

diff --git a/core/src/main/java/org/jruby/ir/representations/CFG.java b/core/src/main/java/org/jruby/ir/representations/CFG.java
@@ -2,7 +2,6 @@
 
 import org.jruby.dirgra.DirectedGraph;
 import org.jruby.dirgra.Edge;
-import org.jruby.ir.IRClosure;
 import org.jruby.ir.IRManager;
 import org.jruby.ir.IRScope;
 import org.jruby.ir.Operation;
@@ -476,6 +475,19 @@ private boolean mergeBBs(BasicBlock a, BasicBlock b) {
                 addEdge(a, e.getDestination().getData(), e.getType());
             }
 
+            // Move all incoming edges of b to be incoming edges of a.
+            for (Edge<BasicBlock> e : getIncomingEdges(b)) {
+                BasicBlock fixupBB = e.getSource().getData();
+                removeEdge(fixupBB, b);
+                addEdge(fixupBB, a, e.getType());
+
+                // a -fall-through->b handled above. Any jumps to b must be pointed to a's label.
+                Instr fixupLastInstr = fixupBB.getLastInstr();
+                if (fixupLastInstr instanceof JumpTargetInstr) {
+                    ((JumpTargetInstr) fixupLastInstr).setJumpTarget(a.getLabel());
+                }
+            }
+
             // Delete bb
             removeBB(b);