8290432: C2 compilation fails with assert(node->_last_del == _last) failed: must have deleted the edge just produced

Reviewed-by: kvn, thartmann, chagedorn

Author: y1yang0

src/hotspot/share/opto/loopnode.cpp

@@ -3657,11 +3657,13 @@ bool PhaseIdealLoop::is_deleteable_safept(Node* sfpt) {
 void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
   assert(loop->_head->is_CountedLoop(), "");
   CountedLoopNode *cl = loop->_head->as_CountedLoop();
-  if (!cl->is_valid_counted_loop(T_INT))
+  if (!cl->is_valid_counted_loop(T_INT)) {
     return;         // skip malformed counted loop
+  }
   Node *incr = cl->incr();
-  if (incr == NULL)
+  if (incr == NULL) {
     return;         // Dead loop?
+  }
   Node *init = cl->init_trip();
   Node *phi  = cl->phi();
   int stride_con = cl->stride_con();
@@ -3670,25 +3672,33 @@ void PhaseIdealLoop::replace_parallel_iv(IdealLoopTree *loop) {
   for (DUIterator i = cl->outs(); cl->has_out(i); i++) {
     Node *out = cl->out(i);
     // Look for other phis (secondary IVs). Skip dead ones
-    if (!out->is_Phi() || out == phi || !has_node(out))
+    if (!out->is_Phi() || out == phi || !has_node(out)) {
       continue;
+    }
+
     PhiNode* phi2 = out->as_Phi();
-    Node *incr2 = phi2->in( LoopNode::LoopBackControl );
+    Node* incr2 = phi2->in(LoopNode::LoopBackControl);
     // Look for induction variables of the form:  X += constant
     if (phi2->region() != loop->_head ||
         incr2->req() != 3 ||
         incr2->in(1)->uncast() != phi2 ||
         incr2 == incr ||
         incr2->Opcode() != Op_AddI ||
-        !incr2->in(2)->is_Con())
+        !incr2->in(2)->is_Con()) {
       continue;
+    }
 
+    if (incr2->in(1)->is_ConstraintCast() &&
+        !(incr2->in(1)->in(0)->is_IfProj() && incr2->in(1)->in(0)->in(0)->is_RangeCheck())) {
+      // Skip AddI->CastII->Phi case if CastII is not controlled by local RangeCheck
+      continue;
+    }
     // Check for parallel induction variable (parallel to trip counter)
     // via an affine function.  In particular, count-down loops with
     // count-up array indices are common. We only RCE references off
     // the trip-counter, so we need to convert all these to trip-counter
     // expressions.
-    Node *init2 = phi2->in( LoopNode::EntryControl );
+    Node* init2 = phi2->in(LoopNode::EntryControl);
     int stride_con2 = incr2->in(2)->get_int();
 
     // The ratio of the two strides cannot be represented as an int

test/hotspot/jtreg/compiler/c2/TestUnexpectedParallelIV.java

@@ -0,0 +1,95 @@
+/*
+ * Copyright (c) 2022, Alibaba Group Holding Limited. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+/**
+ * @test
+ * @bug 8290432
+ * @summary Unexpected parallel induction variable pattern was recongized
+ *
+ * @run main/othervm -XX:-TieredCompilation -Xcomp
+ *           -XX:CompileCommand=compileonly,compiler.c2.TestUnexpectedParallelIV::test
+ *           -XX:CompileCommand=compileonly,compiler.c2.TestUnexpectedParallelIV::test2
+ *           -XX:CompileCommand=quiet
+ *           -XX:CompileCommand=dontinline,compiler.c2.TestUnexpectedParallelIV::* compiler.c2.TestUnexpectedParallelIV
+ */
+
+package compiler.c2;
+
+public class TestUnexpectedParallelIV {
+
+    static boolean bFld;
+
+    static int dontInline() {
+        return 0;
+    }
+
+    static int test2(int i1) {
+        int i2, i3 = 0, i4, i5 = 0, i6;
+        for (i2 = 0; 4 > i2; ++i2) {
+            for (i4 = 1; i4 < 5; ++i4) {
+                i3 -= --i1;
+                i6 = 1;
+                while (++i6 < 2) {
+                    dontInline();
+                    if (bFld) {
+                        i1 = 5;
+                    }
+                }
+                if (bFld) {
+                    break;
+                }
+            }
+        }
+        return i3;
+    }
+
+    static long test(int val, boolean b) {
+        long ret = 0;
+        long dArr[] = new long[100];
+        for (int i = 15; 293 > i; ++i) {
+            ret = val;
+            int j = 1;
+            while (++j < 6) {
+                int k = (val--);
+                for (long l = i; 1 > l; ) {
+                    if (k != 0) {
+                        ret += dontInline();
+                    }
+                }
+                if (b) {
+                    break;
+                }
+            }
+        }
+        return ret;
+    }
+
+    public static void main(String[] args) {
+        for (int i = 0; i < 1000; i++) {
+            test(0, false);
+        }
+
+        test2(5);
+    }
+}