6661247: Internal bug in 32-bit HotSpot optimizer while bit manipulations

Summary: copy elimination of a constant value results in incorrect execution
Reviewed-by: kvn, sgoldman, rasbold

src/share/vm/opto/chaitin.hpp

@@ -457,7 +457,8 @@ private:
   bool may_be_copy_of_callee( Node *def ) const;
 
   // If nreg already contains the same constant as val then eliminate it
-  bool eliminate_copy_of_constant(Node* val, Block *current_block, Node_List& value, Node_List &regnd,
+  bool eliminate_copy_of_constant(Node* val, Node* n,
+                                  Block *current_block, Node_List& value, Node_List &regnd,
                                   OptoReg::Name nreg, OptoReg::Name nreg2);
   // Extend the node to LRG mapping
   void add_reference( const Node *node, const Node *old_node);

src/share/vm/opto/postaloc.cpp

@@ -253,7 +253,8 @@ int PhaseChaitin::elide_copy( Node *n, int k, Block *current_block, Node_List &v
 // nodes can represent the same constant so the type and rule of the
 // MachNode must be checked to ensure equivalence.
 //
-bool PhaseChaitin::eliminate_copy_of_constant(Node* val, Block *current_block,
+bool PhaseChaitin::eliminate_copy_of_constant(Node* val, Node* n,
+                                              Block *current_block,
                                               Node_List& value, Node_List& regnd,
                                               OptoReg::Name nreg, OptoReg::Name nreg2) {
   if (value[nreg] != val && val->is_Con() &&
@@ -269,12 +270,12 @@ bool PhaseChaitin::eliminate_copy_of_constant(Node* val, Block *current_block,
     // Since they are equivalent the second one if redundant and can
     // be removed.
     //
-    // val will be replaced with the old value but val might have
+    // n will be replaced with the old value but n might have
     // kills projections associated with it so remove them now so that
     // yank_if_dead will be able to elminate the copy once the uses
     // have been transferred to the old[value].
-    for (DUIterator_Fast imax, i = val->fast_outs(imax); i < imax; i++) {
-      Node* use = val->fast_out(i);
+    for (DUIterator_Fast imax, i = n->fast_outs(imax); i < imax; i++) {
+      Node* use = n->fast_out(i);
       if (use->is_Proj() && use->outcnt() == 0) {
         // Kill projections have no users and one input
         use->set_req(0, C->top());
@@ -521,7 +522,7 @@ void PhaseChaitin::post_allocate_copy_removal() {
         // then 'n' is a useless copy.  Do not update the register->node
         // mapping so 'n' will go dead.
         if( value[nreg] != val ) {
-          if (eliminate_copy_of_constant(val, b, value, regnd, nreg, OptoReg::Bad)) {
+          if (eliminate_copy_of_constant(val, n, b, value, regnd, nreg, OptoReg::Bad)) {
             n->replace_by(regnd[nreg]);
             j -= yank_if_dead(n,b,&value,&regnd);
           } else {
@@ -549,7 +550,7 @@ void PhaseChaitin::post_allocate_copy_removal() {
           nreg_lo = tmp.find_first_elem();
         }
         if( value[nreg] != val || value[nreg_lo] != val ) {
-          if (eliminate_copy_of_constant(n, b, value, regnd, nreg, nreg_lo)) {
+          if (eliminate_copy_of_constant(val, n, b, value, regnd, nreg, nreg_lo)) {
             n->replace_by(regnd[nreg]);
             j -= yank_if_dead(n,b,&value,&regnd);
           } else {

test/compiler/6661247/Test.java

+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ */
+
+/*
+ * @test
+ * @bug 6661247
+ * @summary Internal bug in 32-bit HotSpot optimizer while bit manipulations
+ */
+
+import java.util.Random;
+import java.nio.*;
+
+// This isn't a completely reliable test for 6661247 since the results
+// depend on what the local schedule looks like but it does reproduce
+// the issue in current builds.
+
+public class Test {
+
+    public static void test(boolean[] src, int srcPos, LongBuffer dest, long destPos, int count) {
+        int countStart = (destPos & 63) == 0 ? 0 : 64 - (int)(destPos & 63);
+        if (countStart > count)
+            countStart = count;
+        for (int srcPosMax = srcPos + countStart; srcPos < srcPosMax; srcPos++, destPos++) {
+            if (src[srcPos])
+                dest.put((int)(destPos >>> 6), dest.get((int)(destPos >>> 6)) | 1L << (destPos & 63));
+            else
+                dest.put((int)(destPos >>> 6), dest.get((int)(destPos >>> 6)) & ~(1L << (destPos & 63)));
+        }
+        count -= countStart;
+        int cnt = count >>> 6;
+        for (int k = (int)(destPos >>> 6), kMax = k + cnt; k < kMax; k++) {
+            int low = (src[srcPos] ? 1 : 0)
+                | (src[srcPos + 1] ? 1 << 1 : 0)
+                | (src[srcPos + 2] ? 1 << 2 : 0)
+                | (src[srcPos + 3] ? 1 << 3 : 0)
+                | (src[srcPos + 4] ? 1 << 4 : 0)
+                | (src[srcPos + 5] ? 1 << 5 : 0)
+                | (src[srcPos + 6] ? 1 << 6 : 0)
+                | (src[srcPos + 7] ? 1 << 7 : 0)
+                | (src[srcPos + 8] ? 1 << 8 : 0)
+                | (src[srcPos + 9] ? 1 << 9 : 0)
+                | (src[srcPos + 10] ? 1 << 10 : 0)
+                | (src[srcPos + 11] ? 1 << 11 : 0)
+                | (src[srcPos + 12] ? 1 << 12 : 0)
+                | (src[srcPos + 13] ? 1 << 13 : 0)
+                | (src[srcPos + 14] ? 1 << 14 : 0)
+                | (src[srcPos + 15] ? 1 << 15 : 0)
+                | (src[srcPos + 16] ? 1 << 16 : 0)
+                | (src[srcPos + 17] ? 1 << 17 : 0)
+                | (src[srcPos + 18] ? 1 << 18 : 0)
+                | (src[srcPos + 19] ? 1 << 19 : 0)
+                | (src[srcPos + 20] ? 1 << 20 : 0)
+                | (src[srcPos + 21] ? 1 << 21 : 0)
+                | (src[srcPos + 22] ? 1 << 22 : 0)
+                | (src[srcPos + 23] ? 1 << 23 : 0)
+                | (src[srcPos + 24] ? 1 << 24 : 0)
+                | (src[srcPos + 25] ? 1 << 25 : 0)
+                | (src[srcPos + 26] ? 1 << 26 : 0)
+                | (src[srcPos + 27] ? 1 << 27 : 0)
+                | (src[srcPos + 28] ? 1 << 28 : 0)
+                | (src[srcPos + 29] ? 1 << 29 : 0)
+                | (src[srcPos + 30] ? 1 << 30 : 0)
+                | (src[srcPos + 31] ? 1 << 31 : 0)
+                ;
+            srcPos += 32;
+            int high = (src[srcPos] ? 1 : 0)        // PROBLEM!
+                | (src[srcPos + 1] ? 1 << 1 : 0)
+                | (src[srcPos + 2] ? 1 << 2 : 0)
+                | (src[srcPos + 3] ? 1 << 3 : 0)
+                | (src[srcPos + 4] ? 1 << 4 : 0)
+                | (src[srcPos + 5] ? 1 << 5 : 0)
+                | (src[srcPos + 6] ? 1 << 6 : 0)
+                | (src[srcPos + 7] ? 1 << 7 : 0)
+                | (src[srcPos + 8] ? 1 << 8 : 0)
+                | (src[srcPos + 9] ? 1 << 9 : 0)
+                | (src[srcPos + 10] ? 1 << 10 : 0)
+                | (src[srcPos + 11] ? 1 << 11 : 0)
+                | (src[srcPos + 12] ? 1 << 12 : 0)
+                | (src[srcPos + 13] ? 1 << 13 : 0)
+                | (src[srcPos + 14] ? 1 << 14 : 0)
+                | (src[srcPos + 15] ? 1 << 15 : 0)
+                | (src[srcPos + 16] ? 1 << 16 : 0)
+                | (src[srcPos + 17] ? 1 << 17 : 0)
+                | (src[srcPos + 18] ? 1 << 18 : 0)
+                | (src[srcPos + 19] ? 1 << 19 : 0)
+                | (src[srcPos + 20] ? 1 << 20 : 0)
+                | (src[srcPos + 21] ? 1 << 21 : 0)
+                | (src[srcPos + 22] ? 1 << 22 : 0)
+                | (src[srcPos + 23] ? 1 << 23 : 0)
+                | (src[srcPos + 24] ? 1 << 24 : 0)
+                | (src[srcPos + 25] ? 1 << 25 : 0)
+                | (src[srcPos + 26] ? 1 << 26 : 0)
+                | (src[srcPos + 27] ? 1 << 27 : 0)
+                | (src[srcPos + 28] ? 1 << 28 : 0)
+                | (src[srcPos + 29] ? 1 << 29 : 0)
+                | (src[srcPos + 30] ? 1 << 30 : 0)
+                | (src[srcPos + 31] ? 1 << 31 : 0)
+                ;
+            srcPos += 32;
+            dest.put(k, ((long)low & 0xFFFFFFFFL) | (((long)high) << 32));
+            destPos += 64;
+        }
+        int countFinish = count & 63;
+        for (int srcPosMax = srcPos + countFinish; srcPos < srcPosMax; srcPos++, destPos++) {
+            if (src[srcPos])
+                dest.put((int)(destPos >>> 6), dest.get((int)(destPos >>> 6)) | 1L << (destPos & 63));
+            else
+                dest.put((int)(destPos >>> 6), dest.get((int)(destPos >>> 6)) & ~(1L << (destPos & 63)));
+        }
+    }
+    public static void main(String[] args) {
+        Random r = new Random();
+        int entries = 1000;
+        boolean[] src = new boolean[entries * 64];
+        long[] dest = new long[entries];
+        long[] result = new long[entries];
+
+        for (int c = 0; c < 2000; c++) {
+            for (int i = 0; i < entries; i++) {
+                long l = r.nextLong();
+                for (int bit = 0; bit < 64; bit++) {
+                    src[i * 64 + bit] = (l & (1L << bit)) != 0;
+                }
+                dest[i] = 0;
+                result[i] = l;
+            }
+            test(src, 0, LongBuffer.wrap(dest, 0, dest.length), 0, src.length);
+            for (int i = 0; i < entries; i++) {
+                if (dest[i] != result[i]) {
+                    throw new InternalError(i + ": " + Long.toHexString(dest[i]) + " != " + Long.toHexString(result[i]));
+                }
+            }
+        }
+    }
+}