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195d8173c7
java-1.8.0-openjdk/jdk8172850-rh1640127-01-register_allocator_crash.patch
Jiri Vanek 195d8173c7 renamed all patches to new convention 
bug1-bug2-..-bugN-XY-lowercase_comment_suffix_or_jdkpart.patch
 XY is number 01-99 for patches which are order sensitive or simply counts together
 where bugs are jdkIJK or prLMN or rhOPQ and if more bugs (which is desired) then in jdk->pr->rh order.
 I..Q are numbers corresponding to:
 https://bugs.openjdk.java.net/browse/JDK-IJK
 https://icedtea.classpath.org/bugzilla/show_bug.cgi?id=LMN
 https://bugzilla.redhat.com/show_bug.cgi?id=OPQ
2018-11-20 10:58:25 +01:00

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# HG changeset patch
# User thartmann
# Date 1539594027 -7200
# Node ID e044997c2edaeae97866394a7f8e2ddebbd41392
# Parent 99212080341058548d449a22d1381e79353ec5b5
8172850: Anti-dependency on membar causes crash in register allocator due to invalid instruction scheduling
Summary: Regression test and additional asserts. The problem is fixed by 8087341.
Reviewed-by: kvn
diff -r 992120803410 -r e044997c2eda src/share/vm/opto/cfgnode.cpp
--- openjdk/hotspot/src/share/vm/opto/cfgnode.cpp Mon Oct 22 05:26:38 2018 -0400
+++ openjdk/hotspot/src/share/vm/opto/cfgnode.cpp Mon Oct 15 11:00:27 2018 +0200
@@ -2016,6 +2016,7 @@
uint ideal_reg = _type->ideal_reg();
assert( ideal_reg != Node::NotAMachineReg, "invalid type at Phi" );
if( ideal_reg == 0 ) return RegMask::Empty;
+ assert(ideal_reg != Op_RegFlags, "flags register is not spillable");
return *(Compile::current()->matcher()->idealreg2spillmask[ideal_reg]);
}
diff -r 992120803410 -r e044997c2eda src/share/vm/opto/coalesce.cpp
--- openjdk/hotspot/src/share/vm/opto/coalesce.cpp Mon Oct 22 05:26:38 2018 -0400
+++ openjdk/hotspot/src/share/vm/opto/coalesce.cpp Mon Oct 15 11:00:27 2018 +0200
@@ -292,7 +292,14 @@
// Copy any flags as well
_phc.clone_projs(pred, pred->end_idx(), m, copy, _phc._lrg_map);
} else {
- const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()];
+ int ireg = m->ideal_reg();
+ if (ireg == 0 || ireg == Op_RegFlags) {
+ assert(false, err_msg("attempted to spill a non-spillable item: %d: %s, ireg = %d",
+ m->_idx, m->Name(), ireg));
+ C->record_method_not_compilable("attempted to spill a non-spillable item");
+ return;
+ }
+ const RegMask *rm = C->matcher()->idealreg2spillmask[ireg];
copy = new (C) MachSpillCopyNode(m, *rm, *rm);
// Find a good place to insert. Kinda tricky, use a subroutine
insert_copy_with_overlap(pred,copy,phi_name,src_name);
@@ -326,7 +333,14 @@
b->insert_node(copy, l++);
l += _phc.clone_projs(b, l, m, copy, _phc._lrg_map);
} else {
- const RegMask *rm = C->matcher()->idealreg2spillmask[m->ideal_reg()];
+ int ireg = m->ideal_reg();
+ if (ireg == 0 || ireg == Op_RegFlags) {
+ assert(false, err_msg("attempted to spill a non-spillable item: %d: %s, ireg = %d",
+ m->_idx, m->Name(), ireg));
+ C->record_method_not_compilable("attempted to spill a non-spillable item");
+ return;
+ }
+ const RegMask *rm = C->matcher()->idealreg2spillmask[ireg];
copy = new (C) MachSpillCopyNode(m, *rm, *rm);
// Insert the copy in the basic block, just before us
b->insert_node(copy, l++);
@@ -373,7 +387,14 @@
if( k < b->_num_succs )
continue; // Live out; do not pre-split
// Split the lrg at this use
- const RegMask *rm = C->matcher()->idealreg2spillmask[inp->ideal_reg()];
+ int ireg = inp->ideal_reg();
+ if (ireg == 0 || ireg == Op_RegFlags) {
+ assert(false, err_msg("attempted to spill a non-spillable item: %d: %s, ireg = %d",
+ inp->_idx, inp->Name(), ireg));
+ C->record_method_not_compilable("attempted to spill a non-spillable item");
+ return;
+ }
+ const RegMask *rm = C->matcher()->idealreg2spillmask[ireg];
Node *copy = new (C) MachSpillCopyNode( inp, *rm, *rm );
// Insert the copy in the use-def chain
n->set_req(inpidx, copy );
diff -r 992120803410 -r e044997c2eda src/share/vm/opto/machnode.cpp
--- openjdk/hotspot/src/share/vm/opto/machnode.cpp Mon Oct 22 05:26:38 2018 -0400
+++ openjdk/hotspot/src/share/vm/opto/machnode.cpp Mon Oct 15 11:00:27 2018 +0200
@@ -619,6 +619,7 @@
}
// Values outside the domain represent debug info
+ assert(in(idx)->ideal_reg() != Op_RegFlags, "flags register is not spillable");
return *Compile::current()->matcher()->idealreg2spillmask[in(idx)->ideal_reg()];
}
diff -r 992120803410 -r e044997c2eda src/share/vm/opto/matcher.cpp
--- openjdk/hotspot/src/share/vm/opto/matcher.cpp Mon Oct 22 05:26:38 2018 -0400
+++ openjdk/hotspot/src/share/vm/opto/matcher.cpp Mon Oct 15 11:00:27 2018 +0200
@@ -95,6 +95,7 @@
idealreg2spillmask [Op_VecD] = NULL;
idealreg2spillmask [Op_VecX] = NULL;
idealreg2spillmask [Op_VecY] = NULL;
+ idealreg2spillmask [Op_RegFlags] = NULL;
idealreg2debugmask [Op_RegI] = NULL;
idealreg2debugmask [Op_RegN] = NULL;
@@ -106,6 +107,7 @@
idealreg2debugmask [Op_VecD] = NULL;
idealreg2debugmask [Op_VecX] = NULL;
idealreg2debugmask [Op_VecY] = NULL;
+ idealreg2debugmask [Op_RegFlags] = NULL;
idealreg2mhdebugmask[Op_RegI] = NULL;
idealreg2mhdebugmask[Op_RegN] = NULL;
@@ -117,6 +119,7 @@
idealreg2mhdebugmask[Op_VecD] = NULL;
idealreg2mhdebugmask[Op_VecX] = NULL;
idealreg2mhdebugmask[Op_VecY] = NULL;
+ idealreg2mhdebugmask[Op_RegFlags] = NULL;
debug_only(_mem_node = NULL;) // Ideal memory node consumed by mach node
}
diff -r 992120803410 -r e044997c2eda test/compiler/gcbarriers/TestMembarDependencies.java
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ openjdk/hotspot/test/compiler/gcbarriers/TestMembarDependencies.java Mon Oct 15 11:00:27 2018 +0200
@@ -0,0 +1,98 @@
+/*
+ * Copyright (c) 2017, Oracle and/or its affiliates. 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 TestMembarDependencies
+ * @bug 8172850
+ * @summary Tests correct scheduling of memory loads around MembarVolatile emitted by GC barriers.
+ * @library /testlibrary
+ * @run driver compiler.membars.TestMembarDependencies
+ */
+
+package compiler.membars;
+
+import com.oracle.java.testlibrary.*;
+
+public class TestMembarDependencies {
+ private static TestMembarDependencies f1;
+ private static TestMembarDependencies f2;
+
+ public static void main(String args[]) throws Throwable {
+ if (args.length == 0) {
+ // For debugging, add "-XX:+TraceOptoPipelining"
+ OutputAnalyzer oa = ProcessTools.executeTestJvm("-XX:+IgnoreUnrecognizedVMOptions",
+ "-XX:-TieredCompilation", "-XX:-BackgroundCompilation", "-XX:+PrintOpto",
+ "-XX:CompileCommand=compileonly,compiler.membars.TestMembarDependencies::test*",
+ "-XX:CompileCommand=dontinline,compiler.membars.TestMembarDependencies::test_m1",
+ TestMembarDependencies.class.getName(), "run");
+ // C2 should not crash or bail out from compilation
+ oa.shouldHaveExitValue(0);
+ oa.shouldNotMatch("Bailout: Recompile without subsuming loads");
+ System.out.println(oa.getOutput());
+ } else {
+ f2 = new TestMembarDependencies();
+ // Trigger compilation of test1 and test2
+ for (int i = 0; i < 10_000; ++i) {
+ f2.test1(f2);
+ f2.test2(f2);
+ }
+ }
+ }
+
+ public void test_m1() { }
+ public void test_m2() { }
+
+ public void test1(TestMembarDependencies obj) {
+ // Try/catch/finally is used to create a CFG block without a test + jmpCon
+ // allowing GCM to schedule the testN_mem_reg0 instruction into that block.
+ try {
+ // Method call defines memory state that is then
+ // used by subsequent instructions/blocks (see below).
+ test_m1();
+ } catch (Exception e) {
+
+ } finally {
+ // Oop write to field emits a GC post-barrier with a MembarVolatile
+ // which has a wide memory effect (kills all memory). This creates an
+ // anti-dependency on all surrounding memory loads.
+ f1 = obj;
+ }
+ // The empty method m2 is inlined but the null check of f2 remains. It is encoded
+ // as CmpN(LoadN(MEM), NULL) where MEM is the memory after the call to test_m1().
+ // This is matched to testN_mem_reg0 on x86 which is scheduled before the barrier
+ // in the try/catch block due to the anti-dependency on the MembarVolatile.
+ // C2 crashes in the register allocator when trying to spill the flag register
+ // to keep the result of the testN instruction live from the try/catch block
+ // until it is here.
+ f2.test_m2();
+ }
+
+ public void test2(TestMembarDependencies obj) {
+ // Same as test1 but without try/catch/finally.
+ // This causes C2 to bail out in block local scheduling because testN_mem_reg0 is
+ // scheduled into a block that already contains another test + jmpCon instruction.
+ test_m1();
+ f1 = obj;
+ f2.test_m2();
+ }
+}
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