8242429: Better implementation for sign extract

Reviewed-by: vlivanov, thartmann

src/hotspot/cpu/aarch64/aarch64.ad

@@ -10574,30 +10574,6 @@ instruct divI(iRegINoSp dst, iRegIorL2I src1, iRegIorL2I src2) %{
   ins_pipe(idiv_reg_reg);
 %}
 
-instruct signExtract(iRegINoSp dst, iRegIorL2I src1, immI_31 div1, immI_31 div2) %{
-  match(Set dst (URShiftI (RShiftI src1 div1) div2));
-  ins_cost(INSN_COST);
-  format %{ "lsrw $dst, $src1, $div1" %}
-  ins_encode %{
-    __ lsrw(as_Register($dst$$reg), as_Register($src1$$reg), 31);
-  %}
-  ins_pipe(ialu_reg_shift);
-%}
-
-instruct div2Round(iRegINoSp dst, iRegIorL2I src, immI_31 div1, immI_31 div2) %{
-  match(Set dst (AddI src (URShiftI (RShiftI src div1) div2)));
-  ins_cost(INSN_COST);
-  format %{ "addw $dst, $src, LSR $div1" %}
-
-  ins_encode %{
-    __ addw(as_Register($dst$$reg),
-              as_Register($src$$reg),
-              as_Register($src$$reg),
-              Assembler::LSR, 31);
-  %}
-  ins_pipe(ialu_reg);
-%}
-
 // Long Divide
 
 instruct divL(iRegLNoSp dst, iRegL src1, iRegL src2) %{
@@ -10610,30 +10586,6 @@ instruct divL(iRegLNoSp dst, iRegL src1, iRegL src2) %{
   ins_pipe(ldiv_reg_reg);
 %}
 
-instruct signExtractL(iRegLNoSp dst, iRegL src1, immI_63 div1, immI_63 div2) %{
-  match(Set dst (URShiftL (RShiftL src1 div1) div2));
-  ins_cost(INSN_COST);
-  format %{ "lsr $dst, $src1, $div1" %}
-  ins_encode %{
-    __ lsr(as_Register($dst$$reg), as_Register($src1$$reg), 63);
-  %}
-  ins_pipe(ialu_reg_shift);
-%}
-
-instruct div2RoundL(iRegLNoSp dst, iRegL src, immI_63 div1, immI_63 div2) %{
-  match(Set dst (AddL src (URShiftL (RShiftL src div1) div2)));
-  ins_cost(INSN_COST);
-  format %{ "add $dst, $src, $div1" %}
-
-  ins_encode %{
-    __ add(as_Register($dst$$reg),
-              as_Register($src$$reg),
-              as_Register($src$$reg),
-              Assembler::LSR, 63);
-  %}
-  ins_pipe(ialu_reg);
-%}
-
 // Integer Remainder
 
 instruct modI(iRegINoSp dst, iRegIorL2I src1, iRegIorL2I src2) %{

src/hotspot/share/opto/mulnode.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2020, 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
@@ -1166,6 +1166,18 @@ Node *URShiftINode::Ideal(PhaseGVN *phase, bool can_reshape) {
       phase->type(shl->in(2)) == t2 )
     return new AndINode( shl->in(1), phase->intcon(mask) );
 
+  // Check for (x >> n) >>> 31. Replace with (x >>> 31)
+  Node *shr = in(1);
+  if ( in1_op == Op_RShiftI ) {
+    Node *in11 = shr->in(1);
+    Node *in12 = shr->in(2);
+    const TypeInt *t11 = phase->type(in11)->isa_int();
+    const TypeInt *t12 = phase->type(in12)->isa_int();
+    if ( t11 && t2 && t2->is_con(31) && t12 && t12->is_con() ) {
+      return new URShiftINode(in11, phase->intcon(31));
+    }
+  }
+
   return NULL;
 }
 
@@ -1295,6 +1307,17 @@ Node *URShiftLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
       phase->type(shl->in(2)) == t2 )
     return new AndLNode( shl->in(1), phase->longcon(mask) );
 
+  // Check for (x >> n) >>> 63. Replace with (x >>> 63)
+  Node *shr = in(1);
+  if ( shr->Opcode() == Op_RShiftL ) {
+    Node *in11 = shr->in(1);
+    Node *in12 = shr->in(2);
+    const TypeLong *t11 = phase->type(in11)->isa_long();
+    const TypeInt *t12 = phase->type(in12)->isa_int();
+    if ( t11 && t2 && t2->is_con(63) && t12 && t12->is_con() ) {
+      return new URShiftLNode(in11, phase->intcon(63));
+    }
+  }
   return NULL;
 }
 

src/hotspot/share/opto/subnode.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2020, 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
@@ -252,6 +252,18 @@ Node *SubINode::Ideal(PhaseGVN *phase, bool can_reshape){
     return new SubINode( add1, in2->in(1) );
   }
 
+  // Convert "0-(A>>31)" into "(A>>>31)"
+  if ( op2 == Op_RShiftI ) {
+    Node *in21 = in2->in(1);
+    Node *in22 = in2->in(2);
+    const TypeInt *zero = phase->type(in1)->isa_int();
+    const TypeInt *t21 = phase->type(in21)->isa_int();
+    const TypeInt *t22 = phase->type(in22)->isa_int();
+    if ( t21 && t22 && zero == TypeInt::ZERO && t22->is_con(31) ) {
+      return new URShiftINode(in21, in22);
+    }
+  }
+
   return NULL;
 }
 
@@ -361,6 +373,18 @@ Node *SubLNode::Ideal(PhaseGVN *phase, bool can_reshape) {
     return new SubLNode( add1, in2->in(1) );
   }
 
+  // Convert "0L-(A>>63)" into "(A>>>63)"
+  if ( op2 == Op_RShiftL ) {
+    Node *in21 = in2->in(1);
+    Node *in22 = in2->in(2);
+    const TypeLong *zero = phase->type(in1)->isa_long();
+    const TypeLong *t21 = phase->type(in21)->isa_long();
+    const TypeInt *t22 = phase->type(in22)->isa_int();
+    if ( t21 && t22 && zero == TypeLong::ZERO && t22->is_con(63) ) {
+      return new URShiftLNode(in21, in22);
+    }
+  }
+
   return NULL;
 }
 

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

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, Arm 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 8242429
+ * @summary Better implementation for sign extract.
+ *
+ * @run main/othervm -XX:-TieredCompilation -XX:CompileCommand=dontinline,compiler.c2.TestSignExtract::signExtract*
+ *      compiler.c2.TestSignExtract
+ */
+package compiler.c2;
+
+public class TestSignExtract {
+
+    private static final long[] LONG_VALUES = {0L, 0xFFFFFFFFL, 0x12L, -1L, -123L, -0x12L, Long.MAX_VALUE, Long.MIN_VALUE};
+    private static final int[] INT_VALUES = {0, 0x1234, -1, -0x12345678, Integer.MAX_VALUE, Integer.MIN_VALUE};
+
+
+    private static int signExtractInt1(int x) {
+        return (x >> 1) >>> 31;
+    }
+
+    private static int signExtractInt2(int x) {
+        return (x >> 32) >>> 31;
+    }
+
+    private static int signExtractInt3(int x) {
+        return (x >> 31) >>> 31;
+    }
+
+    private static int signExtractInt4(int x) {
+        return 0 - (x >> 31);
+    }
+
+    private static long signExtractLong1(long x) {
+        return (x >> 1) >>> 63;
+    }
+
+    private static long signExtractLong2(long x) {
+        return (x >> 54) >>> 63;
+    }
+
+    private static long signExtractLong3(long x) {
+        return (x >> 63) >>> 63;
+    }
+
+    private static long signExtractLong4(long x) {
+        return 0 - (x >> 63);
+    }
+
+    private static int WARMUP = 5000;
+
+    public static void main(String[] args) {
+        for (int i = 0; i < WARMUP; i++) {
+            for (int e : INT_VALUES) {
+                // "(A >> n) >>> 31" => "(A >>> 31)"
+                assert e >>> 31 == signExtractInt1(e);
+                assert e >>> 31 == signExtractInt2(e);
+                assert e >>> 31 == signExtractInt3(e);
+                // "0 - (A >> 31)" => "(A >>> 31)"
+                assert e >>> 31 == signExtractInt4(e);
+            }
+
+            for (long e : LONG_VALUES) {
+                // "(A >> n) >>> 63" => "(A >>> 63)"
+                assert e >>> 63 == signExtractLong1(e);
+                assert e >>> 63 == signExtractLong2(e);
+                assert e >>> 63 == signExtractLong3(e);
+                // "0 - (A >> 63)" => "(A >>> 63)"
+                assert e >>> 63 == signExtractLong4(e);
+            }
+        }
+    }
+}