8323429: Missing C2 optimization for FP min/max when both inputs are same

Reviewed-by: roland, chagedorn

src/hotspot/share/opto/addnode.cpp

@@ -1424,6 +1424,14 @@ Node* MinLNode::Ideal(PhaseGVN* phase, bool can_reshape) {
   return nullptr;
 }
 
+Node* MaxNode::Identity(PhaseGVN* phase) {
+  if (in(1) == in(2)) {
+      return in(1);
+  }
+
+  return AddNode::Identity(phase);
+}
+
 //------------------------------add_ring---------------------------------------
 const Type* MinFNode::add_ring(const Type* t0, const Type* t1 ) const {
   const TypeF* r0 = t0->isa_float_constant();

src/hotspot/share/opto/addnode.hpp

@@ -269,6 +269,7 @@ public:
   virtual int max_opcode() const = 0;
   virtual int min_opcode() const = 0;
   Node* IdealI(PhaseGVN* phase, bool can_reshape);
+  virtual Node* Identity(PhaseGVN* phase);
 
   static Node* unsigned_max(Node* a, Node* b, const Type* t, PhaseGVN& gvn) {
     return build_min_max(a, b, true, true, t, gvn);

test/hotspot/jtreg/compiler/intrinsics/math/TestMinMaxOpt.java

@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 2024, Red Hat, Inc. 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 8323429
+ * @summary Test min and max optimizations
+ * @library /test/lib /
+ * @run driver compiler.intrinsics.math.TestMinMaxOpt
+ */
+
+package compiler.intrinsics.math;
+
+import compiler.lib.ir_framework.Argument;
+import compiler.lib.ir_framework.Arguments;
+import compiler.lib.ir_framework.Check;
+import compiler.lib.ir_framework.IR;
+import compiler.lib.ir_framework.IRNode;
+import compiler.lib.ir_framework.Test;
+import compiler.lib.ir_framework.TestFramework;
+
+public class TestMinMaxOpt {
+    public static void main(String[] args) {
+        TestFramework.run();
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MIN_I})
+    private static int testIntMin(int v) {
+        return Math.min(v, v);
+    }
+
+    @Check(test = "testIntMin")
+    public static void checkTestIntMin(int result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MAX_I})
+    private static int testIntMax(int v) {
+        return Math.max(v, v);
+    }
+
+    @Check(test = "testIntMax")
+    public static void checkTestIntMax(int result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MIN_L})
+    private static long testLongMin(long v) {
+        return Math.min(v, v);
+    }
+
+    @Check(test = "testLongMin")
+    public static void checkTestLongMin(long result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MAX_L})
+    private static long testLongMax(long v) {
+        return Math.max(v, v);
+    }
+
+    @Check(test = "testLongMax")
+    public static void checkTestLongMax(long result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MIN_F})
+    private static float testFloatMin(float v) {
+        return Math.min(v, v);
+    }
+
+    @Check(test = "testFloatMin")
+    public static void checkTestFloatMin(float result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MAX_F})
+    private static float testFloatMax(float v) {
+        return Math.max(v, v);
+    }
+
+    @Check(test = "testFloatMax")
+    public static void checkTestFloatMax(float result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MIN_D})
+    private static double testDoubleMin(double v) {
+        return Math.min(v, v);
+    }
+
+    @Check(test = "testDoubleMin")
+    public static void checkTestDoubleMin(double result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+
+    @Test
+    @Arguments(values = {Argument.NUMBER_42})
+    @IR(failOn = {IRNode.MAX_D})
+    private static double testDoubleMax(double v) {
+        return Math.max(v, v);
+    }
+
+    @Check(test = "testDoubleMax")
+    public static void checkTestDoubleMax(double result) {
+        if (result != 42) {
+            throw new RuntimeException("Incorrect result: " + result);
+        }
+    }
+}

test/hotspot/jtreg/compiler/lib/ir_framework/IRNode.java

@@ -819,7 +819,12 @@ public class IRNode {
 
     public static final String MAX = PREFIX + "MAX" + POSTFIX;
     static {
-        beforeMatchingNameRegex(MAX, "Max(I|L)");
+        beforeMatchingNameRegex(MAX, "Max(I|L|F|D)");
+    }
+
+    public static final String MAX_D = PREFIX + "MAX_D" + POSTFIX;
+    static {
+        beforeMatchingNameRegex(MAX_D, "MaxD");
     }
 
     public static final String MAX_D_REDUCTION_REG = PREFIX + "MAX_D_REDUCTION_REG" + POSTFIX;
@@ -832,6 +837,11 @@ public class IRNode {
         machOnlyNameRegex(MAX_D_REG, "maxD_reg");
     }
 
+    public static final String MAX_F = PREFIX + "MAX_F" + POSTFIX;
+    static {
+        beforeMatchingNameRegex(MAX_F, "MaxF");
+    }
+
     public static final String MAX_F_REDUCTION_REG = PREFIX + "MAX_F_REDUCTION_REG" + POSTFIX;
     static {
         machOnlyNameRegex(MAX_F_REDUCTION_REG, "maxF_reduction_reg");
@@ -887,6 +897,11 @@ public class IRNode {
         beforeMatchingNameRegex(MIN, "Min(I|L)");
     }
 
+    public static final String MIN_D = PREFIX + "MIN_D" + POSTFIX;
+    static {
+        beforeMatchingNameRegex(MIN_D, "MinD");
+    }
+
     public static final String MIN_D_REDUCTION_REG = PREFIX + "MIN_D_REDUCTION_REG" + POSTFIX;
     static {
         machOnlyNameRegex(MIN_D_REDUCTION_REG, "minD_reduction_reg");
@@ -897,6 +912,11 @@ public class IRNode {
         machOnlyNameRegex(MIN_D_REG, "minD_reg");
     }
 
+    public static final String MIN_F = PREFIX + "MIN_F" + POSTFIX;
+    static {
+        beforeMatchingNameRegex(MIN_F, "MinF");
+    }
+
     public static final String MIN_F_REDUCTION_REG = PREFIX + "MIN_F_REDUCTION_REG" + POSTFIX;
     static {
         machOnlyNameRegex(MIN_F_REDUCTION_REG, "minF_reduction_reg");

test/hotspot/jtreg/compiler/vectorization/runner/BasicDoubleOpTest.java

@@ -240,7 +240,7 @@ public class BasicDoubleOpTest extends VectorizationTestRunner {
 
     @Test
     @IR(applyIfCPUFeatureOr = {"asimd", "true", "avx", "true"},
-        counts = {IRNode.MAX_VD, ">0"})
+        counts = {IRNode.MAX_VD, "0"})
     public double[] vectorMax_8322090() {
         double[] res = new double[SIZE];
         for (int i = 0; i < SIZE; i++) {