From 88017f6ea6934e5d229271b21dfd8399e5505a03 Mon Sep 17 00:00:00 2001
From: Akira Saitoh <saiaki@jp.ibm.com>
Date: Tue, 30 Aug 2022 15:48:21 +0900
Subject: [PATCH] AArch64: Inline Math.min and max

Implement the inlined version of java/lang/Math.min and max.

Signed-off-by: Akira Saitoh <saiaki@jp.ibm.com>
---
 .../aarch64/codegen/J9CodeGenerator.cpp       |  7 ++-
 .../aarch64/codegen/J9TreeEvaluator.cpp       | 49 +++++++++++++++++++
 2 files changed, 55 insertions(+), 1 deletion(-)

diff --git a/runtime/compiler/aarch64/codegen/J9CodeGenerator.cpp b/runtime/compiler/aarch64/codegen/J9CodeGenerator.cpp
index 6fb9ddcd52d..e897becbf68 100644
--- a/runtime/compiler/aarch64/codegen/J9CodeGenerator.cpp
+++ b/runtime/compiler/aarch64/codegen/J9CodeGenerator.cpp
@@ -1,5 +1,5 @@
 /*******************************************************************************
- * Copyright (c) 2019, 2021 IBM Corp. and others
+ * Copyright (c) 2019, 2022 IBM Corp. and others
  *
  * This program and the accompanying materials are made available under
  * the terms of the Eclipse Public License 2.0 which accompanies this
@@ -215,5 +215,10 @@ J9::ARM64::CodeGenerator::supportsInliningOfIsInstance()
 bool
 J9::ARM64::CodeGenerator::suppressInliningOfRecognizedMethod(TR::RecognizedMethod method)
    {
+   if (method == TR::java_lang_Math_min_F ||
+       method == TR::java_lang_Math_max_F)
+      {
+      return true;
+      }
    return false;
    }
diff --git a/runtime/compiler/aarch64/codegen/J9TreeEvaluator.cpp b/runtime/compiler/aarch64/codegen/J9TreeEvaluator.cpp
index 2aee375f1e3..0a090448b70 100644
--- a/runtime/compiler/aarch64/codegen/J9TreeEvaluator.cpp
+++ b/runtime/compiler/aarch64/codegen/J9TreeEvaluator.cpp
@@ -5094,6 +5094,34 @@ static TR::Register *VMinlineCompareAndSwapObject(TR::Node *node, TR::CodeGenera
    return resultReg;
    }
 
+/**
+ * @brief Generates instruction sequence for java/lang/Math.min and max
+ *
+ * @param[in] node: node
+ * @param[in] isMax: true if operation is max
+ * @param[in] isDouble: true if type is double
+ * @param[in] cg: CodeGenerator
+ * @return the result register
+ */
+static TR::Register *
+VMinlineMathMinMax(TR::Node *node, bool isMax, bool isDouble, TR::CodeGenerator *cg)
+   {
+   TR::Node *firstChild = node->getFirstChild();
+   TR::Node *secondChild = node->getSecondChild();
+   TR::Register *lhsReg = cg->evaluate(firstChild);
+   TR::Register *rhsReg = cg->evaluate(secondChild);
+   TR::Register *resReg = cg->allocateRegister(TR_FPR);
+   TR::InstOpCode::Mnemonic op = isMax ? (isDouble ? TR::InstOpCode::fmaxd : TR::InstOpCode::fmaxs) :
+                                         (isDouble ? TR::InstOpCode::fmind : TR::InstOpCode::fmins);
+   generateTrg1Src2Instruction(cg, op, node, resReg, lhsReg, rhsReg);
+
+   node->setRegister(resReg);
+   cg->decReferenceCount(firstChild);
+   cg->decReferenceCount(secondChild);
+
+   return resReg;
+   }
+
 bool
 J9::ARM64::CodeGenerator::inlineDirectCall(TR::Node *node, TR::Register *&resultReg)
    {
@@ -5135,6 +5163,27 @@ J9::ARM64::CodeGenerator::inlineDirectCall(TR::Node *node, TR::Register *&result
             return true;
             }
 
+         case TR::java_lang_Math_max_D:
+            {
+            resultReg = VMinlineMathMinMax(node, true, true, cg);
+            return true;
+            }
+         case TR::java_lang_Math_max_F:
+            {
+            resultReg = VMinlineMathMinMax(node, true, false, cg);
+            return true;
+            }
+         case TR::java_lang_Math_min_D:
+            {
+            resultReg = VMinlineMathMinMax(node, false, true, cg);
+            return true;
+            }
+         case TR::java_lang_Math_min_F:
+            {
+            resultReg = VMinlineMathMinMax(node, false, false, cg);
+            return true;
+            }
+
          case TR::sun_misc_Unsafe_compareAndSwapInt_jlObjectJII_Z:
             {
             // In Java9 and newer this can be either the jdk.internal JNI method or the sun.misc Java wrapper.