From ab06a878f888827026424530781f0af414a8a611 Mon Sep 17 00:00:00 2001
From: Shaojin Wen <swen@openjdk.org>
Date: Sun, 22 Sep 2024 01:01:31 +0000
Subject: [PATCH] 8340544: Optimize setLocalsFromArg

Reviewed-by: redestad, liach
---
 .../classfile/impl/StackMapGenerator.java     | 41 ++++++++++---------
 1 file changed, 22 insertions(+), 19 deletions(-)

diff --git a/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java b/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
index c6564c289d6f5..f5cd9b80af844 100644
--- a/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
+++ b/src/java.base/share/classes/jdk/internal/classfile/impl/StackMapGenerator.java
@@ -1043,34 +1043,37 @@ private void setLocalRawInternal(int index, Type type) {
         void setLocalsFromArg(String name, MethodTypeDesc methodDesc, boolean isStatic, Type thisKlass) {
             int localsSize = 0;
             // Pre-emptively create a locals array that encompass all parameter slots
-            checkLocal(methodDesc.parameterCount() + (isStatic ? -1 : 0));
+            checkLocal(Util.parameterSlots(methodDesc) + (isStatic ? -1 : 0));
+            Type type;
+            Type[] locals = this.locals;
             if (!isStatic) {
-                localsSize++;
                 if (OBJECT_INITIALIZER_NAME.equals(name) && !CD_Object.equals(thisKlass.sym)) {
-                    setLocal(0, Type.UNITIALIZED_THIS_TYPE);
+                    type = Type.UNITIALIZED_THIS_TYPE;
                     flags |= FLAG_THIS_UNINIT;
                 } else {
-                    setLocalRawInternal(0, thisKlass);
+                    type = thisKlass;
                 }
+                locals[localsSize++] = type;
             }
             for (int i = 0; i < methodDesc.parameterCount(); i++) {
                 var desc = methodDesc.parameterType(i);
-                if (!desc.isPrimitive()) {
-                    setLocalRawInternal(localsSize++, Type.referenceType(desc));
-                } else switch (desc.descriptorString().charAt(0)) {
-                    case 'J' -> {
-                        setLocalRawInternal(localsSize++, Type.LONG_TYPE);
-                        setLocalRawInternal(localsSize++, Type.LONG2_TYPE);
-                    }
-                    case 'D' -> {
-                        setLocalRawInternal(localsSize++, Type.DOUBLE_TYPE);
-                        setLocalRawInternal(localsSize++, Type.DOUBLE2_TYPE);
+                if (desc == CD_long) {
+                    locals[localsSize    ] = Type.LONG_TYPE;
+                    locals[localsSize + 1] = Type.LONG2_TYPE;
+                    localsSize += 2;
+                } else if (desc == CD_double) {
+                    locals[localsSize    ] = Type.DOUBLE_TYPE;
+                    locals[localsSize + 1] = Type.DOUBLE2_TYPE;
+                    localsSize += 2;
+                } else {
+                    if (desc instanceof ReferenceClassDescImpl) {
+                        type = Type.referenceType(desc);
+                    } else if (desc == CD_float) {
+                        type = Type.FLOAT_TYPE;
+                    } else {
+                        type = Type.INTEGER_TYPE;
                     }
-                    case 'I', 'Z', 'B', 'C', 'S' ->
-                        setLocalRawInternal(localsSize++, Type.INTEGER_TYPE);
-                    case 'F' ->
-                        setLocalRawInternal(localsSize++, Type.FLOAT_TYPE);
-                    default -> throw new AssertionError("Should not reach here");
+                    locals[localsSize++] = type;
                 }
             }
             this.localsSize = localsSize;