papermc/Spigot-Server-Patches/0171-Speedup-BlockPos-by-fixing-inlining.patch

From 329e237f6cfee08bd844148fd37f97e3f18841de Mon Sep 17 00:00:00 2001
From: Techcable <Techcable@outlook.com>
Date: Wed, 30 Nov 2016 20:56:58 -0600
Subject: [PATCH] Speedup BlockPos by fixing inlining

Normally the JVM can inline virtual getters by having two sets of code, one is the 'optimized' code and the other is the 'deoptimized' code.
If a single type is used 99% of the time, then its worth it to inline, and to revert to 'deoptimized' the 1% of the time we encounter other types.
But if two types are encountered commonly, then the JVM can't inline them both, and the call overhead remains.

This scenario also occurs with BlockPos and MutableBlockPos.
The variables in BlockPos are final, so MutableBlockPos can't modify them.
MutableBlockPos fixes this by adding custom mutable variables, and overriding the getters to access them.

This approach with utility methods that operate on MutableBlockPos and BlockPos.
Specific examples are BlockPosition.up(), and World.isValidLocation().
It makes these simple methods much slower than they need to be.

This should result in an across the board speedup in anything that accesses blocks or does logic with positions.

This is based upon conclusions drawn from inspecting the assenmbly generated bythe JIT compiler on my mircorbenchmarks.
They had 'callq' (invoke) instead of 'mov' (get from memory) instructions.

diff --git a/src/main/java/net/minecraft/server/BaseBlockPosition.java b/src/main/java/net/minecraft/server/BaseBlockPosition.java
index 679d5504e..8e737718e 100644
--- a/src/main/java/net/minecraft/server/BaseBlockPosition.java
+++ b/src/main/java/net/minecraft/server/BaseBlockPosition.java
@@ -7,11 +7,12 @@ import javax.annotation.concurrent.Immutable;
 public class BaseBlockPosition implements Comparable<BaseBlockPosition> {
 
     public static final BaseBlockPosition ZERO = new BaseBlockPosition(0, 0, 0);
-    private final int a;
-    private final int b;
-    private final int c;
-    // Paper start
-    public boolean isValidLocation() {
+    // Paper start - Make mutable and protected for MutableBlockPos and PooledBlockPos
+    protected int a;
+    protected int b;
+    protected int c;
+
+    public final boolean isValidLocation() {
         return a >= -30000000 && c >= -30000000 && a < 30000000 && c < 30000000 && b >= 0 && b < 256;
     }
     public boolean isInvalidYLocation() {
@@ -49,17 +50,19 @@ public class BaseBlockPosition implements Comparable<BaseBlockPosition> {
         return this.getY() == baseblockposition.getY() ? (this.getZ() == baseblockposition.getZ() ? this.getX() - baseblockposition.getX() : this.getZ() - baseblockposition.getZ()) : this.getY() - baseblockposition.getY();
     }
 
-    public int getX() {
+    // Paper start - Only allow a single implementation
+    public final int getX() {
         return this.a;
     }
 
-    public int getY() {
+    public final int getY() {
         return this.b;
     }
 
-    public int getZ() {
+    public final int getZ() {
         return this.c;
     }
+    // Paper end
 
     public BaseBlockPosition d(BaseBlockPosition baseblockposition) {
         return new BaseBlockPosition(this.getY() * baseblockposition.getZ() - this.getZ() * baseblockposition.getY(), this.getZ() * baseblockposition.getX() - this.getX() * baseblockposition.getZ(), this.getX() * baseblockposition.getY() - this.getY() * baseblockposition.getX());
diff --git a/src/main/java/net/minecraft/server/BlockPosition.java b/src/main/java/net/minecraft/server/BlockPosition.java
index b3c1f550c..6a0b3a62d 100644
--- a/src/main/java/net/minecraft/server/BlockPosition.java
+++ b/src/main/java/net/minecraft/server/BlockPosition.java
@@ -211,19 +211,21 @@ public class BlockPosition extends BaseBlockPosition {
                         if (this.b == null) {
                             this.b = new BlockPosition.MutableBlockPosition(i, j, k);
                             return this.b;
-                        } else if (this.b.b == l && this.b.c == i1 && this.b.d == j1) {
+                        // Paper start - b, c, d, refer to x, y, z, and as such, a, b, c of BaseBlockPosition
+                        } else if (((BaseBlockPosition)this.b).a == l && ((BaseBlockPosition)this.b).b == i1 && ((BaseBlockPosition)this.b).c == j1) {
                             return (BlockPosition.MutableBlockPosition) this.endOfData();
                         } else {
-                            if (this.b.b < l) {
-                                ++this.b.b;
-                            } else if (this.b.c < i1) {
-                                this.b.b = i;
-                                ++this.b.c;
-                            } else if (this.b.d < j1) {
-                                this.b.b = i;
-                                this.b.c = j;
-                                ++this.b.d;
+                            if (((BaseBlockPosition) this.b).a < l) {
+                                ++((BaseBlockPosition) this.b).a;
+                            } else if (((BaseBlockPosition) this.b).b < i1) {
+                                ((BaseBlockPosition) this.b).a = i;
+                                ++((BaseBlockPosition) this.b).b;
+                            } else if (((BaseBlockPosition) this.b).c < j1) {
+                                ((BaseBlockPosition) this.b).a = i;
+                                ((BaseBlockPosition) this.b).b = j;
+                                ++((BaseBlockPosition) this.b).c;
                             }
+                            // Paper end
 
                             return this.b;
                         }
@@ -338,6 +340,8 @@ public class BlockPosition extends BaseBlockPosition {
 
     public static class MutableBlockPosition extends BlockPosition {
 
+        // Paper start - Remove variables
+        /*
         protected int b;
         protected int c;
         protected int d;
@@ -350,6 +354,7 @@ public class BlockPosition extends BaseBlockPosition {
         public boolean isInvalidYLocation() {
             return c < 0 || c >= 256;
         }
+        */
         // Paper end
 
         public MutableBlockPosition() {
@@ -362,9 +367,11 @@ public class BlockPosition extends BaseBlockPosition {
 
         public MutableBlockPosition(int i, int j, int k) {
             super(0, 0, 0);
-            this.b = i;
-            this.c = j;
-            this.d = k;
+            // Paper start - Modify base position variables
+            ((BaseBlockPosition) this).a = i;
+            ((BaseBlockPosition) this).b = j;
+            ((BaseBlockPosition) this).c = k;
+            // Paper end
         }
 
         public BlockPosition a(double d0, double d1, double d2) {
@@ -383,6 +390,8 @@ public class BlockPosition extends BaseBlockPosition {
             return super.a(enumblockrotation).h();
         }
 
+        // Paper start - Use superclass methods
+        /*
         public int getX() {
             return this.b;
         }
@@ -394,12 +403,16 @@ public class BlockPosition extends BaseBlockPosition {
         public int getZ() {
             return this.d;
         }
+        */
+        // Paper end
 
         public void setValues(int x, int y, int z) { c(x, y, z); } // Paper - OBFHELPER
         public BlockPosition.MutableBlockPosition c(int i, int j, int k) {
-            this.b = i;
-            this.c = j;
-            this.d = k;
+            // Paper start - Modify base position variables
+            ((BaseBlockPosition) this).a = i;
+            ((BaseBlockPosition) this).b = j;
+            ((BaseBlockPosition) this).c = k;
+            // Paper end
             return this;
         }
 
@@ -416,11 +429,11 @@ public class BlockPosition extends BaseBlockPosition {
         }
 
         public BlockPosition.MutableBlockPosition c(EnumDirection enumdirection, int i) {
-            return this.c(this.b + enumdirection.getAdjacentX() * i, this.c + enumdirection.getAdjacentY() * i, this.d + enumdirection.getAdjacentZ() * i);
+            return this.c(this.getX() + enumdirection.getAdjacentX() * i, this.getY() + enumdirection.getAdjacentY() * i, this.getZ() + enumdirection.getAdjacentZ() * i); // Paper - USE THE BLEEPING GETTERS
         }
 
         public void p(int i) {
-            this.c = i;
+            ((BaseBlockPosition) this).b = i; // Paper - Modify base variable
         }
 
         public BlockPosition h() {
-- 
2.16.1