From d4113a6744b4399953b9ee851734693f754ab238 Mon Sep 17 00:00:00 2001
From: Alexey Andreev <konsoletyper@gmail.com>
Date: Thu, 28 Sep 2023 17:00:51 +0200
Subject: [PATCH] classlib: improve Math min/max implementations in C and Wasm

Follow-up to ihromant's "fix Math min/max functions in JS"
---
 .../org/teavm/classlib/java/lang/TMath.java     | 17 +++++++++++++++++
 .../org/teavm/backend/wasm/WasmRuntime.java     |  8 ++++++++
 .../wasm/intrinsics/WasmRuntimeIntrinsic.java   |  8 ++++++++
 3 files changed, 33 insertions(+)

diff --git a/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java b/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java
index a795ac211..01b7b9c23 100644
--- a/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java
+++ b/classlib/src/main/java/org/teavm/classlib/java/lang/TMath.java
@@ -16,6 +16,7 @@
 package org.teavm.classlib.java.lang;
 
 import org.teavm.backend.javascript.spi.GeneratedBy;
+import org.teavm.backend.wasm.WasmRuntime;
 import org.teavm.backend.wasm.runtime.WasmSupport;
 import org.teavm.classlib.PlatformDetector;
 import org.teavm.interop.Import;
@@ -197,11 +198,15 @@ public final class TMath extends TObject {
 
     @GeneratedBy(MathNativeGenerator.class)
     @NoSideEffects
+    @Unmanaged
     private static native float minImpl(double a, double b);
 
+    @Unmanaged
     public static double min(double a, double b) {
         if (PlatformDetector.isJavaScript()) {
             return minImpl(a, b);
+        } else if (PlatformDetector.isWebAssembly()) {
+            return WasmRuntime.min(a, b);
         }
         if (a != a) {
             return a;
@@ -214,11 +219,15 @@ public final class TMath extends TObject {
 
     @GeneratedBy(MathNativeGenerator.class)
     @NoSideEffects
+    @Unmanaged
     private static native float maxImpl(double a, double b);
 
+    @Unmanaged
     public static double max(double a, double b) {
         if (PlatformDetector.isJavaScript()) {
             return maxImpl(a, b);
+        } else if (PlatformDetector.isWebAssembly()) {
+            return WasmRuntime.max(a, b);
         }
         if (a != a) {
             return a;
@@ -231,11 +240,15 @@ public final class TMath extends TObject {
 
     @GeneratedBy(MathNativeGenerator.class)
     @NoSideEffects
+    @Unmanaged
     private static native float minImpl(float a, float b);
 
+    @Unmanaged
     public static float min(float a, float b) {
         if (PlatformDetector.isJavaScript()) {
             return minImpl(a, b);
+        } else if (PlatformDetector.isWebAssembly()) {
+            return WasmRuntime.min(a, b);
         }
         if (a != a) {
             return a;
@@ -248,11 +261,15 @@ public final class TMath extends TObject {
 
     @GeneratedBy(MathNativeGenerator.class)
     @NoSideEffects
+    @Unmanaged
     private static native float maxImpl(float a, float b);
 
+    @Unmanaged
     public static float max(float a, float b) {
         if (PlatformDetector.isJavaScript()) {
             return maxImpl(a, b);
+        } else if (PlatformDetector.isWebAssembly()) {
+            return WasmRuntime.max(a, b);
         }
         if (a != a) {
             return a;
diff --git a/core/src/main/java/org/teavm/backend/wasm/WasmRuntime.java b/core/src/main/java/org/teavm/backend/wasm/WasmRuntime.java
index 8e78e53ca..fb0f4278a 100644
--- a/core/src/main/java/org/teavm/backend/wasm/WasmRuntime.java
+++ b/core/src/main/java/org/teavm/backend/wasm/WasmRuntime.java
@@ -51,6 +51,14 @@ public final class WasmRuntime {
         return gt(a, b) ? 1 : lt(a, b) ? -1 : 0;
     }
 
+    public static native float min(float a, float b);
+
+    public static native double min(double a, double b);
+
+    public static native float max(float a, float b);
+
+    public static native double max(double a, double b);
+
     public static float remainder(float a, float b) {
         return a - (float) (int) (a / b) * b;
     }
diff --git a/core/src/main/java/org/teavm/backend/wasm/intrinsics/WasmRuntimeIntrinsic.java b/core/src/main/java/org/teavm/backend/wasm/intrinsics/WasmRuntimeIntrinsic.java
index 09d8d07bf..0acc58f10 100644
--- a/core/src/main/java/org/teavm/backend/wasm/intrinsics/WasmRuntimeIntrinsic.java
+++ b/core/src/main/java/org/teavm/backend/wasm/intrinsics/WasmRuntimeIntrinsic.java
@@ -40,6 +40,8 @@ public class WasmRuntimeIntrinsic implements WasmIntrinsic {
             case "lt":
             case "gtu":
             case "ltu":
+            case "min":
+            case "max":
             case "initStack":
             case "callFunctionFromTable":
                 return true;
@@ -63,6 +65,12 @@ public class WasmRuntimeIntrinsic implements WasmIntrinsic {
             case "gtu":
                 return comparison(WasmIntBinaryOperation.GT_UNSIGNED, WasmFloatBinaryOperation.GT,
                         invocation, manager);
+            case "min":
+                return comparison(WasmIntBinaryOperation.GT_SIGNED, WasmFloatBinaryOperation.MIN,
+                        invocation, manager);
+            case "max":
+                return comparison(WasmIntBinaryOperation.GT_SIGNED, WasmFloatBinaryOperation.MAX,
+                        invocation, manager);
             case "callFunctionFromTable": {
                 var call = new WasmIndirectCall(manager.generate(invocation.getArguments().get(0)));
                 call.getArguments().add(manager.generate(invocation.getArguments().get(1)));