From 7108dfbac7eceda910644d4f5fcef590a7ab2bc0 Mon Sep 17 00:00:00 2001
From: Alexey Andreev <konsoletyper@gmail.com>
Date: Sun, 19 Nov 2023 20:12:44 +0100
Subject: [PATCH] classlib: fix Math exact operations in C and WebAssembly
 backends

---
 .../java/org/teavm/classlib/java/lang/TMath.java   | 14 ++++++--------
 .../org/teavm/classlib/java/lang/MathTest.java     |  7 ++++++-
 .../java/time/TestDateTimesImplementation.java     |  3 ---
 3 files changed, 12 insertions(+), 12 deletions(-)

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 b97ad798b..587237586 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
@@ -254,7 +254,7 @@ public final class TMath extends TObject {
             return 0;
         }
         int total = a * b;
-        if (total / b != a || (a == Integer.MIN_VALUE && b == -1) || (b == Integer.MIN_VALUE && a == -1)) {
+        if ((a == Integer.MIN_VALUE && b == -1) || (b == Integer.MIN_VALUE && a == -1) || total / b != a) {
             throw new ArithmeticException();
         }
         return total;
@@ -273,26 +273,24 @@ public final class TMath extends TObject {
             return 0;
         }
         long total = a * b;
-        if (total / b != a || (a == Long.MIN_VALUE && b == -1) || (b == Long.MIN_VALUE && a == -1)) {
+        if ((a == Long.MIN_VALUE && b == -1) || (b == Long.MIN_VALUE && a == -1) || total / b != a) {
             throw new ArithmeticException();
         }
         return total;
     }
 
     public static int divideExact(int a, int b) {
-        int q = a / b;
-        if ((a & b & q) < 0) { // all 3 are negative
+        if (a == Integer.MIN_VALUE && b == -1) {
             throw new ArithmeticException();
         }
-        return q;
+        return a / b;
     }
 
     public static long divideExact(long a, long b) {
-        long q = a / b;
-        if ((a & b & q) < 0) { // all 3 are negative
+        if (a == Long.MIN_VALUE && b == -1) {
             throw new ArithmeticException();
         }
-        return q;
+        return a / b;
     }
 
     @Unmanaged
diff --git a/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java b/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java
index 1ea9542d2..6a882a9f9 100644
--- a/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java
+++ b/tests/src/test/java/org/teavm/classlib/java/lang/MathTest.java
@@ -202,7 +202,6 @@ public class MathTest {
     }
 
     @Test
-    @SkipPlatform({TestPlatform.WEBASSEMBLY, TestPlatform.WASI, TestPlatform.C})
     public void exacts() {
         try {
             Math.incrementExact(Integer.MAX_VALUE);
@@ -258,6 +257,12 @@ public class MathTest {
         } catch (ArithmeticException e) {
             // ok
         }
+        try {
+            Math.divideExact(Integer.MIN_VALUE, -1);
+            fail();
+        } catch (ArithmeticException e) {
+            // ok
+        }
         IntStream.rangeClosed(-10, 10).forEach(x -> {
             assertEquals(x + 1, Math.incrementExact(x));
             assertEquals(x - 1, Math.decrementExact(x));
diff --git a/tests/src/test/java/org/teavm/classlib/java/time/TestDateTimesImplementation.java b/tests/src/test/java/org/teavm/classlib/java/time/TestDateTimesImplementation.java
index a821ebd27..0a7511159 100644
--- a/tests/src/test/java/org/teavm/classlib/java/time/TestDateTimesImplementation.java
+++ b/tests/src/test/java/org/teavm/classlib/java/time/TestDateTimesImplementation.java
@@ -48,9 +48,7 @@ package org.teavm.classlib.java.time;
 
 import static org.testng.Assert.assertEquals;
 import org.junit.runner.RunWith;
-import org.teavm.junit.SkipPlatform;
 import org.teavm.junit.TeaVMTestRunner;
-import org.teavm.junit.TestPlatform;
 import org.testng.annotations.DataProvider;
 import org.testng.annotations.Test;
 
@@ -309,7 +307,6 @@ public class TestDateTimesImplementation {
     }
 
     @Test(dataProvider = "safeMultiplyLongLongProviderOverflow", expectedExceptions = ArithmeticException.class)
-    @SkipPlatform({TestPlatform.C, TestPlatform.WEBASSEMBLY, TestPlatform.WASI})
     public void test_safeMultiplyLongLong_overflow(long a, long b) {
         Math.multiplyExact(a, b);
     }