From eeb71363a5fa2b0e48b52ba797637f16ec969dc9 Mon Sep 17 00:00:00 2001
From: Frotty <Frotty@users.noreply.github.com>
Date: Mon, 12 Oct 2026 09:51:23 +0200
Subject: [PATCH] Jass: print a large real literal as the float it means, a
 compile-time real without an exponent

---
 .../wurstio/CompiletimeFunctionRunner.java    | 16 +++++-
 .../translation/imtojass/ExprTranslation.java | 51 ++++++++++++++++++-
 .../tests/CompiletimeHashtableTests.java      | 15 ++++++
 .../wurstscript/tests/CompiletimeTests.java   | 26 ++++++++++
 .../wurstscript/tests/InterpreterTests.java   |  4 +-
 .../tests/LuaBackendAuditTests.java           | 39 ++++++++++++++
 docs/WC3_RUNTIME.md                           |  2 +-
 7 files changed, 147 insertions(+), 6 deletions(-)

diff --git a/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/CompiletimeFunctionRunner.java b/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/CompiletimeFunctionRunner.java
index 6be94c336..39b1eb6d3 100644
--- a/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/CompiletimeFunctionRunner.java
+++ b/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstio/CompiletimeFunctionRunner.java
@@ -480,13 +480,25 @@ private String literalText(ILconstString value, Element trace) {
         return value.text();
     }
 
+    /**
+     * A real as a decimal literal both backends read: the shortest decimal which reads back as the
+     * same float, without the exponent Java prints from 10^7 on and below 10^-3, which Jass does not parse.
+     */
+    private static String realLiteral(Element trace, float value) {
+        if (!Float.isFinite(value)) {
+            throw new InterpreterException(trace, "The compile-time real " + value + " has no literal.");
+        }
+        String plain = new java.math.BigDecimal(Float.toString(value)).toPlainString();
+        return plain.contains(".") ? plain : plain + ".";
+    }
+
     private ImExpr constantToExpr(Element trace, ILconst value, @Nullable ImType expectedType) {
         if (value instanceof ILconstBool iLconstBool) {
             return JassIm.ImBoolVal(iLconstBool.getVal());
         } else if (value instanceof ILconstInt iLconstInt) {
             return JassIm.ImIntVal(iLconstInt.getVal());
         } else if (value instanceof ILconstReal iLconstReal) {
-            return JassIm.ImRealVal("" + iLconstReal.getVal());
+            return JassIm.ImRealVal(realLiteral(trace, iLconstReal.getVal()));
         } else if (value instanceof ILconstString iLconstString) {
             return JassIm.ImStringVal(literalText(iLconstString, trace));
         } else if (value instanceof ILconstNull) {
@@ -1110,7 +1122,7 @@ private ImExpr constantToExprHashtable(Element trace, ImVar htVar, IlConstHandle
                             JassIm.ImVarAccess(htVar),
                             JassIm.ImIntVal(parentKey),
                             JassIm.ImIntVal(childKey),
-                            JassIm.ImRealVal("" + iv.getVal())
+                            JassIm.ImRealVal(realLiteral(trace, iv.getVal()))
                     ), false, CallType.NORMAL));
                 } else if (v instanceof ILconstString iv) {
                     if (saveStr == null) {
diff --git a/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/imtojass/ExprTranslation.java b/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/imtojass/ExprTranslation.java
index 9613ec3dd..2e8b35ac2 100644
--- a/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/imtojass/ExprTranslation.java
+++ b/de.peeeq.wurstscript/src/main/java/de/peeeq/wurstscript/translation/imtojass/ExprTranslation.java
@@ -8,6 +8,8 @@
 import de.peeeq.wurstscript.translation.imtranslation.ImTranslator;
 import de.peeeq.wurstscript.types.TypesHelper;
 
+import java.math.BigDecimal;
+
 import static de.peeeq.wurstscript.jassAst.JassAst.*;
 
 public class ExprTranslation {
@@ -111,7 +113,54 @@ public static JassExpr translate(ImOperatorCall e, ImToJassTranslator translator
 
 
     public static JassExpr translate(ImRealVal e, ImToJassTranslator translator) {
-        return JassExprRealVal(e.getValR());
+        return realLiteral(e);
+    }
+
+    private static final BigDecimal TWO_TO_24 = BigDecimal.valueOf(1 << 24);
+    /** The largest power of two whose literal Jass reads exactly. */
+    private static final int MAX_FACTOR_EXPONENT = 30;
+
+    /**
+     * The Jass for the float a real literal means. Jass reads a literal's integer part as a 32-bit
+     * integer and truncates it past 2^24 (measured on the 3.0.0 client: the literal 3000000000. is
+     * negative, 10000000000. reads as 1410065408, 16777219. as 16777218), while it reads an exact
+     * float below 2^31 exactly. So past 2^24, where every float is an integer, the backend prints
+     * the float's own digits, and from 2^31 on a product of exact factors, its odd part and powers
+     * of two, which Jass multiplies exactly. A literal past the largest float, which the interpreter
+     * reads as infinity, is the largest float: Jass has no product which gives infinity (measured
+     * too: 2^150 compares below 3e38 and prints as 0.000, while the largest float compares above it).
+     */
+    private static JassExpr realLiteral(ImRealVal e) {
+        String literal = e.getValR();
+        if (new BigDecimal(literal).abs().compareTo(TWO_TO_24) <= 0) {
+            return JassExprRealVal(literal);
+        }
+        float value = Float.parseFloat(literal);
+        float magnitude = Math.min(Math.abs(value), Float.MAX_VALUE);
+        JassExpr result;
+        if (magnitude < 2147483648f) {
+            result = JassExprRealVal(new BigDecimal(magnitude).toBigInteger() + ".");
+        } else {
+            // magnitude = odd * 2^exponent, with odd below 2^24
+            int exponent = Math.getExponent(magnitude) - 23;
+            long odd = (long) Math.scalb(magnitude, -exponent);
+            int zeros = Long.numberOfTrailingZeros(odd);
+            odd >>= zeros;
+            exponent += zeros;
+            if (odd == 1) {
+                int factor = Math.min(exponent, MAX_FACTOR_EXPONENT);
+                result = JassExprRealVal((1L << factor) + ".");
+                exponent -= factor;
+            } else {
+                result = JassExprRealVal(odd + ".");
+            }
+            while (exponent > 0) {
+                int factor = Math.min(exponent, MAX_FACTOR_EXPONENT);
+                result = JassExprBinary(result, JassOpMult(), JassExprRealVal((1L << factor) + "."));
+                exponent -= factor;
+            }
+        }
+        return value < 0 ? JassExprUnary(JassOpMinus(), result) : result;
     }
 
     public static JassExpr translate(ImStatementExpr e, ImToJassTranslator translator) {
diff --git a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeHashtableTests.java b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeHashtableTests.java
index 744088c4c..6c392007b 100644
--- a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeHashtableTests.java
+++ b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeHashtableTests.java
@@ -52,6 +52,21 @@ public void valuesOfDifferentTypesShareAKeyAndAreReplayed() {
             "        testSuccess()"));
     }
 
+    /** Java prints these reals with an exponent, which Jass does not parse; the replay writes decimals. */
+    @Test
+    public void largeAndSmallRealsAreReplayedAsDecimals() {
+        test().executeProg(true).executeProgOnlyAfterTransforms().runCompiletimeFunctions(true).lines(program(
+            "@noinline function w(real x) returns real",
+            "    return x",
+            "@compiletime",
+            "function fill()",
+            "    SaveReal(h, 1, 1, w(10000.) * w(1000.))",
+            "    SaveReal(h, 1, 2, w(1.) / w(1024.))",
+            "init",
+            "    if LoadReal(h, 1, 1) == 10000000. and LoadReal(h, 1, 2) == 0.0009765625",
+            "        testSuccess()"));
+    }
+
     @Test
     public void flushedAndRemovedEntriesAreNotReplayed() {
         test().executeProg(true).executeProgOnlyAfterTransforms().runCompiletimeFunctions(true).lines(program(
diff --git a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeTests.java b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeTests.java
index e8a30f8ea..cd5386487 100644
--- a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeTests.java
+++ b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/CompiletimeTests.java
@@ -4,8 +4,12 @@
 import ch.qos.logback.classic.spi.ILoggingEvent;
 import ch.qos.logback.core.read.ListAppender;
 import org.slf4j.LoggerFactory;
+import com.google.common.base.Charsets;
+import com.google.common.io.Files;
 import org.testng.annotations.Test;
 
+import java.io.File;
+import java.io.IOException;
 import java.util.List;
 
 import static org.testng.Assert.assertEquals;
@@ -60,6 +64,28 @@ public void testSimpleCompiletimeReal() {
                 "        testSuccess()");
     }
 
+    /** Java prints a float from 10^7 on and below 10^-3 with an exponent, which Jass does not parse. */
+    @Test
+    public void compiletimeRealsBecomeDecimalLiterals() throws IOException {
+        test().executeProg(true)
+            .runCompiletimeFunctions(true)
+            .lines("package Test",
+                "native testSuccess()",
+                "function compiletime(real r) returns real",
+                "    return r",
+                "@noinline function w(real x) returns real",
+                "    return x",
+                "constant big = compiletime(w(10000.) * w(1000.))",
+                "constant huge = compiletime(w(30000.) * w(100000.) * w(1000.))",
+                "constant small = compiletime(w(1.) / w(1024.))",
+                "init",
+                "    if not (big != w(10000.) * w(1000.)) and not (huge != w(30000.) * w(100000.) * w(1000.))",
+                "        and not (small != w(1.) / w(1024.))",
+                "        testSuccess()");
+        String jass = Files.toString(new File(TEST_OUTPUT_PATH + "CompiletimeTests_compiletimeRealsBecomeDecimalLiterals_no_opts.j"), Charsets.UTF_8);
+        assertFalse(java.util.regex.Pattern.compile("\\d[eE][-+]?\\d").matcher(jass).find(), "no exponent:\n" + jass);
+    }
+
     @Test
     public void testCompiletimeArray() {
         test().executeProg(true)
diff --git a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/InterpreterTests.java b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/InterpreterTests.java
index 4fd3d00a2..447c41ce3 100644
--- a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/InterpreterTests.java
+++ b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/InterpreterTests.java
@@ -408,8 +408,8 @@ public void derivedAndLessCommonConstants() {
 
     /**
      * Every expected value here was measured on the 3.0.0 client. A real past 2^31 is computed (w keeps it from
-     * folding): Jass reads a real literal past 2^31 wrapped (the literal 3000000000. is negative), which the
-     * interpreter does not model, and which is what R2S, R2SW and R2I of such a literal show.
+     * folding), as it was in the measurement: Jass reads such a literal wrapped as written (the literal
+     * 3000000000. is negative), which is why the Jass backend prints it otherwise.
      */
     @Test
     public void stringNativesAsMeasured() {
diff --git a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/LuaBackendAuditTests.java b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/LuaBackendAuditTests.java
index 2e385e589..94f235d8a 100644
--- a/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/LuaBackendAuditTests.java
+++ b/de.peeeq.wurstscript/src/test/java/tests/wurstscript/tests/LuaBackendAuditTests.java
@@ -7669,6 +7669,45 @@ public void r2iSaturatesInEveryRun() {
             "        testSuccess()");
     }
 
+    /**
+     * Jass reads a real literal's integer part as a 32-bit integer (measured on the 3.0.0 client: the
+     * literal 3000000000. is negative, 10000000000. reads as 1410065408), and truncates one past 2^24
+     * (16777219. reads as 16777218). So the Jass backend prints the float the literal means: its exact
+     * digits below 2^31, and above that a product of exact factors, which Jass multiplies exactly.
+     * The test Lua computes in double, where 16777219. is exact, so only the Jass shows that one.
+     */
+    @Test
+    public void largeRealLiteralsMeanTheSameFloatInEveryRun() throws IOException {
+        test().testLua(true).luaOnly(false).executeProg().lines(
+            "package Test",
+            "native testSuccess()",
+            "@extern native R2I(real r) returns int",
+            "@noinline function w(real x) returns real",
+            "    return x",
+            "function same(real a, real b) returns boolean",
+            "    return not (a != b)",
+            "init",
+            "    let big = w(30000.) * w(100000.)",
+            "    let tenTo10 = w(100000.) * w(100000.)",
+            "    if same(3000000000., big) and same(-3000000000., -big) and 3000000000. > 0.",
+            "        and same(w(6000000000.) / 3000000000., 2.) and same(w(1.) - 3000000000., 1. - big)",
+            "        and same(10000000000., tenTo10) and w(16777219.) > 0.",
+            "        and same(100000000000000000000., tenTo10 * tenTo10)",
+            // the stdlib's REAL_MAX: past the largest float, so infinity to a float, and finite to the test Lua
+            "        and 340282366920938000000000000000000000000. > w(3000.) * w(100000.) * tenTo10 * tenTo10 * tenTo10",
+            "        and -340282366920938000000000000000000000000. < -(w(3000.) * w(100000.) * tenTo10 * tenTo10 * tenTo10)",
+            "        and R2I(3000000000.) == 2147483647 and R2I(-3000000000.) == -2147483648",
+            "        testSuccess()");
+        String jass = compiledJass("largeRealLiteralsMeanTheSameFloatInEveryRun");
+        java.util.regex.Matcher literal = java.util.regex.Pattern.compile("(?<![\\w.])(\\d+)\\.").matcher(jass);
+        while (literal.find()) {
+            assertTrue("Jass reads " + literal.group() + " wrapped:\n" + jass,
+                new java.math.BigInteger(literal.group(1)).bitLength() <= 31);
+        }
+        assertFalse("Jass truncates 16777219.:\n" + jass, jass.contains("16777219."));
+        assertTrue("the float 16777219. means is printed:\n" + jass, jass.contains("16777220."));
+    }
+
     @Test
     public void realModIsModuloRealsFormulaInEveryRun() {
         test().testLua(true).luaOnly(false).withStdLib().executeProg().lines(
diff --git a/docs/WC3_RUNTIME.md b/docs/WC3_RUNTIME.md
index a48dbf8fd..7c1d2be6a 100644
--- a/docs/WC3_RUNTIME.md
+++ b/docs/WC3_RUNTIME.md
@@ -47,7 +47,7 @@ Every client simulates the same game from the same inputs; anything that makes t
 * **measured, 3.0.0** Jass literals and `S2R` are not correctly rounded and the two disagree: `0.1` reads one float high, `1.1` one float low, `S2R("100.0")` one above 100. Short exact binary fractions (`0.5`, `0.75`, `100.0`, `123456.78125`) read exactly; integer parts past 2^24 are truncated. This is why `SimpleRewrites.foldRealExactly` folds only exact literals and exact results.
 * **measured, 3.0.0** Lua reals have a 24-bit mantissa, not 53: `(2^24 + 1) - 2^24` is 0, the literal `16777217.` reads as 16777216, `0.9999999999999999` reads as exactly 1, and `0.7 + 0.1 + 0.1 + 0.1` computes to 1 - 2^-23. Literals are rounded to nearest and each arithmetic result is truncated, which neither double nor 32-bit float arithmetic reproduces. One `R2I` result is not evidence of a precision: `R2I(0.7 + 0.1 + 0.1 + 0.1)` is 0 for that reason, not because of doubles.
 * **measured, 3.0.0** `R2I` truncates, and saturates outside the 32-bit range, in Jass and in the game's Lua alike: a computed 5000000320 is 2147483647, its negative -2147483648, a computed 1e20 2147483647. Inside the range the arithmetic `x // 1 | 0` agrees with it; outside, the Lua lowering answers the bound itself (`LuaNativeLowering.lowerRealToInt`, `ExprTranslation.realToInt`). Integer arithmetic wraps at 32 bits on both (`2147483647 + 1` is -2147483648).
-* **measured, 3.0.0** `R2S` and `R2SW` print the whole integer part of a computed value (3e9 is `3000000000.000`, -3e9 `-3000000000.000`); a computed 5e9 prints as `5000000320.000`, which the interpreter does not model. Jass reads a real literal whose integer part passes 2^31 wrapped to 32 bits, signed: the literal `3000000000.` is negative and `10000000000.` reads as 1410065408. What `R2S`, `R2SW` and `R2I` of such a literal answer is that, not the native; the interpreter does not model it, and Lua reads the literal correctly.
+* **measured, 3.0.0** `R2S` and `R2SW` print the whole integer part of a computed value (3e9 is `3000000000.000`, -3e9 `-3000000000.000`); a computed 5e9 prints as `5000000320.000`, which the interpreter does not model. Jass reads a real literal whose integer part passes 2^31 wrapped to 32 bits, signed: the literal `3000000000.` is negative, `10000000000.` reads as 1410065408 and `1e20` written out as 1661992960, which is 10^20 modulo 2^32. Lua reads such a literal correctly. So the Jass backend prints the float a literal means wherever Jass would read it otherwise (`imtojass.ExprTranslation.realLiteral`): past 2^24 the float's own digits (`16777219.` becomes `16777220.`), and from 2^31 on a product of exact factors, its odd part and powers of two up to 2^30 (`3000000000.` becomes `5859375. * 512.`), which reads as the literal's float in the game. A literal past the largest float, such as the stdlib's `REAL_MAX` (2^128), is printed as the largest float: Jass has no product which gives infinity (2^150 compares below 3e38 and prints as `0.000`), and the largest float compares above 3e38 (its `R2S` is `inf`). A compile-time real is written as a plain decimal, since Jass parses no exponent.
 * **measured, 3.0.0** A real modulo is Blizzard.j's `ModuloReal` on Jass, `a - I2R(R2I(a / b)) * b` plus `b` when negative. The same formula in the game's Lua gives Jass's result for every dividend both read alike (54 of 54 probed); Lua's float `%` and `math.fmod` do not: `360. % 7.` is 3.0000153 with either and 3 in Jass, `7.5 % 360.` is 7.4999995 and 7.5, and `-7.5 % 2.5` is 2.4999993 with fmod and its correction and 0 in Jass. The integer `%` agrees with Jass's `ModuloInteger` for a positive divisor on every value probed, the 32-bit edges included. So a real modulo is that formula with `R2I` as Lua arithmetic, and only an integer one by a positive literal is `%` (`LuaNativeLowering`).
 * **measured, 3.0.0** A real division by zero stops the thread in Jass: `1. / 0.`, `-1. / 0.`, `0. / 0.`, `5. % 0.` and `ModuloReal(5., 0.)` all do. The game's Lua goes on: `1. / 0.` is 1.7014e38 (the largest float, not an infinity), `-1. / 0.` its negative, `0. / 0.` is 1, and the Lua real modulo by 0 answers a number. The interpreters stop as Jass does (`WurstOperator.divideReal`); the Lua backend adds no check, which would cost every real division.