Improve float to string conversion

classlib/src/main/java/org/teavm/classlib/impl/text/DoubleAnalyzer.java

@@ -130,6 +130,9 @@ public final class DoubleAnalyzer {
         if (decMantissa >= 1000000000000000000L) {
             decExponent++;
             decMantissa /= 10;
+        } else if (decMantissa < 100000000000000000L) {
+            decExponent--;
+            decMantissa *= 10;
         }
 
         result.mantissa = decMantissa;

classlib/src/main/java/org/teavm/classlib/impl/text/FloatAnalyzer.java

@@ -0,0 +1,174 @@
+/*
+ *  Copyright 2018 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.impl.text;
+
+import java.util.Arrays;
+
+public final class FloatAnalyzer {
+    public static final int PRECISION = 9;
+    public static final int MAX_POS = 100000000;
+
+    private static final int MAX_ABS_DEC_EXP = 50;
+    private static final int[] mantissa10Table = new int[MAX_ABS_DEC_EXP * 2];
+    private static final int[] exp10Table = new int[MAX_ABS_DEC_EXP * 2];
+
+    private FloatAnalyzer() {
+    }
+
+    static {
+        int decMantissaOne = 2000000000;
+
+        int mantissa = decMantissaOne;
+        int exponent = 127;
+
+        for (int i = 0; i < MAX_ABS_DEC_EXP; ++i) {
+            mantissa10Table[i + MAX_ABS_DEC_EXP] = Integer.divideUnsigned(mantissa, 20);
+            exp10Table[i + MAX_ABS_DEC_EXP] = exponent;
+
+            mantissa = Integer.divideUnsigned(mantissa, 10);
+            int remainder = Integer.remainderUnsigned(mantissa, 10);
+            while (mantissa <= decMantissaOne && (mantissa & (1 << 31)) == 0) {
+                mantissa <<= 1;
+                exponent++;
+                remainder <<= 1;
+            }
+            mantissa += remainder / 10;
+        }
+
+        int maxMantissa = Integer.MAX_VALUE / 10;
+        mantissa = decMantissaOne;
+        exponent = 127;
+        for (int i = 0; i < MAX_ABS_DEC_EXP; ++i) {
+            int nextMantissa = mantissa;
+            int shift = 0;
+            while (nextMantissa > maxMantissa) {
+                nextMantissa >>= 1;
+                shift++;
+                exponent--;
+            }
+
+            nextMantissa *= 10;
+            if (shift > 0) {
+                long shiftedOffPart = mantissa & ((1 << shift) - 1);
+                nextMantissa += (shiftedOffPart * 10) >> shift;
+            }
+            mantissa = nextMantissa;
+
+            mantissa10Table[MAX_ABS_DEC_EXP - i - 1] = Integer.divideUnsigned(mantissa, 20);
+            exp10Table[MAX_ABS_DEC_EXP - i - 1] = exponent;
+        }
+    }
+
+    public static void analyze(float d, Result result) {
+        int bits = Float.floatToIntBits(d);
+        result.sign = (bits & (1 << 31)) != 0;
+        int mantissa = bits & ((1 << 23) - 1);
+        int exponent = (bits >> 23) & ((1 << 8) - 1);
+        if (mantissa == 0 && exponent == 0) {
+            result.mantissa = 0;
+            result.exponent = 0;
+            return;
+        }
+
+        int errorShift = 0;
+        if (exponent == 0) {
+            mantissa <<= 1;
+            while ((mantissa & (1L << 23)) == 0) {
+                mantissa <<= 1;
+                exponent--;
+                ++errorShift;
+            }
+        } else {
+            mantissa |= 1 << 23;
+        }
+
+        int decExponent = Arrays.binarySearch(exp10Table, exponent);
+        if (decExponent < 0) {
+            decExponent = -decExponent - 2;
+        }
+        int binExponentCorrection = exponent - exp10Table[decExponent];
+        int mantissaShift = 9 + binExponentCorrection;
+
+        int decMantissa = (int) (((long) mantissa * mantissa10Table[decExponent]) >>> (32 - mantissaShift));
+        if (decMantissa >= 1000000000) {
+            ++decExponent;
+            binExponentCorrection = exponent - exp10Table[decExponent];
+            mantissaShift = 9 + binExponentCorrection;
+            decMantissa = (int) (((long) mantissa * mantissa10Table[decExponent]) >>> (32 - mantissaShift));
+        }
+
+        errorShift = 31 - mantissaShift - errorShift;
+        int error = errorShift >= 0
+                ? mantissa10Table[decExponent] >>> errorShift
+                : mantissa10Table[decExponent] << (-errorShift);
+        int upError = (error + 1) >> 1;
+        int downError = error >> 1;
+        if (mantissa == (1 << 22)) {
+            downError >>= 2;
+        }
+
+        int lowerPos = findLowerDistanceToZero(decMantissa, downError);
+        int upperPos = findUpperDistanceToZero(decMantissa, upError);
+        if (lowerPos > upperPos) {
+            decMantissa = (decMantissa / lowerPos) * lowerPos;
+        } else if (lowerPos < upperPos) {
+            decMantissa = (decMantissa / upperPos) * upperPos + upperPos;
+        } else {
+            decMantissa = ((decMantissa + upperPos / 2) / upperPos) * upperPos;
+        }
+
+        if (decMantissa >= 1000000000) {
+            decExponent++;
+            decMantissa /= 10;
+        } else if (decMantissa < 100000000) {
+            decExponent--;
+            decMantissa *= 10;
+        }
+
+        result.mantissa = decMantissa;
+        result.exponent = decExponent - MAX_ABS_DEC_EXP;
+    }
+
+    private static int findLowerDistanceToZero(int mantissa, int error) {
+        int pos = 10;
+        while (pos <= error) {
+            pos *= 10;
+        }
+        int mantissaRight = mantissa % pos;
+        if (mantissaRight >= error / 2) {
+            pos /= 10;
+        }
+        return pos;
+    }
+
+    private static int findUpperDistanceToZero(int mantissa, int error) {
+        int pos = 10;
+        while (pos <= error) {
+            pos *= 10;
+        }
+        int mantissaRight = mantissa % pos;
+        if (pos - mantissaRight > error / 2) {
+            pos /= 10;
+        }
+        return pos;
+    }
+
+    public static class Result {
+        public int mantissa;
+        public int exponent;
+        public boolean sign;
+    }
+}

classlib/src/main/java/org/teavm/classlib/java/lang/IntegerNativeGenerator.java

@@ -0,0 +1,43 @@
+/*
+ *  Copyright 2018 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.classlib.java.lang;
+
+import java.io.IOException;
+import org.teavm.backend.javascript.spi.Injector;
+import org.teavm.backend.javascript.spi.InjectorContext;
+import org.teavm.model.MethodReference;
+
+public class IntegerNativeGenerator implements Injector {
+    @Override
+    public void generate(InjectorContext context, MethodReference methodRef) throws IOException {
+        switch (methodRef.getName()) {
+            case "divideUnsigned":
+                context.getWriter().append("$rt_udiv(");
+                context.writeExpr(context.getArgument(0));
+                context.getWriter().append(",").ws();
+                context.writeExpr(context.getArgument(1));
+                context.getWriter().append(")");
+                break;
+            case "remainderUnsigned":
+                context.getWriter().append("$rt_umod(");
+                context.writeExpr(context.getArgument(0));
+                context.getWriter().append(",").ws();
+                context.writeExpr(context.getArgument(1));
+                context.getWriter().append(")");
+                break;
+        }
+    }
+}

classlib/src/main/java/org/teavm/classlib/java/lang/TAbstractStringBuilder.java

@@ -16,13 +16,12 @@
 package org.teavm.classlib.java.lang;
 
 import org.teavm.classlib.impl.text.DoubleAnalyzer;
+import org.teavm.classlib.impl.text.FloatAnalyzer;
 import org.teavm.classlib.java.io.TSerializable;
 import org.teavm.classlib.java.util.TArrays;
 
 class TAbstractStringBuilder extends TObject implements TSerializable, TCharSequence {
     static class Constants {
-        static float[] powersOfTen = { 1E1f, 1E2f, 1E4f, 1E8f, 1E16f, 1E32f };
-        static float[] negPowersOfTen = { 1E-1f, 1E-2f, 1E-4f, 1E-8f, 1E-16f, 1E-32f };
         static int[] intPowersOfTen = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000,
                 1000000000 };
         static long[] longPowersOfTen = { 1, 10, 100, 1000, 10000, 100000, 1000000, 10000000, 100000000,
@@ -30,12 +29,8 @@ class TAbstractStringBuilder extends TObject implements TSerializable, TCharSequ
                 1000000000000000L, 10000000000000000L, 100000000000000000L, 1000000000000000000L };
         static final long[] longLogPowersOfTen = { 1, 10, 100, 10000, 100000000, 10000000000000000L, };
 
-        static final int FLOAT_DECIMAL_PRECISION = 7;
-        static final float FLOAT_DECIMAL_FACTOR = 1E6f;
-        static final int FLOAT_MAX_EXPONENT = 38;
-        static final int FLOAT_MAX_POS = 1000000;
-
         static final DoubleAnalyzer.Result doubleAnalysisResult = new DoubleAnalyzer.Result();
+        static final FloatAnalyzer.Result floatAnalysisResult = new FloatAnalyzer.Result();
     }
 
     char[] buffer;
@@ -225,54 +220,21 @@ class TAbstractStringBuilder extends TObject implements TSerializable, TCharSequ
             buffer[target++] = 'y';
             return this;
         }
-        // Get absolute value
+
-        boolean negative = false;
+        FloatAnalyzer.Result number = Constants.floatAnalysisResult;
+        FloatAnalyzer.analyze(value, number);
+        int mantissa = number.mantissa;
+        int exp = number.exponent;
+        boolean negative = number.sign;
+        int intPart = 1;
         int sz = 1; // Decimal point always included
-        if (value < 0) {
+        if (negative) {
             negative = true;
-            value = -value;
             ++sz; // including '-' sign of mantissa
         }
 
-        // Split into decimal mantissa and decimal exponent
-        int exp = 0;
-        int mantissa = 0;
-        int intPart = 1;
-        int digits = 0;
-        if (value >= 1) {
-            int bit = 32;
-            exp = 0;
-            float digit = 1;
-            for (int i = Constants.powersOfTen.length - 1; i >= 0; --i) {
-                if ((exp | bit) <= Constants.FLOAT_MAX_EXPONENT && Constants.powersOfTen[i] * digit <= value) {
-                    digit *= Constants.powersOfTen[i];
-                    exp |= bit;
-                }
-                bit >>= 1;
-            }
-            mantissa = (int) ((value / (digit / Constants.FLOAT_DECIMAL_FACTOR)) + 0.5f);
-        } else {
-            int bit = 32;
-            exp = 0;
-            float digit = 1;
-            for (int i = Constants.negPowersOfTen.length - 1; i >= 0; --i) {
-                if ((exp | bit) <= 38 && Constants.negPowersOfTen[i] * digit * 10 > value) {
-                    digit *= Constants.negPowersOfTen[i];
-                    exp |= bit;
-                }
-                bit >>= 1;
-            }
-            exp = -exp;
-            mantissa = (int) (((value * Constants.FLOAT_MAX_POS) / digit) + 0.5f);
-
-            while (mantissa >= 10000000) {
-                mantissa /= 10;
-                exp--;
-            }
-        }
-
         // Remove trailing zeros
-        digits = Constants.FLOAT_DECIMAL_PRECISION;
+        int digits = FloatAnalyzer.PRECISION;
         int zeros = trailingDecimalZeros(mantissa);
         if (zeros > 0) {
             digits -= zeros;
@@ -312,7 +274,7 @@ class TAbstractStringBuilder extends TObject implements TSerializable, TCharSequ
         if (negative) {
             buffer[target++] = '-';
         }
-        int pos = Constants.FLOAT_MAX_POS;
+        int pos = FloatAnalyzer.MAX_POS;
         for (int i = 0; i < digits; ++i) {
             int intDigit;
             if (pos > 0) {

classlib/src/main/java/org/teavm/classlib/java/lang/TInteger.java

@@ -16,6 +16,7 @@
 package org.teavm.classlib.java.lang;
 
 import static org.teavm.classlib.impl.IntegerUtil.toUnsignedLogRadixString;
+import org.teavm.backend.javascript.spi.InjectedBy;
 
 public class TInteger extends TNumber implements TComparable<TInteger> {
     public static final int SIZE = 32;
@@ -353,4 +354,10 @@ public class TInteger extends TNumber implements TComparable<TInteger> {
     public static int signum(int i) {
         return (i >> 31) | (-i >>> 31);
     }
+
+    @InjectedBy(IntegerNativeGenerator.class)
+    public static native int divideUnsigned(int dividend, int divisor);
+
+    @InjectedBy(IntegerNativeGenerator.class)
+    public static native int remainderUnsigned(int dividend, int divisor);
 }

core/src/main/java/org/teavm/backend/c/CTarget.java

@@ -47,6 +47,7 @@ import org.teavm.backend.c.intrinsic.AllocatorIntrinsic;
 import org.teavm.backend.c.intrinsic.ExceptionHandlingIntrinsic;
 import org.teavm.backend.c.intrinsic.FunctionIntrinsic;
 import org.teavm.backend.c.intrinsic.GCIntrinsic;
+import org.teavm.backend.c.intrinsic.IntegerIntrinsic;
 import org.teavm.backend.c.intrinsic.Intrinsic;
 import org.teavm.backend.c.intrinsic.IntrinsicFactory;
 import org.teavm.backend.c.intrinsic.LongIntrinsic;
@@ -236,6 +237,7 @@ public class CTarget implements TeaVMTarget, TeaVMCHost {
         intrinsics.add(new FunctionIntrinsic(characteristics, exportDependencyListener.getResolvedMethods()));
         intrinsics.add(new RuntimeClassIntrinsic());
         intrinsics.add(new LongIntrinsic());
+        intrinsics.add(new IntegerIntrinsic());
 
         List<Generator> generators = new ArrayList<>();
         generators.add(new ArrayGenerator());

core/src/main/java/org/teavm/backend/c/intrinsic/IntegerIntrinsic.java

@@ -0,0 +1,55 @@
+/*
+ *  Copyright 2018 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.c.intrinsic;
+
+import org.teavm.ast.InvocationExpr;
+import org.teavm.model.MethodReference;
+
+public class IntegerIntrinsic implements Intrinsic {
+    @Override
+    public boolean canHandle(MethodReference method) {
+        if (!method.getClassName().equals(Integer.class.getName())) {
+            return false;
+        }
+        switch (method.getName()) {
+            case "divideUnsigned":
+            case "remainderUnsigned":
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    @Override
+    public void apply(IntrinsicContext context, InvocationExpr invocation) {
+        switch (invocation.getMethod().getName()) {
+            case "divideUnsigned":
+                writeBinary(context, invocation, "/");
+                break;
+            case "remainderUnsigned":
+                writeBinary(context, invocation, "%");
+                break;
+        }
+    }
+
+    private void writeBinary(IntrinsicContext context, InvocationExpr invocation, String operation) {
+        context.writer().print("((int32_t) ((uint32_t) ");
+        context.emit(invocation.getArguments().get(0));
+        context.writer().print(" " + operation + " (uint32_t) ");
+        context.emit(invocation.getArguments().get(1));
+        context.writer().print("))");
+    }
+}

core/src/main/java/org/teavm/backend/javascript/rendering/StatementRenderer.java

@@ -694,7 +694,12 @@ public class StatementRenderer implements ExprVisitor, StatementVisitor {
                     visitBinary(expr, "-", expr.getType() == OperationType.INT);
                     break;
                 case MULTIPLY:
+                    if (expr.getType() != OperationType.INT || isSmallInteger(expr.getFirstOperand())
+                            || isSmallInteger(expr.getSecondOperand())) {
                         visitBinary(expr, "*", expr.getType() == OperationType.INT);
+                    } else {
+                        visitBinaryFunction(expr, naming.getNameForFunction("$rt_imul"));
+                    }
                     break;
                 case DIVIDE:
                     visitBinary(expr, "/", expr.getType() == OperationType.INT);
@@ -759,6 +764,20 @@ public class StatementRenderer implements ExprVisitor, StatementVisitor {
         }
     }
 
+    private static boolean isSmallInteger(Expr expr) {
+        if (!(expr instanceof ConstantExpr)) {
+            return false;
+        }
+
+        Object constant = ((ConstantExpr) expr).getValue();
+        if (!(constant instanceof Integer)) {
+            return false;
+        }
+
+        int value = (Integer) constant;
+        return Math.abs(value) < (1 << 18);
+    }
+
     @Override
     public void visit(UnaryExpr expr) {
         try {

core/src/main/java/org/teavm/backend/wasm/WasmTarget.java

@@ -49,6 +49,7 @@ import org.teavm.backend.wasm.intrinsics.ExceptionHandlingIntrinsic;
 import org.teavm.backend.wasm.intrinsics.FloatIntrinsic;
 import org.teavm.backend.wasm.intrinsics.FunctionIntrinsic;
 import org.teavm.backend.wasm.intrinsics.GCIntrinsic;
+import org.teavm.backend.wasm.intrinsics.IntegerIntrinsic;
 import org.teavm.backend.wasm.intrinsics.LongIntrinsic;
 import org.teavm.backend.wasm.intrinsics.MutatorIntrinsic;
 import org.teavm.backend.wasm.intrinsics.ObjectIntrinsic;
@@ -345,6 +346,7 @@ public class WasmTarget implements TeaVMTarget, TeaVMWasmHost {
         context.addIntrinsic(new FloatIntrinsic());
         context.addIntrinsic(new DoubleIntrinsic());
         context.addIntrinsic(new LongIntrinsic());
+        context.addIntrinsic(new IntegerIntrinsic());
         context.addIntrinsic(new ObjectIntrinsic());
         context.addGenerator(new ArrayGenerator());
 

core/src/main/java/org/teavm/backend/wasm/intrinsics/IntegerIntrinsic.java

@@ -0,0 +1,56 @@
+/*
+ *  Copyright 2018 Alexey Andreev.
+ *
+ *  Licensed under the Apache License, Version 2.0 (the "License");
+ *  you may not use this file except in compliance with the License.
+ *  You may obtain a copy of the License at
+ *
+ *       http://www.apache.org/licenses/LICENSE-2.0
+ *
+ *  Unless required by applicable law or agreed to in writing, software
+ *  distributed under the License is distributed on an "AS IS" BASIS,
+ *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *  See the License for the specific language governing permissions and
+ *  limitations under the License.
+ */
+package org.teavm.backend.wasm.intrinsics;
+
+import org.teavm.ast.InvocationExpr;
+import org.teavm.backend.wasm.model.expression.WasmExpression;
+import org.teavm.backend.wasm.model.expression.WasmIntBinary;
+import org.teavm.backend.wasm.model.expression.WasmIntBinaryOperation;
+import org.teavm.backend.wasm.model.expression.WasmIntType;
+import org.teavm.model.MethodReference;
+
+public class IntegerIntrinsic implements WasmIntrinsic {
+    @Override
+    public boolean isApplicable(MethodReference methodReference) {
+        if (!methodReference.getClassName().equals(Integer.class.getName())) {
+            return false;
+        }
+
+        switch (methodReference.getName()) {
+            case "divideUnsigned":
+            case "remainderUnsigned":
+                return true;
+            default:
+                return false;
+        }
+    }
+
+    @Override
+    public WasmExpression apply(InvocationExpr invocation, WasmIntrinsicManager manager) {
+        switch (invocation.getMethod().getName()) {
+            case "divideUnsigned":
+                return new WasmIntBinary(WasmIntType.INT32, WasmIntBinaryOperation.DIV_UNSIGNED,
+                        manager.generate(invocation.getArguments().get(0)),
+                        manager.generate(invocation.getArguments().get(1)));
+            case "remainderUnsigned":
+                return new WasmIntBinary(WasmIntType.INT32, WasmIntBinaryOperation.REM_UNSIGNED,
+                        manager.generate(invocation.getArguments().get(0)),
+                        manager.generate(invocation.getArguments().get(1)));
+            default:
+                throw new AssertionError();
+        }
+    }
+}

core/src/main/resources/org/teavm/backend/javascript/runtime.js

@@ -623,3 +623,29 @@ function Long_toNumber(val) {
     }
     return 0x100000000 * hi + lo;
 }
+
+var $rt_imul = Math.imul || function(a, b) {
+    var ah = (a >>> 16) & 0xFFFF;
+    var al = a & 0xFFFF;
+    var bh = (b >>> 16) & 0xFFFF;
+    var bl = b & 0xFFFF;
+    return (al * bl + (((ah * bl + al * bh) << 16) >>> 0)) | 0;
+};
+var $rt_udiv = function(a, b) {
+    if (a < 0) {
+        a += 0x100000000;
+    }
+    if (b < 0) {
+        b += 0x100000000;
+    }
+    return (a / b) | 0;
+};
+var $rt_umod = function(a, b) {
+    if (a < 0) {
+        a += 0x100000000;
+    }
+    if (b < 0) {
+        b += 0x100000000;
+    }
+    return (a % b) | 0;
+};

tests/src/test/java/org/teavm/classlib/java/lang/StringBuilderTest.java

@@ -164,8 +164,8 @@ public class StringBuilderTest {
     @Test
     public void minFloatAppended() {
         StringBuilder sb = new StringBuilder();
-        sb.append(1.175494E-38f);
+        sb.append(1.17549E-38f);
-        assertEquals("1.175494E-38", sb.toString());
+        assertEquals("1.17549E-38", sb.toString());
     }
 
     @Test