Wasm: fix bugs in DWARF generator, emit DW_LNE_end_sequence after each function

core/src/main/java/org/teavm/backend/wasm/dwarf/DwarfConstants.java

@@ -55,6 +55,8 @@ public final class DwarfConstants {
     public static final int DW_LNS_SET_EPILOGUE_BEGIN = 0x0B;
     public static final int DW_LNS_SET_ISA = 0x0C;
 
+    public static final int DW_LNE_END_SEQUENCE = 0x01;
+
     private DwarfConstants() {
     }
 }

core/src/main/java/org/teavm/backend/wasm/generate/DwarfGenerator.java

@@ -122,6 +122,10 @@ public class DwarfGenerator {
         lines.lineNumber(address, fileName, lineNumber);
     }
 
+    public void endLineNumberSequence(int address) {
+        lines.endLineNumberSequence(address);
+    }
+
     public DwarfInfoWriter getInfoWriter() {
         return infoWriter;
     }

core/src/main/java/org/teavm/backend/wasm/generate/DwarfLinesGenerator.java

@@ -19,6 +19,7 @@ import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_FORM_DATA2;
 import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_FORM_LINE_STRP;
 import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_LNCT_DIRECTORY_INDEX;
 import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_LNCT_PATH;
+import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_LNE_END_SEQUENCE;
 import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_LNS_ADVANCE_LINE;
 import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_LNS_ADVANCE_PC;
 import static org.teavm.backend.wasm.dwarf.DwarfConstants.DW_LNS_COPY;
@@ -171,7 +172,28 @@ class DwarfLinesGenerator {
             instructionsBlob.writeLEB(fileRef);
             changed = true;
         }
-        if (address != this.address || line != this.line) {
+        if (advanceTo(address, line)) {
+            changed = true;
+        }
+        if (changed) {
+            instructionsBlob.writeByte(DW_LNS_COPY);
+        }
+    }
+
+    void endLineNumberSequence(int address) {
+        advanceTo(address, line);
+        instructionsBlob.writeByte(0);
+        instructionsBlob.writeByte(1);
+        instructionsBlob.writeByte(DW_LNE_END_SEQUENCE);
+        this.line = 1;
+        this.file = 0;
+        this.address = 0;
+    }
+
+    private boolean advanceTo(int address, int line) {
+        if (address == this.address && line == this.line) {
+            return false;
+        }
         int lineIncrement = line - this.line;
         int addressIncrement = address - this.address;
         if (!tryEmitSpecial(lineIncrement, addressIncrement)) {
@@ -181,16 +203,12 @@ class DwarfLinesGenerator {
             }
             if (addressIncrement != 0) {
                 instructionsBlob.writeByte(DW_LNS_ADVANCE_PC);
-                    instructionsBlob.writeSLEB(addressIncrement);
+                instructionsBlob.writeLEB(addressIncrement);
             }
         }
-            changed = true;
         this.line = line;
         this.address = address;
-        }
+        return true;
-        if (changed) {
-            instructionsBlob.writeByte(DW_LNS_COPY);
-        }
     }
 
     private boolean tryEmitSpecial(int lineIncrement, int addressIncrement) {

core/src/main/java/org/teavm/backend/wasm/render/WasmBinaryRenderer.java

@@ -275,8 +275,8 @@ public class WasmBinaryRenderer {
 
         section.writeLEB(functions.size());
         for (var function : functions) {
-            var body = renderFunction(function, section.getPosition());
+            var body = renderFunction(function, section.getPosition() + 4);
-            section.writeLEB(body.length);
+            section.writeLEB4(body.length);
             section.writeBytes(body);
         }
 
@@ -322,12 +322,16 @@ public class WasmBinaryRenderer {
         for (WasmExpression part : function.getBody()) {
             part.acceptVisitor(visitor);
         }
-        code.writeByte(0x0B);
 
+        if (dwarfGenerator != null) {
+            dwarfGenerator.endLineNumberSequence(offset + code.getPosition());
+        }
+
+        code.writeByte(0x0B);
         if (dwarfGenerator != null && function.getName() != null) {
             infoWriter.tag(getMethodAbbrev());
             infoWriter.writeInt(dwarfGenerator.strings.stringRef(function.getName()));
-            infoWriter.writeInt(offset);
+            infoWriter.writeInt(offset - 4);
             infoWriter.writeInt(offset + code.getPosition());
             infoWriter.emptyTag();
         }

core/src/main/java/org/teavm/backend/wasm/render/WasmBinaryWriter.java

@@ -92,6 +92,16 @@ public class WasmBinaryWriter {
         }
     }
 
+    public void writeLEB4(int v) {
+        alloc(4);
+        for (int i = 0; i < 3; ++i) {
+            int digit = v & 0x7F;
+            data[pointer++] = (byte) (digit | 0x80);
+            v >>>= 7;
+        }
+        data[pointer++] = (byte) (v & 0x7F);
+    }
+
     public void writeSignedLEB(int v) {
         alloc(5);
         while (true) {