Optimize access to Loc.filename

compiler/src/dmd/e2ir.d

@@ -6953,10 +6953,11 @@ elem* buildArrayIndexError(ref IRState irs, Loc loc, elem* index, elem* length)
 /// Returns: elem representing a C-string (char*) to the filename
 elem* locToFileElem(const ref IRState irs, Loc loc) {
     elem* efile;
-    if (loc.filename)
+
+    if (auto fname = loc.filename)
     {
-        const len = strlen(loc.filename);
+        const len = strlen(fname);
-        Symbol* s = toStringSymbol(loc.filename, len, 1);
+        Symbol* s = toStringSymbol(fname, len, 1);
         efile = el_ptr(s);
     }
     else

compiler/src/dmd/location.d

@@ -95,7 +95,19 @@ nothrow:
      */
     extern (C++) const(char)* filename() const @nogc
     {
-        return SourceLoc(this).filename.ptr; // _filename;
+        if (this.index == 0)
+            return null;
+
+        const i = fileTableIndex(this.index);
+        if (locFileTable[i].substitutions.length > 0)
+        {
+            const si = locFileTable[i].getSubstitutionIndex(this.index - locFileTable[i].startIndex);
+            const fname = locFileTable[i].substitutions[si].filename;
+            if (fname.length > 0)
+                return fname.ptr;
+        }
+
+        return locFileTable[i].filename.ptr;
     }
 
     extern (C++) const(char)* toChars(
@@ -379,7 +391,23 @@ struct BaseLoc
         if (substitutions.length == 0)
             return loc;
 
-        const offset = loc.fileOffset;
+        const i = getSubstitutionIndex(loc.fileOffset);
+        if (substitutions[i].filename.length > 0)
+            loc.filename = substitutions[i].filename;
+        loc.linnum += substitutions[i].startLine;
+        return loc;
+    }
+
+    /// Resolve an offset into this file to a filename + line + column
+    private SourceLoc getSourceLoc(uint offset) @nogc
+    {
+        const i = getLineIndex(offset);
+        const sl = SourceLoc(filename, cast(int) (i + startLine), cast(int) (1 + offset - lines[i]), offset);
+        return substitute(sl);
+    }
+
+    private size_t getSubstitutionIndex(uint offset) @nogc
+    {
         size_t lo = 0;
         size_t hi = substitutions.length + -1;
         size_t mid = 0;
@@ -389,12 +417,7 @@ struct BaseLoc
             if (substitutions[mid].startIndex <= offset)
             {
                 if (mid == substitutions.length - 1 || substitutions[mid + 1].startIndex > offset)
-                {
+                    return mid;
-                    if (substitutions[mid].filename.length > 0)
-                        loc.filename = substitutions[mid].filename;
-                    loc.linnum += substitutions[mid].startLine;
-                    return loc;
-                }
 
                 lo = mid + 1;
             }
@@ -406,14 +429,6 @@ struct BaseLoc
         assert(0);
     }
 
-    /// Resolve an offset into this file to a filename + line + column
-    private SourceLoc getSourceLoc(uint offset) @nogc
-    {
-        const i = getLineIndex(offset);
-        const sl = SourceLoc(filename, cast(int) (i + startLine), cast(int) (1 + offset - lines[i]), offset);
-        return substitute(sl);
-    }
-
     /// Binary search the index in `this.lines` corresponding to `offset`
     private size_t getLineIndex(uint offset) @nogc
     {

compiler/src/dmd/timetrace.d

@@ -382,13 +382,14 @@ private struct TimeTraceProfiler
 
         void writeLocation(Loc loc)
         {
-            if (loc.filename())
+            SourceLoc sl = SourceLoc(loc);
+            if (sl.filename.length > 0)
             {
-                writeEscapeJSONString(buf, loc.filename().toDString());
+                writeEscapeJSONString(buf, sl.filename);
-                if (loc.linnum())
+                if (sl.line)
                 {
                     buf.writeByte(':');
-                    buf.print(loc.linnum());
+                    buf.print(sl.line);
                 }
             }
             else