Proposal for a fix of issue #2044 and #2066

The solution is to separate the meaning of "," and "+" layout
file combination operators in strm2x tools:

* "+" does "blending"
* "," does merge

"+" has priority over "," ('a+b,c' acts as '(a+b),c').
NOTE: LEF caching only happens across "+".

src/buddies/src/bd/bdConverterMain.cc

@@ -43,8 +43,13 @@ int converter_main (int argc, char *argv[], const std::string &format)
   generic_reader_options.add_options (cmd);
 
   cmd << tl::arg ("input",  &infile,  "The input file (any format, may be gzip compressed)",
-                  "You can use '+' or ',' to supply multiple files which will be read after each other into the same layout. "
-                  "This provides some cheap, but risky way of merging files. Beware of cell name conflicts.")
+                  "Multiple files can be combined using '+' or ','. '+' will combine the files in 'blending' mode. "
+                  "In this mode it is possible to combine identically named cells into one cell for example. This mode "
+                  "needs to be used with care and there some constraints - e.g. the database unit of the involved "
+                  "layouts needs to be the same. When using ',' as a separator, blending is not used, but the layouts "
+                  "are merged by first creating two layouts and then combining them into one. This mode is more robust "
+                  "but does not allow cell merging. '+' combination has higher priority than ',' - i.e. 'a+b,c' is "
+                  "understood as '(a+b),c'.")
       << tl::arg ("output", &outfile, tl::sprintf ("The output file (%s format)", format))
     ;
 

src/buddies/src/bd/bdReaderOptions.cc

@@ -22,6 +22,8 @@
 
 #include "bdReaderOptions.h"
 #include "dbLoadLayoutOptions.h"
+#include "dbLayerMapping.h"
+#include "dbCellMapping.h"
 #include "tlCommandLineParser.h"
 
 #include "tlStream.h"
@@ -831,15 +833,28 @@ static std::string::size_type find_file_sep (const std::string &s, std::string::
   }
 }
 
-static std::vector<std::string> split_file_list (const std::string &infile)
+static std::vector<std::vector<std::string> > split_file_list (const std::string &infile)
 {
-  std::vector<std::string> files;
+  std::vector<std::vector<std::string> > files;
+  files.push_back (std::vector<std::string> ());
 
   size_t p = 0;
-  for (size_t pp = 0; (pp = find_file_sep (infile, p)) != std::string::npos; p = pp + 1) {
-    files.push_back (std::string (infile, p, pp - p));
+  while (true) {
+
+    size_t sep = find_file_sep (infile, p);
+    if (sep == std::string::npos) {
+      files.back ().push_back (std::string (infile, p));
+      return files;
+    }
+
+    files.back ().push_back (std::string (infile, p, sep - p));
+    if (infile [sep] == ',') {
+      files.push_back (std::vector<std::string> ());
+    }
+
+    p = sep + 1;
+
   }
-  files.push_back (std::string (infile, p));
 
   return files;
 }
@@ -850,16 +865,47 @@ void read_files (db::Layout &layout, const std::string &infile, const db::LoadLa
   //    db::LayoutLocker locker (&layout);
   //  but there are yet unknown side effects
 
-  //  enter a LEF caching context for chaining multiple DEF with the same LEF
-  db::LoadLayoutOptions local_options (options);
-  local_options.set_option_by_name ("lefdef_config.lef_context_enabled", true);
+  std::vector<std::vector<std::string> > files = split_file_list (infile);
 
-  std::vector<std::string> files = split_file_list (infile);
+  for (auto ff = files.begin (); ff != files.end (); ++ff) {
+
+    //  enter a LEF caching context for chaining multiple DEF with the same LEF
+    db::LoadLayoutOptions local_options (options);
+    local_options.set_option_by_name ("lefdef_config.lef_context_enabled", true);
+
+    db::Layout tmp;
+    db::Layout *ly = (ff == files.begin () ? &layout : &tmp);
+
+    for (auto f = ff->begin (); f != ff->end (); ++f) {
+      tl::InputStream stream (*f);
+      db::Reader reader (stream);
+      if (f != ff->begin ()) {
+        reader.set_expected_dbu (ly->dbu ());
+      }
+      reader.read (*ly, local_options);
+    }
+
+    if (ly != &layout) {
+
+      //  Move over cells from read layout to destination ("," separated blocks).
+      //  This path does not imply limitations in terms of DBU compatibility etc.
+
+      std::vector<db::cell_index_type> cells_target;
+      std::vector<db::cell_index_type> cells_source;
+      for (auto c = tmp.begin_top_down (); c != tmp.end_top_cells (); ++c) {
+        cells_source.push_back (*c);
+        cells_target.push_back (layout.add_cell (tmp.cell_name (*c)));
+      }
+
+      db::LayerMapping lm;
+      lm.create_full (layout, tmp);
+      db::CellMapping cm;
+      cm.create_multi_mapping_full (layout, cells_target, tmp, cells_source);
+
+      layout.move_tree_shapes (tmp, cm, lm);
+
+    }
 
-  for (std::vector<std::string>::const_iterator f = files.begin (); f != files.end (); ++f) {
-    tl::InputStream stream (*f);
-    db::Reader reader (stream);
-    reader.read (layout, local_options);
   }
 }
 

src/buddies/unit_tests/bdConverterTests.cc

@@ -483,7 +483,7 @@ TEST(10)
   std::string input;
   for (size_t i = 0; i < sizeof (def_files) / sizeof (def_files[0]); ++i) {
     if (i > 0) {
-      input += ",";
+      input += "+";
     }
     input += def_dir + "/" + def_files[i];
   }
@@ -510,3 +510,85 @@ TEST(10)
 
   db::compare_layouts (this, layout, input_au, db::WriteOAS);
 }
+
+//  Merging with +
+TEST(11_1)
+{
+  std::string input_dir = tl::testdata ();
+  input_dir += "/bd";
+
+  std::string input_au = input_dir + "/strm2oas_au_1.oas";
+  std::string input = input_dir + "/strm2oas_1.oas+" + input_dir + "/strm2oas_2.oas";
+
+  std::string output = this->tmp_file ("strm2oas_1.oas");
+  const char *argv[] = { "x",
+                         "--blend-mode=0",
+                         input.c_str (),
+                         output.c_str ()
+                       };
+
+  EXPECT_EQ (bd::converter_main (sizeof (argv) / sizeof (argv[0]), (char **) argv, bd::GenericWriterOptions::oasis_format_name), 0);
+
+  db::Layout layout;
+  {
+    tl::InputStream stream (output);
+    db::LoadLayoutOptions options;
+    db::Reader reader (stream);
+    reader.read (layout, options);
+  }
+
+  db::compare_layouts (this, layout, input_au, db::WriteOAS);
+}
+
+//  Merging with + not allowed on different DBUs
+TEST(11_2)
+{
+  std::string input_dir = tl::testdata ();
+  input_dir += "/bd";
+
+  std::string input_au = input_dir + "/strm2oas_au_1.oas";
+  std::string input = input_dir + "/strm2oas_1.oas+" + input_dir + "/strm2oas_2_10nm.oas";
+
+  std::string output = this->tmp_file ("strm2oas_1.oas");
+  const char *argv[] = { "x",
+                         "--blend-mode=0",
+                         input.c_str (),
+                         output.c_str ()
+                       };
+
+  try {
+    bd::converter_main (sizeof (argv) / sizeof (argv[0]), (char **) argv, bd::GenericWriterOptions::oasis_format_name);
+    EXPECT_EQ (1, 0);
+  } catch (tl::Exception &ex) {
+    EXPECT_EQ (ex.msg (), "Former and present database units are not compatible: 0.001 (former) vs. 0.01 (present)");
+  }
+}
+
+//  Merging with + not allowed on different DBUs
+TEST(11_3)
+{
+  std::string input_dir = tl::testdata ();
+  input_dir += "/bd";
+
+  std::string input_au = input_dir + "/strm2oas_au_3.oas";
+  std::string input = input_dir + "/strm2oas_1.oas," + input_dir + "/strm2oas_2_10nm.oas";
+
+  std::string output = this->tmp_file ("strm2oas_3.oas");
+  const char *argv[] = { "x",
+                         "--blend-mode=0",
+                         input.c_str (),
+                         output.c_str ()
+                       };
+
+  EXPECT_EQ (bd::converter_main (sizeof (argv) / sizeof (argv[0]), (char **) argv, bd::GenericWriterOptions::oasis_format_name), 0);
+
+  db::Layout layout;
+  {
+    tl::InputStream stream (output);
+    db::LoadLayoutOptions options;
+    db::Reader reader (stream);
+    reader.read (layout, options);
+  }
+
+  db::compare_layouts (this, layout, input_au, db::WriteOAS);
+}

src/db/db/dbReader.cc

@@ -82,7 +82,6 @@ ReaderBase::init (const db::LoadLayoutOptions &options)
   m_last_warning.clear ();
   m_warn_count_for_same_message = 0;
   m_first_warning = true;
-  m_expected_dbu = 0.0;
 }
 
 bool

src/db/db/dbReader.h

@@ -259,6 +259,22 @@ public:
     return mp_actual_reader->warnings_as_errors ();
   }
 
+  /**
+   *  @brief Sets the expected database unit (see ReaderBase)
+   */
+  void set_expected_dbu (double dbu)
+  {
+    return mp_actual_reader->set_expected_dbu (dbu);
+  }
+
+  /**
+   *  @brief Gets the expected database unit
+   */
+  double expected_dbu () const
+  {
+    return mp_actual_reader->expected_dbu ();
+  }
+
 private:
   ReaderBase *mp_actual_reader;
   tl::InputStream &m_stream;