abc9_ops: update docs

diff --git a/passes/techmap/abc9_ops.cc b/passes/techmap/abc9_ops.cc
index 5521bdf621264f5522b8bcb7ee6d015b2014b0fc..a87a94b1d85bd3936124231e40420228b306663b 100644 (file)
--- a/passes/techmap/abc9_ops.cc
+++ b/passes/techmap/abc9_ops.cc
@@ -1516,29 +1516,28 @@ struct Abc9OpsPass : public Pass {
                log("        derive all used (* abc9_box *) requiring bypass, or (* abc9_flop *) (if\n");
                log("        -dff option) whitebox modules. with (* abc9_box *) modules, bypassing is\n");
                log("        necessary if sequential elements (e.g. $dff, $mem, etc.) are discovered\n");
-               log("        inside, to ensure that any combinatorial paths are correctly captured.\n");
+               log("        inside to ensure that any combinatorial paths are correctly captured.\n");
                log("        with (* abc9_flop *) modules, only those containing $dff/$_DFF_[NP]_\n");
                log("        cells with zero initial state -- due to an ABC limitation -- will be\n");
-               log("        derived. for such derived modules, add a rule inside the '$abc9_unmap'\n");
-               log("        design that can map a cell instantiating a derived module back to the\n");
-               log("        original cell with parameters.\n");
+               log("        derived.\n");
                log("\n");
                log("    -prep_bypass\n");
                log("        create techmap rules in the '$abc9_map' and '$abc9_unmap' designs for\n");
                log("        bypassing sequential (* abc9_box *) modules using a combinatorial box\n");
-               log("        (named *_$abc9_byp) that has inherited all its $specify2 (simple path)\n");
-               log("        cells.\n");
+               log("        (named *_$abc9_byp). this bypass box will only contain ports that are\n");
+               log("        referenced by a simple path declaration ($specify2 cell) inside a\n");
+               log("        specify block.\n");
                log("\n");
                log("    -prep_dff\n");
                log("        select all (* abc9_flop *) modules instantiated in the design and store\n");
                log("        in the named selection '$abc9_flops'.\n");
                log("\n");
                log("    -prep_dff_submod\n");
-               log("        within (* abc9_flop *) modules, attach dummy buffers to all ports and move\n");
-               log("        all $specify3/$specrule cells that share a 'DST' port with the $_DFF_[NP]_.Q\n");
-               log("        port from this 'Q' port to the DFF's 'D' port. this is to ensure that all\n");
-               log("        module ports will exist in any submodule, and prepare such specify cells to\n");
-               log("        be moved within.\n");
+               log("        within (* abc9_flop *) modules, rewrite all edge-sensitive path\n");
+               log("        declarations and $setup() timing checks ($specify3 and $specrule cells)\n");
+               log("        that share a 'DST' port with the $_DFF_[NP]_.Q port from this 'Q' port to\n");
+               log("        the DFF's 'D' port. this is to prepare such specify cells to be moved\n");
+               log("        into the flop box.\n");
                log("\n");
                log("    -prep_dff_unmap\n");
                log("        populate the '$abc9_unmap' design with techmap rules for mapping *_$abc9_flop\n");