Thanks for the overview.
I worked at Silicon Compilers from 1986 through the Mentor acquisition. We never considered our tools High Level Synthesis rather it was an environment that had:
* Many configurable logic blocks (SRAM, Datapath, Muliplier, IO Pads, Random Logic, ALU, etc.)
* Place & Route
* Floor Planning
* IR Drop Analysis
* Package editor
* Cycle based simulation
* Transistor-level static timing analysis
* Logic Synthesis
* Schematic Capture
The Genesil product line was dropped by Mentor, although the GDT product line along with Lsim lived a bit longer at Mentor.