Vlog-Hammer -- A Verilog Synthesis Regression Test
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This test generates a large number of small Verilog modules and checks
different synthesis tools for equivialence. The following tools are
supported:

	Yosys (no specific version)
	Xilinx Vivado WebPack (2018.3)
	Xilinx ISE (XST) WebPack (14.7)
	Altera Quartus II Web Edition (17.0)
	Cadence Conformal LEC (8.1)
	Synopsys Design Compiler (C-2009.06)

Note: Cadence Conformal and Synopsys Design Compiler are disabled by
default. Add "lec" and "dc" to SYN_LIST in the Makefile to enable them.

The built-in SAT-solver in Yosys is used for formal equivalence checking.
The test cases that fail this check and the found example patterns are
then tried using the following Verilog simulators:

	Xilinx ISIM (from Xilinx ISE 14.7)
	Xilinx XSIM (from Xilinx Vivado 2018.3)
	Modelsim 10.5b (from Quartus 17.0)
	Icarus Verilog (no specific version)
	Verilator (no specific version)
	Yosys (no specific version)

Note: XST and ISIM is disabled by default as Xilinx won't fix bugs in those
tools anymore.

Instructions:

 * Install Yosys (yosys), Icarus Verilog (iverilog) and Verilator
 * Install Xilinx Vivado WebPack 2018.3 in /opt/Xilinx/Vivado/2018.3/
 * Install Altera Quartus Web Edition 17.0 in /opt/intelFPGA_lite/17.0

 * Generate Test Cases:

	make purge generate

 * Synthesize Test Cases:

	make -j4 -l8 syn

 * Check Individual Synthesis Results vs. Yosys RTL:

	make -j4 -l8 check

 * Generate Reports on Failed Test Cases:

	make -j4 -l8 report