Hi Adrien and Patrick,
 are your results for the gcc, mcode or llvm backend?

-Pascal

On Thu, Aug 6, 2015 at 3:09 PM, Lehmann, Patrick
<[email protected]> wrote:
> Hello Adrien,
>
> I'm one of the developers of the PoC-Library. => 
> https://github.com/VLSI-EDA/PoC
> This library comes with a set of testbenches and some Python tools to 
> abstract the simulation runs for different simulators.
>
> Currently we support:
> - iSim (14.7)
> - xSim (2014.x/2015.x)
> - GHDL (+GTKwave as viewer) and
> - vSim (QuestaSim - tested with 10.2c)
>
> I used PoC's simple "arith_prefix_and" module from 
> "src/arith/arith_prefix_and.vhdl". It builds a carry-chain based AND gate.
> The implementation used Xilinx's XORCY and MUXCY primitives.
>
> arith_prefix_and: Number of input bits = 8:
> iSim: 3.7574 sec
> xSim: 3.1700 sec
> vSim: 3.3036 sec
> ghdl: 1.0233 sec
>
> A second more expensive example is a wide-adder (arith_addw.vhdl). This adder 
> is designed for wide inputs. The testbench
> uses only a few bits to reduce runtime.
>
> arith_addw: Number of input bits = 9
> iSim: 92.7182 sec
> ghdl: 71.2711 sec
> vSim: 38.4598 sec
> xSim: 27.4511 sec
>
> So in my opinion: Yes, ghdl is mostly faster than iSim and xSim. Especially 
> the compiling part is much faster. While iSim/xSim and vSim search the
> files and check them, ghdl is already simulating :).
>
> Regards
>     Patrick
>
> -----------------------------------
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>
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>
> -----Original Message-----
> From: Ghdl-discuss [mailto:[email protected]] On Behalf Of Adrien 
> Prost-Boucle
> Sent: Thursday, August 06, 2015 8:26 PM
> To: GHDL discuss list <[email protected]>
> Subject: [Ghdl-discuss] Simulation speed compared to ISim, XSim: GHDL shines
>
> Hi everybody,
>
> I've launched simulation of more than 12 (personal) VHDL designs, with GHDL, 
> Xilinx's ISim from ISE Design Suite 2013.1 (full) and with Xilinx's XSim from 
> Vivado Design Suite 2015.1 (full).
>
> My initial goal was to find how much slower GHDL was compared to these 
> commercial simulators.
> Note: I compiled GHDL against gcc 4.9 with isl, cloog, lto. Not tested 
> without. My PC is 64 bits ArchLinux.
>
> I got a very nice surprise: all simulations were at least 2 times faster, 
> sometimes 4 times faster, than ISim and XSim.
>
> For a design with an extreme density of generate statements, with even some 
> recursive component instantiation, XSim did spend 10-15 minutes analyzing the 
> "data flow" during elaboration. The generated simulator did the simulation in 
> ~8 minutes.
> That design was elaborated in 20 seconds by GHDL, and the simulation took 
> only 3 minutes :-)
>
> The only step done slower by GHDL is analysis, because it is not 
> multithreaded. But that has a rather low importance.
>
> Anybody can do some comparison with Altera tool or Modelsim?
>
> Regards,
> Adrien
>
>
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