Added an option to disable the LUT mapping cache

Signed-off-by: Maciej Kurc <mkurc@antmicro.com>

fpga_interchange/arch.cc

@@ -814,10 +814,12 @@ bool Arch::place()
     archInfoToAttributes();
 
     // Print site LUT mapping caching stats
+    if (!getCtx()->arch_args.disable_lut_mapping_cache) {
         log_info("Site LUT mapping cache stats:\n");
         log_info("    miss ratio: %.1f%%\n", getCtx()->site_lut_mapping_cache.getMissRatio() * 100.0f);
         log_info("    peak size : %zuMB (%zu items)\n", getCtx()->site_lut_mapping_cache.getSizeMB(),
                  getCtx()->site_lut_mapping_cache.getCount());
+    }
 
     getCtx()->check();
 

fpga_interchange/arch.h

@@ -39,9 +39,9 @@
 #include "dedicated_interconnect.h"
 #include "lookahead.h"
 #include "pseudo_pip_model.h"
+#include "site_lut_mapping_cache.h"
 #include "site_router.h"
 #include "site_routing_cache.h"
-#include "site_lut_mapping_cache.h"
 
 NEXTPNR_NAMESPACE_BEGIN
 
@@ -51,6 +51,7 @@ struct ArchArgs
     std::string package;
     bool rebuild_lookahead;
     bool dont_write_lookahead;
+    bool disable_lut_mapping_cache;
 };
 
 struct ArchRanges

fpga_interchange/main.cc

@@ -57,6 +57,7 @@ po::options_description FpgaInterchangeCommandHandler::getArchOptions()
     specific.add_options()("package", po::value<std::string>(), "Package to use");
     specific.add_options()("rebuild-lookahead", "Ignore lookahead cache and rebuild");
     specific.add_options()("dont-write-lookahead", "Don't write the lookahead file");
+    specific.add_options()("disable-lut-mapping-cache", "Disable caching of LUT mapping solutions in site router");
 
     return specific;
 }
@@ -76,6 +77,7 @@ std::unique_ptr<Context> FpgaInterchangeCommandHandler::createContext(dict<std::
     ArchArgs chipArgs;
     chipArgs.rebuild_lookahead = vm.count("rebuild_lookahead") != 0;
     chipArgs.dont_write_lookahead = vm.count("dont_write_lookahead") != 0;
+    chipArgs.disable_lut_mapping_cache = vm.count("disable-lut-mapping-cache") != 0;
 
     if (!vm.count("chipdb")) {
         log_error("chip database binary must be provided\n");

fpga_interchange/site_lut_mapping_cache.h

@@ -20,8 +20,8 @@
 #ifndef SITE_LUT_MAPPING_CACHE_H
 #define SITE_LUT_MAPPING_CACHE_H
 
-#include "nextpnr_namespaces.h"
 #include "idstring.h"
+#include "nextpnr_namespaces.h"
 #include "site_arch.h"
 
 NEXTPNR_NAMESPACE_BEGIN

fpga_interchange/site_router.cc

@@ -1041,13 +1041,14 @@ static void apply_routing(Context *ctx, const SiteArch &site_arch, pool<std::pai
 static bool map_luts_in_site(const SiteInformation &site_info, pool<std::pair<IdString, IdString>> *blocked_wires)
 {
     const Context *ctx = site_info.ctx;
+    bool enable_cache = !ctx->arch_args.disable_lut_mapping_cache;
 
     // Create a site LUT mapping key
     SiteLutMappingKey key = SiteLutMappingKey::create(site_info);
 
     // Get the solution from cache. If not found then compute it
     SiteLutMappingResult lutMapping;
-    if (!ctx->site_lut_mapping_cache.get(key, &lutMapping)) {
+    if (!enable_cache || !ctx->site_lut_mapping_cache.get(key, &lutMapping)) {
 
         const std::vector<LutElement> &lut_elements = ctx->lut_elements.at(site_info.tile_type);
         std::vector<LutMapper> lut_mappers;
@@ -1090,8 +1091,10 @@ static bool map_luts_in_site(const SiteInformation &site_info, pool<std::pair<Id
         lutMapping.isValid = res;
 
         // Add the solution to the cache
+        if (enable_cache) {
             ctx->site_lut_mapping_cache.add(key, lutMapping);
         }
+    }
 
     // Apply the solution if valid
     if (lutMapping.isValid) {