From 979e7b8709c77e30a6b01345e6541cbb7c03e7a8 Mon Sep 17 00:00:00 2001
From: whitequark <whitequark@whitequark.org>
Date: Wed, 10 Mar 2021 06:18:42 +0000
Subject: [PATCH] Only depend on Abseil in threaded builds.

Abseil has a hard dependency on threads (not just in the build system
but in many places in the base libraries), so there is no way to use
it on WASI at the moment.
---
 CMakeLists.txt    | 6 ++++--
 common/router2.cc | 6 ++++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 2c8e38a8..b3df6a58 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -274,8 +274,10 @@ foreach (family ${ARCH})
     # Include the family-specific CMakeFile
     include(${family}/family.cmake)
     foreach (target ${family_targets})
-        target_link_libraries(${target} PRIVATE absl::flat_hash_map)
-        target_link_libraries(${target} PRIVATE absl::flat_hash_set)
+        if (USE_THREADS)
+            target_link_libraries(${target} PRIVATE absl::flat_hash_map)
+            target_link_libraries(${target} PRIVATE absl::flat_hash_set)
+        endif()
 
         # Include family-specific source files to all family targets and set defines appropriately
         target_include_directories(${target} PRIVATE ${family}/ ${CMAKE_CURRENT_BINARY_DIR}/generated/)
diff --git a/common/router2.cc b/common/router2.cc
index 0a3a4e94..b145db81 100644
--- a/common/router2.cc
+++ b/common/router2.cc
@@ -27,7 +27,9 @@
  */
 
 #include "router2.h"
+#if !defined(NPNR_DISABLE_THREADS)
 #include <absl/container/flat_hash_map.h>
+#endif
 #include <algorithm>
 #include <boost/container/flat_map.hpp>
 #include <chrono>
@@ -191,7 +193,11 @@ struct Router2
         }
     }
 
+#if defined(NPNR_DISABLE_THREADS)
+    std::unordered_map<WireId, int> wire_to_idx;
+#else
     absl::flat_hash_map<WireId, int> wire_to_idx;
+#endif
     std::vector<PerWireData> flat_wires;
 
     PerWireData &wire_data(WireId w) { return flat_wires[wire_to_idx.at(w)]; }