Extremum Sum Potential

CMakeLists.txt

@@ -324,6 +324,10 @@ if(IPC_TOOLKIT_WITH_FILIB)
   target_link_libraries(ipc_toolkit PUBLIC filib::filib)
 endif()
 
+# Exact arithmetic (geogram's MultiPrecision PSM)
+include(geogram_multi_precision)
+target_link_libraries(ipc_toolkit PRIVATE geogram::multi_precision)
+
 # Block-accelerated Hessian assembly
 if(IPC_TOOLKIT_WITH_MESHFEM_SPARSE)
   include(meshfem_sparse)

cmake/find/FindSIMD.cmake

@@ -339,10 +339,10 @@ function(test_avx_availability)
 	elseif(CMAKE_CXX_COMPILER_ID MATCHES "Intel")
 		set(AVX_FLAGS "-xHost")
 	elseif(MSVC)
+		# /arch: is single-valued on MSVC: emitting both downgrades to AVX.
 		if(DETECTED_AVX_20)
 			SET(AVX_FLAGS "${AVX_FLAGS} /arch:AVX2")
-		endif()
-		if(DETECTED_AVX_10)
+		elseif(DETECTED_AVX_10)
 			SET(AVX_FLAGS "${AVX_FLAGS} /arch:AVX")
 		endif()
 	endif()

cmake/ipc_toolkit/ipc_toolkit_tests_data.cmake

@@ -30,7 +30,7 @@ else()
         SOURCE_DIR ${IPC_TOOLKIT_TESTS_DATA_DIR}
 
         GIT_REPOSITORY https://github.com/ipc-sim/ipc-toolkit-tests-data.git
-        GIT_TAG c7eba549d9a80d15569a013c473f0aff104ac44a
+        GIT_TAG 05696a21b8662f6cd12f8469eeb35ee9a5cc0493
 
         CONFIGURE_COMMAND ""
         BUILD_COMMAND ""

cmake/recipes/geogram_multi_precision.cmake

@@ -0,0 +1,90 @@
+# Geogram's MultiPrecision Pluggable Software Module
+# (https://github.com/BrunoLevy/geogram)
+# License: BSD 3-Clause License
+if(TARGET geogram::multi_precision)
+    return()
+endif()
+
+message(STATUS "Third-party: creating target 'geogram::multi_precision'")
+
+# The PSM is a standalone extract of geogram's exact arithmetic
+# (expansion_nt), so we download its release archive instead of building all
+# of geogram.
+set(GEOGRAM_MULTI_PRECISION_VERSION "1.10.1")
+
+include(CPM)
+CPMAddPackage(
+    NAME geogram_multi_precision
+    URL "https://github.com/BrunoLevy/geogram/releases/download/v${GEOGRAM_MULTI_PRECISION_VERSION}/MultiPrecision_psm_${GEOGRAM_MULTI_PRECISION_VERSION}.zip"
+    URL_HASH SHA256=1c4fa0ef6422547f08b11891a0f934b90a2bc91359dcfaeb89a490b3878c0e18
+    DOWNLOAD_ONLY YES
+)
+
+# The archive also ships an optional CGAL example that carries an LGPL-3.0
+# header. We never build it, so we delete it to keep the build tree free of
+# non-permissive files.
+file(REMOVE_RECURSE "${geogram_multi_precision_SOURCE_DIR}/CGAL")
+
+# Downstream projects (e.g., PolyFEM) may link their own full copy of geogram,
+# which defines the same GEO:: symbols as the PSM. Linking both would either
+# fail with duplicate symbols (static) or silently mix two geogram versions
+# (shared). Instead, we compile a copy of the PSM with its namespace renamed
+# from GEO to ipc_geogram, so the two can never collide. We write the copy to
+# the build tree so a shared CPM source cache is never modified.
+set(GEOGRAM_MULTI_PRECISION_DIR
+    "${CMAKE_CURRENT_BINARY_DIR}/geogram_multi_precision")
+foreach(file IN ITEMS MultiPrecision_psm.h MultiPrecision_psm.cpp)
+    file(READ "${geogram_multi_precision_SOURCE_DIR}/${file}" content)
+    # GEO only appears as the namespace name ("namespace GEO", "GEO::", and
+    # "using namespace GEO"). Matching it as a whole word leaves macros such
+    # as GEO_OS_WINDOWS untouched.
+    string(REGEX REPLACE "([^A-Za-z0-9_])GEO([^A-Za-z0-9_])"
+        "\\1ipc_geogram\\2" content "${content}")
+    # If a future PSM spells the namespace in a way the pattern above misses,
+    # the copy would silently keep GEO:: symbols and could clash again, so we
+    # fail loudly instead.
+    string(REGEX MATCH "(^|[^A-Za-z0-9_])GEO([^A-Za-z0-9_]|$)"
+        leftover "${content}")
+    if(leftover)
+        message(FATAL_ERROR
+            "Failed to rename namespace GEO to ipc_geogram in ${file}.")
+    endif()
+    file(WRITE "${GEOGRAM_MULTI_PRECISION_DIR}/tmp/${file}" "${content}")
+    # Copy only when the content changed, so we don't trigger rebuilds.
+    configure_file("${GEOGRAM_MULTI_PRECISION_DIR}/tmp/${file}"
+        "${GEOGRAM_MULTI_PRECISION_DIR}/${file}" COPYONLY)
+endforeach()
+
+add_library(geogram_multi_precision STATIC
+    "${GEOGRAM_MULTI_PRECISION_DIR}/MultiPrecision_psm.cpp"
+)
+add_library(geogram::multi_precision ALIAS geogram_multi_precision)
+
+target_include_directories(geogram_multi_precision SYSTEM PUBLIC
+    "$<BUILD_INTERFACE:${GEOGRAM_MULTI_PRECISION_DIR}>"
+)
+
+# The PSM header assumes geogram is a shared library unless told otherwise. On
+# MSVC that marks every symbol __declspec(dllimport), which breaks linking
+# against our static build, so we define GEO_STATIC_LIBS for the library and
+# everything that includes its header.
+target_compile_definitions(geogram_multi_precision PUBLIC GEO_STATIC_LIBS)
+
+target_compile_features(geogram_multi_precision PUBLIC cxx_std_17)
+set_target_properties(geogram_multi_precision PROPERTIES
+    POSITION_INDEPENDENT_CODE ON
+)
+
+# The expansion arithmetic relies on error-free transforms, which break if the
+# compiler fuses a*b+c into an FMA, so we turn off contraction. We also silence
+# the third-party warnings.
+if(MSVC)
+    target_compile_options(geogram_multi_precision PRIVATE "/fp:precise" "/w")
+else()
+    target_compile_options(geogram_multi_precision PRIVATE
+        "-ffp-contract=off" "-w"
+    )
+endif()
+
+# Folder name for IDE
+set_target_properties(geogram_multi_precision PROPERTIES FOLDER "ThirdParty")

docs/source/_static/graphviz/dependencies.dot

@@ -98,4 +98,6 @@ digraph "IPC Toolkit Dependencies" {
     // MeshFEMSparse -> Eigen3_Eigen
     "node17" -> "node9" [color = "#8FB976";];
     // MeshFEMSparse -> tbb
+    "node18" [label = "geogram_multi_precision\n(geogram::multi_precision)";shape = box;style = "rounded,filled";fillcolor = "#D5E8D4";color = "#8FB976";];
+    "node5" -> "node18" [color = "#BE6562";];
 }