Add autodetection of integer model

Author: filikat

cmake/sources.cmake

@@ -243,12 +243,14 @@ set(factor_highs_headers
     ipm/hipo/factorhighs/Timing.h)
 
 set(hipo_util_sources
+    ipm/hipo/auxiliary/AutoDetect.cpp
     ipm/hipo/auxiliary/Auxiliary.cpp
     ipm/hipo/auxiliary/KrylovMethods.cpp
     ipm/hipo/auxiliary/Log.cpp
     ipm/hipo/auxiliary/VectorOperations.cpp)
 
 set(hipo_util_headers
+    ipm/hipo/auxiliary/AutoDetect.h
     ipm/hipo/auxiliary/Auxiliary.h
     ipm/hipo/auxiliary/IntConfig.h
     ipm/hipo/auxiliary/KrylovMethods.h

highs/io/HighsIO.cpp

@@ -14,6 +14,7 @@
 #include <cstdarg>
 #include <cstdio>
 
+#include "ipm/hipo/auxiliary/AutoDetect.h"
 #include "lp_data/HighsLp.h"
 #include "lp_data/HighsOptions.h"
 
@@ -34,6 +35,9 @@ void highsLogHeader(const HighsLogOptions& log_options,
 #else
   highsLogUser(log_options, HighsLogType::kInfo, "Using blas: unknown\n");
 #endif
+
+  highsLogUser(log_options, HighsLogType::kInfo, "Blas integer model: %s\n",
+               hipo::getBlasIntegerModelString().c_str());
 #endif
 }
 

highs/ipm/hipo/auxiliary/AutoDetect.cpp

@@ -0,0 +1,66 @@
+#include "AutoDetect.h"
+
+namespace hipo {
+
+extern "C" {
+int64_t cblas_isamax(const int64_t N, const float* X, const int64_t incX);
+}
+BlasIntegerModel getBlasIntegerModel() {
+  // Test if BLAS uses 32-bit integers (LP64) or 64-bit integers (ILP64) at
+  // runtime. Inspired by libblastrampoline's autodetection.c
+
+  // Even though isamax is declared to use 64-bit integers, it may actually
+  // use 32-bit integers. If a negative number is passed as first argument,
+  // isamax returns 0. If the correct value of 3 is passed, it returns 2
+  // instead.
+
+  static BlasIntegerModel blas_model = BlasIntegerModel::not_set;
+
+  if (blas_model == BlasIntegerModel::not_set) {
+    // This is a very negative 64-bit number, but it is just 3 if only the lower
+    // 32 bits are used.
+    const int64_t n = 0xffffffff00000003;
+
+    const float X[3] = {1.0f, 2.0f, 3.0f};
+
+    const int64_t incx = 1;
+    int64_t max_idx = cblas_isamax(n, X, incx);
+
+    // Ignore potential upper 32 bits of the result
+    max_idx = max_idx & 0xffffffff;
+
+    if (max_idx == 0) {
+      // isamax read negative n and returned 0, so it's using ilp64
+      blas_model = BlasIntegerModel::ilp64;
+
+    } else if (max_idx == 2) {
+      // isamax read correct n and returned 2, so it's using lp64
+      blas_model = BlasIntegerModel::lp64;
+
+    } else {
+      // something went wrong
+      blas_model = BlasIntegerModel::unknown;
+    }
+  }
+
+  return blas_model;
+}
+std::string getBlasIntegerModelString() {
+  BlasIntegerModel blas_model = getBlasIntegerModel();
+
+  switch (blas_model) {
+    case BlasIntegerModel::not_set:
+      return "Not set";
+
+    case BlasIntegerModel::unknown:
+      return "Unknown";
+
+    case BlasIntegerModel::lp64:
+      return "LP64";
+
+    case BlasIntegerModel::ilp64:
+      return "ILP64";
+  }
+}
+
+}  // namespace hipo

highs/ipm/hipo/auxiliary/AutoDetect.h

@@ -0,0 +1,16 @@
+#ifndef HIPO_AUTO_DETECT_H
+#define HIPO_AUTO_DETECT_H
+
+#include <string>
+
+namespace hipo {
+// Detect BLAS integer model
+enum class BlasIntegerModel { not_set, unknown, lp64, ilp64 };
+BlasIntegerModel getBlasIntegerModel();
+std::string getBlasIntegerModelString();
+
+
+
+}  // namespace hipo
+
+#endif