Add std/vir::transform with simd execution policy

ChangeLog:

	* Makefile: Add transform.cc to ext tests.
	* testsuite/tests/transform.cc: New test.
	* vir/simd_execution.h (simd_load_and_invoke): New overloads.
	(detail::prologue): New; generalized from for_each prologue.
	(simd_transform_prologue): New.
	(simd_transform_epilogue): New.
	(vir::for_each): Replace prologue code with detail::prologue.
	(vir::transform): New.
	(std::transform): New.
	* vir/simdize.h (simd_tuple): Add memory_alignment member.
	* vir/test.cpp: Add simple vir::transform tests.

Makefile

@@ -25,6 +25,7 @@ $(testdirext)/Makefile: $(srcdir)/testsuite/generate_makefile.sh Makefile
 	@echo "Generating simd testsuite subdirs and Makefiles ..."
 	@mkdir -p $(testdirext)
 	@echo for_each.cc > $(testdirext)/testsuite_files_simd
+	@echo transform.cc >> $(testdirext)/testsuite_files_simd
 	@cd $(testdirext) && ../generate_makefile.sh --destination="." --sim="$(sim)" --testflags="-O2 $(testflags)" $(CXX) -std=gnu++2a $(CXXFLAGS) -DVIR_SIMD_TS_DROPIN
 
 testsuite-%: testsuite/build-%/Makefile

testsuite/tests/transform.cc

@@ -0,0 +1,70 @@
+// expensive: * [1-9] * *
+#include "bits/main.h"
+
+#include <numeric>
+#include <vector>
+
+#include <vir/simd_iota.h>
+#include <vir/simd_execution.h>
+
+template <typename T>
+  struct Point2D
+  {
+    T x,y;
+  };
+
+template <typename V>
+  void
+  test()
+  {
+#if VIR_HAVE_SIMD_EXECUTION
+    constexpr int N = V::size();
+    using T = typename V::value_type;
+    std::vector<T> data0, data1;
+    std::vector<int> dataInt;
+    std::vector<Point2D<T>> data2;
+    data0.resize(N * 16 - 1);
+    data1.resize(N * 16 - 1);
+    dataInt.resize(N * 16 - 1);
+    data2.resize(N * 16 - 1);
+    std::iota(data0.begin(), data0.end(), T());
+/*    std::for_each(data2.begin(), data2.end(), [](auto& d) {
+      d.x = T();
+      d.y = T();
+    });*/
+
+    VERIFY(data0 != data1);
+
+    constexpr auto exec_simd = vir::execution::simd.prefer_size<N>();
+
+    T i = 0;
+    vir::transform(exec_simd, data0, data1, [&i](auto v) {
+      COMPARE(v, vir::iota_v<decltype(v)> + i);
+      i += v.size();
+      return v;
+    });
+    COMPARE(i, T(data0.size()));
+    COMPARE(data0, data1);
+
+    vir::transform(exec_simd.template unroll_by<2>(), data0, data1, [&i](auto v) {
+      return v + 1;
+    });
+    vir::transform(exec_simd, data0, data1, data2, [&i](auto v0, auto v1) {
+      return Point2D{v0, v1 + 2};
+    });
+
+    for (std::size_t i = 0; i < data2.size(); ++i)
+      {
+        COMPARE(data2[i].x, T(i));
+        COMPARE(data2[i].y, T(i + 3));
+      }
+
+    std::transform(exec_simd.prefer_aligned(), data2.begin(), data2.end(), dataInt.begin(),
+                   [](const auto& v) {
+                     return vir::stdx::static_simd_cast<vir::simdize<int, v.size()>>(
+                              std::get<1>(v.as_tuple()) - std::get<0>(v.as_tuple()));
+                   });
+    for (int x : dataInt)
+      COMPARE(x, 3);
+#endif // VIR_HAVE_SIMD_EXECUTION
+  }