[unittests] Add unittest for getPartialTilePrefixes

In https://reviews.llvm.org/D36278 it was pointed out that the behavior of
getPartialTilePrefixes is not very well understood. To allow for a better
understanding, we first provide some basic unittests.

llvm-svn: 310175

polly/include/polly/ScheduleOptimizer.h

@@ -333,4 +333,21 @@ private:
                     MicroKernelParamsTy MicroKernelParams);
 };
 
+/// Build the desired set of partial tile prefixes.
+///
+/// We build a set of partial tile prefixes, which are prefixes of the vector
+/// loop that have exactly VectorWidth iterations.
+///
+/// 1. Get all prefixes of the vector loop.
+/// 2. Extend it to a set, which has exactly VectorWidth iterations for
+///    any prefix from the set that was built on the previous step.
+/// 3. Subtract loop domain from it, project out the vector loop dimension and
+///    get a set of prefixes, which don't have exactly VectorWidth iterations.
+/// 4. Subtract it from all prefixes of the vector loop and get the desired
+///    set.
+///
+/// @param ScheduleRange A range of a map, which describes a prefix schedule
+///                      relation.
+isl::set getPartialTilePrefixes(isl::set ScheduleRange, int VectorWidth);
+
 #endif

polly/lib/Transform/ScheduleOptimizer.cpp

@@ -308,23 +308,7 @@ static isl::set addExtentConstraints(isl::set Set, int VectorWidth) {
   return Set.add_constraint(ExtConstr);
 }
 
-/// Build the desired set of partial tile prefixes.
-///
-/// We build a set of partial tile prefixes, which are prefixes of the vector
-/// loop that have exactly VectorWidth iterations.
-///
-/// 1. Get all prefixes of the vector loop.
-/// 2. Extend it to a set, which has exactly VectorWidth iterations for
-///    any prefix from the set that was built on the previous step.
-/// 3. Subtract loop domain from it, project out the vector loop dimension and
-///    get a set of prefixes, which don't have exactly VectorWidth iterations.
-/// 4. Subtract it from all prefixes of the vector loop and get the desired
-///    set.
-///
-/// @param ScheduleRange A range of a map, which describes a prefix schedule
-///                      relation.
-static isl::set getPartialTilePrefixes(isl::set ScheduleRange,
-                                       int VectorWidth) {
+isl::set getPartialTilePrefixes(isl::set ScheduleRange, int VectorWidth) {
   unsigned Dims = ScheduleRange.dim(isl::dim::set);
   isl::set LoopPrefixes = ScheduleRange.project_out(isl::dim::set, Dims - 1, 1);
   isl::set ExtentPrefixes = LoopPrefixes.add_dims(isl::dim::set, 1);

polly/unittests/CMakeLists.txt

@@ -23,3 +23,4 @@ add_subdirectory(Isl)
 add_subdirectory(Flatten)
 add_subdirectory(DeLICM)
 add_subdirectory(ScopPassManager)
+add_subdirectory(ScheduleOptimizer)

polly/unittests/ScheduleOptimizer/ScheduleOptimizerTest.cpp

@@ -0,0 +1,60 @@
+//===- ScheduleOptimizerTest.cpp ------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "polly/ScheduleOptimizer.h"
+#include "gtest/gtest.h"
+#include "isl/stream.h"
+#include "isl/val.h"
+
+using namespace isl;
+namespace {
+
+TEST(ScheduleOptimizer, getPartialTilePrefixes) {
+
+  isl_ctx *ctx = isl_ctx_alloc();
+
+  {
+    // Verify that for loop with 3 iterations starting at 0 that is
+    // pre-vectorized (strip-mined with a factor of 2), we correctly identify
+    // that only the first two iterations are full vector iterations.
+    isl::map Schedule(
+        ctx, "{[i] -> [floor(i/2), i - 2 * floor(i/2)] : 0 <= i < 3 }");
+    isl::set ScheduleRange = Schedule.range();
+    isl::set Result = getPartialTilePrefixes(ScheduleRange, 2);
+
+    EXPECT_TRUE(Result.is_equal(isl::set(ctx, "{[0]}")));
+  }
+
+  {
+    // Verify that for loop with 3 iterations starting at 1 that is
+    // pre-vectorized (strip-mined with a factor of 2), we correctly identify
+    // that only the last two iterations are full vector iterations.
+    isl::map Schedule(
+        ctx, "{[i] -> [floor(i/2), i - 2 * floor(i/2)] : 1 <= i < 4 }");
+    isl::set ScheduleRange = Schedule.range();
+    isl::set Result = getPartialTilePrefixes(ScheduleRange, 2);
+
+    EXPECT_TRUE(Result.is_equal(isl::set(ctx, "{[1]}")));
+  }
+
+  {
+    // Verify that for loop with 6 iterations starting at 1 that is
+    // pre-vectorized (strip-mined with a factor of 2), we correctly identify
+    // that all but the first and the last iteration are full vector iterations.
+    isl::map Schedule(
+        ctx, "{[i] -> [floor(i/2), i - 2 * floor(i/2)] : 1 <= i < 6 }");
+    isl::set ScheduleRange = Schedule.range();
+    isl::set Result = getPartialTilePrefixes(ScheduleRange, 2);
+
+    EXPECT_TRUE(Result.is_equal(isl::set(ctx, "{[1]; [2]}")));
+  }
+
+  isl_ctx_free(ctx);
+}
+} // anonymous namespace